# HG changeset patch
# User Igor Sysoev <http://sysoev.ru>
# Date 1223841600 -14400
# Node ID b246022ef4543cf779e3a0e040922d069c109171
# Parent  b453a4324c60689e0def20c4fcd1311726726640
nginx 0.7.18

    *) Change: the "underscores_in_headers" directive; now nginx does not
       allows underscores in a client request header line names.

    *) Feature: the ngx_http_secure_link_module.

    *) Feature: the "real_ip_header" directive supports any header.

    *) Feature: the "log_subrequest" directive.

    *) Feature: the $realpath_root variable.

    *) Feature: the "http_502" and "http_504" parameters of the
       "proxy_next_upstream" directive.

    *) Bugfix: the "http_503" parameter of the "proxy_next_upstream" or
       "fastcgi_next_upstream" directives did not work.

    *) Bugfix: nginx might send a "Transfer-Encoding: chunked" heaer line
       for HEAD requests.

    *) Bugfix: now accept threshold depends on worker_connections.

diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,29 @@
 
+Changes with nginx 0.7.18                                        13 Oct 2008
+
+    *) Change: the "underscores_in_headers" directive; now nginx does not 
+       allows underscores in a client request header line names.
+
+    *) Feature: the ngx_http_secure_link_module.
+
+    *) Feature: the "real_ip_header" directive supports any header.
+
+    *) Feature: the "log_subrequest" directive.
+
+    *) Feature: the $realpath_root variable.
+
+    *) Feature: the "http_502" and "http_504" parameters of the 
+       "proxy_next_upstream" directive.
+
+    *) Bugfix: the "http_503" parameter of the "proxy_next_upstream" or 
+       "fastcgi_next_upstream" directives did not work.
+
+    *) Bugfix: nginx might send a "Transfer-Encoding: chunked" heaer line 
+       for HEAD requests.
+
+    *) Bugfix: now accept threshold depends on worker_connections.
+
+
 Changes with nginx 0.7.17                                        15 Sep 2008
 
     *) Feature: now the "directio" directive works on Linux.
diff --git a/CHANGES.ru b/CHANGES.ru
--- a/CHANGES.ru
+++ b/CHANGES.ru
@@ -1,4 +1,30 @@
 
+Изменения в nginx 0.7.18                                          13.10.2008
+
+    *) Изменение: директива underscores_in_headers; теперь nginx по 
+       умолчанию не разрешает подчёркивания в именах строк в заголовке 
+       запроса клиента.
+
+    *) Добавление: модуль ngx_http_secure_link_module.
+
+    *) Добавление: директива real_ip_header поддерживает любой заголовок.
+
+    *) Добавление: директива log_subrequest.
+
+    *) Добавление: переменная $realpath_root.
+
+    *) Добавление: параметры http_502 и http_504 в директиве 
+       proxy_next_upstream.
+
+    *) Исправление: параметр http_503 в директивах proxy_next_upstream или 
+       fastcgi_next_upstream не работал.
+
+    *) Исправление: nginx мог выдавать строку "Transfer-Encoding: chunked" 
+       для запросов HEAD.
+
+    *) Исправление: теперь accept-лимит зависит от числа worker_connections.
+
+
 Изменения в nginx 0.7.17                                          15.09.2008
 
     *) Добавление: директива directio теперь работает на Linux.
diff --git a/auto/modules b/auto/modules
--- a/auto/modules
+++ b/auto/modules
@@ -284,6 +284,12 @@ if [ $HTTP_BROWSER = YES ]; then
     HTTP_SRCS="$HTTP_SRCS $HTTP_BROWSER_SRCS"
 fi
 
+if [ $HTTP_SECURE_LINK = YES ]; then
+    USE_MD5=YES
+    HTTP_MODULES="$HTTP_MODULES $HTTP_SECURE_LINK_MODULE"
+    HTTP_SRCS="$HTTP_SRCS $HTTP_SECURE_LINK_SRCS"
+fi
+
 if [ $HTTP_FLV = YES ]; then
     HTTP_MODULES="$HTTP_MODULES $HTTP_FLV_MODULE"
     HTTP_SRCS="$HTTP_SRCS $HTTP_FLV_SRCS"
diff --git a/auto/options b/auto/options
--- a/auto/options
+++ b/auto/options
@@ -77,6 +77,7 @@ HTTP_MEMCACHED=YES
 HTTP_LIMIT_ZONE=YES
 HTTP_EMPTY_GIF=YES
 HTTP_BROWSER=YES
+HTTP_SECURE_LINK=NO
 HTTP_FLV=NO
 HTTP_GZIP_STATIC=NO
 HTTP_UPSTREAM_IP_HASH=YES
@@ -173,6 +174,7 @@ do
         --with-http_flv_module)          HTTP_FLV=YES               ;;
         --with-http_gzip_static_module)  HTTP_GZIP_STATIC=YES       ;;
         --with-http_random_index_module) HTTP_RANDOM_INDEX=YES      ;;
+        --with-http_secure_link_module)  HTTP_SECURE_LINK=YES       ;;
 
         --without-http_charset_module)   HTTP_CHARSET=NO            ;;
         --without-http_gzip_module)      HTTP_GZIP=NO               ;;
@@ -290,6 +292,7 @@ cat << END
   --with-http_flv_module             enable ngx_http_flv_module
   --with-http_gzip_static_module     enable ngx_http_gzip_static_module
   --with-http_random_index_module    enable ngx_http_random_index_module
+  --with-http_secure_link_module     enable ngx_http_secure_link_module
   --with-http_stub_status_module     enable ngx_http_stub_status_module
 
   --without-http_charset_module      disable ngx_http_charset_module
diff --git a/auto/sources b/auto/sources
--- a/auto/sources
+++ b/auto/sources
@@ -425,6 +425,10 @@ HTTP_BROWSER_MODULE=ngx_http_browser_mod
 HTTP_BROWSER_SRCS=src/http/modules/ngx_http_browser_module.c
 
 
+HTTP_SECURE_LINK_MODULE=ngx_http_secure_link_module
+HTTP_SECURE_LINK_SRCS=src/http/modules/ngx_http_secure_link_module.c
+
+
 HTTP_FLV_MODULE=ngx_http_flv_module
 HTTP_FLV_SRCS=src/http/modules/ngx_http_flv_module.c
 
diff --git a/src/core/nginx.h b/src/core/nginx.h
--- a/src/core/nginx.h
+++ b/src/core/nginx.h
@@ -8,7 +8,7 @@
 #define _NGINX_H_INCLUDED_
 
 
-#define NGINX_VERSION      "0.7.17"
+#define NGINX_VERSION      "0.7.19"
 #define NGINX_VER          "nginx/" NGINX_VERSION
 
