new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_upstream.c
@@ -0,0 +1,1204 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+#include <ngx_event_connect.h>
+
+
+static void ngx_http_upstream_check_broken_connection(ngx_event_t *ev);
+static void ngx_http_upstream_connect(ngx_http_request_t *r,
+                                      ngx_http_upstream_t *u);
+static void ngx_http_upstream_reinit(ngx_http_request_t *r,
+                                     ngx_http_upstream_t *u);
+static void ngx_http_upstream_send_request(ngx_http_request_t *r,
+                                           ngx_http_upstream_t *u);
+static void ngx_http_upstream_send_request_handler(ngx_event_t *wev);
+static void ngx_http_upstream_process_header(ngx_event_t *rev);
+static void ngx_http_upstream_send_response(ngx_http_request_t *r,
+                                            ngx_http_upstream_t *u);
+static void ngx_http_upstream_process_body(ngx_event_t *ev);
+static void ngx_http_upstream_dummy_handler(ngx_event_t *wev);
+static void ngx_http_upstream_next(ngx_http_request_t *r,
+                                   ngx_http_upstream_t *u,
+                                   ngx_uint_t ft_type);
+static void ngx_http_upstream_finalize_request(ngx_http_request_t *r,
+                                               ngx_http_upstream_t *u,
+                                               ngx_int_t rc);
+
+static size_t ngx_http_upstream_log_status_getlen(ngx_http_request_t *r,
+                                                  uintptr_t data);
+static u_char *ngx_http_upstream_log_status(ngx_http_request_t *r, u_char *buf,
+                                            ngx_http_log_op_t *op);
+
+
+static ngx_int_t ngx_http_upstream_add_log_formats(ngx_conf_t *cf);
+
+
+ngx_http_module_t  ngx_http_upstream_module_ctx = {
+    ngx_http_upstream_add_log_formats,     /* pre conf */
+    
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    NULL,                                  /* create server configuration */
+    NULL,                                  /* merge server configuration */
+
+    NULL,                                  /* create location configuration */
+    NULL                                   /* merge location configuration */
+};
+    
+
+ngx_module_t  ngx_http_upstream_module = {
+    NGX_MODULE,
+    &ngx_http_upstream_module_ctx,         /* module context */
+    NULL,                                  /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    NULL,                                  /* init module */
+    NULL                                   /* init process */
+};
+
+
+static ngx_http_log_op_name_t ngx_http_upstream_log_fmt_ops[] = {
+    { ngx_string("upstream_status"), 0, NULL,
+                                        ngx_http_upstream_log_status_getlen,
+                                        ngx_http_upstream_log_status },
+    { ngx_null_string, 0, NULL, NULL, NULL }
+};
+
+
+char *ngx_http_upstream_header_errors[] = {
+    "upstream sent invalid header",
+    "upstream sent too long header line"
+};
+
+
+void ngx_http_upstream_init(ngx_http_request_t *r)
+{
+    ngx_connection_t     *c;
+    ngx_http_upstream_t  *u;
+
+    c = r->connection;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
+                   "http init upstream, client timer: %d", c->read->timer_set);
+
+    if (c->read->timer_set) {
+        ngx_del_timer(c->read);
+    }
+
+    c->read->event_handler = ngx_http_upstream_check_broken_connection;
+    
+    if (ngx_event_flags & NGX_USE_CLEAR_EVENT) {
+    
+        c->write->event_handler = ngx_http_upstream_check_broken_connection;
+
+        if (!c->write->active) {
+            if (ngx_add_event(c->write, NGX_WRITE_EVENT,
+                                                NGX_CLEAR_EVENT) == NGX_ERROR)
+            {
+                ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+                return;
+            }
+        }
+    }
+
+    u = r->upstream;
+
+    u->method = r->method;
+
+    if (u->create_request(r) == NGX_ERROR) {
+        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    u->peer.log = r->connection->log;
+    u->saved_ctx = r->connection->log->data;
+    u->saved_handler = r->connection->log->handler;
+    r->connection->log->data = u->log_ctx;
+    r->connection->log->handler = u->log_handler;
+
+    u->output.sendfile = r->connection->sendfile;
+    u->output.pool = r->pool;
+    u->output.bufs.num = 1;
