Upstream: the "transparent" parameter of proxy_bind and friends.

This parameter lets binding the proxy connection to a non-local address.
Upstream will see the connection as coming from that address.
When used with $remote_addr, upstream will accept the connection from real
client address.

Example:

    proxy_bind $remote_addr transparent;

1 files changed, 21 insertions, 1 deletions

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index ec4e33f1c..5f08e3909 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -5788,7 +5788,7 @@ ngx_http_upstream_bind_set_slot(ngx_conf_t *cf, ngx_command_t *cmd,
 
     value = cf->args->elts;
 
-    if (ngx_strcmp(value[1].data, "off") == 0) {
+    if (cf->args->nelts == 2 && ngx_strcmp(value[1].data, "off") == 0) {
         *plocal = NULL;
         return NGX_CONF_OK;
     }
@@ -5841,6 +5841,22 @@ ngx_http_upstream_bind_set_slot(ngx_conf_t *cf, ngx_command_t *cmd,
         }
     }
 
+    if (cf->args->nelts > 2) {
+        if (ngx_strcmp(value[2].data, "transparent") == 0) {
+#if (NGX_HAVE_TRANSPARENT_PROXY)
+            local->transparent = 1;
+#else
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "transparent proxying is not supported "
+                               "on this platform, ignored");
+#endif
+        } else {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "invalid parameter \"%V\"", &value[2]);
+            return NGX_CONF_ERROR;
+        }
+    }
+
     return NGX_CONF_OK;
 }
 
@@ -5858,6 +5874,10 @@ ngx_http_upstream_set_local(ngx_http_request_t *r, ngx_http_upstream_t *u,
         return NGX_OK;
     }
 
+#if (NGX_HAVE_TRANSPARENT_PROXY)
+    u->peer.transparent = local->transparent;
+#endif
+
     if (local->value == NULL) {
         u->peer.local = local->addr;
         return NGX_OK;