 #define NGINX_VAR          "NGINX"
diff --git a/src/core/ngx_config.h b/src/core/ngx_config.h
--- a/src/core/ngx_config.h
+++ b/src/core/ngx_config.h
@@ -110,8 +110,6 @@ typedef intptr_t        ngx_flag_t;
 #define ngx_inline      inline
 #endif
 
-#define NGX_ACCEPT_THRESHOLD   100
-
 #ifndef INADDR_NONE  /* Solaris */
 #define INADDR_NONE  ((unsigned int) -1)
 #endif
diff --git a/src/core/ngx_connection.c b/src/core/ngx_connection.c
--- a/src/core/ngx_connection.c
+++ b/src/core/ngx_connection.c
@@ -593,7 +593,7 @@ ngx_get_connection(ngx_socket_t s, ngx_l
 
     if (c == NULL) {
         ngx_log_error(NGX_LOG_ALERT, log, 0,
-                      "%ui worker_connections is not enough",
+                      "%ui worker_connections are not enough",
                       ngx_cycle->connection_n);
 
         /* ngx_mutex_unlock */
diff --git a/src/event/ngx_event_accept.c b/src/event/ngx_event_accept.c
--- a/src/event/ngx_event_accept.c
+++ b/src/event/ngx_event_accept.c
@@ -82,7 +82,7 @@ ngx_event_accept(ngx_event_t *ev)
         ngx_atomic_fetch_add(ngx_stat_accepted, 1);
 #endif
 
-        ngx_accept_disabled = NGX_ACCEPT_THRESHOLD
+        ngx_accept_disabled = ngx_cycle->connection_n / 8
                               - ngx_cycle->free_connection_n;
 
         c = ngx_get_connection(s, ev->log);
diff --git a/src/http/modules/ngx_http_chunked_filter_module.c b/src/http/modules/ngx_http_chunked_filter_module.c
--- a/src/http/modules/ngx_http_chunked_filter_module.c
+++ b/src/http/modules/ngx_http_chunked_filter_module.c
@@ -53,7 +53,8 @@ ngx_http_chunked_header_filter(ngx_http_
     if (r->headers_out.status == NGX_HTTP_NOT_MODIFIED
         || r->headers_out.status == NGX_HTTP_NO_CONTENT
         || r->headers_out.status == NGX_HTTP_CREATED
-        || r != r->main)
+        || r != r->main
+        || (r->method & NGX_HTTP_HEAD))
     {
         return ngx_http_next_header_filter(r);
     }
diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -1031,7 +1031,7 @@ ngx_http_fastcgi_process_header(ngx_http
 
             part_start = u->buffer.pos;
 
-            rc = ngx_http_parse_header_line(r, &u->buffer);
+            rc = ngx_http_parse_header_line(r, &u->buffer, 1);
 
             ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                            "http fastcgi parser: %d", rc);
@@ -1076,7 +1076,7 @@ ngx_http_fastcgi_process_header(ngx_http
 
                     f->split_parts->nelts = 0;
 
-                    rc = ngx_http_parse_header_line(r, &buf);
+                    rc = ngx_http_parse_header_line(r, &buf, 1);
 
                     h->key.len = r->header_name_end - r->header_name_start;
                     h->key.data = r->header_name_start;
diff --git a/src/http/modules/ngx_http_log_module.c b/src/http/modules/ngx_http_log_module.c
--- a/src/http/modules/ngx_http_log_module.c
+++ b/src/http/modules/ngx_http_log_module.c
@@ -28,6 +28,7 @@ struct ngx_http_log_op_s {
 
 typedef struct {
     ngx_str_t                   name;
+    ngx_array_t                *flushes;
     ngx_array_t                *ops;        /* array of ngx_http_log_op_t */
 } ngx_http_log_fmt_t;
 
@@ -49,7 +50,7 @@ typedef struct {
     ngx_http_log_script_t      *script;
     time_t                      disk_full_time;
     time_t                      error_log_time;
-    ngx_array_t                *ops;        /* array of ngx_http_log_op_t */
+    ngx_http_log_fmt_t         *format;
 } ngx_http_log_t;
 
 
@@ -113,7 +114,7 @@ static char *ngx_http_log_set_log(ngx_co
 static char *ngx_http_log_set_format(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
 static char *ngx_http_log_compile_format(ngx_conf_t *cf,
-    ngx_array_t *ops, ngx_array_t *args, ngx_uint_t s);
+    ngx_array_t *flushes, ngx_array_t *ops, ngx_array_t *args, ngx_uint_t s);
 static char *ngx_http_log_open_file_cache(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
 static ngx_int_t ngx_http_log_init(ngx_conf_t *cf);
@@ -242,9 +243,11 @@ ngx_http_log_handler(ngx_http_request_t 
             continue;
         }
 
+        ngx_http_script_flush_no_cacheable_variables(r, log[l].format->flushes);
+
         len = 0;
-        op = log[l].ops->elts;
-        for (i = 0; i < log[l].ops->nelts; i++) {
+        op = log[l].format->ops->elts;
+        for (i = 0; i < log[l].format->ops->nelts; i++) {
             if (op[i].len == 0) {
                 len += op[i].getlen(r, op[i].data);
 
@@ -271,7 +274,7 @@ ngx_http_log_handler(ngx_http_request_t 
 
                 p = file->pos;
 
-                for (i = 0; i < log[l].ops->nelts; i++) {
+                for (i = 0; i < log[l].format->ops->nelts; i++) {
                     p = op[i].run(r, p, &op[i]);
                 }
 
@@ -290,7 +293,7 @@ ngx_http_log_handler(ngx_http_request_t 
 
         p = line;
 
-        for (i = 0; i < log[l].ops->nelts; i++) {
+        for (i = 0; i < log[l].format->ops->nelts; i++) {
             p = op[i].run(r, p, &op[i]);
         }
 
@@ -726,6 +729,8 @@ ngx_http_log_create_main_conf(ngx_conf_t
     fmt->name.len = sizeof("combined") - 1;
     fmt->name.data = (u_char *) "combined";
 
+    fmt->flushes = NULL;
+
     fmt->ops = ngx_array_create(cf->pool, 16, sizeof(ngx_http_log_op_t));
     if (fmt->ops == NULL) {
         return NGX_CONF_ERROR;
@@ -806,7 +811,7 @@ ngx_http_log_merge_loc_conf(ngx_conf_t *
     fmt = lmcf->formats.elts;
 
