new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_header_filter_module.c
@@ -0,0 +1,478 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+#include <nginx.h>
+
+
+static ngx_int_t ngx_http_header_filter_init(ngx_cycle_t *cycle);
+static ngx_int_t ngx_http_header_filter(ngx_http_request_t *r);
+
+
+static ngx_http_module_t  ngx_http_header_filter_module_ctx = {
+    NULL,                                  /* 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_header_filter_module = {
+    NGX_MODULE,
+    &ngx_http_header_filter_module_ctx,    /* module context */
+    NULL,                                  /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    ngx_http_header_filter_init,           /* init module */
+    NULL                                   /* init process */
+};
+
+
+static char server_string[] = "Server: " NGINX_VER CRLF;
+
+
+static ngx_str_t http_codes[] = {
+
+    ngx_string("200 OK"),
+    ngx_null_string,  /* "201 Created" */
+    ngx_null_string,  /* "202 Accepted" */
+    ngx_null_string,  /* "203 Non-Authoritative Information" */
+    ngx_null_string,  /* "204 No Content" */
+    ngx_null_string,  /* "205 Reset Content" */
+    ngx_string("206 Partial Content"),
+
+    /* ngx_null_string, */  /* "207 Multi-Status" */
+
+#define NGX_HTTP_LEVEL_200  7
+
+    /* ngx_null_string, */  /* "300 Multiple Choices" */
+
+    ngx_string("301 Moved Permanently"),
+    ngx_string("302 Moved Temporarily"),
+    ngx_null_string,  /* "303 See Other" */
+    ngx_string("304 Not Modified"),
+
+    /* ngx_null_string, */  /* "305 Use Proxy" */
+    /* ngx_null_string, */  /* "306 unused" */
+    /* ngx_null_string, */  /* "307 Temporary Redirect" */
+
+#define NGX_HTTP_LEVEL_300  4
+
+    ngx_string("400 Bad Request"),
+    ngx_string("401 Unauthorized"),
+    ngx_string("402 Payment Required"),
+    ngx_string("403 Forbidden"),
+    ngx_string("404 Not Found"),
+    ngx_string("405 Not Allowed"),
+    ngx_string("406 Not Acceptable"),
+    ngx_null_string,  /* "407 Proxy Authentication Required" */
+    ngx_string("408 Request Time-out"),
+    ngx_null_string,  /* "409 Conflict" */
+    ngx_string("410 Gone"),
+    ngx_string("411 Length Required"),
+    ngx_null_string,  /* "412 Precondition Failed" */
+    ngx_string("413 Request Entity Too Large"),
+    ngx_null_string,  /* "414 Request-URI Too Large", but we never send it
+                       * because we treat such requests as the HTTP/0.9
+                       * requests and send only a body without a header
+                       */
+    ngx_null_string,  /* "415 Unsupported Media Type" */
+    ngx_string("416 Requested Range Not Satisfiable"),
+
+    /* ngx_null_string, */  /* "417 Expectation Failed" */
+    /* ngx_null_string, */  /* "418 unused" */
+    /* ngx_null_string, */  /* "419 unused" */
+    /* ngx_null_string, */  /* "420 unused" */
+    /* ngx_null_string, */  /* "421 unused" */
+    /* ngx_null_string, */  /* "422 Unprocessable Entity" */
+    /* ngx_null_string, */  /* "423 Locked" */
+    /* ngx_null_string, */  /* "424 Failed Dependency" */
+
+#define NGX_HTTP_LEVEL_400  17
+
+    ngx_string("500 Internal Server Error"),
+    ngx_string("501 Method Not Implemented"),
+    ngx_string("502 Bad Gateway"),
+    ngx_string("503 Service Temporarily Unavailable"),
+    ngx_string("504 Gateway Time-out")
+
+    /* ngx_null_string, */  /* "505 HTTP Version Not Supported" */
+    /* ngx_null_string, */  /* "506 Variant Also Negotiates" */
+    /* ngx_null_string, */  /* "507 Insufficient Storage" */
+    /* ngx_null_string, */  /* "508 unused" */
+    /* ngx_null_string, */  /* "509 unused" */
+    /* ngx_null_string, */  /* "510 Not Extended" */
+};
+
+
+ngx_http_header_t  ngx_http_headers_out[] = {
+    { ngx_string("Server"), offsetof(ngx_http_headers_out_t, server) },