+    u->output.output_filter = ngx_chain_writer;
+    u->output.filter_ctx = &u->writer;
+
+    u->writer.pool = r->pool;
+
+    if (ngx_array_init(&u->states, r->pool, u->peer.peers->number,
+                               sizeof(ngx_http_upstream_state_t)) == NGX_ERROR)
+    {
+        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    if (!(u->state = ngx_push_array(&u->states))) {
+        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
+
+    ngx_http_upstream_connect(r, u);
+}
+
+
+static void ngx_http_upstream_check_broken_connection(ngx_event_t *ev)
+{
+    int                  n;
+    char                 buf[1];
+    ngx_err_t            err; 
+    ngx_connection_t     *c;
+    ngx_http_request_t   *r;
+    ngx_http_upstream_t  *u;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ev->log, 0,
+                   "http upstream check client, write event:%d", ev->write);
+
+#if (NGX_HAVE_KQUEUE)
+
+    if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
+
+        if (!ev->pending_eof) {
+            return;
+        }
+
+        ev->eof = 1;
+
+        if (ev->kq_errno) {
+            ev->error = 1;
+        }
+
+        c = ev->data;
+        r = c->data;
+        u = r->upstream;
+
+        if (!u->cachable && u->peer.connection) {
+            ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
+                          "kevent() reported that client closed "
+                          "prematurely connection, "
+                          "so upstream connection is closed too");
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_CLIENT_CLOSED_REQUEST);
+            return;
+        }
+
+        ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
+                      "kevent() reported that client closed "
+                      "prematurely connection");
+
+        if (u->peer.connection == NULL) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_CLIENT_CLOSED_REQUEST);
+            return;
+        }
+
+        return;
+    }
+
+#endif
+
+    c = ev->data;
+
+    n = recv(c->fd, buf, 1, MSG_PEEK);
+
+    err = ngx_socket_errno;
+
+    /*
+     * we do not need to disable the write event because
+     * that event has NGX_USE_CLEAR_EVENT type
+     */
+
+    if (ev->write && (n >= 0 || err == NGX_EAGAIN)) {
+        return;
+    }
+
+    r = c->data;
+    u = r->upstream;
+
+    if ((ngx_event_flags & NGX_USE_LEVEL_EVENT) && ev->active) {
+        if (ngx_del_event(ev, NGX_READ_EVENT, 0) == NGX_ERROR) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+    }
+
+    if (n > 0) {
+        return;
+    }
+
+    ev->eof = 1;
+
+    if (n == -1) {
+        if (err == NGX_EAGAIN) {
+            return;
+        }
+
+        ev->error = 1;
+
+    } else {
+        /* n == 0 */
+        err = 0;
+    }
+
+    if (!u->cachable && u->peer.connection) {
+        ngx_log_error(NGX_LOG_INFO, ev->log, err,
+                      "client closed prematurely connection, "
+                      "so upstream connection is closed too");
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
+        return;
+    }
+
+    ngx_log_error(NGX_LOG_INFO, ev->log, err,
+                  "client closed prematurely connection");
+
+    if (u->peer.connection == NULL) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
+        return;
+    }
+}
+
+
+static void ngx_http_upstream_connect(ngx_http_request_t *r,
+                                      ngx_http_upstream_t *u)
+{
+    ngx_int_t            rc;
+    ngx_connection_t    *c;
+    ngx_http_log_ctx_t  *ctx;
+
+    ctx = r->connection->log->data;
+    ctx->action = "connecting to upstream";
+
+    r->connection->single_connection = 0;
+
+    rc = ngx_event_connect_peer(&u->peer);
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "http upstream connect: %i", rc);
+
+    if (rc == NGX_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    u->state->peer = &u->peer.peers->peer[u->peer.cur_peer].name;
+
+    if (rc == NGX_CONNECT_ERROR) {
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
+        return;
+    }
+
+    c = u->peer.connection;
+
+    c->data = r;
+    c->write->event_handler = ngx_http_upstream_send_request_handler;
+    c->read->event_handler = ngx_http_upstream_process_header;
+
+    c->sendfile = r->connection->sendfile;
+
+    c->pool = r->pool;
+    c->read->log = c->write->log = c->log = r->connection->log;
+
+    /* init or reinit the ngx_output_chain() and ngx_chain_writer() contexts */
+
+    u->writer.out = NULL;