     /* the default "combined" format */
-    log->ops = fmt[0].ops;
+    log->format = &fmt[0];
     lmcf->combined_used = 1;
 
     return NGX_CONF_OK;
@@ -900,7 +905,7 @@ ngx_http_log_set_log(ngx_conf_t *cf, ngx
         if (fmt[i].name.len == name.len
             && ngx_strcasecmp(fmt[i].name.data, name.data) == 0)
         {
-            log->ops = fmt[i].ops;
+            log->format = &fmt[i];
             goto buffer;
         }
     }
@@ -985,22 +990,28 @@ ngx_http_log_set_format(ngx_conf_t *cf, 
 
     fmt->name = value[1];
 
+    fmt->flushes = ngx_array_create(cf->pool, 4, sizeof(ngx_int_t));
+    if (fmt->flushes == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
     fmt->ops = ngx_array_create(cf->pool, 16, sizeof(ngx_http_log_op_t));
     if (fmt->ops == NULL) {
         return NGX_CONF_ERROR;
     }
 
-    return ngx_http_log_compile_format(cf, fmt->ops, cf->args, 2);
+    return ngx_http_log_compile_format(cf, fmt->flushes, fmt->ops, cf->args, 2);
 }
 
 
 static char *
-ngx_http_log_compile_format(ngx_conf_t *cf, ngx_array_t *ops,
-    ngx_array_t *args, ngx_uint_t s)
+ngx_http_log_compile_format(ngx_conf_t *cf, ngx_array_t *flushes,
+    ngx_array_t *ops, ngx_array_t *args, ngx_uint_t s)
 {
     u_char              *data, *p, ch;
     size_t               i, len;
     ngx_str_t           *value, var;
+    ngx_int_t           *flush;
     ngx_uint_t           bracket;
     ngx_http_log_op_t   *op;
     ngx_http_log_var_t  *v;
@@ -1114,6 +1125,16 @@ ngx_http_log_compile_format(ngx_conf_t *
                     return NGX_CONF_ERROR;
                 }
 
+                if (flushes) {
+
+                    flush = ngx_array_push(flushes);
+                    if (flush == NULL) {
+                        return NGX_CONF_ERROR;
+                    }
+
+                    *flush = op->data; /* variable index */
+                }
+
             found:
 
                 continue;
@@ -1299,7 +1320,7 @@ ngx_http_log_init(ngx_conf_t *cf)
         *value = ngx_http_combined_fmt;
         fmt = lmcf->formats.elts;
 
-        if (ngx_http_log_compile_format(cf, fmt->ops, &a, 0)
+        if (ngx_http_log_compile_format(cf, NULL, fmt->ops, &a, 0)
             != NGX_CONF_OK)
         {
             return NGX_ERROR;
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -147,7 +147,9 @@ static ngx_conf_bitmask_t  ngx_http_prox
     { ngx_string("timeout"), NGX_HTTP_UPSTREAM_FT_TIMEOUT },
     { ngx_string("invalid_header"), NGX_HTTP_UPSTREAM_FT_INVALID_HEADER },
     { 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_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
     { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
     { ngx_null_string, 0 }
@@ -1214,7 +1216,7 @@ ngx_http_proxy_process_header(ngx_http_r
 
     for ( ;; ) {
 
-        rc = ngx_http_parse_header_line(r, &r->upstream->buffer);
+        rc = ngx_http_parse_header_line(r, &r->upstream->buffer, 1);
 
         if (rc == NGX_OK) {
 
diff --git a/src/http/modules/ngx_http_range_filter_module.c b/src/http/modules/ngx_http_range_filter_module.c
--- a/src/http/modules/ngx_http_range_filter_module.c
+++ b/src/http/modules/ngx_http_range_filter_module.c
@@ -654,7 +654,13 @@ ngx_http_range_singlepart_body(ngx_http_
             ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                            "http range body skip");
 
+            if (buf->in_file) {
+                buf->file_pos = buf->file_last;
+            }
+
             buf->pos = buf->last;
+            buf->sync = 1;
+
             continue;
         }
 
diff --git a/src/http/modules/ngx_http_realip_module.c b/src/http/modules/ngx_http_realip_module.c
--- a/src/http/modules/ngx_http_realip_module.c
+++ b/src/http/modules/ngx_http_realip_module.c
@@ -9,6 +9,11 @@
 #include <ngx_http.h>
 
 
+#define NGX_HTTP_REALIP_XREALIP  0
+#define NGX_HTTP_REALIP_XFWD     1
+#define NGX_HTTP_REALIP_HEADER   2
+
+
 /* AF_INET only */
 
 typedef struct {
@@ -19,7 +24,9 @@ typedef struct {
 
 typedef struct {
     ngx_array_t       *from;     /* array of ngx_http_realip_from_t */
-    ngx_uint_t         xfwd;
+    ngx_uint_t         type;
+    ngx_uint_t         hash;
+    ngx_str_t          header;
 } ngx_http_realip_loc_conf_t;
 
 
@@ -34,19 +41,13 @@ static ngx_int_t ngx_http_realip_handler
 static void ngx_http_realip_cleanup(void *data);
 static char *ngx_http_realip_from(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
+static char *ngx_http_realip(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static void *ngx_http_realip_create_loc_conf(ngx_conf_t *cf);
 static char *ngx_http_realip_merge_loc_conf(ngx_conf_t *cf,
     void *parent, void *child);
 static ngx_int_t ngx_http_realip_init(ngx_conf_t *cf);
 
 
-static ngx_conf_enum_t  ngx_http_realip_header[] = {
-    { ngx_string("X-Forwarded-For"), 1 },
-    { ngx_string("X-Real-IP"), 0 },
-    { ngx_null_string, 0 }
-};
-
-
 static ngx_command_t  ngx_http_realip_commands[] = {
 
     { ngx_string("set_real_ip_from"),
@@ -58,10 +59,10 @@ static ngx_command_t  ngx_http_realip_co
 
     { ngx_string("real_ip_header"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
-      ngx_conf_set_enum_slot,
+      ngx_http_realip,
       NGX_HTTP_LOC_CONF_OFFSET,
-      offsetof(ngx_http_realip_loc_conf_t, xfwd),
-      &ngx_http_realip_header },
+      0,
+      NULL },
 
       ngx_null_command
 };
@@ -105,7 +106,9 @@ ngx_http_realip_handler(ngx_http_request
     u_char                      *ip, *p;
     size_t                       len;
     in_addr_t                    addr;
-    ngx_uint_t                   i;
+    ngx_uint_t                   i, hash;
+    ngx_list_part_t             *part;
+    ngx_table_elt_t             *header;
     struct sockaddr_in          *sin;
     ngx_connection_t            *c;
     ngx_pool_cleanup_t          *cln;
@@ -130,7 +133,10 @@ ngx_http_realip_handler(ngx_http_request
         return NGX_DECLINED;
     }
 