+    { ngx_string("Date"), offsetof(ngx_http_headers_out_t, date) },
+    { ngx_string("Content-Type"),
+                 offsetof(ngx_http_headers_out_t, content_type) },
+    { ngx_string("Content-Length"),
+                 offsetof(ngx_http_headers_out_t, content_length) },
+    { ngx_string("Content-Encoding"),
+                 offsetof(ngx_http_headers_out_t, content_encoding) },
+    { ngx_string("Location"), offsetof(ngx_http_headers_out_t, location) },
+    { ngx_string("Last-Modified"),
+                 offsetof(ngx_http_headers_out_t, last_modified) },
+    { ngx_string("Accept-Ranges"),
+                 offsetof(ngx_http_headers_out_t, accept_ranges) },
+    { ngx_string("Expires"), offsetof(ngx_http_headers_out_t, expires) },
+    { ngx_string("Cache-Control"),
+                 offsetof(ngx_http_headers_out_t, cache_control) },
+    { ngx_string("ETag"), offsetof(ngx_http_headers_out_t, etag) },
+
+    { ngx_null_string, 0 }
+};
+
+
+static ngx_int_t
+ngx_http_header_filter(ngx_http_request_t *r)
+{
+    u_char                    *p;
+    size_t                     len;
+    ngx_uint_t                 status, i;
+    ngx_buf_t                 *b;
+    ngx_chain_t                out;
+    ngx_list_part_t           *part;
+    ngx_table_elt_t           *header;
+    ngx_http_core_loc_conf_t  *clcf;
+
+    if (r->http_version < NGX_HTTP_VERSION_10) {
+        return NGX_OK;
+    }
+
+    if (r->method == NGX_HTTP_HEAD) {
+        r->header_only = 1;
+    }
+
+    if (r->headers_out.last_modified_time != -1) {
+        if (r->headers_out.status != NGX_HTTP_OK
+            && r->headers_out.status != NGX_HTTP_NOT_MODIFIED
+            && r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT)
+        {
+            r->headers_out.last_modified_time = -1;
+            r->headers_out.last_modified = NULL;
+        }
+    }
+
+    len = sizeof("HTTP/1.x ") - 1 + sizeof(CRLF) - 1
+          /* the end of the header */
+          + sizeof(CRLF) - 1;
+
+    /* status line */
+
+    if (r->headers_out.status_line.len) {
+        len += r->headers_out.status_line.len;
+#if (NGX_SUPPRESS_WARN)
+        status = NGX_INVALID_ARRAY_INDEX;
+#endif
+
+    } else {
+
+        if (r->headers_out.status < NGX_HTTP_MOVED_PERMANENTLY) {
+            /* 2XX */
+            status = r->headers_out.status - NGX_HTTP_OK;
+
+        } else if (r->headers_out.status < NGX_HTTP_BAD_REQUEST) {
+            /* 3XX */
+            status = r->headers_out.status - NGX_HTTP_MOVED_PERMANENTLY
+                                           + NGX_HTTP_LEVEL_200;
+
+            if (r->headers_out.status == NGX_HTTP_NOT_MODIFIED) {
+                r->header_only = 1;
+            }
+
+        } else if (r->headers_out.status < NGX_HTTP_INTERNAL_SERVER_ERROR) {
+            /* 4XX */
+            status = r->headers_out.status - NGX_HTTP_BAD_REQUEST
+                                           + NGX_HTTP_LEVEL_200
+                                           + NGX_HTTP_LEVEL_300;
+
+        } else {
+            /* 5XX */
+            status = r->headers_out.status - NGX_HTTP_INTERNAL_SERVER_ERROR
+                                           + NGX_HTTP_LEVEL_200
+                                           + NGX_HTTP_LEVEL_300
+                                           + NGX_HTTP_LEVEL_400;
+        }
+
+        len += http_codes[status].len;
+    }
+
+    if (r->headers_out.server && r->headers_out.server->key.len) {
+        len += r->headers_out.server->key.len
+               + r->headers_out.server->value.len + 2;
+    } else {
+        len += sizeof(server_string) - 1;
+    }
+
+    if (r->headers_out.date && r->headers_out.date->key.len) {
+        len += r->headers_out.date->key.len
+               + r->headers_out.date->value.len + 2;
+    } else {