+    u->writer.last = &u->writer.out;
+    u->writer.connection = c;
+    u->writer.limit = 0;
+
+    if (u->request_sent) {
+        ngx_http_upstream_reinit(r, u);
+    }
+
+    if (r->request_body->buf) {
+        if (r->request_body->temp_file) {
+
+            if (!(u->output.free = ngx_alloc_chain_link(r->pool))) {
+                ngx_http_upstream_finalize_request(r, u,
+                                                NGX_HTTP_INTERNAL_SERVER_ERROR);
+                return;
+            }
+
+            u->output.free->buf = r->request_body->buf;
+            u->output.free->next = NULL;
+            u->output.allocated = 1;
+
+            r->request_body->buf->pos = r->request_body->buf->start;
+            r->request_body->buf->last = r->request_body->buf->start;
+            r->request_body->buf->tag = u->output.tag;
+
+        } else {
+            r->request_body->buf->pos = r->request_body->buf->start;
+        }
+    }
+
+    u->request_sent = 0;
+
+    if (rc == NGX_AGAIN) {
+        ngx_add_timer(c->write, u->conf->connect_timeout);
+        return;
+    }
+
+    /* rc == NGX_OK */
+
+    ngx_http_upstream_send_request(r, u);
+}
+
+
+static void ngx_http_upstream_reinit(ngx_http_request_t *r,
+                                     ngx_http_upstream_t *u)
+{
+    ngx_chain_t  *cl;
+
+    if (u->reinit_request(r) == NGX_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    /* reinit the request chain */
+    
+    for (cl = r->request_body->bufs; cl; cl = cl->next) {
+        cl->buf->pos = cl->buf->start;
+        cl->buf->file_pos = 0;
+    }
+
+    /* reinit the ngx_output_chain() context */
+
+    u->output.buf = NULL;
+    u->output.in = NULL;
+    u->output.free = NULL;
+    u->output.busy = NULL;
+    
+    /* reinit u->header_in buffer */
+    
+#if 0
+    if (u->cache) {
+        u->header_in.pos = u->header_in.start + u->cache->ctx.header_size;
+        u->header_in.last = u->header_in.pos;
+
+    } else {
+        u->header_in.pos = u->header_in.start;
+        u->header_in.last = u->header_in.start;
+    }
+#else
+        u->header_in.pos = u->header_in.start;
+        u->header_in.last = u->header_in.start;
+#endif
+
+    /* add one more state */
+
+    if (!(u->state = ngx_push_array(&u->states))) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
+
+    u->status = 0;
+    u->status_count = 0;
+}
+
+
+static void ngx_http_upstream_send_request(ngx_http_request_t *r,
+                                           ngx_http_upstream_t *u)
+{
+    int                  rc;
+    ngx_connection_t    *c;
+    ngx_http_log_ctx_t  *ctx;
+    
+    c = u->peer.connection;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
+                   "http upstream send request");
+
+#if (NGX_HAVE_KQUEUE)
+
+    if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT)
+        && !u->request_sent
+        && c->write->pending_eof)
+    {
+        ngx_log_error(NGX_LOG_ERR, c->log, c->write->kq_errno,
+                      "connect() failed");
+
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
+        return;
+    }
+
+#endif
+
+    ctx = c->log->data;
+    ctx->action = "sending request to upstream";
+
+    rc = ngx_output_chain(&u->output,
+                          u->request_sent ? NULL : r->request_body->bufs);
+
+    u->request_sent = 1;
+
+    if (rc == NGX_ERROR) {
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
+        return;
+    }
+
+    if (c->write->timer_set) {
+        ngx_del_timer(c->write);
+    }
+
+    if (rc == NGX_AGAIN) {
+        ngx_add_timer(c->write, u->conf->send_timeout);
+
+        if (ngx_handle_write_event(c->write, u->conf->send_lowat) == NGX_ERROR)
+        {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+
+        return;
+    }
+
+    /* rc == NGX_OK */
+
+    if (c->tcp_nopush == NGX_TCP_NOPUSH_SET) {
+        if (ngx_tcp_push(c->fd) == NGX_ERROR) {
+            ngx_log_error(NGX_LOG_CRIT, c->log, ngx_socket_errno,
+                          ngx_tcp_push_n " failed");
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return; 
+        }
+
+        c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
+        return;
+    }
+    
+    ngx_add_timer(c->read, u->conf->read_timeout);
+
+#if 1
+    if (c->read->ready) {
+    
+        /* post aio operation */
+
+        /*
+         * TODO comment
+         * although we can post aio operation just in the end
+         * of ngx_http_upstream_connect() CHECK IT !!!
