new file mode 100644
--- /dev/null
+++ b/src/http/modules/ngx_http_grpc_module.c
@@ -0,0 +1,4571 @@
+
+/*
+ * Copyright (C) Maxim Dounin
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+
+typedef struct {
+    ngx_array_t               *flushes;
+    ngx_array_t               *lengths;
+    ngx_array_t               *values;
+    ngx_hash_t                 hash;
+} ngx_http_grpc_headers_t;
+
+
+typedef struct {
+    ngx_http_upstream_conf_t   upstream;
+
+    ngx_http_grpc_headers_t    headers;
+    ngx_array_t               *headers_source;
+
+    ngx_str_t                  host;
+    ngx_uint_t                 host_set;
+
+#if (NGX_HTTP_SSL)
+    ngx_uint_t                 ssl;
+    ngx_uint_t                 ssl_protocols;
+    ngx_str_t                  ssl_ciphers;
+    ngx_uint_t                 ssl_verify_depth;
+    ngx_str_t                  ssl_trusted_certificate;
+    ngx_str_t                  ssl_crl;
+    ngx_str_t                  ssl_certificate;
+    ngx_str_t                  ssl_certificate_key;
+    ngx_array_t               *ssl_passwords;
+#endif
+} ngx_http_grpc_loc_conf_t;
+
+
+typedef enum {
+    ngx_http_grpc_st_start = 0,
+    ngx_http_grpc_st_length_2,
+    ngx_http_grpc_st_length_3,
+    ngx_http_grpc_st_type,
+    ngx_http_grpc_st_flags,
+    ngx_http_grpc_st_stream_id,
+    ngx_http_grpc_st_stream_id_2,
+    ngx_http_grpc_st_stream_id_3,
+    ngx_http_grpc_st_stream_id_4,
+    ngx_http_grpc_st_payload,
+    ngx_http_grpc_st_padding
+} ngx_http_grpc_state_e;
+
+
+typedef struct {
+    size_t                     init_window;
+    size_t                     send_window;
+    size_t                     recv_window;
+    ngx_uint_t                 last_stream_id;
+} ngx_http_grpc_conn_t;
+
+
+typedef struct {
+    ngx_http_grpc_state_e      state;
+    ngx_uint_t                 frame_state;
+    ngx_uint_t                 fragment_state;
+
+    ngx_chain_t               *in;
+    ngx_chain_t               *out;
+    ngx_chain_t               *free;
+    ngx_chain_t               *busy;
+
+    ngx_http_grpc_conn_t      *connection;
+
+    ngx_uint_t                 id;
+
+    ssize_t                    send_window;
+    size_t                     recv_window;
+
+    size_t                     rest;
+    ngx_uint_t                 stream_id;
+    u_char                     type;
+    u_char                     flags;
+    u_char                     padding;
+
+    ngx_uint_t                 error;
+    ngx_uint_t                 window_update;
+
+    ngx_uint_t                 setting_id;
+    ngx_uint_t                 setting_value;
+
+    u_char                     ping_data[8];
+
+    ngx_uint_t                 index;
+    ngx_str_t                  name;
+    ngx_str_t                  value;
+
+    u_char                    *field_end;
+    size_t                     field_length;
+    size_t                     field_rest;
+    u_char                     field_state;
+
+    unsigned                   literal:1;
+    unsigned                   field_huffman:1;
+
+    unsigned                   header_sent:1;
+    unsigned                   output_closed:1;
+    unsigned                   parsing_headers:1;
+    unsigned                   end_stream:1;
+    unsigned                   status:1;
+
+    ngx_http_request_t        *request;
+} ngx_http_grpc_ctx_t;
+
+
+typedef struct {
+    u_char                     length_0;
+    u_char                     length_1;
+    u_char                     length_2;
+    u_char                     type;
+    u_char                     flags;
+    u_char                     stream_id_0;
+    u_char                     stream_id_1;
+    u_char                     stream_id_2;
+    u_char                     stream_id_3;
+} ngx_http_grpc_frame_t;
+
+
+static ngx_int_t ngx_http_grpc_create_request(ngx_http_request_t *r);
+static ngx_int_t ngx_http_grpc_reinit_request(ngx_http_request_t *r);
+static ngx_int_t ngx_http_grpc_body_output_filter(void *data, ngx_chain_t *in);
+static ngx_int_t ngx_http_grpc_process_header(ngx_http_request_t *r);
+static ngx_int_t ngx_http_grpc_filter_init(void *data);
+static ngx_int_t ngx_http_grpc_filter(void *data, ssize_t bytes);
+
+static ngx_int_t ngx_http_grpc_parse_frame(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_header(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_fragment(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_validate_header_name(ngx_http_request_t *r,
+    ngx_str_t *s);
+static ngx_int_t ngx_http_grpc_validate_header_value(ngx_http_request_t *r,
+    ngx_str_t *s);
+static ngx_int_t ngx_http_grpc_parse_rst_stream(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_goaway(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_window_update(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_settings(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+static ngx_int_t ngx_http_grpc_parse_ping(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b);
+
+static ngx_int_t ngx_http_grpc_send_settings_ack(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx);
+static ngx_int_t ngx_http_grpc_send_ping_ack(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx);
+static ngx_int_t ngx_http_grpc_send_window_update(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx);
+
+static ngx_chain_t *ngx_http_grpc_get_buf(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx);
+static ngx_http_grpc_ctx_t *ngx_http_grpc_get_ctx(ngx_http_request_t *r);
+static ngx_int_t ngx_http_grpc_get_connection_data(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_peer_connection_t *pc);
+static void ngx_http_grpc_cleanup(void *data);
+
+static void ngx_http_grpc_abort_request(ngx_http_request_t *r);
+static void ngx_http_grpc_finalize_request(ngx_http_request_t *r,
+    ngx_int_t rc);
+
+static void *ngx_http_grpc_create_loc_conf(ngx_conf_t *cf);
+static char *ngx_http_grpc_merge_loc_conf(ngx_conf_t *cf,
+    void *parent, void *child);
+static ngx_int_t ngx_http_grpc_init_headers(ngx_conf_t *cf,
+    ngx_http_grpc_loc_conf_t *conf, ngx_http_grpc_headers_t *headers,
+    ngx_keyval_t *default_headers);
+
+static char *ngx_http_grpc_pass(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
+
+#if (NGX_HTTP_SSL)
+static char *ngx_http_grpc_ssl_password_file(ngx_conf_t *cf,
+    ngx_command_t *cmd, void *conf);
+static ngx_int_t ngx_http_grpc_set_ssl(ngx_conf_t *cf,
+    ngx_http_grpc_loc_conf_t *glcf);
+#endif
+
+
+static ngx_conf_bitmask_t  ngx_http_grpc_next_upstream_masks[] = {
+    { ngx_string("error"), NGX_HTTP_UPSTREAM_FT_ERROR },
+    { ngx_string("timeout"), NGX_HTTP_UPSTREAM_FT_TIMEOUT },
+    { ngx_string("invalid_header"), NGX_HTTP_UPSTREAM_FT_INVALID_HEADER },
+    { ngx_string("non_idempotent"), NGX_HTTP_UPSTREAM_FT_NON_IDEMPOTENT },
+    { ngx_string("http_500"), NGX_HTTP_UPSTREAM_FT_HTTP_500 },
+    { ngx_string("http_502"), NGX_HTTP_UPSTREAM_FT_HTTP_502 },
+    { ngx_string("http_503"), NGX_HTTP_UPSTREAM_FT_HTTP_503 },
+    { ngx_string("http_504"), NGX_HTTP_UPSTREAM_FT_HTTP_504 },
+    { ngx_string("http_403"), NGX_HTTP_UPSTREAM_FT_HTTP_403 },
+    { ngx_string("http_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { ngx_string("http_429"), NGX_HTTP_UPSTREAM_FT_HTTP_429 },
+    { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
+    { ngx_null_string, 0 }
+};
+
+
+#if (NGX_HTTP_SSL)
+
+static ngx_conf_bitmask_t  ngx_http_grpc_ssl_protocols[] = {
+    { ngx_string("SSLv2"), NGX_SSL_SSLv2 },
+    { ngx_string("SSLv3"), NGX_SSL_SSLv3 },
+    { ngx_string("TLSv1"), NGX_SSL_TLSv1 },
+    { ngx_string("TLSv1.1"), NGX_SSL_TLSv1_1 },
+    { ngx_string("TLSv1.2"), NGX_SSL_TLSv1_2 },
+    { ngx_string("TLSv1.3"), NGX_SSL_TLSv1_3 },
+    { ngx_null_string, 0 }
+};
+
+#endif
+
+
+static ngx_command_t  ngx_http_grpc_commands[] = {
+
+    { ngx_string("grpc_pass"),
+      NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF|NGX_CONF_TAKE1,
+      ngx_http_grpc_pass,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+    { ngx_string("grpc_bind"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE12,
+      ngx_http_upstream_bind_set_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.local),
+      NULL },
+
+    { ngx_string("grpc_connect_timeout"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.connect_timeout),
+      NULL },
+
+    { ngx_string("grpc_send_timeout"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.send_timeout),
+      NULL },
+
+    { ngx_string("grpc_intercept_errors"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.intercept_errors),
+      NULL },
+
+    { ngx_string("grpc_buffer_size"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_size_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.buffer_size),
+      NULL },
+
+    { ngx_string("grpc_read_timeout"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.read_timeout),
+      NULL },
+
+    { ngx_string("grpc_next_upstream"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
+      ngx_conf_set_bitmask_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.next_upstream),
+      &ngx_http_grpc_next_upstream_masks },
+
+    { ngx_string("grpc_next_upstream_tries"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_num_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.next_upstream_tries),
+      NULL },
+
+    { ngx_string("grpc_next_upstream_timeout"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.next_upstream_timeout),
+      NULL },
+
+    { ngx_string("grpc_set_header"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2,
+      ngx_conf_set_keyval_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, headers_source),
+      NULL },
+
+    { ngx_string("grpc_pass_header"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_array_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.pass_headers),
+      NULL },
+
+    { ngx_string("grpc_hide_header"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_array_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.hide_headers),
+      NULL },
+
+    { ngx_string("grpc_ignore_headers"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
+      ngx_conf_set_bitmask_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.ignore_headers),
+      &ngx_http_upstream_ignore_headers_masks },
+
+#if (NGX_HTTP_SSL)
+
+    { ngx_string("grpc_ssl_session_reuse"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.ssl_session_reuse),
+      NULL },
+
+    { ngx_string("grpc_ssl_protocols"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
+      ngx_conf_set_bitmask_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_protocols),
+      &ngx_http_grpc_ssl_protocols },
+
+    { ngx_string("grpc_ssl_ciphers"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_ciphers),
+      NULL },
+
+    { ngx_string("grpc_ssl_name"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_http_set_complex_value_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.ssl_name),
+      NULL },
+
+    { ngx_string("grpc_ssl_server_name"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.ssl_server_name),
+      NULL },
+
+    { ngx_string("grpc_ssl_verify"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, upstream.ssl_verify),
+      NULL },
+
+    { ngx_string("grpc_ssl_verify_depth"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_num_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_verify_depth),
+      NULL },
+
+    { ngx_string("grpc_ssl_trusted_certificate"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_trusted_certificate),
+      NULL },
+
+    { ngx_string("grpc_ssl_crl"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_crl),
+      NULL },
+
+    { ngx_string("grpc_ssl_certificate"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_certificate),
+      NULL },
+
+    { ngx_string("grpc_ssl_certificate_key"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_grpc_loc_conf_t, ssl_certificate_key),
+      NULL },
+
+    { ngx_string("grpc_ssl_password_file"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_http_grpc_ssl_password_file,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+#endif
+
+      ngx_null_command
+};
+
+
+static ngx_http_module_t  ngx_http_grpc_module_ctx = {
+    NULL,                                  /* preconfiguration */
+    NULL,                                  /* postconfiguration */
+
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    NULL,                                  /* create server configuration */
+    NULL,                                  /* merge server configuration */
+
+    ngx_http_grpc_create_loc_conf,         /* create location configuration */
+    ngx_http_grpc_merge_loc_conf           /* merge location configuration */
+};
+
+
+ngx_module_t  ngx_http_grpc_module = {
+    NGX_MODULE_V1,
+    &ngx_http_grpc_module_ctx,             /* module context */
+    ngx_http_grpc_commands,                /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    NULL,                                  /* init master */
+    NULL,                                  /* init module */
+    NULL,                                  /* init process */
+    NULL,                                  /* init thread */
+    NULL,                                  /* exit thread */
+    NULL,                                  /* exit process */
+    NULL,                                  /* exit master */
+    NGX_MODULE_V1_PADDING
+};
+
+
+static u_char  ngx_http_grpc_connection_start[] =
+    "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"         /* connection preface */
+
+    "\x00\x00\x12\x04\x00\x00\x00\x00\x00"     /* settings frame */
+    "\x00\x01\x00\x00\x00\x00"                 /* header table size */
+    "\x00\x02\x00\x00\x00\x00"                 /* disable push */
+    "\x00\x04\x7f\xff\xff\xff"                 /* initial window */
+
+    "\x00\x00\x04\x08\x00\x00\x00\x00\x00"     /* window update frame */
+    "\x7f\xff\x00\x00";
+
+
+static ngx_keyval_t  ngx_http_grpc_headers[] = {
+    { ngx_string("Content-Length"), ngx_string("$content_length") },
+    { ngx_string("Host"), ngx_string("") },
+    { ngx_string("Connection"), ngx_string("") },
+    { ngx_string("Transfer-Encoding"), ngx_string("") },
+    { ngx_string("TE"), ngx_string("") },
+    { ngx_string("Keep-Alive"), ngx_string("") },
+    { ngx_string("Expect"), ngx_string("") },
+    { ngx_string("Upgrade"), ngx_string("") },