-    if (rlcf->xfwd == 0) {
+    switch (rlcf->type) {
+
+    case NGX_HTTP_REALIP_XREALIP:
+
         if (r->headers_in.x_real_ip == NULL) {
             return NGX_DECLINED;
         }
@@ -138,7 +144,10 @@ ngx_http_realip_handler(ngx_http_request
         len = r->headers_in.x_real_ip->value.len;
         ip = r->headers_in.x_real_ip->value.data;
 
-    } else {
+        break;
+
+    case NGX_HTTP_REALIP_XFWD:
+
         if (r->headers_in.x_forwarded_for == NULL) {
             return NGX_DECLINED;
         }
@@ -154,8 +163,46 @@ ngx_http_realip_handler(ngx_http_request
                 break;
             }
         }
+
+        break;
+
+    default: /* NGX_HTTP_REALIP_HEADER */
+
+        part = &r->headers_in.headers.part;
+        header = part->elts;
+
+        hash = rlcf->hash;
+        len = rlcf->header.len;
+        p = rlcf->header.data;
+
+        for (i = 0; /* void */ ; i++) {
+
+            if (i >= part->nelts) {
+                if (part->next == NULL) {
+                    break;
+                }
+
+                part = part->next;
+                header = part->elts;
+                i = 0;
+            }
+
+            if (hash == header[i].hash
+                && len == header[i].key.len
+                && ngx_strncmp(p, header[i].lowcase_key, len) == 0)
+            {
+                len = header[i].value.len;
+                ip = header[i].value.data;
+
+                goto found;
+            }
+        }
+
+        return NGX_DECLINED;
     }
 
+found:
+
     c = r->connection;
 
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "realip: \"%s\"", ip);
@@ -231,10 +278,10 @@ ngx_http_realip_from(ngx_conf_t *cf, ngx
 {
     ngx_http_realip_loc_conf_t *rlcf = conf;
 
-    ngx_int_t                 rc;
-    ngx_str_t                *value;
-    ngx_inet_cidr_t           in_cidr;
-    ngx_http_realip_from_t   *from;
+    ngx_int_t                rc;
+    ngx_str_t               *value;
+    ngx_inet_cidr_t          in_cidr;
+    ngx_http_realip_from_t  *from;
 
     if (rlcf->from == NULL) {
         rlcf->from = ngx_array_create(cf->pool, 2,
@@ -271,6 +318,33 @@ ngx_http_realip_from(ngx_conf_t *cf, ngx
 }
 
 
+static char *
+ngx_http_realip(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_realip_loc_conf_t *rlcf = conf;
+
+    ngx_str_t  *value;
+
+    value = cf->args->elts;
+
+    if (ngx_strcmp(value[1].data, "X-Real-IP") == 0) {
+        rlcf->type = NGX_HTTP_REALIP_XREALIP;
+        return NGX_CONF_OK;
+    }
+
+    if (ngx_strcmp(value[1].data, "X-Forwarded-For") == 0) {
+        rlcf->type = NGX_HTTP_REALIP_XFWD;
+        return NGX_CONF_OK;
+    }
+
+    rlcf->type = NGX_HTTP_REALIP_HEADER;
+    rlcf->hash = ngx_hash_strlow(value[1].data, value[1].data, value[1].len);
+    rlcf->header = value[1];
+
+    return NGX_CONF_OK;
+}
+
+
 static void *
 ngx_http_realip_create_loc_conf(ngx_conf_t *cf)
 {
@@ -285,9 +359,11 @@ ngx_http_realip_create_loc_conf(ngx_conf
      * set by ngx_pcalloc():
      *
      *     conf->from = NULL;
+     *     conf->hash = 0;
+     *     conf->header = { 0, NULL };
      */
 
-    conf->xfwd = NGX_CONF_UNSET_UINT;
+    conf->type = NGX_CONF_UNSET_UINT;
 
     return conf;
 }
@@ -303,7 +379,12 @@ ngx_http_realip_merge_loc_conf(ngx_conf_
         conf->from = prev->from;
     }
 
-    ngx_conf_merge_uint_value(conf->xfwd, prev->xfwd, 0);
+    ngx_conf_merge_uint_value(conf->type, prev->type, NGX_HTTP_REALIP_XREALIP);
+
+    if (conf->header.len == 0) {
+        conf->hash = prev->hash;
+        conf->header = prev->header;
+    }
 