+         * it's better to do here because we postpone header buffer allocation
+         */
+
+        ngx_http_upstream_process_header(c->read);
+        return;
+    }
+#endif
+
+    c->write->event_handler = ngx_http_upstream_dummy_handler;
+
+    if (ngx_handle_level_write_event(c->write) == NGX_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+}
+
+
+static void ngx_http_upstream_send_request_handler(ngx_event_t *wev)
+{
+    ngx_connection_t     *c;
+    ngx_http_request_t   *r;
+    ngx_http_log_ctx_t   *ctx;
+    ngx_http_upstream_t  *u;
+
+    c = wev->data;
+    r = c->data;
+    u = r->upstream;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, wev->log, 0,
+                   "http upstream send request handler");
+
+    if (wev->timedout) {
+        ctx = c->log->data;
+        ctx->action = "sending request to upstream";
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
+        return;
+    }
+
+    if (r->connection->write->eof && (!u->cachable || !u->request_sent)) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    ngx_http_upstream_send_request(r, u);
+}
+
+
+static void ngx_http_upstream_process_header(ngx_event_t *rev)
+{
+    ssize_t               n;
+    ngx_int_t             rc;
+    ngx_connection_t     *c;
+    ngx_http_request_t   *r;
+    ngx_http_log_ctx_t   *ctx;
+    ngx_http_upstream_t  *u;
+
+    c = rev->data;
+    r = c->data;
+    u = r->upstream;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, rev->log, 0,
+                   "http upstream process handler");
+
+    ctx = c->log->data;
+    ctx->action = "reading response header from upstream";
+
+    if (rev->timedout) {
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
+        return;
+    }
+    
+    if (u->header_in.start == NULL) {
+        u->header_in.start = ngx_palloc(r->pool, u->conf->header_buffer_size);
+        if (u->header_in.start == NULL) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+
+        u->header_in.pos = u->header_in.start;
+        u->header_in.last = u->header_in.start;
+        u->header_in.end = u->header_in.last + u->conf->header_buffer_size;
+        u->header_in.temporary = 1;
+
+        u->header_in.tag = u->output.tag;
+
+#if 0
+        if (u->cache) {
+            u->header_in.pos += u->cache->ctx.header_size;
+            u->header_in.last = u->header_in.pos;
+        }
+#endif
+    }
+
+    n = ngx_recv(u->peer.connection, u->header_in.last,
+                 u->header_in.end - u->header_in.last);
+
+    if (n == NGX_AGAIN) {
+#if 0
+        ngx_add_timer(rev, u->read_timeout);
+#endif
+
+        if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+
+        return;
+    }
+
+    if (n == 0) {
+        ngx_log_error(NGX_LOG_ERR, rev->log, 0,
+                      "upstream prematurely closed connection");
+    }
+
+    if (n == NGX_ERROR || n == 0) {
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
+        return;
+    }
+
+    if (n == NGX_HTTP_INTERNAL_SERVER_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    u->header_in.last += n;
+
+#if 0
+    u->valid_header_in = 0;
+
+    u->peer.cached = 0;
+#endif
+
+    rc = u->process_header(r);
+
+    if (rc == NGX_AGAIN) {
+#if 0
+        ngx_add_timer(rev, u->read_timeout);
+#endif
+
+        if (u->header_in.last == u->header_in.end) {
+            ngx_log_error(NGX_LOG_ERR, rev->log, 0,
+                          "upstream sent too big header");
+
+            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
+            return;
+        }
+
+        if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+
+        return;
+    }
+
+    if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
+        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