+    { ngx_null_string, ngx_null_string }
+};
+
+
+static ngx_str_t  ngx_http_grpc_hide_headers[] = {
+    ngx_string("Date"),
+    ngx_string("Server"),
+    ngx_string("X-Accel-Expires"),
+    ngx_string("X-Accel-Redirect"),
+    ngx_string("X-Accel-Limit-Rate"),
+    ngx_string("X-Accel-Buffering"),
+    ngx_string("X-Accel-Charset"),
+    ngx_null_string
+};
+
+
+static ngx_int_t
+ngx_http_grpc_handler(ngx_http_request_t *r)
+{
+    ngx_int_t                  rc;
+    ngx_http_upstream_t       *u;
+    ngx_http_grpc_ctx_t       *ctx;
+    ngx_http_grpc_loc_conf_t  *glcf;
+
+    if (ngx_http_upstream_create(r) != NGX_OK) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    glcf = ngx_http_get_module_loc_conf(r, ngx_http_grpc_module);
+
+    u = r->upstream;
+
+#if (NGX_HTTP_SSL)
+    u->ssl = (glcf->upstream.ssl != NULL);
+
+    if (u->ssl) {
+        ngx_str_set(&u->schema, "grpcs://");
+
+    } else {
+        ngx_str_set(&u->schema, "grpc://");
+    }
+#else
+    ngx_str_set(&u->schema, "grpc://");
+#endif
+
+    u->output.tag = (ngx_buf_tag_t) &ngx_http_grpc_module;
+
+    u->conf = &glcf->upstream;
+
+    u->create_request = ngx_http_grpc_create_request;
+    u->reinit_request = ngx_http_grpc_reinit_request;
+    u->process_header = ngx_http_grpc_process_header;
+    u->abort_request = ngx_http_grpc_abort_request;
+    u->finalize_request = ngx_http_grpc_finalize_request;
+
+    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_grpc_ctx_t));
+    if (ctx == NULL) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    ctx->request = r;
+
+    ngx_http_set_ctx(r, ctx, ngx_http_grpc_module);
+
+    u->input_filter_init = ngx_http_grpc_filter_init;
+    u->input_filter = ngx_http_grpc_filter;
+    u->input_filter_ctx = ctx;
+
+    r->request_body_no_buffering = 1;
+
+    rc = ngx_http_read_client_request_body(r, ngx_http_upstream_init);
+
+    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
+        return rc;
+    }
+
+    return NGX_DONE;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_create_request(ngx_http_request_t *r)
+{
+    u_char                       *p, *tmp, *key_tmp, *val_tmp, *headers_frame;
+    size_t                        len, tmp_len, key_len, val_len, uri_len;
+    uintptr_t                     escape;
+    ngx_buf_t                    *b;
+    ngx_uint_t                    i, next;
+    ngx_chain_t                  *cl, *body;
+    ngx_list_part_t              *part;
+    ngx_table_elt_t              *header;
+    ngx_http_upstream_t          *u;
+    ngx_http_grpc_frame_t        *f;
+    ngx_http_script_code_pt       code;
+    ngx_http_grpc_loc_conf_t     *glcf;
+    ngx_http_script_engine_t      e, le;
+    ngx_http_script_len_code_pt   lcode;
+
+    u = r->upstream;
+
+    glcf = ngx_http_get_module_loc_conf(r, ngx_http_grpc_module);
+
+    len = sizeof(ngx_http_grpc_connection_start) - 1
+          + sizeof(ngx_http_grpc_frame_t);             /* headers frame */
+
+    /* :method header */
+
+    if (r->method == NGX_HTTP_GET || r->method == NGX_HTTP_POST) {
+        len += 1;
+        tmp_len = 0;
+
+    } else {
+        len += 1 + NGX_HTTP_V2_INT_OCTETS + r->method_name.len;
+        tmp_len = r->method_name.len;
+    }
+
+    /* :scheme header */
+
+    len += 1;
+
+    /* :path header */
+
+    if (r->valid_unparsed_uri) {
+        escape = 0;
+        uri_len = r->unparsed_uri.len;
+
+    } else {
+        escape = 2 * ngx_escape_uri(NULL, r->uri.data, r->uri.len,
+                                    NGX_ESCAPE_URI);
+        uri_len = r->uri.len + escape + sizeof("?") - 1 + r->args.len;
+    }
+
+    len += 1 + NGX_HTTP_V2_INT_OCTETS + uri_len;
+
+    if (tmp_len < uri_len) {
+        tmp_len = uri_len;
+    }
+
+    /* :authority header */
+
+    if (!glcf->host_set) {
+        len += 1 + NGX_HTTP_V2_INT_OCTETS + glcf->host.len;
+
+        if (tmp_len < glcf->host.len) {
+            tmp_len = glcf->host.len;
+        }
+    }
+
+    /* other headers */
+
+    ngx_http_script_flush_no_cacheable_variables(r, glcf->headers.flushes);
+    ngx_memzero(&le, sizeof(ngx_http_script_engine_t));
+
+    le.ip = glcf->headers.lengths->elts;
+    le.request = r;
+    le.flushed = 1;
+
+    while (*(uintptr_t *) le.ip) {
+
+        lcode = *(ngx_http_script_len_code_pt *) le.ip;
+        key_len = lcode(&le);
+
+        for (val_len = 0; *(uintptr_t *) le.ip; val_len += lcode(&le)) {
+            lcode = *(ngx_http_script_len_code_pt *) le.ip;
+        }
+        le.ip += sizeof(uintptr_t);
+
+        if (val_len == 0) {
+            continue;
+        }
+
+        len += 1 + NGX_HTTP_V2_INT_OCTETS + key_len
+                 + NGX_HTTP_V2_INT_OCTETS + val_len;
+
+        if (tmp_len < key_len) {
+            tmp_len = key_len;
+        }
+
+        if (tmp_len < val_len) {
+            tmp_len = val_len;
+        }
+    }
+
+    if (glcf->upstream.pass_request_headers) {
+        part = &r->headers_in.headers.part;
+        header = part->elts;
+
+        for (i = 0; /* void */; i++) {
+
+            if (i >= part->nelts) {
+                if (part->next == NULL) {
+                    break;
+                }
+
+                part = part->next;
+                header = part->elts;
+                i = 0;
+            }
+
+            if (ngx_hash_find(&glcf->headers.hash, header[i].hash,
+                              header[i].lowcase_key, header[i].key.len))
+            {
+                continue;
+            }
+
+            len += 1 + NGX_HTTP_V2_INT_OCTETS + header[i].key.len
+                     + NGX_HTTP_V2_INT_OCTETS + header[i].value.len;
+
+            if (tmp_len < header[i].key.len) {
+                tmp_len = header[i].key.len;
+            }
+
+            if (tmp_len < header[i].value.len) {
+                tmp_len = header[i].value.len;
+            }
+        }
+    }
+
+    /* continuation frames */
+
+    len += sizeof(ngx_http_grpc_frame_t)
+           * (len / NGX_HTTP_V2_DEFAULT_FRAME_SIZE);
+
+
+    b = ngx_create_temp_buf(r->pool, len);
+    if (b == NULL) {
+        return NGX_ERROR;
+    }
+
+    cl = ngx_alloc_chain_link(r->pool);
+    if (cl == NULL) {
+        return NGX_ERROR;
+    }
+
+    cl->buf = b;
+    cl->next = NULL;
+
+    tmp = ngx_palloc(r->pool, tmp_len * 3);
+    if (tmp == NULL) {
+        return NGX_ERROR;
+    }
+
+    key_tmp = tmp + tmp_len;
+    val_tmp = tmp + 2 * tmp_len;
+
+    /* connection preface */
+
+    b->last = ngx_copy(b->last, ngx_http_grpc_connection_start,
+                       sizeof(ngx_http_grpc_connection_start) - 1);
+
+    /* headers frame */
+
+    headers_frame = b->last;
+
+    f = (ngx_http_grpc_frame_t *) b->last;
+    b->last += sizeof(ngx_http_grpc_frame_t);
+
+    f->length_0 = 0;
+    f->length_1 = 0;
+    f->length_2 = 0;
+    f->type = NGX_HTTP_V2_HEADERS_FRAME;
+    f->flags = 0;
+    f->stream_id_0 = 0;
+    f->stream_id_1 = 0;
+    f->stream_id_2 = 0;
+    f->stream_id_3 = 1;
+
+    if (r->method == NGX_HTTP_GET) {
+        *b->last++ = ngx_http_v2_indexed(NGX_HTTP_V2_METHOD_GET_INDEX);
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":method: GET\"");
+
+    } else if (r->method == NGX_HTTP_POST) {
+        *b->last++ = ngx_http_v2_indexed(NGX_HTTP_V2_METHOD_POST_INDEX);
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":method: POST\"");
+
+    } else {
+        *b->last++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_METHOD_INDEX);
+        b->last = ngx_http_v2_write_value(b->last, r->method_name.data,
+                                          r->method_name.len, tmp);
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":method: %V\"", &r->method_name);
+    }
+
+#if (NGX_HTTP_SSL)
+    if (glcf->ssl) {
+        *b->last++ = ngx_http_v2_indexed(NGX_HTTP_V2_SCHEME_HTTPS_INDEX);
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":scheme: https\"");
+    } else
+#endif
+    {
+        *b->last++ = ngx_http_v2_indexed(NGX_HTTP_V2_SCHEME_HTTP_INDEX);
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":scheme: http\"");
+    }
+
+    if (r->valid_unparsed_uri) {
+
+        if (r->unparsed_uri.len == 1 && r->unparsed_uri.data[0] == '/') {
+            *b->last++ = ngx_http_v2_indexed(NGX_HTTP_V2_PATH_ROOT_INDEX);
+
+        } else {
+            *b->last++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_PATH_INDEX);
+            b->last = ngx_http_v2_write_value(b->last, r->unparsed_uri.data,
+                                              r->unparsed_uri.len, tmp);
+        }
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":path: %V\"", &r->unparsed_uri);
+
+    } else if (escape || r->args.len > 0) {
+        p = val_tmp;
+
+        if (escape) {
+            p = (u_char *) ngx_escape_uri(p, r->uri.data, r->uri.len,
+                                          NGX_ESCAPE_URI);
+
+        } else {
+            p = ngx_copy(p, r->uri.data, r->uri.len);
+        }
+
+        if (r->args.len > 0) {
+            *p++ = '?';
+            p = ngx_copy(p, r->args.data, r->args.len);
+        }
+
+        *b->last++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_PATH_INDEX);
+        b->last = ngx_http_v2_write_value(b->last, val_tmp, p - val_tmp, tmp);
+
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":path: %*s\"", p - val_tmp, val_tmp);
+
+    } else {
+        *b->last++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_PATH_INDEX);
+        b->last = ngx_http_v2_write_value(b->last, r->uri.data,
+                                          r->uri.len, tmp);
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":path: %V\"", &r->uri);
+    }
+
+    if (!glcf->host_set) {
+        *b->last++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_AUTHORITY_INDEX);
+        b->last = ngx_http_v2_write_value(b->last, glcf->host.data,
+                                          glcf->host.len, tmp);
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: \":authority: %V\"", &glcf->host);
+    }
+
+    ngx_memzero(&e, sizeof(ngx_http_script_engine_t));
+
+    e.ip = glcf->headers.values->elts;
+    e.request = r;
+    e.flushed = 1;
+
+    le.ip = glcf->headers.lengths->elts;
+
+    while (*(uintptr_t *) le.ip) {
+
+        lcode = *(ngx_http_script_len_code_pt *) le.ip;
+        key_len = lcode(&le);
+
+        for (val_len = 0; *(uintptr_t *) le.ip; val_len += lcode(&le)) {
+            lcode = *(ngx_http_script_len_code_pt *) le.ip;
+        }
+        le.ip += sizeof(uintptr_t);
+
+        if (val_len == 0) {
+            e.skip = 1;
+
+            while (*(uintptr_t *) e.ip) {
+                code = *(ngx_http_script_code_pt *) e.ip;
+                code((ngx_http_script_engine_t *) &e);
+            }
+            e.ip += sizeof(uintptr_t);
+
+            e.skip = 0;
+
+            continue;
+        }
+
+        *b->last++ = 0;
+
+        e.pos = key_tmp;
+
+        code = *(ngx_http_script_code_pt *) e.ip;
+        code((ngx_http_script_engine_t *) &e);
+
+        b->last = ngx_http_v2_write_name(b->last, key_tmp, key_len, tmp);
+
+        e.pos = val_tmp;
+
+        while (*(uintptr_t *) e.ip) {
+            code = *(ngx_http_script_code_pt *) e.ip;
+            code((ngx_http_script_engine_t *) &e);
+        }
+        e.ip += sizeof(uintptr_t);
+
+        b->last = ngx_http_v2_write_value(b->last, val_tmp, val_len, tmp);
+
+#if (NGX_DEBUG)
+        if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
+            ngx_strlow(key_tmp, key_tmp, key_len);
+
+            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc header: \"%*s: %*s\"",
+                           key_len, key_tmp, val_len, val_tmp);
+        }
+#endif
+    }
+
+    if (glcf->upstream.pass_request_headers) {
+        part = &r->headers_in.headers.part;
+        header = part->elts;
+
+        for (i = 0; /* void */; i++) {
+
+            if (i >= part->nelts) {
+                if (part->next == NULL) {
+                    break;
+                }
+
+                part = part->next;
+                header = part->elts;
+                i = 0;
+            }
+
+            if (ngx_hash_find(&glcf->headers.hash, header[i].hash,
+                              header[i].lowcase_key, header[i].key.len))
+            {
+                continue;
+            }
+
+            *b->last++ = 0;
+
+            b->last = ngx_http_v2_write_name(b->last, header[i].key.data,
+                                             header[i].key.len, tmp);
+
+            b->last = ngx_http_v2_write_value(b->last, header[i].value.data,
+                                              header[i].value.len, tmp);
+
+#if (NGX_DEBUG)
+            if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
+                ngx_strlow(tmp, header[i].key.data, header[i].key.len);
+
+                ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc header: \"%*s: %V\"",
+                               header[i].key.len, tmp, &header[i].value);
+            }
+#endif
+        }
+    }
+
+    /* update headers frame length */
+
+    len = b->last - headers_frame - sizeof(ngx_http_grpc_frame_t);
+
+    if (len > NGX_HTTP_V2_DEFAULT_FRAME_SIZE) {
+        len = NGX_HTTP_V2_DEFAULT_FRAME_SIZE;
+        next = 1;
+
+    } else {
+        next = 0;
+    }
+
+    f = (ngx_http_grpc_frame_t *) headers_frame;
+
+    f->length_0 = (u_char) ((len >> 16) & 0xff);
+    f->length_1 = (u_char) ((len >> 8) & 0xff);
+    f->length_2 = (u_char) (len & 0xff);
+
+    /* create additional continuation frames */
+
+    p = headers_frame;
+
+    while (next) {
+        p += sizeof(ngx_http_grpc_frame_t) + NGX_HTTP_V2_DEFAULT_FRAME_SIZE;
+        len = b->last - p;
+
+        ngx_memmove(p + sizeof(ngx_http_grpc_frame_t), p, len);
+        b->last += sizeof(ngx_http_grpc_frame_t);
+
+        if (len > NGX_HTTP_V2_DEFAULT_FRAME_SIZE) {
+            len = NGX_HTTP_V2_DEFAULT_FRAME_SIZE;
+            next = 1;
+
+        } else {
+            next = 0;
+        }
+
+        f = (ngx_http_grpc_frame_t *) p;
+
+        f->length_0 = (u_char) ((len >> 16) & 0xff);
+        f->length_1 = (u_char) ((len >> 8) & 0xff);
+        f->length_2 = (u_char) (len & 0xff);
+        f->type = NGX_HTTP_V2_CONTINUATION_FRAME;
+        f->flags = 0;
+        f->stream_id_0 = 0;
+        f->stream_id_1 = 0;
+        f->stream_id_2 = 0;
+        f->stream_id_3 = 1;
+    }
+
+    f->flags |= NGX_HTTP_V2_END_HEADERS_FLAG;
+
+#if (NGX_DEBUG)