     return NGX_CONF_OK;
 }
diff --git a/src/http/modules/ngx_http_secure_link_module.c b/src/http/modules/ngx_http_secure_link_module.c
new file mode 100644
--- /dev/null
+++ b/src/http/modules/ngx_http_secure_link_module.c
@@ -0,0 +1,193 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+#include <ngx_md5.h>
+
+
+typedef struct {
+    ngx_str_t  secret;
+} ngx_http_secure_link_conf_t;
+
+
+static void *ngx_http_secure_link_create_conf(ngx_conf_t *cf);
+static char *ngx_http_secure_link_merge_conf(ngx_conf_t *cf, void *parent,
+    void *child);
+static ngx_int_t ngx_http_secure_link_add_variables(ngx_conf_t *cf);
+
+
+static ngx_command_t  ngx_http_secure_link_commands[] = {
+
+    { ngx_string("secure_link_secret"),
+      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_secure_link_conf_t, secret),
+      NULL },
+
+      ngx_null_command
+};
+
+
+static ngx_http_module_t  ngx_http_secure_link_module_ctx = {
+    ngx_http_secure_link_add_variables,    /* preconfiguration */
+    NULL,                                  /* postconfiguration */
+
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    NULL,                                  /* create server configuration */
+    NULL,                                  /* merge server configuration */
+
+    ngx_http_secure_link_create_conf,      /* create location configuration */
+    ngx_http_secure_link_merge_conf        /* merge location configuration */
+};
+
+
+ngx_module_t  ngx_http_secure_link_module = {
+    NGX_MODULE_V1,
+    &ngx_http_secure_link_module_ctx,      /* module context */
+    ngx_http_secure_link_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 ngx_str_t  ngx_http_secure_link = ngx_string("secure_link");
+
+
+static ngx_int_t
+ngx_http_secure_link_variable(ngx_http_request_t *r,
+     ngx_http_variable_value_t *v, uintptr_t data)
+{
+    u_char                        *p, *start, *end, *last;
+    size_t                         len;
+    ngx_int_t                      n;
+    ngx_uint_t                     i;
+    ngx_md5_t                      md5;
+    ngx_http_secure_link_conf_t  *conf;
+    u_char                         hash[16];
+
+    conf = ngx_http_get_module_loc_conf(r, ngx_http_secure_link_module);
+
+    if (conf->secret.len == 0) {
+        goto not_found;
+    }
+
+    p = &r->unparsed_uri.data[1];
+    last = r->unparsed_uri.data + r->unparsed_uri.len;
+
+    while (p < last) {
+        if (*p++ == '/') {
+            start = p;
+            goto md5_start;
+        }
+    }
+
+    goto not_found;
+
+md5_start:
+
+    while (p < last) {
+        if (*p++ == '/') {
+            end = p - 1;
+            goto url_start;
+        }
+    }
+
+    goto not_found;
+
+url_start:
+
+    len = last - p;
+
+    if (end - start != 32 || len < 3) {
+        goto not_found;
+    }
+
+    ngx_md5_init(&md5);
+    ngx_md5_update(&md5, p, len);
+    ngx_md5_update(&md5, conf->secret.data, conf->secret.len);
+    ngx_md5_final(hash, &md5);
+
+    for (i = 0; i < 16; i++) {
+        n = ngx_hextoi(&start[2 * i], 2);
+        if (n == NGX_ERROR || n != hash[i]) {
+            goto not_found;
+        }
+    }
+
+    v->len = len;
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+    v->data = p;
+
+    return NGX_OK;
+
+not_found:
+
+    v->not_found = 1;
+
+    return NGX_OK;
+}
+
+
+static void *
+ngx_http_secure_link_create_conf(ngx_conf_t *cf)
+{
+    ngx_http_secure_link_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_secure_link_conf_t));
+    if (conf == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    /*
+     * set by ngx_pcalloc():
+     *
+     *     conf->secret = { 0, NULL }
+     */
+
+    return conf;
+}
+
+
+static char *
+ngx_http_secure_link_merge_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_http_secure_link_conf_t *prev = parent;
+    ngx_http_secure_link_conf_t *conf = child;
+
+    ngx_conf_merge_str_value(conf->secret, prev->secret, "");
+
+    return NGX_CONF_OK;
+}
+
+
+static ngx_int_t
+ngx_http_secure_link_add_variables(ngx_conf_t *cf)
+{
+    ngx_http_variable_t  *var;
+
+    var = ngx_http_add_variable(cf, &ngx_http_secure_link, NGX_HTTP_VAR_NOHASH);
+    if (var == NULL) {
+        return NGX_ERROR;
+    }
+
+    var->get_handler = ngx_http_secure_link_variable;
+
+    return NGX_OK;
+}
diff --git a/src/http/modules/perl/nginx.pm b/src/http/modules/perl/nginx.pm
--- a/src/http/modules/perl/nginx.pm
+++ b/src/http/modules/perl/nginx.pm
@@ -47,7 +47,7 @@ our @EXPORT = qw(
     HTTP_INSUFFICIENT_STORAGE
 );
 
-our $VERSION = '0.7.17';
+our $VERSION = '0.7.19';
 
 require XSLoader;
 XSLoader::load('nginx', $VERSION);
diff --git a/src/http/ngx_http.h b/src/http/ngx_http.h
--- a/src/http/ngx_http.h
+++ b/src/http/ngx_http.h
@@ -72,7 +72,8 @@ ngx_int_t ngx_http_parse_complex_uri(ngx
     ngx_uint_t merge_slashes);
 ngx_int_t ngx_http_parse_unsafe_uri(ngx_http_request_t *r, ngx_str_t *uri,
     ngx_str_t *args, ngx_uint_t *flags);
-ngx_int_t ngx_http_parse_header_line(ngx_http_request_t *r, ngx_buf_t *b);
+ngx_int_t ngx_http_parse_header_line(ngx_http_request_t *r, ngx_buf_t *b,
+    ngx_uint_t allow_underscores);
 ngx_int_t ngx_http_parse_multi_header_lines(ngx_array_t *headers,
     ngx_str_t *name, ngx_str_t *value);
 
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -231,6 +231,13 @@ static ngx_command_t  ngx_http_core_comm
       offsetof(ngx_http_core_srv_conf_t, merge_slashes),
       NULL },
 
+    { ngx_string("underscores_in_headers"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_SRV_CONF_OFFSET,
+      offsetof(ngx_http_core_srv_conf_t, underscores_in_headers),
+      NULL },
+
     { ngx_string("location"),
       NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE12,
       ngx_http_core_location,
@@ -487,6 +494,13 @@ static ngx_command_t  ngx_http_core_comm
       offsetof(ngx_http_core_loc_conf_t, log_not_found),
       NULL },
 
+    { ngx_string("log_subrequest"),
+      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_core_loc_conf_t, log_subrequest),
+      NULL },
+
     { ngx_string("recursive_error_pages"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -2527,6 +2541,7 @@ ngx_http_core_create_srv_conf(ngx_conf_t
     cscf->client_header_buffer_size = NGX_CONF_UNSET_SIZE;
     cscf->ignore_invalid_headers = NGX_CONF_UNSET;
     cscf->merge_slashes = NGX_CONF_UNSET;
+    cscf->underscores_in_headers = NGX_CONF_UNSET;
 
     return cscf;
 }
@@ -2605,6 +2620,9 @@ ngx_http_core_merge_srv_conf(ngx_conf_t 
 
     ngx_conf_merge_value(conf->merge_slashes, prev->merge_slashes, 1);
 
+    ngx_conf_merge_value(conf->underscores_in_headers,
+                              prev->underscores_in_headers, 0);
+
     return NGX_CONF_OK;
 }
 
@@ -2663,6 +2681,7 @@ ngx_http_core_create_loc_conf(ngx_conf_t
     lcf->msie_padding = NGX_CONF_UNSET;
     lcf->msie_refresh = NGX_CONF_UNSET;
     lcf->log_not_found = NGX_CONF_UNSET;
+    lcf->log_subrequest = NGX_CONF_UNSET;
     lcf->recursive_error_pages = NGX_CONF_UNSET;
     lcf->server_tokens = NGX_CONF_UNSET;
     lcf->types_hash_max_size = NGX_CONF_UNSET_UINT;
@@ -2887,6 +2906,7 @@ ngx_http_core_merge_loc_conf(ngx_conf_t 
     ngx_conf_merge_value(conf->msie_padding, prev->msie_padding, 1);
     ngx_conf_merge_value(conf->msie_refresh, prev->msie_refresh, 0);
     ngx_conf_merge_value(conf->log_not_found, prev->log_not_found, 1);
+    ngx_conf_merge_value(conf->log_subrequest, prev->log_subrequest, 0);
     ngx_conf_merge_value(conf->recursive_error_pages,
                               prev->recursive_error_pages, 0);
     ngx_conf_merge_value(conf->server_tokens, prev->server_tokens, 1);
@@ -3271,6 +3291,17 @@ ngx_http_core_root(ngx_conf_t *cf, ngx_c
         return NGX_CONF_ERROR;
     }
 