+        return;
+    }
+
+    if (rc == NGX_ERROR || rc == NGX_HTTP_INTERNAL_SERVER_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    /* rc == NGX_OK */
+
+    ngx_http_upstream_send_response(r, u);
+}
+
+
+static void ngx_http_upstream_send_response(ngx_http_request_t *r,
+                                            ngx_http_upstream_t *u)
+{
+    ngx_event_pipe_t          *p;
+    ngx_http_core_loc_conf_t  *clcf;
+
+
+    if (u->send_header(r) == NGX_HTTP_INTERNAL_SERVER_ERROR) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    u->header_sent = 1;
+
+    /* TODO: preallocate event_pipe bufs, look "Content-Length" */
+
+#if 0
+
+    if (u->cache && u->cache->ctx.file.fd != NGX_INVALID_FILE) {
+        if (ngx_close_file(u->cache->ctx.file.fd) == NGX_FILE_ERROR) {
+            ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno,
+                          ngx_close_file_n " \"%s\" failed",
+                          u->cache->ctx.file.name.data);
+        }
+    }
+
+    if (u->cachable) {
+        header = (ngx_http_cache_header_t *) u->header_in->start;
+
+        header->expires = u->cache->ctx.expires;
+        header->last_modified = u->cache->ctx.last_modified;
+        header->date = u->cache->ctx.date;
+        header->length = r->headers_out.content_length_n;
+        u->cache->ctx.length = r->headers_out.content_length_n;
+
+        header->key_len = u->cache->ctx.key0.len;
+        ngx_memcpy(&header->key, u->cache->ctx.key0.data, header->key_len);
+        header->key[header->key_len] = LF;
+    }
+
+#endif
+
+    p = &u->pipe;
+
+    p->output_filter = (ngx_event_pipe_output_filter_pt) ngx_http_output_filter;
+    p->output_ctx = r;
+    p->tag = u->output.tag;
+    p->bufs = u->conf->bufs;     
+    p->busy_size = u->conf->busy_buffers_size;
+    p->upstream = u->peer.connection;
+    p->downstream = r->connection;
+    p->pool = r->pool;
+    p->log = r->connection->log;
+    
+    p->cachable = u->cachable;
+
+    if (!(p->temp_file = ngx_pcalloc(r->pool, sizeof(ngx_temp_file_t)))) {
+        ngx_http_upstream_finalize_request(r, u, 0);
+        return;
+    }
+
+    p->temp_file->file.fd = NGX_INVALID_FILE;
+    p->temp_file->file.log = r->connection->log;
+    p->temp_file->path = u->conf->temp_path;
+    p->temp_file->pool = r->pool;
+    
+    if (u->cachable) {
+        p->temp_file->persistent = 1;
+    } else {
+        p->temp_file->warn = "an upstream response is buffered "
+                             "to a temporary file";
+    }
+
+    p->max_temp_file_size = u->conf->max_temp_file_size;
+    p->temp_file_write_size = u->conf->temp_file_write_size;
+
+    if (!(p->preread_bufs = ngx_alloc_chain_link(r->pool))) {
+        ngx_http_upstream_finalize_request(r, u, 0);
+        return;
+    }
+    p->preread_bufs->buf = &u->header_in;
+    p->preread_bufs->next = NULL;
+    u->header_in.recycled = 1;
+
+    p->preread_size = u->header_in.last - u->header_in.pos;
+
+    if (u->cachable) {
+        p->buf_to_file = ngx_calloc_buf(r->pool);
+        if (p->buf_to_file == NULL) {
+            ngx_http_upstream_finalize_request(r, u, 0);
+            return;
+        }
+        p->buf_to_file->pos = u->header_in.start;
+        p->buf_to_file->last = u->header_in.pos;
+        p->buf_to_file->temporary = 1;
+    }
+
+    if (ngx_event_flags & NGX_USE_AIO_EVENT) {
+        /* the posted aio operation may currupt a shadow buffer */
+        p->single_buf = 1;
+    }
+
+    /* TODO: p->free_bufs = 0 if use ngx_create_chain_of_bufs() */
+    p->free_bufs = 1;
+
+    /*
+     * event_pipe would do u->header_in.last += p->preread_size
+     * as though these bytes were read
+     */
+    u->header_in.last = u->header_in.pos;
+
+    if (u->conf->cyclic_temp_file) {