+    if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
+        u_char  buf[512];
+        size_t  n, m;
+
+        n = ngx_min(b->last - b->pos, 256);
+        m = ngx_hex_dump(buf, b->pos, n) - buf;
+
+        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header: %*s%s, len: %uz",
+                       m, buf, b->last - b->pos > 256 ? "..." : "",
+                       b->last - b->pos);
+    }
+#endif
+
+    if (r->request_body_no_buffering) {
+
+        u->request_bufs = cl;
+
+    } else {
+
+        body = u->request_bufs;
+        u->request_bufs = cl;
+
+        if (body == NULL) {
+            f = (ngx_http_grpc_frame_t *) headers_frame;
+            f->flags |= NGX_HTTP_V2_END_STREAM_FLAG;
+        }
+
+        while (body) {
+            b = ngx_alloc_buf(r->pool);
+            if (b == NULL) {
+                return NGX_ERROR;
+            }
+
+            ngx_memcpy(b, body->buf, sizeof(ngx_buf_t));
+
+            cl->next = ngx_alloc_chain_link(r->pool);
+            if (cl->next == NULL) {
+                return NGX_ERROR;
+            }
+
+            cl = cl->next;
+            cl->buf = b;
+
+            body = body->next;
+        }
+
+        b->last_buf = 1;
+    }
+
+    u->output.output_filter = ngx_http_grpc_body_output_filter;
+    u->output.filter_ctx = r;
+
+    b->flush = 1;
+    cl->next = NULL;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_reinit_request(ngx_http_request_t *r)
+{
+    ngx_http_grpc_ctx_t  *ctx;
+
+    ctx = ngx_http_get_module_ctx(r, ngx_http_grpc_module);
+
+    if (ctx == NULL) {
+        return NGX_OK;
+    }
+
+    ctx->state = 0;
+    ctx->header_sent = 0;
+    ctx->output_closed = 0;
+    ctx->parsing_headers = 0;
+    ctx->end_stream = 0;
+    ctx->status = 0;
+    ctx->connection = NULL;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_body_output_filter(void *data, ngx_chain_t *in)
+{
+    ngx_http_request_t  *r = data;
+
+    off_t                   file_pos;
+    u_char                 *p, *pos, *start;
+    size_t                  len, limit;
+    ngx_buf_t              *b;
+    ngx_int_t               rc;
+    ngx_uint_t              next, last;
+    ngx_chain_t            *cl, *out, **ll;
+    ngx_http_grpc_ctx_t    *ctx;
+    ngx_http_grpc_frame_t  *f;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc output filter");
+
+    ctx = ngx_http_grpc_get_ctx(r);
+
+    if (ctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    if (in) {
+        if (ngx_chain_add_copy(r->pool, &ctx->in, in) != NGX_OK) {
+            return NGX_ERROR;
+        }
+    }
+
+    out = NULL;
+    ll = &out;
+
+    if (!ctx->header_sent) {
+        /* first buffer contains headers */
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc output header");
+
+        ctx->header_sent = 1;
+
+        if (ctx->id != 1) {
+            /*
+             * keepalive connection: skip connection preface,
+             * update stream identifiers
+             */
+
+            b = ctx->in->buf;
+            b->pos += sizeof(ngx_http_grpc_connection_start) - 1;
+
+            p = b->pos;
+
+            while (p < b->last) {
+                f = (ngx_http_grpc_frame_t *) p;
+                p += sizeof(ngx_http_grpc_frame_t);
+
+                f->stream_id_0 = (u_char) ((ctx->id >> 24) & 0xff);
+                f->stream_id_1 = (u_char) ((ctx->id >> 16) & 0xff);
+                f->stream_id_2 = (u_char) ((ctx->id >> 8) & 0xff);
+                f->stream_id_3 = (u_char) (ctx->id & 0xff);
+
+                p += (f->length_0 << 16) + (f->length_1 << 8) + f->length_2;
+            }
+        }
+
+        if (ctx->in->buf->last_buf) {
+            ctx->output_closed = 1;
+        }
+
+        *ll = ctx->in;
+        ll = &ctx->in->next;
+
+        ctx->in = ctx->in->next;
+    }
+
+    if (ctx->out) {
+        /* queued control frames */
+
+        *ll = ctx->out;
+
+        for (cl = ctx->out, ll = &cl->next; cl; cl = cl->next) {
+            ll = &cl->next;
+        }
+
+        ctx->out = NULL;
+    }
+
+    f = NULL;
+    last = 0;
+
+    limit = ngx_max(0, ctx->send_window);
+
+    if (limit > ctx->connection->send_window) {
+        limit = ctx->connection->send_window;
+    }
+
+    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc output limit: %uz w:%z:%uz",
+                   limit, ctx->send_window, ctx->connection->send_window);
+
+#if (NGX_SUPPRESS_WARN)
+    file_pos = 0;
+    pos = NULL;
+    cl = NULL;
+#endif
+
+    in = ctx->in;
+
+    while (in && limit > 0) {
+
+        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, r->connection->log, 0,
+                       "grpc output in  l:%d f:%d %p, pos %p, size: %z "
+                       "file: %O, size: %O",
+                       in->buf->last_buf,
+                       in->buf->in_file,
+                       in->buf->start, in->buf->pos,
+                       in->buf->last - in->buf->pos,
+                       in->buf->file_pos,
+                       in->buf->file_last - in->buf->file_pos);
+
+        if (ngx_buf_special(in->buf)) {
+            goto next;
+        }
+
+        if (in->buf->in_file) {
+            file_pos = in->buf->file_pos;
+
+        } else {
+            pos = in->buf->pos;
+        }
+
+        next = 0;
+
+        do {
+
+            cl = ngx_http_grpc_get_buf(r, ctx);
+            if (cl == NULL) {
+                return NGX_ERROR;
+            }
+
+            b = cl->buf;
+
+            f = (ngx_http_grpc_frame_t *) b->last;
+            b->last += sizeof(ngx_http_grpc_frame_t);
+
+            *ll = cl;
+            ll = &cl->next;
+
+            cl = ngx_chain_get_free_buf(r->pool, &ctx->free);
+            if (cl == NULL) {
+                return NGX_ERROR;
+            }
+
+            b = cl->buf;
+            start = b->start;
+
+            ngx_memcpy(b, in->buf, sizeof(ngx_buf_t));
+
+            /*
+             * restore b->start to preserve memory allocated in the buffer,
+             * to reuse it later for headers and control frames
+             */
+
+            b->start = start;
+
+            if (in->buf->in_file) {
+                b->file_pos = file_pos;
+                file_pos += ngx_min(NGX_HTTP_V2_DEFAULT_FRAME_SIZE, limit);
+
+                if (file_pos >= in->buf->file_last) {
+                    file_pos = in->buf->file_last;
+                    next = 1;
+                }
+
+                b->file_last = file_pos;
+                len = (ngx_uint_t) (file_pos - b->file_pos);
+
+            } else {
+                b->pos = pos;
+                pos += ngx_min(NGX_HTTP_V2_DEFAULT_FRAME_SIZE, limit);
+
+                if (pos >= in->buf->last) {
+                    pos = in->buf->last;
+                    next = 1;
+                }
+
+                b->last = pos;
+                len = (ngx_uint_t) (pos - b->pos);
+            }
+
+            b->tag = (ngx_buf_tag_t) &ngx_http_grpc_body_output_filter;
+            b->shadow = in->buf;
+            b->last_shadow = next;
+
+            b->last_buf = 0;
+            b->last_in_chain = 0;
+
+            *ll = cl;
+            ll = &cl->next;
+
+            f->length_0 = (u_char) ((len >> 16) & 0xff);
+            f->length_1 = (u_char) ((len >> 8) & 0xff);
+            f->length_2 = (u_char) (len & 0xff);
+            f->type = NGX_HTTP_V2_DATA_FRAME;
+            f->flags = 0;
+            f->stream_id_0 = (u_char) ((ctx->id >> 24) & 0xff);
+            f->stream_id_1 = (u_char) ((ctx->id >> 16) & 0xff);
+            f->stream_id_2 = (u_char) ((ctx->id >> 8) & 0xff);
+            f->stream_id_3 = (u_char) (ctx->id & 0xff);
+
+            limit -= len;
+            ctx->send_window -= len;
+            ctx->connection->send_window -= len;
+
+        } while (!next && limit > 0);
+
+        if (!next) {
+            /*
+             * if the buffer wasn't fully sent due to flow control limits,
+             * preserve position for future use
+             */
+
+            if (in->buf->in_file) {
+                in->buf->file_pos = file_pos;
+
+            } else {
+                in->buf->pos = pos;
+            }
+
+            break;
+        }
+
+    next:
+
+        if (in->buf->last_buf) {
+            last = 1;
+        }
+
+        in = in->next;
+    }
+
+    ctx->in = in;
+
+    if (last) {
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc output last");
+
+        ctx->output_closed = 1;
+
+        if (f) {
+            f->flags |= NGX_HTTP_V2_END_STREAM_FLAG;
+
+        } else {
+            cl = ngx_http_grpc_get_buf(r, ctx);
+            if (cl == NULL) {
+                return NGX_ERROR;
+            }
+
+            b = cl->buf;
+
+            f = (ngx_http_grpc_frame_t *) b->last;
+            b->last += sizeof(ngx_http_grpc_frame_t);
+
+            f->length_0 = 0;
+            f->length_1 = 0;
+            f->length_2 = 0;
+            f->type = NGX_HTTP_V2_DATA_FRAME;
+            f->flags = NGX_HTTP_V2_END_STREAM_FLAG;
+            f->stream_id_0 = (u_char) ((ctx->id >> 24) & 0xff);
+            f->stream_id_1 = (u_char) ((ctx->id >> 16) & 0xff);
+            f->stream_id_2 = (u_char) ((ctx->id >> 8) & 0xff);
+            f->stream_id_3 = (u_char) (ctx->id & 0xff);
+
+            *ll = cl;
+            ll = &cl->next;
+        }
+
+        cl->buf->last_buf = 1;
+    }
+
+    *ll = NULL;
+
+#if (NGX_DEBUG)
+
+    for (cl = out; cl; cl = cl->next) {
+        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, r->connection->log, 0,
+                       "grpc output out l:%d f:%d %p, pos %p, size: %z "
+                       "file: %O, size: %O",
+                       cl->buf->last_buf,
+                       cl->buf->in_file,
+                       cl->buf->start, cl->buf->pos,
+                       cl->buf->last - cl->buf->pos,
+                       cl->buf->file_pos,
+                       cl->buf->file_last - cl->buf->file_pos);
+    }
+
+    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc output limit: %uz w:%z:%uz",
+                   limit, ctx->send_window, ctx->connection->send_window);
+
+#endif
+
+    rc = ngx_chain_writer(&r->upstream->writer, out);
+
+    ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &out,
+                            (ngx_buf_tag_t) &ngx_http_grpc_body_output_filter);
+
+    for (cl = ctx->free; cl; cl = cl->next) {
+
+        /* mark original buffers as sent */
+
+        if (cl->buf->shadow) {
+            if (cl->buf->last_shadow) {
+                b = cl->buf->shadow;
+                b->pos = b->last;
+            }
+
+            cl->buf->shadow = NULL;
+        }
+    }
+
+    if (rc == NGX_OK && ctx->in) {
+        rc = NGX_AGAIN;
+    }
+
+    return rc;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_process_header(ngx_http_request_t *r)
+{
+    ngx_str_t                      *status_line;
+    ngx_int_t                       rc, status;
+    ngx_buf_t                      *b;
+    ngx_table_elt_t                *h;
+    ngx_http_upstream_t            *u;
+    ngx_http_grpc_ctx_t            *ctx;
+    ngx_http_upstream_header_t     *hh;
+    ngx_http_upstream_main_conf_t  *umcf;
+
+    u = r->upstream;
+    b = &u->buffer;
+
+#if (NGX_DEBUG)
+    if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
+        u_char  buf[512];
+        size_t  n, m;
+
+        n = ngx_min(b->last - b->pos, 256);
+        m = ngx_hex_dump(buf, b->pos, n) - buf;
+
+        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc response: %*s%s, len: %uz",
+                       m, buf, b->last - b->pos > 256 ? "..." : "",
+                       b->last - b->pos);
+    }
+#endif
+
+    ctx = ngx_http_grpc_get_ctx(r);
+
+    if (ctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);
+
+    for ( ;; ) {
+
+        if (ctx->state < ngx_http_grpc_st_payload) {
+
+            rc = ngx_http_grpc_parse_frame(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+
+                /*
+                 * there can be a lot of window update frames,
+                 * so we reset buffer if it is empty and we haven't
+                 * started parsing headers yet
+                 */
+
+                if (!ctx->parsing_headers) {
+                    b->pos = b->start;
+                    b->last = b->pos;
+                }
+
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            /*
+             * RFC 7540 says that implementations MUST discard frames
+             * that have unknown or unsupported types.  However, extension
+             * frames that appear in the middle of a header block are
+             * not permitted.  Also, for obvious reasons CONTINUATION frames
+             * cannot appear before headers, and DATA frames are not expected
+             * to appear before all headers are parsed.
+             */
+
+            if (ctx->type == NGX_HTTP_V2_DATA_FRAME
+                || (ctx->type == NGX_HTTP_V2_CONTINUATION_FRAME
+                    && !ctx->parsing_headers)
+                || (ctx->type != NGX_HTTP_V2_CONTINUATION_FRAME
+                    && ctx->parsing_headers))
+            {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent unexpected http2 frame: %d",
+                              ctx->type);
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            if (ctx->stream_id && ctx->stream_id != ctx->id) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent frame for unknown stream %ui",
+                              ctx->stream_id);
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+        }
+
+        /* frame payload */
+
+        if (ctx->type == NGX_HTTP_V2_RST_STREAM_FRAME) {
+
+            rc = ngx_http_grpc_parse_rst_stream(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream rejected request with error %ui",
+                          ctx->error);
+
+            return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_GOAWAY_FRAME) {
+
+            rc = ngx_http_grpc_parse_goaway(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            /*
+             * If stream_id is lower than one we use, our
+             * request won't be processed and needs to be retried.
+             * If stream_id is greater or equal to the one we use,
+             * we can continue normally (except we can't use this
+             * connection for additional requests).  If there is
+             * a real error, the connection will be closed.