+    if (ngx_strstr(value[1].data, "$realpath_root")
+        || ngx_strstr(value[1].data, "${realpath_root}"))
+    {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "the $realpath_root variable may not be used "
+                           "in the \"%V\" directive",
+                           &cmd->name);
+
+        return NGX_CONF_ERROR;
+    }
+
     lcf->alias = alias;
     lcf->root = value[1];
 
diff --git a/src/http/ngx_http_core_module.h b/src/http/ngx_http_core_module.h
--- a/src/http/ngx_http_core_module.h
+++ b/src/http/ngx_http_core_module.h
@@ -155,6 +155,7 @@ typedef struct {
 
     ngx_flag_t                  ignore_invalid_headers;
     ngx_flag_t                  merge_slashes;
+    ngx_flag_t                  underscores_in_headers;
 
     ngx_http_core_loc_conf_t  **named_locations;
 } ngx_http_core_srv_conf_t;
@@ -310,6 +311,7 @@ struct ngx_http_core_loc_conf_s {
     ngx_flag_t    msie_padding;            /* msie_padding */
     ngx_flag_t    msie_refresh;            /* msie_refresh */
     ngx_flag_t    log_not_found;           /* log_not_found */
+    ngx_flag_t    log_subrequest;          /* log_subrequest */
     ngx_flag_t    recursive_error_pages;   /* recursive_error_pages */
     ngx_flag_t    server_tokens;           /* server_tokens */
 
diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -700,7 +700,8 @@ done:
 
 
 ngx_int_t
-ngx_http_parse_header_line(ngx_http_request_t *r, ngx_buf_t *b)
+ngx_http_parse_header_line(ngx_http_request_t *r, ngx_buf_t *b,
+    ngx_uint_t allow_underscores)
 {
     u_char      c, ch, *p;
     ngx_uint_t  hash, i;
@@ -720,7 +721,7 @@ ngx_http_parse_header_line(ngx_http_requ
     static u_char  lowcase[] =
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
         "\0\0\0\0\0\0\0\0\0\0\0\0\0-\0\0" "0123456789\0\0\0\0\0\0"
-        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0_"
+        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0\0"
         "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0\0"
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
@@ -779,6 +780,19 @@ ngx_http_parse_header_line(ngx_http_requ
                 break;
             }
 
+            if (ch == '_') {
+                if (allow_underscores) {
+                    hash = ngx_hash(hash, ch);
+                    r->lowcase_header[i++] = ch;
+                    i &= (NGX_HTTP_LC_HEADER_LEN - 1);
+
+                } else {
+                    r->invalid_header = 1;
+                }
+
+                break;
+            }
+
             if (ch == ':') {
                 r->header_name_end = p;
                 state = sw_space_before_value;
diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -47,6 +47,7 @@ static void ngx_http_lingering_close_han
 static ngx_int_t ngx_http_post_action(ngx_http_request_t *r);
 static void ngx_http_close_request(ngx_http_request_t *r, ngx_int_t error);
 static void ngx_http_request_done(ngx_http_request_t *r, ngx_int_t error);
+static void ngx_http_log_request(ngx_http_request_t *r);
 static void ngx_http_close_connection(ngx_connection_t *c);
 
 static u_char *ngx_http_log_error(ngx_log_t *log, u_char *buf, size_t len);
@@ -902,7 +903,8 @@ ngx_http_process_request_headers(ngx_eve
             }
         }
 
-        rc = ngx_http_parse_header_line(r, r->header_in);
+        rc = ngx_http_parse_header_line(r, r->header_in,
+                                        cscf->underscores_in_headers);
 
         if (rc == NGX_OK) {
 
@@ -1758,6 +1760,17 @@ ngx_http_finalize_request(ngx_http_reque
         return;
     }
 
+    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
+
+    if (r != r->main && !r->logged) {
+
+        if (clcf->log_subrequest) {
+            ngx_http_log_request(r);
+        }
+
+        r->logged = 1;
+    }
+
     if (r != r->main || rc == NGX_AGAIN) {
         if (ngx_http_set_write_handler(r) != NGX_OK) {
             return;
@@ -1856,8 +1869,6 @@ ngx_http_finalize_request(ngx_http_reque
         return;
     }
 
-    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
-
     if (!ngx_terminate
          && !ngx_exiting
          && r->keepalive
@@ -2603,14 +2614,11 @@ ngx_http_close_request(ngx_http_request_
 static void
 ngx_http_request_done(ngx_http_request_t *r, ngx_int_t error)
 {
-    ngx_log_t                  *log;
-    ngx_uint_t                  i, n;
-    struct linger               linger;
-    ngx_http_cleanup_t         *cln;
-    ngx_http_log_ctx_t         *ctx;
-    ngx_http_handler_pt        *log_handler;
-    ngx_http_core_loc_conf_t   *clcf;
-    ngx_http_core_main_conf_t  *cmcf;
+    ngx_log_t                 *log;
+    struct linger              linger;
+    ngx_http_cleanup_t        *cln;
+    ngx_http_log_ctx_t        *ctx;
+    ngx_http_core_loc_conf_t  *clcf;
 
     log = r->connection->log;
 
@@ -2645,13 +2653,7 @@ ngx_http_request_done(ngx_http_request_t
 
     log->action = "logging request";
 
-    cmcf = ngx_http_get_module_main_conf(r, ngx_http_core_module);
-
-    log_handler = cmcf->phases[NGX_HTTP_LOG_PHASE].handlers.elts;
-    n = cmcf->phases[NGX_HTTP_LOG_PHASE].handlers.nelts;
-    for (i = 0; i < n; i++) {
-        log_handler[i](r);
-    }
+    ngx_http_log_request(r);
 
     log->action = "closing request";
 