+
+        /*
+         * we need to disable the use of sendfile() if we use cyclic temp file
+         * because the writing a new data may interfere with sendfile()
+         * that uses the same kernel file pages (at least on FreeBSD)
+         */
+
+        p->cyclic_temp_file = 1;
+        r->connection->sendfile = 0;
+
+    } else {
+        p->cyclic_temp_file = 0;
+    }
+
+    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
+
+    p->read_timeout = u->conf->read_timeout;
+    p->send_timeout = clcf->send_timeout;
+    p->send_lowat = clcf->send_lowat;
+
+    u->peer.connection->read->event_handler = ngx_http_upstream_process_body;
+    r->connection->write->event_handler = ngx_http_upstream_process_body;
+
+    ngx_http_upstream_process_body(u->peer.connection->read);
+}
+
+
+static void ngx_http_upstream_process_body(ngx_event_t *ev)
+{
+    ngx_connection_t     *c;
+    ngx_http_request_t   *r;
+    ngx_http_log_ctx_t   *ctx;
+    ngx_http_upstream_t  *u;
+    ngx_event_pipe_t     *p;
+
+    c = ev->data;
+    r = c->data;
+    u = r->upstream;
+
+    ctx = ev->log->data;
+
+    if (ev->write) {
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0,
+                       "http proxy process downstream");
+        ctx->action = "sending to client";
+    
+    } else {
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0,
+                       "http proxy process upstream");
+        ctx->action = "reading upstream body";
+    }
+    
+    p = &u->pipe;
+
+    if (ev->timedout) {
+        if (ev->write) {
+            p->downstream_error = 1;
+            ngx_log_error(NGX_LOG_ERR, c->log, NGX_ETIMEDOUT,
+                          "client timed out");
+
+        } else {
+            p->upstream_error = 1; 
+            ngx_log_error(NGX_LOG_ERR, c->log, NGX_ETIMEDOUT,
+                          "upstream timed out");
+        }
+
+    } else {
+        if (ngx_event_pipe(p, ev->write) == NGX_ABORT) {
+            ngx_http_upstream_finalize_request(r, u, 0);
+            return;
+        }
+    }
+    
+    if (u->peer.connection) {
+
+#if (NGX_HTTP_FILE_CACHE)
+
+        if (p->upstream_done && u->cachable) {
+            if (ngx_http_cache_update(r) == NGX_ERROR) {
+                ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
+                ngx_http_upstream_finalize_request(r, u, 0);
+                return;
+            }
+
+        } else if (p->upstream_eof && u->cachable) {
+
+            /* TODO: check length & update cache */
+
+            if (ngx_http_cache_update(r) == NGX_ERROR) {
+                ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
+                ngx_http_upstream_finalize_request(r, u, 0);
+                return;
+            }
+        }
+
+#endif
+
+        if (p->upstream_done || p->upstream_eof || p->upstream_error) {
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ev->log, 0,
+                           "http proxy upstream exit: %p", p->out);
+#if 0
+            ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
+#endif
+            ngx_http_upstream_finalize_request(r, u, 0);
+            return;
+        }
+    }
+
+    if (p->downstream_error) {
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0,
+                       "http proxy downstream error");
+
+        if (!u->cachable && u->peer.connection) {
+            ngx_http_upstream_finalize_request(r, u, 0);
+        }
+    }
+}
+
+
+static void ngx_http_upstream_dummy_handler(ngx_event_t *wev)
+{
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, wev->log, 0,
+                   "http upstream dummy handler");
+}
+
+
+static void ngx_http_upstream_next(ngx_http_request_t *r,
+                                   ngx_http_upstream_t *u,