+             */
+
+            if (ctx->stream_id < ctx->id) {
+
+                /* TODO: we can retry non-idempotent requests */
+
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent goaway with error %ui",
+                              ctx->error);
+
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_WINDOW_UPDATE_FRAME) {
+
+            rc = ngx_http_grpc_parse_window_update(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            if (ctx->in) {
+                ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_SETTINGS_FRAME) {
+
+            rc = ngx_http_grpc_parse_settings(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            if (ctx->in) {
+                ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_PING_FRAME) {
+
+            rc = ngx_http_grpc_parse_ping(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+            }
+
+            ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_PUSH_PROMISE_FRAME) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent unexpected push promise frame");
+            return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+        }
+
+        if (ctx->type != NGX_HTTP_V2_HEADERS_FRAME
+            && ctx->type != NGX_HTTP_V2_CONTINUATION_FRAME)
+        {
+            /* priority, unknown frames */
+
+            if (b->last - b->pos < (ssize_t) ctx->rest) {
+                ctx->rest -= b->last - b->pos;
+                b->pos = b->last;
+                return NGX_AGAIN;
+            }
+
+            b->pos += ctx->rest;
+            ctx->rest = 0;
+            ctx->state = ngx_http_grpc_st_start;
+
+            continue;
+        }
+
+        /* headers */
+
+        for ( ;; ) {
+
+            rc = ngx_http_grpc_parse_header(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                break;
+            }
+
+            if (rc == NGX_OK) {
+
+                /* a header line has been parsed successfully */
+
+                ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc header: \"%V: %V\"",
+                               &ctx->name, &ctx->value);
+
+                if (ctx->name.len && ctx->name.data[0] == ':') {
+
+                    if (ctx->name.len != sizeof(":status") - 1
+                        || ngx_strncmp(ctx->name.data, ":status",
+                                       sizeof(":status") - 1)
+                           != 0)
+                    {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent invalid header \"%V: %V\"",
+                                      &ctx->name, &ctx->value);
+                        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                    }
+
+                    if (ctx->status) {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent duplicate :status header");
+                        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                    }
+
+                    status_line = &ctx->value;
+
+                    if (status_line->len != 3) {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent invalid :status \"%V\"",
+                                      status_line);
+                        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                    }
+
+                    status = ngx_atoi(status_line->data, 3);
+
+                    if (status == NGX_ERROR) {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent invalid :status \"%V\"",
+                                      status_line);
+                        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                    }
+
+                    if (status < NGX_HTTP_OK) {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent unexpected :status \"%V\"",
+                                      status_line);
+                        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                    }
+
+                    u->headers_in.status_n = status;
+
+                    if (u->state && u->state->status == 0) {
+                        u->state->status = status;
+                    }
+
+                    ctx->status = 1;
+
+                    continue;
+
+                } else if (!ctx->status) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent no :status header");
+                    return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+                }
+
+                h = ngx_list_push(&u->headers_in.headers);
+                if (h == NULL) {
+                    return NGX_ERROR;
+                }
+
+                h->key = ctx->name;
+                h->value = ctx->value;
+                h->lowcase_key = h->key.data;
+                h->hash = ngx_hash_key(h->key.data, h->key.len);
+
+                hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,
+                                   h->lowcase_key, h->key.len);
+
+                if (hh && hh->handler(r, h, hh->offset) != NGX_OK) {
+                    return NGX_ERROR;
+                }
+
+                continue;
+            }
+
+            if (rc == NGX_HTTP_PARSE_HEADER_DONE) {
+
+                /* a whole header has been parsed successfully */
+
+                ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc header done");
+
+                if (ctx->end_stream
+                    && ctx->in == NULL
+                    && ctx->out == NULL
+                    && ctx->output_closed
+                    && b->last == b->pos)
+                {
+                    u->keepalive = 1;
+                }
+
+                return NGX_OK;
+            }
+
+            /* there was error while a header line parsing */
+
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent invalid header");
+
+            return NGX_HTTP_UPSTREAM_INVALID_HEADER;
+        }
+
+        /* rc == NGX_AGAIN */
+
+        if (ctx->rest == 0) {
+            ctx->state = ngx_http_grpc_st_start;
+            continue;
+        }
+
+        return NGX_AGAIN;
+    }
+}
+
+
+static ngx_int_t
+ngx_http_grpc_filter_init(void *data)
+{
+    ngx_http_grpc_ctx_t  *ctx = data;
+
+    ngx_http_request_t   *r;
+    ngx_http_upstream_t  *u;
+
+    r = ctx->request;
+    u = r->upstream;
+
+    u->length = 1;
+
+    if (ctx->end_stream) {
+        u->length = 0;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_filter(void *data, ssize_t bytes)
+{
+    ngx_http_grpc_ctx_t  *ctx = data;
+
+    ngx_int_t             rc;
+    ngx_buf_t            *b, *buf;
+    ngx_chain_t          *cl, **ll;
+    ngx_table_elt_t      *h;
+    ngx_http_request_t   *r;
+    ngx_http_upstream_t  *u;
+
+    r = ctx->request;
+    u = r->upstream;
+    b = &u->buffer;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc filter bytes:%z", bytes);
+
+    b->pos = b->last;
+    b->last += bytes;
+
+    for (cl = u->out_bufs, ll = &u->out_bufs; cl; cl = cl->next) {
+        ll = &cl->next;
+    }
+
+    for ( ;; ) {
+
+        if (ctx->state < ngx_http_grpc_st_payload) {
+
+            rc = ngx_http_grpc_parse_frame(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            if ((ctx->type == NGX_HTTP_V2_CONTINUATION_FRAME
+                 && !ctx->parsing_headers)
+                || (ctx->type != NGX_HTTP_V2_CONTINUATION_FRAME
+                    && ctx->parsing_headers))
+            {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent unexpected http2 frame: %d",
+                              ctx->type);
+                return NGX_ERROR;
+            }
+
+            if (ctx->type == NGX_HTTP_V2_DATA_FRAME) {
+
+                if (ctx->stream_id != ctx->id) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent data frame "
+                                  "for unknown stream %ui",
+                                  ctx->stream_id);
+                    return NGX_ERROR;
+                }
+
+                if (ctx->rest > ctx->recv_window) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream violated stream flow control, "
+                                  "received %uz data frame with window %uz",
+                                  ctx->rest, ctx->recv_window);
+                    return NGX_ERROR;
+                }
+
+                if (ctx->rest > ctx->connection->recv_window) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream violated connection flow control, "
+                                  "received %uz data frame with window %uz",
+                                  ctx->rest, ctx->connection->recv_window);
+                    return NGX_ERROR;
+                }
+
+                ctx->recv_window -= ctx->rest;
+                ctx->connection->recv_window -= ctx->rest;
+
+                if (ctx->connection->recv_window < NGX_HTTP_V2_MAX_WINDOW / 4
+                    || ctx->recv_window < NGX_HTTP_V2_MAX_WINDOW / 4)
+                {
+                    if (ngx_http_grpc_send_window_update(r, ctx) != NGX_OK) {
+                        return NGX_ERROR;
+                    }
+
+                    ngx_post_event(u->peer.connection->write,
+                                   &ngx_posted_events);
+                }
+            }
+
+            if (ctx->stream_id && ctx->stream_id != ctx->id) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent frame for unknown stream %ui",
+                              ctx->stream_id);
+                return NGX_ERROR;
+            }
+
+            ctx->padding = 0;
+        }
+
+        if (ctx->state == ngx_http_grpc_st_padding) {
+
+            if (b->last - b->pos < (ssize_t) ctx->rest) {
+                ctx->rest -= b->last - b->pos;
+                b->pos = b->last;
+                return NGX_AGAIN;
+            }
+
+            b->pos += ctx->rest;
+            ctx->rest = 0;
+            ctx->state = ngx_http_grpc_st_start;
+
+            if (ctx->flags & NGX_HTTP_V2_END_STREAM_FLAG) {
+                u->length = 0;
+
+                if (ctx->in == NULL
+                    && ctx->out == NULL
+                    && ctx->output_closed
+                    && b->last == b->pos)
+                {
+                    u->keepalive = 1;
+                }
+
+                break;
+            }
+
+            continue;
+        }
+
+        /* frame payload */
+
+        if (ctx->type == NGX_HTTP_V2_RST_STREAM_FRAME) {
+
+            rc = ngx_http_grpc_parse_rst_stream(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream rejected request with error %ui",
+                          ctx->error);
+
+            return NGX_ERROR;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_GOAWAY_FRAME) {
+
+            rc = ngx_http_grpc_parse_goaway(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            /*
+             * If stream_id is lower than one we use, our
+             * request won't be processed and needs to be retried.
+             * If stream_id is greater or equal to the one we use,
+             * we can continue normally (except we can't use this
+             * connection for additional requests).  If there is
+             * a real error, the connection will be closed.
+             */
+
+            if (ctx->stream_id < ctx->id) {
+
+                /* TODO: we can retry non-idempotent requests */
+
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent goaway with error %ui",
+                              ctx->error);
+
+                return NGX_ERROR;
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_WINDOW_UPDATE_FRAME) {
+
+            rc = ngx_http_grpc_parse_window_update(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            if (ctx->in) {
+                ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_SETTINGS_FRAME) {
+
+            rc = ngx_http_grpc_parse_settings(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            if (ctx->in) {
+                ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            }
+
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_PING_FRAME) {
+
+            rc = ngx_http_grpc_parse_ping(r, ctx, b);
+
+            if (rc == NGX_AGAIN) {
+                return NGX_AGAIN;
+            }
+
+            if (rc == NGX_ERROR) {
+                return NGX_ERROR;
+            }
+
+            ngx_post_event(u->peer.connection->write, &ngx_posted_events);
+            continue;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_PUSH_PROMISE_FRAME) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent unexpected push promise frame");
+            return NGX_ERROR;
+        }
+
+        if (ctx->type == NGX_HTTP_V2_HEADERS_FRAME
+            || ctx->type == NGX_HTTP_V2_CONTINUATION_FRAME)
+        {
+            for ( ;; ) {
+
+                rc = ngx_http_grpc_parse_header(r, ctx, b);
+
+                if (rc == NGX_AGAIN) {
+                    break;
+                }
+
+                if (rc == NGX_OK) {
+
+                    /* a header line has been parsed successfully */
+
+                    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                                   "grpc trailer: \"%V: %V\"",
+                                   &ctx->name, &ctx->value);
+
+                    if (ctx->name.len && ctx->name.data[0] == ':') {
+                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                      "upstream sent invalid "
+                                      "trailer \"%V: %V\"",
+                                      &ctx->name, &ctx->value);
+                        return NGX_ERROR;
+                    }
+
+                    h = ngx_list_push(&u->headers_in.trailers);
+                    if (h == NULL) {
+                        return NGX_ERROR;
+                    }
+
+                    h->key = ctx->name;
+                    h->value = ctx->value;
+                    h->lowcase_key = h->key.data;
+                    h->hash = ngx_hash_key(h->key.data, h->key.len);
+
+                    continue;
+                }
+
+                if (rc == NGX_HTTP_PARSE_HEADER_DONE) {
+
+                    /* a whole header has been parsed successfully */
+
+                    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                                   "grpc trailer done");
+
+                    if (ctx->end_stream) {
+                        u->length = 0;
+
+                        if (ctx->in == NULL
+                            && ctx->out == NULL
+                            && ctx->output_closed
+                            && b->last == b->pos)
+                        {
+                            u->keepalive = 1;
+                        }
+
+                        return NGX_OK;
+                    }
+
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent trailer without "
+                                  "end stream flag");
+                    return NGX_ERROR;
+                }
+
+                /* there was error while a header line parsing */
+
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent invalid trailer");
+
+                return NGX_ERROR;
+            }
+
+            /* rc == NGX_AGAIN */
+
+            if (ctx->rest == 0) {
+                ctx->state = ngx_http_grpc_st_start;
+                continue;
+            }
+
+            return NGX_AGAIN;
+        }
+
+        if (ctx->type != NGX_HTTP_V2_DATA_FRAME) {
+
+            /* priority, unknown frames */
+
+            if (b->last - b->pos < (ssize_t) ctx->rest) {
+                ctx->rest -= b->last - b->pos;
+                b->pos = b->last;
+                return NGX_AGAIN;
+            }
+
+            b->pos += ctx->rest;
+            ctx->rest = 0;
+            ctx->state = ngx_http_grpc_st_start;
+
+            continue;
+        }
+
+        /*
+         * data frame:
+         *
+         * +---------------+
+         * |Pad Length? (8)|
+         * +---------------+-----------------------------------------------+
+         * |                            Data (*)                         ...
+         * +---------------------------------------------------------------+
+         * |                           Padding (*)                       ...