@@ -2684,6 +2686,24 @@ ngx_http_request_done(ngx_http_request_t
 
 
 static void
+ngx_http_log_request(ngx_http_request_t *r)
+{
+    ngx_uint_t                  i, n;
+    ngx_http_handler_pt        *log_handler;
+    ngx_http_core_main_conf_t  *cmcf;
+
+    cmcf = ngx_http_get_module_main_conf(r, ngx_http_core_module);
+
+    log_handler = cmcf->phases[NGX_HTTP_LOG_PHASE].handlers.elts;
+    n = cmcf->phases[NGX_HTTP_LOG_PHASE].handlers.nelts;
+
+    for (i = 0; i < n; i++) {
+        log_handler[i](r);
+    }
+}
+
+
+static void
 ngx_http_close_connection(ngx_connection_t *c)
 {
     ngx_pool_t  *pool;
diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -464,6 +464,7 @@ struct ngx_http_request_s {
     unsigned                          expect_tested:1;
     unsigned                          root_tested:1;
     unsigned                          done:1;
+    unsigned                          logged:1;
     unsigned                          utf8:1;
 
     unsigned                          buffered:4;
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -22,6 +22,10 @@ static void ngx_http_upstream_send_reque
     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 ngx_int_t ngx_http_upstream_test_next(ngx_http_request_t *r,
+    ngx_http_upstream_t *u);
+static ngx_int_t ngx_http_upstream_intercept_errors(ngx_http_request_t *r,
+    ngx_http_upstream_t *u);
 static ngx_int_t ngx_http_upstream_test_connect(ngx_connection_t *c);
 static void ngx_http_upstream_process_body_in_memory(ngx_event_t *rev);
 static void ngx_http_upstream_send_response(ngx_http_request_t *r,
@@ -282,6 +286,15 @@ static ngx_http_variable_t  ngx_http_ups
 };
 
 
+static ngx_http_upstream_next_t  ngx_http_upstream_next_errors[] = {
+    { 500, NGX_HTTP_UPSTREAM_FT_HTTP_500 },
+    { 502, NGX_HTTP_UPSTREAM_FT_HTTP_502 },
+    { 503, NGX_HTTP_UPSTREAM_FT_HTTP_503 },
+    { 504, NGX_HTTP_UPSTREAM_FT_HTTP_504 },
+    { 404, NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { 0, 0 }
+};
+
 void
 ngx_http_upstream_init(ngx_http_request_t *r)
 {
@@ -1047,8 +1060,6 @@ ngx_http_upstream_process_header(ngx_eve
     ngx_connection_t               *c;
     ngx_http_request_t             *r;
     ngx_http_upstream_t            *u;
-    ngx_http_err_page_t            *err_page;
-    ngx_http_core_loc_conf_t       *clcf;
     ngx_http_upstream_header_t     *hh;
     ngx_http_upstream_main_conf_t  *umcf;
 
@@ -1174,85 +1185,21 @@ ngx_http_upstream_process_header(ngx_eve
 
     /* rc == NGX_OK */
 
-    if (u->headers_in.status_n >= NGX_HTTP_BAD_REQUEST
-        && r->subrequest_in_memory)
-    {
-        u->buffer.last = u->buffer.pos;
-    }
-
-    if (u->headers_in.status_n == NGX_HTTP_INTERNAL_SERVER_ERROR) {
-
-        if (u->peer.tries > 1
-            && (u->conf->next_upstream & NGX_HTTP_UPSTREAM_FT_HTTP_500))
-        {
-            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_HTTP_500);
-            return;
+    if (u->headers_in.status_n >= NGX_HTTP_BAD_REQUEST) {
+
+        if (r->subrequest_in_memory) {
+            u->buffer.last = u->buffer.pos;
         }
 
-#if (NGX_HTTP_CACHE)
-
-        if (u->peer.tries == 0
-            && u->stale
-            && (u->conf->use_stale & NGX_HTTP_UPSTREAM_FT_HTTP_500))
-        {
-            ngx_http_upstream_finalize_request(r, u,
-                                              ngx_http_send_cached_response(r));
-            return;
-        }
-
-#endif
-    }
-
-    if (u->headers_in.status_n == NGX_HTTP_NOT_FOUND) {
-
-        if (u->peer.tries > 1
-            && u->conf->next_upstream & NGX_HTTP_UPSTREAM_FT_HTTP_404)
-        {
-            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_HTTP_404);
+        if (ngx_http_upstream_test_next(r, u) == NGX_OK) {
             return;
         }
 
-        if (u->conf->intercept_404) {
-            ngx_http_upstream_finalize_request(r, u, NGX_HTTP_NOT_FOUND);
+        if (ngx_http_upstream_intercept_errors(r, u) == NGX_OK) {
             return;
         }
     }
 
-
-    if (u->headers_in.status_n >= NGX_HTTP_BAD_REQUEST
-        && u->conf->intercept_errors)
-    {
-        clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
-
-        if (clcf->error_pages) {
-
-            err_page = clcf->error_pages->elts;
-            for (i = 0; i < clcf->error_pages->nelts; i++) {
-                if (err_page[i].status == (ngx_int_t) u->headers_in.status_n) {
-
-                    if (u->headers_in.status_n == NGX_HTTP_UNAUTHORIZED) {
-
-                        r->headers_out.www_authenticate =
-                                        ngx_list_push(&r->headers_out.headers);
-
-                        if (r->headers_out.www_authenticate == NULL) {
-                            ngx_http_upstream_finalize_request(r, u,
-                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
-                            return;
-                        }
-
-                        *r->headers_out.www_authenticate =
-                                               *u->headers_in.www_authenticate;
-                    }
-
-                    ngx_http_upstream_finalize_request(r, u,
-                                                       u->headers_in.status_n);
-                    return;
-                }
-            }
-        }
-    }
-
     umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);
 
     if (u->headers_in.x_accel_redirect) {
@@ -1407,6 +1354,101 @@ ngx_http_upstream_process_header(ngx_eve
 