+                                   ngx_uint_t ft_type)
+{
+    ngx_uint_t  status;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "http next upstream, %xD", ft_type);
+
+#if 0
+    ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
+#endif
+
+    if (ft_type != NGX_HTTP_UPSTREAM_FT_HTTP_404) {
+        ngx_event_connect_peer_failed(&u->peer);
+    }
+    
+    if (ft_type == NGX_HTTP_UPSTREAM_FT_TIMEOUT) {
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, NGX_ETIMEDOUT,
+                      "upstream timed out");
+    }
+    
+    if (u->peer.cached && ft_type == NGX_HTTP_UPSTREAM_FT_ERROR) {
+        status = 0;
+
+    } else {
+        switch(ft_type) {
+
+        case NGX_HTTP_UPSTREAM_FT_TIMEOUT:
+            status = NGX_HTTP_GATEWAY_TIME_OUT;
+            break;
+
+        case NGX_HTTP_UPSTREAM_FT_HTTP_500:
+            status = NGX_HTTP_INTERNAL_SERVER_ERROR;
+            break;
+
+        case NGX_HTTP_UPSTREAM_FT_HTTP_404:
+            status = NGX_HTTP_NOT_FOUND;
+            break;
+
+        /*
+         * NGX_HTTP_UPSTREAM_FT_BUSY_LOCK and NGX_HTTP_UPSTREAM_FT_MAX_WAITING
+         * never reach here
+         */
+
+        default:
+            status = NGX_HTTP_BAD_GATEWAY;
+        }
+    }
+
+    if (r->connection->write->eof) {
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
+        return;
+    }
+
+    if (status) {
+        u->state->status = status;
+
+        if (u->peer.tries == 0 || !(u->conf->next_upstream & ft_type))
+        {
+
+#if (NGX_HTTP_CACHE)
+
+            if (u->stale && (u->conf->use_stale & ft_type)) {
+                ngx_http_upstream_finalize_request(r, u,
+                                       ngx_http_proxy_send_cached_response(r));
+                return;
+            }
+
+#endif
+
+            ngx_http_upstream_finalize_request(r, u, status);
+            return;
+        }
+    }
+
+    if (u->peer.connection) {
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "close http upstream connection: %d",
+                       u->peer.connection->fd);
+
+        ngx_close_connection(u->peer.connection);
+    }
+
+#if 0
+    if (u->conf->busy_lock && !u->busy_locked) {
+        ngx_http_upstream_busy_lock(p);
+        return;
+    }
+#endif
+
+    ngx_http_upstream_connect(r, u);
+}
+
+
+static void ngx_http_upstream_finalize_request(ngx_http_request_t *r,
+                                               ngx_http_upstream_t *u,
+                                               ngx_int_t rc)
+{
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "finalize http upstream request");
+
+    u->finalize_request(r, rc);
+
+    if (u->peer.connection) {
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "close http upstream connection: %d",
+                       u->peer.connection->fd);
+
+        ngx_close_connection(u->peer.connection);
+    }
+
+    if (u->header_sent
+        && (rc == NGX_ERROR || rc >= NGX_HTTP_SPECIAL_RESPONSE))
+    {
+        rc = 0;
+    }
+
+    if (u->saved_ctx) {
+        r->connection->log->data = u->saved_ctx;
+        r->connection->log->handler = u->saved_handler;
+    }
+
+    if (u->pipe.temp_file->file.fd) {
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "http upstream temp fd: %d",
+                       u->pipe.temp_file->file.fd);
+    }
+
+#if 0
+    if (u->cache) {
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "http proxy cache fd: %d",
+                       u->cache->ctx.file.fd);
+    }
+#endif
+
+    if (u->pipe.temp_file->file.fd) {
+        r->file.fd = u->pipe.temp_file->file.fd;
+
+#if 0
+    } else if (u->cache) {
+        r->file.fd = u->cache->ctx.file.fd;
+#endif
+    }
+
+    if (rc == 0 && r->main == NULL) {
+        rc = ngx_http_send_last(r);