+         * +---------------------------------------------------------------+
+         */
+
+        if (ctx->flags & NGX_HTTP_V2_PADDED_FLAG) {
+
+            if (ctx->rest == 0) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent too short http2 frame");
+                return NGX_ERROR;
+            }
+
+            if (b->pos == b->last) {
+                return NGX_AGAIN;
+            }
+
+            ctx->flags &= ~NGX_HTTP_V2_PADDED_FLAG;
+            ctx->padding = *b->pos++;
+            ctx->rest -= 1;
+
+            if (ctx->padding > ctx->rest) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent http2 frame with too long "
+                              "padding: %d in frame %uz",
+                              ctx->padding, ctx->rest);
+                return NGX_ERROR;
+            }
+
+            continue;
+        }
+
+        if (ctx->rest == ctx->padding) {
+            goto done;
+        }
+
+        if (b->pos == b->last) {
+            return NGX_AGAIN;
+        }
+
+        cl = ngx_chain_get_free_buf(r->pool, &u->free_bufs);
+        if (cl == NULL) {
+            return NGX_ERROR;
+        }
+
+        *ll = cl;
+        ll = &cl->next;
+
+        buf = cl->buf;
+
+        buf->flush = 1;
+        buf->memory = 1;
+
+        buf->pos = b->pos;
+        buf->tag = u->output.tag;
+
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc output buf %p", buf->pos);
+
+        if (b->last - b->pos < (ssize_t) ctx->rest - ctx->padding) {
+
+            ctx->rest -= b->last - b->pos;
+            b->pos = b->last;
+            buf->last = b->pos;
+
+            return NGX_AGAIN;
+        }
+
+        b->pos += ctx->rest - ctx->padding;
+        buf->last = b->pos;
+        ctx->rest = ctx->padding;
+
+    done:
+
+        if (ctx->padding) {
+            ctx->state = ngx_http_grpc_st_padding;
+            continue;
+        }
+
+        ctx->state = ngx_http_grpc_st_start;
+
+        if (ctx->flags & NGX_HTTP_V2_END_STREAM_FLAG) {
+            u->length = 0;
+
+            if (ctx->in == NULL
+                && ctx->out == NULL
+                && ctx->output_closed
+                && b->last == b->pos)
+            {
+                u->keepalive = 1;
+            }
+
+            break;
+        }
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_frame(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char                 ch, *p;
+    ngx_http_grpc_state_e  state;
+
+    state = ctx->state;
+
+    for (p = b->pos; p < b->last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc frame byte: %02Xd, s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case ngx_http_grpc_st_start:
+            ctx->rest = ch << 16;
+            state = ngx_http_grpc_st_length_2;
+            break;
+
+        case ngx_http_grpc_st_length_2:
+            ctx->rest |= ch << 8;
+            state = ngx_http_grpc_st_length_3;
+            break;
+
+        case ngx_http_grpc_st_length_3:
+            ctx->rest |= ch;
+
+            if (ctx->rest > NGX_HTTP_V2_DEFAULT_FRAME_SIZE) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent too large http2 frame: %uz",
+                              ctx->rest);
+                return NGX_ERROR;
+            }
+
+            state = ngx_http_grpc_st_type;
+            break;
+
+        case ngx_http_grpc_st_type:
+            ctx->type = ch;
+            state = ngx_http_grpc_st_flags;
+            break;
+
+        case ngx_http_grpc_st_flags:
+            ctx->flags = ch;
+            state = ngx_http_grpc_st_stream_id;
+            break;
+
+        case ngx_http_grpc_st_stream_id:
+            ctx->stream_id = (ch & 0x7f) << 24;
+            state = ngx_http_grpc_st_stream_id_2;
+            break;
+
+        case ngx_http_grpc_st_stream_id_2:
+            ctx->stream_id |= ch << 16;
+            state = ngx_http_grpc_st_stream_id_3;
+            break;
+
+        case ngx_http_grpc_st_stream_id_3:
+            ctx->stream_id |= ch << 8;
+            state = ngx_http_grpc_st_stream_id_4;
+            break;
+
+        case ngx_http_grpc_st_stream_id_4:
+            ctx->stream_id |= ch;
+
+            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc frame: %d, len: %uz, f:%d, i:%ui",
+                           ctx->type, ctx->rest, ctx->flags, ctx->stream_id);
+
+            b->pos = p + 1;
+
+            ctx->state = ngx_http_grpc_st_payload;
+            ctx->frame_state = 0;
+
+            return NGX_OK;
+
+        /* suppress warning */
+        case ngx_http_grpc_st_payload:
+        case ngx_http_grpc_st_padding:
+            break;
+        }
+    }
+
+    b->pos = p;
+    ctx->state = state;
+
+    return NGX_AGAIN;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_header(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char     ch, *p, *last;
+    size_t     min;
+    ngx_int_t  rc;
+    enum {
+        sw_start = 0,
+        sw_padding_length,
+        sw_dependency,
+        sw_dependency_2,
+        sw_dependency_3,
+        sw_dependency_4,
+        sw_weight,
+        sw_fragment,
+        sw_padding
+    } state;
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc parse header: start");
+
+        if (ctx->type == NGX_HTTP_V2_HEADERS_FRAME) {
+            ctx->parsing_headers = 1;
+            ctx->fragment_state = 0;
+
+            min = (ctx->flags & NGX_HTTP_V2_PADDED_FLAG ? 1 : 0)
+                  + (ctx->flags & NGX_HTTP_V2_PRIORITY_FLAG ? 5 : 0);
+
+            if (ctx->rest < min) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent headers frame "
+                              "with invalid length: %uz",
+                              ctx->rest);
+                return NGX_ERROR;
+            }
+
+            if (ctx->flags & NGX_HTTP_V2_END_STREAM_FLAG) {
+                ctx->end_stream = 1;
+            }
+
+            if (ctx->flags & NGX_HTTP_V2_PADDED_FLAG) {
+                state = sw_padding_length;
+
+            } else if (ctx->flags & NGX_HTTP_V2_PRIORITY_FLAG) {
+                state = sw_dependency;
+
+            } else {
+                state = sw_fragment;
+            }
+
+        } else if (ctx->type == NGX_HTTP_V2_CONTINUATION_FRAME) {
+            state = sw_fragment;
+        }
+
+        ctx->padding = 0;
+    }
+
+    if (state < sw_fragment) {
+
+        if (b->last - b->pos < (ssize_t) ctx->rest) {
+            last = b->last;
+
+        } else {
+            last = b->pos + ctx->rest;
+        }
+
+        for (p = b->pos; p < last; p++) {
+            ch = *p;
+
+#if 0
+            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc header byte: %02Xd s:%d", ch, state);
+#endif
+
+            /*
+             * headers frame:
+             *
+             * +---------------+
+             * |Pad Length? (8)|
+             * +-+-------------+----------------------------------------------+
+             * |E|                 Stream Dependency? (31)                    |
+             * +-+-------------+----------------------------------------------+
+             * |  Weight? (8)  |
+             * +-+-------------+----------------------------------------------+
+             * |                   Header Block Fragment (*)                ...
+             * +--------------------------------------------------------------+
+             * |                           Padding (*)                      ...
+             * +--------------------------------------------------------------+
+             */
+
+            switch (state) {
+
+            case sw_padding_length:
+
+                ctx->padding = ch;
+
+                if (ctx->flags & NGX_HTTP_V2_PRIORITY_FLAG) {
+                    state = sw_dependency;
+                    break;
+                }
+
+                goto fragment;
+
+            case sw_dependency:
+                state = sw_dependency_2;
+                break;
+
+            case sw_dependency_2:
+                state = sw_dependency_3;
+                break;
+
+            case sw_dependency_3:
+                state = sw_dependency_4;
+                break;
+
+            case sw_dependency_4:
+                state = sw_weight;
+                break;
+
+            case sw_weight:
+                goto fragment;
+
+            /* suppress warning */
+            case sw_start:
+            case sw_fragment:
+            case sw_padding:
+                break;
+            }
+        }
+
+        ctx->rest -= p - b->pos;
+        b->pos = p;
+
+        ctx->frame_state = state;
+        return NGX_AGAIN;
+
+    fragment:
+
+        p++;
+        ctx->rest -= p - b->pos;
+        b->pos = p;
+
+        if (ctx->padding > ctx->rest) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent http2 frame with too long "
+                          "padding: %d in frame %uz",
+                          ctx->padding, ctx->rest);
+            return NGX_ERROR;
+        }
+
+        state = sw_fragment;
+        ctx->frame_state = state;
+    }
+
+    if (state == sw_fragment) {
+
+        rc = ngx_http_grpc_parse_fragment(r, ctx, b);
+
+        if (rc == NGX_AGAIN) {
+            return NGX_AGAIN;
+        }
+
+        if (rc == NGX_ERROR) {
+            return NGX_ERROR;
+        }
+
+        if (rc == NGX_OK) {
+            return NGX_OK;
+        }
+
+        /* rc == NGX_DONE */
+
+        state = sw_padding;
+        ctx->frame_state = state;
+    }
+
+    if (state == sw_padding) {
+
+        if (b->last - b->pos < (ssize_t) ctx->rest) {
+
+            ctx->rest -= b->last - b->pos;
+            b->pos = b->last;
+
+            return NGX_AGAIN;
+        }
+
+        b->pos += ctx->rest;
+        ctx->rest = 0;
+
+        ctx->state = ngx_http_grpc_st_start;
+
+        if (ctx->flags & NGX_HTTP_V2_END_HEADERS_FLAG) {
+
+            if (ctx->fragment_state) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent truncated http2 header");
+                return NGX_ERROR;
+            }
+
+            ctx->parsing_headers = 0;
+
+            return NGX_HTTP_PARSE_HEADER_DONE;
+        }
+
+        return NGX_AGAIN;
+    }
+
+    /* unreachable */
+
+    return NGX_ERROR;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_fragment(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char      ch, *p, *last;
+    size_t      size;
+    ngx_uint_t  index, size_update;
+    enum {
+        sw_start = 0,
+        sw_index,
+        sw_name_length,
+        sw_name_length_2,
+        sw_name_length_3,
+        sw_name_length_4,
+        sw_name,
+        sw_name_bytes,
+        sw_value_length,
+        sw_value_length_2,
+        sw_value_length_3,
+        sw_value_length_4,
+        sw_value,
+        sw_value_bytes
+    } state;
+
+    /* header block fragment */
+
+#if 0
+    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc header fragment %p:%p rest:%uz",
+                   b->pos, b->last, ctx->rest);
+#endif
+
+    if (b->last - b->pos < (ssize_t) ctx->rest - ctx->padding) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest - ctx->padding;
+    }
+
+    state = ctx->fragment_state;
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc header byte: %02Xd s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case sw_start:
+            ctx->index = 0;
+
+            if ((ch & 0x80) == 0x80) {
+                /*
+                 * indexed header:
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 1 |        Index (7+)         |
+                 * +---+---------------------------+
+                 */
+
+                index = ch & ~0x80;
+
+                if (index == 0 || index > 61) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent invalid http2 "
+                                  "table index: %ui", index);
+                    return NGX_ERROR;
+                }
+
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc indexed header: %ui", index);
+
+                ctx->index = index;
+                ctx->literal = 0;
+
+                goto done;
+
+            } else if ((ch & 0xc0) == 0x40) {
+                /*
+                 * literal header with incremental indexing:
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 1 |      Index (6+)       |
+                 * +---+---+-----------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 1 |           0           |
+                 * +---+---+-----------------------+
+                 * | H |     Name Length (7+)      |
+                 * +---+---------------------------+
+                 * |  Name String (Length octets)  |
+                 * +---+---------------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 */
+
+                index = ch & ~0xc0;
+
+                if (index > 61) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent invalid http2 "
+                                  "table index: %ui", index);
+                    return NGX_ERROR;
+                }
+
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc literal header: %ui", index);
+
+                if (index == 0) {
+                    state = sw_name_length;
+                    break;
+                }
+
+                ctx->index = index;
+                ctx->literal = 1;
+
+                state = sw_value_length;
+                break;
+
+            } else if ((ch & 0xe0) == 0x20) {
+                /*
+                 * dynamic table size update:
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 0 | 1 |   Max size (5+)   |
+                 * +---+---------------------------+
+                 */
+
+                size_update = ch & ~0xe0;
+
+                if (size_update > 0) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent invalid http2 "
+                                  "dynamic table size update: %ui",
+                                  size_update);
+                    return NGX_ERROR;
+                }
+
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc table size update: %ui", size_update);
+
+                break;
+
+            } else if ((ch & 0xf0) == 0x10) {
+                /*
+                 *  literal header field never indexed:
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 0 | 0 | 1 |  Index (4+)   |
+                 * +---+---+-----------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 0 | 0 | 1 |       0       |
+                 * +---+---+-----------------------+
+                 * | H |     Name Length (7+)      |
+                 * +---+---------------------------+
+                 * |  Name String (Length octets)  |
+                 * +---+---------------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 */
+
+                index = ch & ~0xf0;
+
+                if (index == 0x0f) {
+                    ctx->index = index;
+                    ctx->literal = 1;
+                    state = sw_index;
+                    break;
+                }
+
+                if (index == 0) {
+                    state = sw_name_length;
+                    break;
+                }
+
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc literal header never indexed: %ui",
+                               index);
+
+                ctx->index = index;
+                ctx->literal = 1;
+
+                state = sw_value_length;
+                break;
+
+            } else if ((ch & 0xf0) == 0x00) {
+                /*
+                 * literal header field without indexing:
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 0 | 0 | 0 |  Index (4+)   |
+                 * +---+---+-----------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 *
+                 *   0   1   2   3   4   5   6   7
+                 * +---+---+---+---+---+---+---+---+
+                 * | 0 | 0 | 0 | 0 |       0       |
+                 * +---+---+-----------------------+
+                 * | H |     Name Length (7+)      |
+                 * +---+---------------------------+
+                 * |  Name String (Length octets)  |
+                 * +---+---------------------------+
+                 * | H |     Value Length (7+)     |
+                 * +---+---------------------------+
+                 * | Value String (Length octets)  |
+                 * +-------------------------------+
+                 */
+
+                index = ch & ~0xf0;
+
+                if (index == 0x0f) {
+                    ctx->index = index;
+                    ctx->literal = 1;
+                    state = sw_index;
+                    break;
+                }
+
+                if (index == 0) {
+                    state = sw_name_length;
+                    break;
+                }
+
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                               "grpc literal header without indexing: %ui",
+                               index);
+
+                ctx->index = index;
+                ctx->literal = 1;
+
+                state = sw_value_length;
+                break;
+            }
+
+            /* not reached */
+
+            return NGX_ERROR;
+
+        case sw_index:
+            ctx->index = ctx->index + (ch & ~0x80);
+
+            if (ch & 0x80) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent http2 table index "
+                              "with continuation flag");
+                return NGX_ERROR;
+            }
+
+            if (ctx->index > 61) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent invalid http2 "
+                              "table index: %ui", ctx->index);
+                return NGX_ERROR;
+            }
+
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc header index: %ui", ctx->index);
+
+            state = sw_value_length;
+            break;
+
+        case sw_name_length:
+            ctx->field_huffman = ch & 0x80 ? 1 : 0;
+            ctx->field_length = ch & ~0x80;
+
+            if (ctx->field_length == 0x7f) {
+                state = sw_name_length_2;
+                break;
+            }
+
+            if (ctx->field_length == 0) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent zero http2 "
+                              "header name length");
+                return NGX_ERROR;
+            }
+
+            state = sw_name;
+            break;
+
+        case sw_name_length_2:
+            ctx->field_length += ch & ~0x80;
+
+            if (ch & 0x80) {
+                state = sw_name_length_3;
+                break;
+            }
+
+            state = sw_name;
+            break;
+
+        case sw_name_length_3:
+            ctx->field_length += (ch & ~0x80) << 7;
+
+            if (ch & 0x80) {
+                state = sw_name_length_4;
+                break;
+            }
+
+            state = sw_name;
+            break;
+
+        case sw_name_length_4:
+            ctx->field_length += (ch & ~0x80) << 14;
+
+            if (ch & 0x80) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent too large http2 "
+                              "header name length");
+                return NGX_ERROR;
+            }
+
+            state = sw_name;
+            break;
+
+        case sw_name:
+            ctx->name.len = ctx->field_huffman ?