+        len += sizeof("Date: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
+    }
+
+    if (r->headers_out.content_length == NULL) {
+        if (r->headers_out.content_length_n >= 0) {
+            len += sizeof("Content-Length: ") - 1 + NGX_OFF_T_LEN + 2;
+        }
+    }
+
+    if (r->headers_out.content_type && r->headers_out.content_type->value.len) {
+        r->headers_out.content_type->key.len = 0;
+        len += sizeof("Content-Type: ") - 1
+               + r->headers_out.content_type->value.len + 2;
+
+        if (r->headers_out.charset.len) {
+            len += sizeof("; charset=") - 1 + r->headers_out.charset.len;
+        }
+    }
+
+    if (r->headers_out.location
+        && r->headers_out.location->value.len
+        && r->headers_out.location->value.data[0] == '/')
+    {
+        r->headers_out.location->key.len = 0;
+        len += sizeof("Location: http://") - 1
+               + r->server_name.len + r->headers_out.location->value.len + 2;
+
+        if (r->port != 80) {
+            len += r->port_text->len;
+        }
+    }
+
+    if (r->headers_out.last_modified && r->headers_out.last_modified->key.len) {
+        len += r->headers_out.last_modified->key.len
+               + r->headers_out.last_modified->value.len + 2;
+
+    } else if (r->headers_out.last_modified_time != -1) {
+        len += sizeof("Last-Modified: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
+    }
+
+    if (r->chunked) {
+        len += sizeof("Transfer-Encoding: chunked" CRLF) - 1;
+    }
+
+    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
+
+    if (r->keepalive) {
+        len += sizeof("Connection: keep-alive" CRLF) - 1;
+
+        /*
+         * MSIE and Opera ignore the "Keep-Alive: timeout=<N>" header.
+         * MSIE keeps the connection alive for about 60-65 seconds.
+         * Opera keeps the connection alive very long.
+         * Mozilla keeps the connection alive for N plus about 1-10 seconds.
+         * Konqueror keeps the connection alive for about N seconds.
+         */
+
+        if (clcf->keepalive_header) {
+            len += sizeof("Keep-Alive: timeout=") - 1 + NGX_TIME_T_LEN + 2;
+        }
+
+    } else {
+        len += sizeof("Connection: closed" CRLF) - 1;
+    }
+
+    part = &r->headers_out.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 (header[i].key.len == 0) {
+            continue;
+        }
+
+        len += header[i].key.len + sizeof(": ") - 1 + header[i].value.len
+               + sizeof(CRLF) - 1;
+    }
+
+    b = ngx_create_temp_buf(r->pool, len);
+    if (b == NULL) {
+        return NGX_ERROR;
+    }
+
+    /* "HTTP/1.x " */
+    b->last = ngx_cpymem(b->last, "HTTP/1.1 ", sizeof("HTTP/1.x ") - 1);
+
+    /* status line */
+    if (r->headers_out.status_line.len) {
+        b->last = ngx_cpymem(b->last, r->headers_out.status_line.data,
+                             r->headers_out.status_line.len);
+
+    } else {
+        b->last = ngx_cpymem(b->last, http_codes[status].data,
+                             http_codes[status].len);
+    }
+    *b->last++ = CR; *b->last++ = LF;
+
+    if (!(r->headers_out.server && r->headers_out.server->key.len)) {
+        b->last = ngx_cpymem(b->last, server_string, sizeof(server_string) - 1);
+    }
+
+    if (!(r->headers_out.date && r->headers_out.date->key.len)) {
+        b->last = ngx_cpymem(b->last, "Date: ", sizeof("Date: ") - 1);
+        b->last = ngx_cpymem(b->last, ngx_cached_http_time.data,
+                             ngx_cached_http_time.len);
+
+        *b->last++ = CR; *b->last++ = LF;
+    }
+
+    if (r->headers_out.content_length == NULL) {
+        if (r->headers_out.content_length_n >= 0) {
+            b->last = ngx_sprintf(b->last, "Content-Length: %O" CRLF,
+                                  r->headers_out.content_length_n);
+        }
+    }
+