+    }
+
+    ngx_http_finalize_request(r, rc);
+}
+
+
+static size_t ngx_http_upstream_log_status_getlen(ngx_http_request_t *r,
+                                                  uintptr_t data)
+{
+    if (r->upstream) {
+        return r->upstream->states.nelts * (3 + 2);
+    }
+
+    return 1;
+}
+
+
+static u_char *ngx_http_upstream_log_status(ngx_http_request_t *r, u_char *buf,
+                                            ngx_http_log_op_t *op)
+{
+    ngx_uint_t                  i;
+    ngx_http_upstream_t        *u;
+    ngx_http_upstream_state_t  *state;
+
+    u = r->upstream;
+
+    if (u == NULL) {
+        *buf = '-';
+        return buf + 1;
+    }
+
+    i = 0;
+    state = u->states.elts;
+
+    for ( ;; ) {
+        if (state[i].status == 0) {
+            *buf++ = '-';
+
+        } else {
+            buf = ngx_sprintf(buf, "%ui", state[i].status);
+        }
+
+        if (++i == u->states.nelts) {
+            return buf;
+        }
+
+        *buf++ = ',';
+        *buf++ = ' ';
+    }
+}
+
+
+u_char *ngx_http_upstream_log_error(void *data, u_char *buf, size_t len)
+{
+    ngx_http_log_ctx_t *ctx = data;
+    
+    u_char                 *p;
+    ngx_int_t               escape;
+    ngx_str_t               uri;
+    ngx_http_request_t     *r;
+    ngx_http_upstream_t    *u;
+    ngx_peer_connection_t  *peer;
+
+    r = ctx->request;
+    u = r->upstream;
+    peer = &u->peer;
+
+    p = ngx_snprintf(buf, len,
+                     " while %s, client: %V, URL: %V, upstream: %V%V%s%V",
+                     ctx->action,
+                     &r->connection->addr_text,
+                     &r->unparsed_uri,
+                     &u->schema,
+                     &peer->peers->peer[peer->cur_peer].name,
+                     peer->peers->peer[peer->cur_peer].uri_separator,
+                     &u->uri);
+    len -= p - buf;
+    buf = p;
+
+    if (r->quoted_uri) {
+        escape = 2 * ngx_escape_uri(NULL, r->uri.data + u->location->len,
+                                    r->uri.len - u->location->len,
+                                    NGX_ESCAPE_URI);
+    } else {
+        escape = 0;
+    }
+
+    if (escape) {
+        if (len >= r->uri.len - u->location->len + escape) {
+
+            ngx_escape_uri(buf, r->uri.data + u->location->len,
+                           r->uri.len - u->location->len, NGX_ESCAPE_URI);
+
+            buf += r->uri.len - u->location->len + escape;
+
+            if (r->args.len == 0) {
+                return buf;
+            }
+
+            len -= r->uri.len - u->location->len + escape;
+
+            return ngx_snprintf(buf, len, "?%V", &r->args);
+        }
+
+        p = ngx_palloc(r->pool, r->uri.len - u->location->len + escape);
+        if (p == NULL) {
+            return buf;
+        }
+
+        ngx_escape_uri(p, r->uri.data + u->location->len,
+                       r->uri.len - u->location->len, NGX_ESCAPE_URI);
+
+        uri.len = r->uri.len - u->location->len + escape;
+        uri.data = p;
+
+    } else {
+        uri.len = r->uri.len - u->location->len;
+        uri.data = r->uri.data + u->location->len;
+
+    }
+
+    return ngx_snprintf(buf, len, "%V%s%V", 
+                        &uri, r->args.len ? "?" : "", &r->args);
+}
+
+
+static ngx_int_t ngx_http_upstream_add_log_formats(ngx_conf_t *cf)
+{
+    ngx_http_log_op_name_t  *op;
+
+    for (op = ngx_http_upstream_log_fmt_ops; op->name.len; op++) { /* void */ }
+    op->run = NULL;
+
+    for (op = ngx_http_log_fmt_ops; op->run; op++) {
+        if (op->name.len == 0) {
+            op = (ngx_http_log_op_name_t *) op->run;
+        }
+    }
+
+    op->run = (ngx_http_log_op_run_pt) ngx_http_upstream_log_fmt_ops;
+
+    return NGX_OK;
+}