+                            ctx->field_length * 8 / 5 : ctx->field_length;
+
+            ctx->name.data = ngx_pnalloc(r->pool, ctx->name.len + 1);
+            if (ctx->name.data == NULL) {
+                return NGX_ERROR;
+            }
+
+            ctx->field_end = ctx->name.data;
+            ctx->field_rest = ctx->field_length;
+            ctx->field_state = 0;
+
+            state = sw_name_bytes;
+
+            /* fall through */
+
+        case sw_name_bytes:
+
+            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc name: len:%uz h:%d last:%uz, rest:%uz",
+                           ctx->field_length,
+                           ctx->field_huffman,
+                           last - p,
+                           ctx->rest - (p - b->pos));
+
+            size = ngx_min(last - p, (ssize_t) ctx->field_rest);
+            ctx->field_rest -= size;
+
+            if (ctx->field_huffman) {
+                if (ngx_http_v2_huff_decode(&ctx->field_state, p, size,
+                                            &ctx->field_end,
+                                            ctx->field_rest == 0,
+                                            r->connection->log)
+                    != NGX_OK)
+                {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent invalid encoded header");
+                    return NGX_ERROR;
+                }
+
+                ctx->name.len = ctx->field_end - ctx->name.data;
+                ctx->name.data[ctx->name.len] = '\0';
+
+            } else {
+                ngx_memcpy(ctx->field_end, p, size);
+                ctx->name.data[ctx->name.len] = '\0';
+            }
+
+            p += size - 1;
+
+            if (ctx->field_rest == 0) {
+                state = sw_value_length;
+            }
+
+            break;
+
+        case sw_value_length:
+            ctx->field_huffman = ch & 0x80 ? 1 : 0;
+            ctx->field_length = ch & ~0x80;
+
+            if (ctx->field_length == 0x7f) {
+                state = sw_value_length_2;
+                break;
+            }
+
+            if (ctx->field_length == 0) {
+                ngx_str_set(&ctx->value, "");
+                goto done;
+            }
+
+            state = sw_value;
+            break;
+
+        case sw_value_length_2:
+            ctx->field_length += ch & ~0x80;
+
+            if (ch & 0x80) {
+                state = sw_value_length_3;
+                break;
+            }
+
+            state = sw_value;
+            break;
+
+        case sw_value_length_3:
+            ctx->field_length += (ch & ~0x80) << 7;
+
+            if (ch & 0x80) {
+                state = sw_value_length_4;
+                break;
+            }
+
+            state = sw_value;
+            break;
+
+        case sw_value_length_4:
+            ctx->field_length += (ch & ~0x80) << 14;
+
+            if (ch & 0x80) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent too large http2 "
+                              "header value length");
+                return NGX_ERROR;
+            }
+
+            state = sw_value;
+            break;
+
+        case sw_value:
+            ctx->value.len = ctx->field_huffman ?
+                             ctx->field_length * 8 / 5 : ctx->field_length;
+
+            ctx->value.data = ngx_pnalloc(r->pool, ctx->value.len + 1);
+            if (ctx->value.data == NULL) {
+                return NGX_ERROR;
+            }
+
+            ctx->field_end = ctx->value.data;
+            ctx->field_rest = ctx->field_length;
+            ctx->field_state = 0;
+
+            state = sw_value_bytes;
+
+            /* fall through */
+
+        case sw_value_bytes:
+
+            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc value: len:%uz h:%d last:%uz, rest:%uz",
+                           ctx->field_length,
+                           ctx->field_huffman,
+                           last - p,
+                           ctx->rest - (p - b->pos));
+
+            size = ngx_min(last - p, (ssize_t) ctx->field_rest);
+            ctx->field_rest -= size;
+
+            if (ctx->field_huffman) {
+                if (ngx_http_v2_huff_decode(&ctx->field_state, p, size,
+                                            &ctx->field_end,
+                                            ctx->field_rest == 0,
+                                            r->connection->log)
+                    != NGX_OK)
+                {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent invalid encoded header");
+                    return NGX_ERROR;
+                }
+
+                ctx->value.len = ctx->field_end - ctx->value.data;
+                ctx->value.data[ctx->value.len] = '\0';
+
+            } else {
+                ngx_memcpy(ctx->field_end, p, size);
+                ctx->value.data[ctx->value.len] = '\0';
+            }
+
+            p += size - 1;
+
+            if (ctx->field_rest == 0) {
+                goto done;
+            }
+
+            break;
+        }
+
+        continue;
+
+    done:
+
+        p++;
+        ctx->rest -= p - b->pos;
+        ctx->fragment_state = sw_start;
+        b->pos = p;
+
+        if (ctx->index) {
+            ctx->name = *ngx_http_v2_get_static_name(ctx->index);
+        }
+
+        if (ctx->index && !ctx->literal) {
+            ctx->value = *ngx_http_v2_get_static_value(ctx->index);
+        }
+
+        if (!ctx->index) {
+            if (ngx_http_grpc_validate_header_name(r, &ctx->name) != NGX_OK) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent invalid header: \"%V: %V\"",
+                              &ctx->name, &ctx->value);
+                return NGX_ERROR;
+            }
+        }
+
+        if (!ctx->index || ctx->literal) {
+            if (ngx_http_grpc_validate_header_value(r, &ctx->value) != NGX_OK) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent invalid header: \"%V: %V\"",
+                              &ctx->name, &ctx->value);
+                return NGX_ERROR;
+            }
+        }
+
+        return NGX_OK;
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->fragment_state = state;
+    b->pos = p;
+
+    if (ctx->rest > ctx->padding) {
+        return NGX_AGAIN;
+    }
+
+    return NGX_DONE;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_validate_header_name(ngx_http_request_t *r, ngx_str_t *s)
+{
+    u_char      ch;
+    ngx_uint_t  i;
+
+    for (i = 0; i < s->len; i++) {
+        ch = s->data[i];
+
+        if (ch == ':' && i > 0) {
+            return NGX_ERROR;
+        }
+
+        if (ch >= 'A' && ch <= 'Z') {
+            return NGX_ERROR;
+        }
+
+        if (ch == '\0' || ch == CR || ch == LF) {
+            return NGX_ERROR;
+        }
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_validate_header_value(ngx_http_request_t *r, ngx_str_t *s)
+{
+    u_char      ch;
+    ngx_uint_t  i;
+
+    for (i = 0; i < s->len; i++) {
+        ch = s->data[i];
+
+        if (ch == '\0' || ch == CR || ch == LF) {
+            return NGX_ERROR;
+        }
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_rst_stream(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char  ch, *p, *last;
+    enum {
+        sw_start = 0,
+        sw_error_2,
+        sw_error_3,
+        sw_error_4
+    } state;
+
+    if (b->last - b->pos < (ssize_t) ctx->rest) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest;
+    }
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+        if (ctx->rest != 4) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent rst stream frame "
+                          "with invalid length: %uz",
+                          ctx->rest);
+            return NGX_ERROR;
+        }
+    }
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc rst byte: %02Xd s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case sw_start:
+            ctx->error = ch << 24;
+            state = sw_error_2;
+            break;
+
+        case sw_error_2:
+            ctx->error |= ch << 16;
+            state = sw_error_3;
+            break;
+
+        case sw_error_3:
+            ctx->error |= ch << 8;
+            state = sw_error_4;
+            break;
+
+        case sw_error_4:
+            ctx->error |= ch;
+            state = sw_start;
+
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc error: %ui", ctx->error);
+
+            break;
+        }
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->frame_state = state;
+    b->pos = p;
+
+    if (ctx->rest > 0) {
+        return NGX_AGAIN;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_goaway(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char  ch, *p, *last;
+    enum {
+        sw_start = 0,
+        sw_last_stream_id_2,
+        sw_last_stream_id_3,
+        sw_last_stream_id_4,
+        sw_error,
+        sw_error_2,
+        sw_error_3,
+        sw_error_4,
+        sw_debug
+    } state;
+
+    if (b->last - b->pos < (ssize_t) ctx->rest) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest;
+    }
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+
+        if (ctx->stream_id) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent goaway frame "
+                          "with non-zero stream id: %ui",
+                          ctx->stream_id);
+            return NGX_ERROR;
+        }
+
+        if (ctx->rest < 8) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent goaway frame "
+                          "with invalid length: %uz",
+                          ctx->rest);
+            return NGX_ERROR;
+        }
+    }
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc goaway byte: %02Xd s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case sw_start:
+            ctx->stream_id = (ch & 0x7f) << 24;
+            state = sw_last_stream_id_2;
+            break;
+
+        case sw_last_stream_id_2:
+            ctx->stream_id |= ch << 16;
+            state = sw_last_stream_id_3;
+            break;
+
+        case sw_last_stream_id_3:
+            ctx->stream_id |= ch << 8;
+            state = sw_last_stream_id_4;
+            break;
+
+        case sw_last_stream_id_4:
+            ctx->stream_id |= ch;
+            state = sw_error;
+            break;
+
+        case sw_error:
+            ctx->error = ch << 24;
+            state = sw_error_2;
+            break;
+
+        case sw_error_2:
+            ctx->error |= ch << 16;
+            state = sw_error_3;
+            break;
+
+        case sw_error_3:
+            ctx->error |= ch << 8;
+            state = sw_error_4;
+            break;
+
+        case sw_error_4:
+            ctx->error |= ch;
+            state = sw_debug;
+            break;
+
+        case sw_debug:
+            break;
+        }
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->frame_state = state;
+    b->pos = p;
+
+    if (ctx->rest > 0) {
+        return NGX_AGAIN;
+    }
+
+    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc goaway: %ui, stream %ui",
+                   ctx->error, ctx->stream_id);
+
+    ctx->state = ngx_http_grpc_st_start;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_window_update(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b)
+{
+    u_char  ch, *p, *last;
+    enum {
+        sw_start = 0,
+        sw_size_2,
+        sw_size_3,
+        sw_size_4
+    } state;
+
+    if (b->last - b->pos < (ssize_t) ctx->rest) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest;
+    }
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+        if (ctx->rest != 4) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent window update frame "
+                          "with invalid length: %uz",
+                          ctx->rest);
+            return NGX_ERROR;
+        }
+    }
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc window update byte: %02Xd s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case sw_start:
+            ctx->window_update = (ch & 0x7f) << 24;
+            state = sw_size_2;
+            break;
+
+        case sw_size_2:
+            ctx->window_update |= ch << 16;
+            state = sw_size_3;
+            break;
+
+        case sw_size_3:
+            ctx->window_update |= ch << 8;
+            state = sw_size_4;
+            break;
+
+        case sw_size_4:
+            ctx->window_update |= ch;
+            state = sw_start;
+            break;
+        }
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->frame_state = state;
+    b->pos = p;
+
+    if (ctx->rest > 0) {
+        return NGX_AGAIN;
+    }
+
+    ctx->state = ngx_http_grpc_st_start;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc window update: %ui", ctx->window_update);
+
+    if (ctx->stream_id) {
+
+        if (ctx->window_update > (size_t) NGX_HTTP_V2_MAX_WINDOW
+                                 - ctx->send_window)
+        {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent too large window update");
+            return NGX_ERROR;
+        }
+
+        ctx->send_window += ctx->window_update;
+
+    } else {
+
+        if (ctx->window_update > NGX_HTTP_V2_MAX_WINDOW
+                                 - ctx->connection->send_window)
+        {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent too large window update");
+            return NGX_ERROR;
+        }
+
+        ctx->connection->send_window += ctx->window_update;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_settings(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx,
+    ngx_buf_t *b)
+{
+    u_char   ch, *p, *last;
+    ssize_t  window_update;
+    enum {
+        sw_start = 0,
+        sw_id,
+        sw_id_2,
+        sw_value,
+        sw_value_2,
+        sw_value_3,
+        sw_value_4
+    } state;
+
+    if (b->last - b->pos < (ssize_t) ctx->rest) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest;
+    }
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+
+        if (ctx->stream_id) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent settings frame "
+                          "with non-zero stream id: %ui",
+                          ctx->stream_id);
+            return NGX_ERROR;
+        }
+
+        if (ctx->flags & NGX_HTTP_V2_ACK_FLAG) {
+            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc settings ack");
+
+            if (ctx->rest != 0) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "upstream sent settings frame "
+                              "with ack flag and non-zero length: %uz",
+                              ctx->rest);
+                return NGX_ERROR;
+            }
+
+            ctx->state = ngx_http_grpc_st_start;
+
+            return NGX_OK;
+        }
+
+        if (ctx->rest % 6 != 0) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent settings frame "
+                          "with invalid length: %uz",
+                          ctx->rest);
+            return NGX_ERROR;
+        }
+    }
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc settings byte: %02Xd s:%d", ch, state);
+#endif
+
+        switch (state) {
+
+        case sw_start:
+        case sw_id:
+            ctx->setting_id = ch << 8;
+            state = sw_id_2;
+            break;
+
+        case sw_id_2:
+            ctx->setting_id |= ch;
+            state = sw_value;
+            break;
+
+        case sw_value:
+            ctx->setting_value = ch << 24;
+            state = sw_value_2;
+            break;
+
+        case sw_value_2:
+            ctx->setting_value |= ch << 16;
+            state = sw_value_3;
+            break;
+
+        case sw_value_3:
+            ctx->setting_value |= ch << 8;
+            state = sw_value_4;
+            break;
+
+        case sw_value_4:
+            ctx->setting_value |= ch;
+            state = sw_id;
+
+            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc setting: %ui %ui",
+                           ctx->setting_id, ctx->setting_value);
+
+            /*
+             * The following settings are defined by the protocol:
+             *
+             * SETTINGS_HEADER_TABLE_SIZE, SETTINGS_ENABLE_PUSH,
+             * SETTINGS_MAX_CONCURRENT_STREAMS, SETTINGS_INITIAL_WINDOW_SIZE,
+             * SETTINGS_MAX_FRAME_SIZE, SETTINGS_MAX_HEADER_LIST_SIZE
+             *
+             * Only SETTINGS_INITIAL_WINDOW_SIZE seems to be needed in
+             * a simple client.