 
 static ngx_int_t
+ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)
+{
+    ngx_uint_t                 status;
+    ngx_http_upstream_next_t  *un;
+
+    if (!(u->conf->next_upstream & NGX_HTTP_UPSTREAM_FT_STATUS)) {
+        return NGX_DECLINED;
+    }
+
+    status = u->headers_in.status_n;
+
+    for (un = ngx_http_upstream_next_errors; un->status; un++) {
+
+        if (status != un->status) {
+            continue;
+        }
+
+        if (u->peer.tries > 1 && (u->conf->next_upstream & un->mask)) {
+            ngx_http_upstream_next(r, u, un->mask);
+            return NGX_OK;
+        }
+
+        if (status == NGX_HTTP_NOT_FOUND && u->conf->intercept_404) {
+            ngx_http_upstream_finalize_request(r, u, NGX_HTTP_NOT_FOUND);
+            return NGX_OK;
+        }
+
+#if (NGX_HTTP_CACHE)
+
+        if (u->peer.tries == 0 && u->stale && (u->conf->use_stale & un->mask)) {
+            ngx_http_upstream_finalize_request(r, u,
+                                              ngx_http_send_cached_response(r));
+            return NGX_OK;
+        }
+
+#endif
+    }
+
+    return NGX_DECLINED;
+}
+
+
+static ngx_int_t
+ngx_http_upstream_intercept_errors(ngx_http_request_t *r,
+    ngx_http_upstream_t *u)
+{
+    ngx_int_t                  status;
+    ngx_uint_t                 i;
+    ngx_table_elt_t           *h;
+    ngx_http_err_page_t       *err_page;
+    ngx_http_core_loc_conf_t  *clcf;
+
+    if (!u->conf->intercept_errors) {
+        return NGX_DECLINED;
+    }
+
+    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
+
+    if (clcf->error_pages == NULL) {
+        return NGX_DECLINED;
+    }
+
+    status = u->headers_in.status_n;
+
+    err_page = clcf->error_pages->elts;
+    for (i = 0; i < clcf->error_pages->nelts; i++) {
+
+        if (err_page[i].status == status) {
+
+            if (status == NGX_HTTP_UNAUTHORIZED) {
+
+                h = ngx_list_push(&r->headers_out.headers);
+
+                if (h == NULL) {
+                    ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+                    return NGX_OK;
+                }
+
+                *h = *u->headers_in.www_authenticate;
+
+                r->headers_out.www_authenticate = h;
+            }
+
+            ngx_http_upstream_finalize_request(r, u, status);
+
+            return NGX_OK;
+        }
+    }
+
+    return NGX_DECLINED;
+}
+
+
+static ngx_int_t
 ngx_http_upstream_test_connect(ngx_connection_t *c)
 {
     int        err;
diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -20,13 +20,20 @@
 #define NGX_HTTP_UPSTREAM_FT_TIMEOUT         0x00000004
 #define NGX_HTTP_UPSTREAM_FT_INVALID_HEADER  0x00000008
 #define NGX_HTTP_UPSTREAM_FT_HTTP_500        0x00000010
-#define NGX_HTTP_UPSTREAM_FT_HTTP_503        0x00000020
-#define NGX_HTTP_UPSTREAM_FT_HTTP_404        0x00000040
-#define NGX_HTTP_UPSTREAM_FT_BUSY_LOCK       0x00000080
-#define NGX_HTTP_UPSTREAM_FT_MAX_WAITING     0x00000100
+#define NGX_HTTP_UPSTREAM_FT_HTTP_502        0x00000020
+#define NGX_HTTP_UPSTREAM_FT_HTTP_503        0x00000040
+#define NGX_HTTP_UPSTREAM_FT_HTTP_504        0x00000080
+#define NGX_HTTP_UPSTREAM_FT_HTTP_404        0x00000100
+#define NGX_HTTP_UPSTREAM_FT_BUSY_LOCK       0x00000200
+#define NGX_HTTP_UPSTREAM_FT_MAX_WAITING     0x00000400
 #define NGX_HTTP_UPSTREAM_FT_NOLIVE          0x40000000
 #define NGX_HTTP_UPSTREAM_FT_OFF             0x80000000
 
+#define NGX_HTTP_UPSTREAM_FT_STATUS          (NGX_HTTP_UPSTREAM_FT_HTTP_500  \
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_502  \
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_503  \
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_504  \
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_404)
 
 #define NGX_HTTP_UPSTREAM_INVALID_HEADER     40
 
@@ -267,6 +274,12 @@ struct ngx_http_upstream_s {
 };
 
 
+typedef struct {
+    ngx_uint_t                      status;
+    ngx_uint_t                      mask;
+} ngx_http_upstream_next_t;
+
+
 ngx_int_t ngx_http_upstream_header_variable(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
 
diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -46,6 +46,8 @@ static ngx_int_t ngx_http_variable_is_ar
     ngx_http_variable_value_t *v, uintptr_t data);
 static ngx_int_t ngx_http_variable_document_root(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
+static ngx_int_t ngx_http_variable_realpath_root(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
 static ngx_int_t ngx_http_variable_request_filename(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
 static ngx_int_t ngx_http_variable_server_name(ngx_http_request_t *r,
@@ -162,6 +164,9 @@ static ngx_http_variable_t  ngx_http_cor
     { ngx_string("document_root"), NULL,
       ngx_http_variable_document_root, 0, NGX_HTTP_VAR_NOCACHEABLE, 0 },
 
+    { ngx_string("realpath_root"), NULL,
+      ngx_http_variable_realpath_root, 0, NGX_HTTP_VAR_NOCACHEABLE, 0 },
+
     { ngx_string("query_string"), NULL, ngx_http_variable_request,
       offsetof(ngx_http_request_t, args),
       NGX_HTTP_VAR_NOCACHEABLE, 0 },
@@ -1000,6 +1005,61 @@ ngx_http_variable_document_root(ngx_http
 
 
 static ngx_int_t
+ngx_http_variable_realpath_root(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data)
+{
+    size_t                     len;
+    ngx_str_t                  path;
+    ngx_http_core_loc_conf_t  *clcf;
+    u_char                     real[NGX_MAX_PATH];
+
+    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
+
+    if (clcf->root_lengths == NULL) {
+        path = clcf->root;
+
+    } else {
+        if (ngx_http_script_run(r, &path, clcf->root_lengths->elts, 1,
+                                clcf->root_values->elts)
+            == NULL)
+        {
+            return NGX_ERROR;
+        }
+
+        path.data[path.len - 1] = '\0';
+
+        if (ngx_conf_full_name((ngx_cycle_t *) ngx_cycle, &path, 0)
+            == NGX_ERROR)
+        {
+            return NGX_ERROR;
+        }
+    }
+
+    if (ngx_realpath(path.data, real) == NULL) {
+        ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno,
+                      ngx_realpath_n " \"%s\" failed", path.data);
+        return NGX_ERROR;
+    }
+
+    len = ngx_strlen(real);
+
+    v->data = ngx_pnalloc(r->pool, len);
+    if (v->data == NULL) {
+        return NGX_ERROR;
+    }
+
+    v->len = len;
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+
+    ngx_memcpy(v->data, real, len);
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
 ngx_http_variable_request_filename(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data)
 {
diff --git a/src/os/unix/ngx_files.h b/src/os/unix/ngx_files.h
--- a/src/os/unix/ngx_files.h
+++ b/src/os/unix/ngx_files.h
@@ -145,6 +145,8 @@ ngx_int_t ngx_set_file_time(u_char *name
 #endif
 
 
+#define ngx_realpath(p, r)       realpath((char *) p, (char *) r)
+#define ngx_realpath_n           "realpath()"
 #define ngx_getcwd(buf, size)    (getcwd(buf, size) != NULL)
 #define ngx_getcwd_n             "getcwd()"
 #define NGX_MAX_PATH             PATH_MAX