Proxy: added HTTP/2 proxy module.

The module allows to use HTTP/2 protocol for proxying.
HTTP/2 proxying is enabled by specifying "proxy_http_version 2".

Example:

    server {
        listen 8000;

        location / {
            proxy_http_version 2;
            proxy_pass https://127.0.0.1:8443;
        }
    }

    server {
        listen 8443 ssl;
        http2 on;

        ssl_certificate certs/example.com.crt;
        ssl_certificate_key certs/example.com.key;

        location / {
            return 200 foo;
        }
    }

auto/modules

@@ -781,6 +781,17 @@ if [ $HTTP = YES ]; then
         . auto/module
     fi
 
+    if [ $HTTP_PROXY = YES -a $HTTP_V2 = YES ]; then
+        ngx_module_name=ngx_http_proxy_v2_module
+        ngx_module_incs=
+        ngx_module_deps=
+        ngx_module_srcs=src/http/modules/ngx_http_proxy_v2_module.c
+        ngx_module_libs=
+        ngx_module_link=$HTTP_V2
+
+        . auto/module
+    fi
+
     if [ $HTTP_PERL != NO ]; then
         ngx_module_name=ngx_http_perl_module
         ngx_module_incs=src/http/modules/perl

src/http/modules/ngx_http_proxy_module.c

@@ -198,6 +198,9 @@ static ngx_conf_post_t  ngx_http_proxy_ssl_conf_command_post =
 static ngx_conf_enum_t  ngx_http_proxy_http_version[] = {
     { ngx_string("1.0"), NGX_HTTP_VERSION_10 },
     { ngx_string("1.1"), NGX_HTTP_VERSION_11 },
+#if (NGX_HTTP_V2)
+    { ngx_string("2"), NGX_HTTP_VERSION_20 },
+#endif
     { ngx_null_string, 0 }
 };
 
@@ -875,6 +878,14 @@ ngx_http_proxy_handler(ngx_http_request_t *r)
     ngx_http_proxy_main_conf_t  *pmcf;
 #endif
 
+    plcf = ngx_http_get_module_loc_conf(r, ngx_http_proxy_module);
+
+#if (NGX_HTTP_V2)
+    if (plcf->http_version == NGX_HTTP_VERSION_20) {
+        return ngx_http_proxy_v2_handler(r);
+    }
+#endif
+
     if (ngx_http_upstream_create(r) != NGX_OK) {
         return NGX_HTTP_INTERNAL_SERVER_ERROR;
     }
@@ -888,8 +899,6 @@ ngx_http_proxy_handler(ngx_http_request_t *r)
 
     ngx_http_set_ctx(r, ctx, ngx_http_proxy_module);
 
-    plcf = ngx_http_get_module_loc_conf(r, ngx_http_proxy_module);
-
     u = r->upstream;
 
     if (plcf->proxy_lengths == NULL) {

src/http/modules/ngx_http_proxy_module.h

@@ -116,6 +116,10 @@ ngx_int_t ngx_http_proxy_rewrite_redirect(ngx_http_request_t *r,
 ngx_int_t ngx_http_proxy_rewrite_cookie(ngx_http_request_t *r,
     ngx_table_elt_t *h);
 
+#if (NGX_HTTP_V2)
+ngx_int_t ngx_http_proxy_v2_handler(ngx_http_request_t *r);
+#endif
+
 
 extern ngx_module_t  ngx_http_proxy_module;