+             */
+
+            if (ctx->setting_id == 0x04) {
+                /* SETTINGS_INITIAL_WINDOW_SIZE */
+
+                if (ctx->setting_value > NGX_HTTP_V2_MAX_WINDOW) {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent settings frame "
+                                  "with too large initial window size: %ui",
+                                  ctx->setting_value);
+                    return NGX_ERROR;
+                }
+
+                window_update = ctx->setting_value
+                                - ctx->connection->init_window;
+                ctx->connection->init_window = ctx->setting_value;
+
+                if (ctx->send_window > 0
+                    && window_update > (ssize_t) NGX_HTTP_V2_MAX_WINDOW
+                                       - ctx->send_window)
+                {
+                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                                  "upstream sent settings frame "
+                                  "with too large initial window size: %ui",
+                                  ctx->setting_value);
+                    return NGX_ERROR;
+                }
+
+                ctx->send_window += window_update;
+            }
+
+            break;
+        }
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->frame_state = state;
+    b->pos = p;
+
+    if (ctx->rest > 0) {
+        return NGX_AGAIN;
+    }
+
+    ctx->state = ngx_http_grpc_st_start;
+
+    return ngx_http_grpc_send_settings_ack(r, ctx);
+}
+
+
+static ngx_int_t
+ngx_http_grpc_parse_ping(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_buf_t *b)
+{
+    u_char  ch, *p, *last;
+    enum {
+        sw_start = 0,
+        sw_data_2,
+        sw_data_3,
+        sw_data_4,
+        sw_data_5,
+        sw_data_6,
+        sw_data_7,
+        sw_data_8
+    } state;
+
+    if (b->last - b->pos < (ssize_t) ctx->rest) {
+        last = b->last;
+
+    } else {
+        last = b->pos + ctx->rest;
+    }
+
+    state = ctx->frame_state;
+
+    if (state == sw_start) {
+
+        if (ctx->stream_id) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent ping frame "
+                          "with non-zero stream id: %ui",
+                          ctx->stream_id);
+            return NGX_ERROR;
+        }
+
+        if (ctx->rest != 8) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent ping frame "
+                          "with invalid length: %uz",
+                          ctx->rest);
+            return NGX_ERROR;
+        }
+
+        if (ctx->flags & NGX_HTTP_V2_ACK_FLAG) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "upstream sent ping frame with ack flag");
+            return NGX_ERROR;
+        }
+    }
+
+    for (p = b->pos; p < last; p++) {
+        ch = *p;
+
+#if 0
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "grpc ping byte: %02Xd s:%d", ch, state);
+#endif
+
+        if (state < sw_data_8) {
+            ctx->ping_data[state] = ch;
+            state++;
+
+        } else {
+            ctx->ping_data[7] = ch;
+            state = sw_start;
+
+            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "grpc ping");
+        }
+    }
+
+    ctx->rest -= p - b->pos;
+    ctx->frame_state = state;
+    b->pos = p;
+
+    if (ctx->rest > 0) {
+        return NGX_AGAIN;
+    }
+
+    ctx->state = ngx_http_grpc_st_start;
+
+    return ngx_http_grpc_send_ping_ack(r, ctx);
+}
+
+
+static ngx_int_t
+ngx_http_grpc_send_settings_ack(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx)
+{
+    ngx_chain_t            *cl, **ll;
+    ngx_http_grpc_frame_t  *f;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc send settings ack");
+
+    for (cl = ctx->out, ll = &ctx->out; cl; cl = cl->next) {
+        ll = &cl->next;
+    }
+
+    cl = ngx_http_grpc_get_buf(r, ctx);
+    if (cl == NULL) {
+        return NGX_ERROR;
+    }
+
+    f = (ngx_http_grpc_frame_t *) cl->buf->last;
+    cl->buf->last += sizeof(ngx_http_grpc_frame_t);
+
+    f->length_0 = 0;
+    f->length_1 = 0;
+    f->length_2 = 0;
+    f->type = NGX_HTTP_V2_SETTINGS_FRAME;
+    f->flags = NGX_HTTP_V2_ACK_FLAG;
+    f->stream_id_0 = 0;
+    f->stream_id_1 = 0;
+    f->stream_id_2 = 0;
+    f->stream_id_3 = 0;
+
+    *ll = cl;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_send_ping_ack(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx)
+{
+    ngx_chain_t            *cl, **ll;
+    ngx_http_grpc_frame_t  *f;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc send ping ack");
+
+    for (cl = ctx->out, ll = &ctx->out; cl; cl = cl->next) {
+        ll = &cl->next;
+    }
+
+    cl = ngx_http_grpc_get_buf(r, ctx);
+    if (cl == NULL) {
+        return NGX_ERROR;
+    }
+
+    f = (ngx_http_grpc_frame_t *) cl->buf->last;
+    cl->buf->last += sizeof(ngx_http_grpc_frame_t);
+
+    f->length_0 = 0;
+    f->length_1 = 0;
+    f->length_2 = 8;
+    f->type = NGX_HTTP_V2_PING_FRAME;
+    f->flags = NGX_HTTP_V2_ACK_FLAG;
+    f->stream_id_0 = 0;
+    f->stream_id_1 = 0;
+    f->stream_id_2 = 0;
+    f->stream_id_3 = 0;
+
+    cl->buf->last = ngx_copy(cl->buf->last, ctx->ping_data, 8);
+
+    *ll = cl;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_send_window_update(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx)
+{
+    size_t                  n;
+    ngx_chain_t            *cl, **ll;
+    ngx_http_grpc_frame_t  *f;
+
+    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc send window update: %uz %uz",
+                   ctx->connection->recv_window, ctx->recv_window);
+
+    for (cl = ctx->out, ll = &ctx->out; cl; cl = cl->next) {
+        ll = &cl->next;
+    }
+
+    cl = ngx_http_grpc_get_buf(r, ctx);
+    if (cl == NULL) {
+        return NGX_ERROR;
+    }
+
+    f = (ngx_http_grpc_frame_t *) cl->buf->last;
+    cl->buf->last += sizeof(ngx_http_grpc_frame_t);
+
+    f->length_0 = 0;
+    f->length_1 = 0;
+    f->length_2 = 4;
+    f->type = NGX_HTTP_V2_WINDOW_UPDATE_FRAME;
+    f->flags = 0;
+    f->stream_id_0 = 0;
+    f->stream_id_1 = 0;
+    f->stream_id_2 = 0;
+    f->stream_id_3 = 0;
+
+    n = NGX_HTTP_V2_MAX_WINDOW - ctx->connection->recv_window;
+    ctx->connection->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+
+    *cl->buf->last++ = (u_char) ((n >> 24) & 0xff);
+    *cl->buf->last++ = (u_char) ((n >> 16) & 0xff);
+    *cl->buf->last++ = (u_char) ((n >> 8) & 0xff);
+    *cl->buf->last++ = (u_char) (n & 0xff);
+
+    f = (ngx_http_grpc_frame_t *) cl->buf->last;
+    cl->buf->last += sizeof(ngx_http_grpc_frame_t);
+
+    f->length_0 = 0;
+    f->length_1 = 0;
+    f->length_2 = 4;
+    f->type = NGX_HTTP_V2_WINDOW_UPDATE_FRAME;
+    f->flags = 0;
+    f->stream_id_0 = (u_char) ((ctx->id >> 24) & 0xff);
+    f->stream_id_1 = (u_char) ((ctx->id >> 16) & 0xff);
+    f->stream_id_2 = (u_char) ((ctx->id >> 8) & 0xff);
+    f->stream_id_3 = (u_char) (ctx->id & 0xff);
+
+    n = NGX_HTTP_V2_MAX_WINDOW - ctx->recv_window;
+    ctx->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+
+    *cl->buf->last++ = (u_char) ((n >> 24) & 0xff);
+    *cl->buf->last++ = (u_char) ((n >> 16) & 0xff);
+    *cl->buf->last++ = (u_char) ((n >> 8) & 0xff);
+    *cl->buf->last++ = (u_char) (n & 0xff);
+
+    *ll = cl;
+
+    return NGX_OK;
+}
+
+
+static ngx_chain_t *
+ngx_http_grpc_get_buf(ngx_http_request_t *r, ngx_http_grpc_ctx_t *ctx)
+{
+    ngx_buf_t    *b;
+    ngx_chain_t  *cl;
+
+    cl = ngx_chain_get_free_buf(r->pool, &ctx->free);
+    if (cl == NULL) {
+        return NULL;
+    }
+
+    b = cl->buf;
+
+    b->tag = (ngx_buf_tag_t) &ngx_http_grpc_body_output_filter;
+    b->temporary = 1;
+    b->flush = 1;
+
+    if (b->start == NULL) {
+
+        /*
+         * each buffer is large enough to hold two window update
+         * frames in a row
+         */
+
+        b->start = ngx_palloc(r->pool, 2 * sizeof(ngx_http_grpc_frame_t) + 8);
+        if (b->start == NULL) {
+            return NULL;
+        }
+
+        b->pos = b->start;
+        b->last = b->start;
+
+        b->end = b->start + 2 * sizeof(ngx_http_grpc_frame_t) + 8;
+    }
+
+    return cl;
+}
+
+
+static ngx_http_grpc_ctx_t *
+ngx_http_grpc_get_ctx(ngx_http_request_t *r)
+{
+    ngx_http_grpc_ctx_t  *ctx;
+    ngx_http_upstream_t  *u;
+
+    ctx = ngx_http_get_module_ctx(r, ngx_http_grpc_module);
+
+    if (ctx->connection == NULL) {
+        u = r->upstream;
+
+        if (ngx_http_grpc_get_connection_data(r, ctx, &u->peer) != NGX_OK) {
+            return NULL;
+        }
+    }
+
+    return ctx;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_get_connection_data(ngx_http_request_t *r,
+    ngx_http_grpc_ctx_t *ctx, ngx_peer_connection_t *pc)
+{
+    ngx_connection_t    *c;
+    ngx_pool_cleanup_t  *cln;
+
+    c = pc->connection;
+
+    if (pc->cached) {
+
+        /*
+         * for cached connections, connection data can be found
+         * in the cleanup handler
+         */
+
+        for (cln = c->pool->cleanup; cln; cln = cln->next) {
+            if (cln->handler == ngx_http_grpc_cleanup) {
+                ctx->connection = cln->data;
+                break;
+            }
+        }
+
+        if (ctx->connection == NULL) {
+            ngx_log_error(NGX_LOG_ERR, c->log, 0,
+                          "no connection data found for "
+                          "keepalive http2 connection");
+            return NGX_ERROR;
+        }
+
+        ctx->send_window = ctx->connection->init_window;
+        ctx->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+
+        ctx->connection->last_stream_id += 2;
+        ctx->id = ctx->connection->last_stream_id;
+
+        return NGX_OK;
+    }
+
+    cln = ngx_pool_cleanup_add(c->pool, sizeof(ngx_http_grpc_conn_t));
+    if (cln == NULL) {
+        return NGX_ERROR;
+    }
+
+    cln->handler = ngx_http_grpc_cleanup;
+    ctx->connection = cln->data;
+
+    ctx->connection->init_window = NGX_HTTP_V2_DEFAULT_WINDOW;
+    ctx->connection->send_window = NGX_HTTP_V2_DEFAULT_WINDOW;
+    ctx->connection->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+
+    ctx->send_window = NGX_HTTP_V2_DEFAULT_WINDOW;
+    ctx->recv_window = NGX_HTTP_V2_MAX_WINDOW;
+
+    ctx->id = 1;
+    ctx->connection->last_stream_id = 1;
+
+    return NGX_OK;
+}
+
+
+static void
+ngx_http_grpc_cleanup(void *data)
+{
+#if 0
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
+                   "grpc cleanup");
+#endif
+    return;
+}
+
+
+static void
+ngx_http_grpc_abort_request(ngx_http_request_t *r)
+{
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "abort grpc request");
+    return;
+}
+
+
+static void
+ngx_http_grpc_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
+{
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "finalize grpc request");
+    return;
+}
+
+
+static void *
+ngx_http_grpc_create_loc_conf(ngx_conf_t *cf)
+{
+    ngx_http_grpc_loc_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_grpc_loc_conf_t));
+    if (conf == NULL) {
+        return NULL;
+    }
+
+    /*
+     * set by ngx_pcalloc():
+     *
+     *     conf->upstream.ignore_headers = 0;
+     *     conf->upstream.next_upstream = 0;
+     *     conf->upstream.hide_headers_hash = { NULL, 0 };
+     *     conf->upstream.ssl_name = NULL;
+     *
+     *     conf->headers_source = NULL;
+     *     conf->headers.lengths = NULL;
+     *     conf->headers.values = NULL;
+     *     conf->headers.hash = { NULL, 0 };
+     *     conf->host = { 0, NULL };
+     *     conf->host_set = 0;
+     *     conf->ssl = 0;
+     *     conf->ssl_protocols = 0;
+     *     conf->ssl_ciphers = { 0, NULL };
+     *     conf->ssl_trusted_certificate = { 0, NULL };
+     *     conf->ssl_crl = { 0, NULL };
+     *     conf->ssl_certificate = { 0, NULL };
+     *     conf->ssl_certificate_key = { 0, NULL };
+     */
+
+    conf->upstream.local = NGX_CONF_UNSET_PTR;
+    conf->upstream.next_upstream_tries = NGX_CONF_UNSET_UINT;
+    conf->upstream.connect_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.send_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.read_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.next_upstream_timeout = NGX_CONF_UNSET_MSEC;
+
+    conf->upstream.buffer_size = NGX_CONF_UNSET_SIZE;
+
+    conf->upstream.hide_headers = NGX_CONF_UNSET_PTR;
+    conf->upstream.pass_headers = NGX_CONF_UNSET_PTR;
+
+    conf->upstream.intercept_errors = NGX_CONF_UNSET;
+
+#if (NGX_HTTP_SSL)
+    conf->upstream.ssl_session_reuse = NGX_CONF_UNSET;
+    conf->upstream.ssl_server_name = NGX_CONF_UNSET;
+    conf->upstream.ssl_verify = NGX_CONF_UNSET;
+    conf->ssl_verify_depth = NGX_CONF_UNSET_UINT;
+    conf->ssl_passwords = NGX_CONF_UNSET_PTR;
+#endif
+
+    /* the hardcoded values */
+    conf->upstream.cyclic_temp_file = 0;
+    conf->upstream.buffering = 0;
+    conf->upstream.ignore_client_abort = 0;
+    conf->upstream.send_lowat = 0;
+    conf->upstream.bufs.num = 0;
+    conf->upstream.busy_buffers_size = 0;
+    conf->upstream.max_temp_file_size = 0;
+    conf->upstream.temp_file_write_size = 0;
+    conf->upstream.pass_request_headers = 1;
+    conf->upstream.pass_request_body = 1;
+    conf->upstream.force_ranges = 0;
+    conf->upstream.pass_trailers = 1;
+    conf->upstream.preserve_output = 1;
+
+    ngx_str_set(&conf->upstream.module, "grpc");
+
+    return conf;
+}
+
+
+static char *
+ngx_http_grpc_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_http_grpc_loc_conf_t *prev = parent;
+    ngx_http_grpc_loc_conf_t *conf = child;
+
+    ngx_int_t                  rc;
+    ngx_hash_init_t            hash;
+    ngx_http_core_loc_conf_t  *clcf;
+
+    ngx_conf_merge_ptr_value(conf->upstream.local,
+                              prev->upstream.local, NULL);
+
+    ngx_conf_merge_uint_value(conf->upstream.next_upstream_tries,