+    if (r->headers_out.content_type && r->headers_out.content_type->value.len) {
+        b->last = ngx_cpymem(b->last, "Content-Type: ",
+                             sizeof("Content-Type: ") - 1);
+        p = b->last;
+        b->last = ngx_cpymem(b->last, r->headers_out.content_type->value.data,
+                             r->headers_out.content_type->value.len);
+
+        if (r->headers_out.charset.len) {
+            b->last = ngx_cpymem(b->last, "; charset=",
+                                 sizeof("; charset=") - 1);
+            b->last = ngx_cpymem(b->last, r->headers_out.charset.data,
+                                 r->headers_out.charset.len);
+
+            r->headers_out.content_type->value.len = b->last - p;
+            r->headers_out.content_type->value.data = p;
+        }
+
+        *b->last++ = CR; *b->last++ = LF;
+    }
+
+    if (r->headers_out.location
+        && r->headers_out.location->value.len
+        && r->headers_out.location->value.data[0] == '/')
+    {
+        p = b->last + sizeof("Location: ") - 1;
+        b->last = ngx_cpymem(b->last, "Location: http://",
+                             sizeof("Location: http://") - 1);
+        b->last = ngx_cpymem(b->last, r->server_name.data,
+                             r->server_name.len);
+        if (r->port != 80) {
+            b->last = ngx_cpymem(b->last, r->port_text->data,
+                                 r->port_text->len);
+        }
+
+        b->last = ngx_cpymem(b->last, r->headers_out.location->value.data,
+                             r->headers_out.location->value.len);
+
+        r->headers_out.location->value.len = b->last - p;
+        r->headers_out.location->value.data = p;
+
+        *b->last++ = CR; *b->last++ = LF;
+    }
+
+    if (!(r->headers_out.last_modified && r->headers_out.last_modified->key.len)
+        && r->headers_out.last_modified_time != -1)
+    {
+        b->last = ngx_cpymem(b->last, "Last-Modified: ",
+                             sizeof("Last-Modified: ") - 1);
+        b->last = ngx_http_time(b->last, r->headers_out.last_modified_time);
+
+        *b->last++ = CR; *b->last++ = LF;
+    }
+
+    if (r->chunked) {
+        b->last = ngx_cpymem(b->last, "Transfer-Encoding: chunked" CRLF,
+                             sizeof("Transfer-Encoding: chunked" CRLF) - 1);
+    }
+
+    if (r->keepalive) {
+        b->last = ngx_cpymem(b->last, "Connection: keep-alive" CRLF,
+                             sizeof("Connection: keep-alive" CRLF) - 1);
+
+        if (clcf->keepalive_header) {
+            b->last = ngx_sprintf(b->last, "Keep-Alive: timeout=%T" CRLF,
+                                  clcf->keepalive_header);
+        }
+
+    } else {
+        b->last = ngx_cpymem(b->last, "Connection: close" CRLF,
+                             sizeof("Connection: close" CRLF) - 1);
+    }
+
+    part = &r->headers_out.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 (header[i].key.len == 0) {
+            continue;
+        }
+
+        b->last = ngx_cpymem(b->last, header[i].key.data, header[i].key.len);
+        *b->last++ = ':' ; *b->last++ = ' ' ;
+
+        b->last = ngx_cpymem(b->last, header[i].value.data,
+                             header[i].value.len);
+        *b->last++ = CR; *b->last++ = LF;
+    }
+
+#if (NGX_DEBUG)
+    *b->last = '\0';
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "%s\n", b->pos);
+#endif
+
+    /* the end of HTTP header */
+    *b->last++ = CR; *b->last++ = LF;
+
+    r->header_size = b->last - b->pos;
+
+    if (r->header_only) {
+        b->last_buf = 1;
+    }
+
+    out.buf = b;
+    out.next = NULL;
+
+    return ngx_http_write_filter(r, &out);
+}
+
+
+static ngx_int_t
+ngx_http_header_filter_init(ngx_cycle_t *cycle)
+{
+    ngx_http_top_header_filter = ngx_http_header_filter;
+
+    return NGX_OK;
+}