+                              prev->upstream.next_upstream_tries, 0);
+
+    ngx_conf_merge_msec_value(conf->upstream.connect_timeout,
+                              prev->upstream.connect_timeout, 60000);
+
+    ngx_conf_merge_msec_value(conf->upstream.send_timeout,
+                              prev->upstream.send_timeout, 60000);
+
+    ngx_conf_merge_msec_value(conf->upstream.read_timeout,
+                              prev->upstream.read_timeout, 60000);
+
+    ngx_conf_merge_msec_value(conf->upstream.next_upstream_timeout,
+                              prev->upstream.next_upstream_timeout, 0);
+
+    ngx_conf_merge_size_value(conf->upstream.buffer_size,
+                              prev->upstream.buffer_size,
+                              (size_t) ngx_pagesize);
+
+    ngx_conf_merge_bitmask_value(conf->upstream.ignore_headers,
+                              prev->upstream.ignore_headers,
+                              NGX_CONF_BITMASK_SET);
+
+    ngx_conf_merge_bitmask_value(conf->upstream.next_upstream,
+                              prev->upstream.next_upstream,
+                              (NGX_CONF_BITMASK_SET
+                               |NGX_HTTP_UPSTREAM_FT_ERROR
+                               |NGX_HTTP_UPSTREAM_FT_TIMEOUT));
+
+    if (conf->upstream.next_upstream & NGX_HTTP_UPSTREAM_FT_OFF) {
+        conf->upstream.next_upstream = NGX_CONF_BITMASK_SET
+                                       |NGX_HTTP_UPSTREAM_FT_OFF;
+    }
+
+    ngx_conf_merge_value(conf->upstream.intercept_errors,
+                              prev->upstream.intercept_errors, 0);
+
+#if (NGX_HTTP_SSL)
+
+    ngx_conf_merge_value(conf->upstream.ssl_session_reuse,
+                              prev->upstream.ssl_session_reuse, 1);
+
+    ngx_conf_merge_bitmask_value(conf->ssl_protocols, prev->ssl_protocols,
+                                 (NGX_CONF_BITMASK_SET|NGX_SSL_TLSv1
+                                  |NGX_SSL_TLSv1_1|NGX_SSL_TLSv1_2));
+
+    ngx_conf_merge_str_value(conf->ssl_ciphers, prev->ssl_ciphers,
+                             "DEFAULT");
+
+    if (conf->upstream.ssl_name == NULL) {
+        conf->upstream.ssl_name = prev->upstream.ssl_name;
+    }
+
+    ngx_conf_merge_value(conf->upstream.ssl_server_name,
+                              prev->upstream.ssl_server_name, 0);
+    ngx_conf_merge_value(conf->upstream.ssl_verify,
+                              prev->upstream.ssl_verify, 0);
+    ngx_conf_merge_uint_value(conf->ssl_verify_depth,
+                              prev->ssl_verify_depth, 1);
+    ngx_conf_merge_str_value(conf->ssl_trusted_certificate,
+                              prev->ssl_trusted_certificate, "");
+    ngx_conf_merge_str_value(conf->ssl_crl, prev->ssl_crl, "");
+
+    ngx_conf_merge_str_value(conf->ssl_certificate,
+                              prev->ssl_certificate, "");
+    ngx_conf_merge_str_value(conf->ssl_certificate_key,
+                              prev->ssl_certificate_key, "");
+    ngx_conf_merge_ptr_value(conf->ssl_passwords, prev->ssl_passwords, NULL);
+
+    if (conf->ssl && ngx_http_grpc_set_ssl(cf, conf) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
+#endif
+
+    hash.max_size = 512;
+    hash.bucket_size = ngx_align(64, ngx_cacheline_size);
+    hash.name = "grpc_headers_hash";
+
+    if (ngx_http_upstream_hide_headers_hash(cf, &conf->upstream,
+            &prev->upstream, ngx_http_grpc_hide_headers, &hash)
+        != NGX_OK)
+    {
+        return NGX_CONF_ERROR;
+    }
+
+    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
+
+    if (clcf->noname && conf->upstream.upstream == NULL) {
+        conf->upstream.upstream = prev->upstream.upstream;
+        conf->host = prev->host;
+#if (NGX_HTTP_SSL)
+        conf->upstream.ssl = prev->upstream.ssl;
+#endif
+    }
+
+    if (clcf->lmt_excpt && clcf->handler == NULL && conf->upstream.upstream) {
+        clcf->handler = ngx_http_grpc_handler;
+    }
+
+    if (conf->headers_source == NULL) {
+        conf->headers = prev->headers;
+        conf->headers_source = prev->headers_source;
+        conf->host_set = prev->host_set;
+    }
+
+    rc = ngx_http_grpc_init_headers(cf, conf, &conf->headers,
+                                    ngx_http_grpc_headers);
+    if (rc != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
+    /*
+     * special handling to preserve conf->headers in the "http" section
+     * to inherit it to all servers
+     */
+
+    if (prev->headers.hash.buckets == NULL
+        && conf->headers_source == prev->headers_source)
+    {
+        prev->headers = conf->headers;
+        prev->host_set = conf->host_set;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_init_headers(ngx_conf_t *cf, ngx_http_grpc_loc_conf_t *conf,
+    ngx_http_grpc_headers_t *headers, ngx_keyval_t *default_headers)
+{
+    u_char                       *p;
+    size_t                        size;
+    uintptr_t                    *code;
+    ngx_uint_t                    i;
+    ngx_array_t                   headers_names, headers_merged;
+    ngx_keyval_t                 *src, *s, *h;
+    ngx_hash_key_t               *hk;
+    ngx_hash_init_t               hash;
+    ngx_http_script_compile_t     sc;
+    ngx_http_script_copy_code_t  *copy;
+
+    if (headers->hash.buckets) {
+        return NGX_OK;
+    }
+
+    if (ngx_array_init(&headers_names, cf->temp_pool, 4, sizeof(ngx_hash_key_t))
+        != NGX_OK)
+    {
+        return NGX_ERROR;
+    }
+
+    if (ngx_array_init(&headers_merged, cf->temp_pool, 4, sizeof(ngx_keyval_t))
+        != NGX_OK)
+    {
+        return NGX_ERROR;
+    }
+
+    headers->lengths = ngx_array_create(cf->pool, 64, 1);
+    if (headers->lengths == NULL) {
+        return NGX_ERROR;
+    }
+
+    headers->values = ngx_array_create(cf->pool, 512, 1);
+    if (headers->values == NULL) {
+        return NGX_ERROR;
+    }
+
+    if (conf->headers_source) {
+
+        src = conf->headers_source->elts;
+        for (i = 0; i < conf->headers_source->nelts; i++) {
+
+            if (src[i].key.len == 4
+                && ngx_strncasecmp(src[i].key.data, (u_char *) "Host", 4) == 0)
+            {
+                conf->host_set = 1;
+            }
+
+            s = ngx_array_push(&headers_merged);
+            if (s == NULL) {
+                return NGX_ERROR;
+            }
+
+            *s = src[i];
+        }
+    }
+
+    h = default_headers;
+
+    while (h->key.len) {
+
+        src = headers_merged.elts;
+        for (i = 0; i < headers_merged.nelts; i++) {
+            if (ngx_strcasecmp(h->key.data, src[i].key.data) == 0) {
+                goto next;
+            }
+        }
+
+        s = ngx_array_push(&headers_merged);
+        if (s == NULL) {
+            return NGX_ERROR;
+        }
+
+        *s = *h;
+
+    next:
+
+        h++;
+    }
+
+
+    src = headers_merged.elts;
+    for (i = 0; i < headers_merged.nelts; i++) {
+
+        hk = ngx_array_push(&headers_names);
+        if (hk == NULL) {
+            return NGX_ERROR;
+        }
+
+        hk->key = src[i].key;
+        hk->key_hash = ngx_hash_key_lc(src[i].key.data, src[i].key.len);
+        hk->value = (void *) 1;
+
+        if (src[i].value.len == 0) {
+            continue;
+        }
+
+        copy = ngx_array_push_n(headers->lengths,
+                                sizeof(ngx_http_script_copy_code_t));
+        if (copy == NULL) {
+            return NGX_ERROR;
+        }
+
+        copy->code = (ngx_http_script_code_pt) ngx_http_script_copy_len_code;
+        copy->len = src[i].key.len;
+
+        size = (sizeof(ngx_http_script_copy_code_t)
+                + src[i].key.len + sizeof(uintptr_t) - 1)
+               & ~(sizeof(uintptr_t) - 1);
+
+        copy = ngx_array_push_n(headers->values, size);
+        if (copy == NULL) {
+            return NGX_ERROR;
+        }
+
+        copy->code = ngx_http_script_copy_code;
+        copy->len = src[i].key.len;
+
+        p = (u_char *) copy + sizeof(ngx_http_script_copy_code_t);
+        ngx_memcpy(p, src[i].key.data, src[i].key.len);
+
+        ngx_memzero(&sc, sizeof(ngx_http_script_compile_t));
+
+        sc.cf = cf;
+        sc.source = &src[i].value;
+        sc.flushes = &headers->flushes;
+        sc.lengths = &headers->lengths;
+        sc.values = &headers->values;
+
+        if (ngx_http_script_compile(&sc) != NGX_OK) {
+            return NGX_ERROR;
+        }
+
+        code = ngx_array_push_n(headers->lengths, sizeof(uintptr_t));
+        if (code == NULL) {
+            return NGX_ERROR;
+        }
+
+        *code = (uintptr_t) NULL;
+
+        code = ngx_array_push_n(headers->values, sizeof(uintptr_t));
+        if (code == NULL) {
+            return NGX_ERROR;
+        }
+
+        *code = (uintptr_t) NULL;
+    }
+
+    code = ngx_array_push_n(headers->lengths, sizeof(uintptr_t));
+    if (code == NULL) {
+        return NGX_ERROR;
+    }
+
+    *code = (uintptr_t) NULL;
+
+
+    hash.hash = &headers->hash;
+    hash.key = ngx_hash_key_lc;
+    hash.max_size = 512;
+    hash.bucket_size = 64;
+    hash.name = "grpc_headers_hash";
+    hash.pool = cf->pool;
+    hash.temp_pool = NULL;
+
+    return ngx_hash_init(&hash, headers_names.elts, headers_names.nelts);
+}
+
+
+static char *
+ngx_http_grpc_pass(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_grpc_loc_conf_t *glcf = conf;
+
+    size_t                     add;
+    ngx_str_t                 *value, *url;
+    ngx_url_t                  u;
+    ngx_http_core_loc_conf_t  *clcf;
+
+    if (glcf->upstream.upstream) {
+        return "is duplicate";
+    }
+
+    value = cf->args->elts;
+    url = &value[1];
+
+    if (ngx_strncasecmp(url->data, (u_char *) "grpc://", 7) == 0) {
+        add = 7;
+
+    } else if (ngx_strncasecmp(url->data, (u_char *) "grpcs://", 8) == 0) {
+
+#if (NGX_HTTP_SSL)
+        glcf->ssl = 1;
+
+        add = 8;
+#else
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "grpcs protocol requires SSL support");
+        return NGX_CONF_ERROR;
+#endif
+
+    } else {
+        add = 0;
+    }
+
+    ngx_memzero(&u, sizeof(ngx_url_t));
+
+    u.url.len = url->len - add;
+    u.url.data = url->data + add;
+    u.no_resolve = 1;
+
+    glcf->upstream.upstream = ngx_http_upstream_add(cf, &u, 0);
+    if (glcf->upstream.upstream == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    if (u.family != AF_UNIX) {
+
+        if (u.no_port) {
+            glcf->host = u.host;
+
+        } else {
+            glcf->host.len = u.host.len + 1 + u.port_text.len;
+            glcf->host.data = u.host.data;
+        }
+
+    } else {
+        ngx_str_set(&glcf->host, "localhost");
+    }
+
+    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
+
+    clcf->handler = ngx_http_grpc_handler;
+
+    if (clcf->name.data[clcf->name.len - 1] == '/') {
+        clcf->auto_redirect = 1;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+#if (NGX_HTTP_SSL)
+
+static char *
+ngx_http_grpc_ssl_password_file(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_grpc_loc_conf_t *glcf = conf;
+
+    ngx_str_t  *value;
+
+    if (glcf->ssl_passwords != NGX_CONF_UNSET_PTR) {
+        return "is duplicate";
+    }
+
+    value = cf->args->elts;
+
+    glcf->ssl_passwords = ngx_ssl_read_password_file(cf, &value[1]);
+
+    if (glcf->ssl_passwords == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_set_ssl(ngx_conf_t *cf, ngx_http_grpc_loc_conf_t *glcf)
+{
+    ngx_pool_cleanup_t  *cln;
+
+    glcf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
+    if (glcf->upstream.ssl == NULL) {
+        return NGX_ERROR;
+    }
+
+    glcf->upstream.ssl->log = cf->log;
+
+    if (ngx_ssl_create(glcf->upstream.ssl, glcf->ssl_protocols, NULL)
+        != NGX_OK)
+    {
+        return NGX_ERROR;
+    }
+
+    cln = ngx_pool_cleanup_add(cf->pool, 0);
+    if (cln == NULL) {
+        return NGX_ERROR;
+    }
+
+    cln->handler = ngx_ssl_cleanup_ctx;
+    cln->data = glcf->upstream.ssl;
+
+    if (glcf->ssl_certificate.len) {
+
+        if (glcf->ssl_certificate_key.len == 0) {
+            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
+                          "no \"grpc_ssl_certificate_key\" is defined "
+                          "for certificate \"%V\"", &glcf->ssl_certificate);
+            return NGX_ERROR;
+        }
+
+        if (ngx_ssl_certificate(cf, glcf->upstream.ssl, &glcf->ssl_certificate,
+                                &glcf->ssl_certificate_key, glcf->ssl_passwords)
+            != NGX_OK)
+        {
+            return NGX_ERROR;
+        }
+    }
+
+    if (ngx_ssl_ciphers(cf, glcf->upstream.ssl, &glcf->ssl_ciphers, 0)
+        != NGX_OK)
+    {
+        return NGX_ERROR;
+    }
+
+    if (glcf->upstream.ssl_verify) {
+        if (glcf->ssl_trusted_certificate.len == 0) {
+            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
+                      "no grpc_ssl_trusted_certificate for grpc_ssl_verify");
+            return NGX_ERROR;
+        }
+
+        if (ngx_ssl_trusted_certificate(cf, glcf->upstream.ssl,
+                                        &glcf->ssl_trusted_certificate,
+                                        glcf->ssl_verify_depth)
+            != NGX_OK)
+        {
+            return NGX_ERROR;
+        }
+
+        if (ngx_ssl_crl(cf, glcf->upstream.ssl, &glcf->ssl_crl) != NGX_OK) {
+            return NGX_ERROR;
+        }
+    }
+
+#ifdef TLSEXT_TYPE_application_layer_protocol_negotiation
+
+    if (SSL_CTX_set_alpn_protos(glcf->upstream.ssl->ctx,
+                                (u_char *) "\x02h2", 3)
+        != 0)
+    {
+        ngx_ssl_error(NGX_LOG_EMERG, cf->log, 0,
+                      "SSL_CTX_set_alpn_protos() failed");
+        return NGX_ERROR;
+    }
+
+#endif
+
+    return NGX_OK;
+}
+
+#endif