Prevented scheduling events on a shared connection.

A shared connection does not own its file descriptor, which means that
ngx_handle_read_event/ngx_handle_write_event calls should do nothing for it.
Currently the c->shared flag is checked in several places in the stream proxy
module prior to calling these functions.  However it was not done everywhere.
Missing checks could lead to calling
ngx_handle_read_event/ngx_handle_write_event on shared connections.

The problem manifested itself when using proxy_upload_rate and resulted in
either duplicate file descriptor error (e.g. with epoll) or incorrect further
udp packet processing (e.g. with kqueue).

The fix is to set and reset the event active flag in a way that prevents
ngx_handle_read_event/ngx_handle_write_event from scheduling socket events.

diff --git a/src/event/ngx_event_udp.c b/src/event/ngx_event_udp.c
index 65eb22fd22e4248c47d3ede38ca0dd9ea0169149..55728305035eb8c31c86854292b9afed0da7dc1e 100644 (file)
--- a/src/event/ngx_event_udp.c
+++ b/src/event/ngx_event_udp.c
@@ -256,7 +256,9 @@ ngx_event_recvmsg(ngx_event_t *ev)
             rev = c->read;
 
             c->udp->buffer = &buf;
+
             rev->ready = 1;
+            rev->active = 0;
 
             rev->handler(rev);
 
@@ -265,6 +267,7 @@ ngx_event_recvmsg(ngx_event_t *ev)
             }
 
             rev->ready = 0;
+            rev->active = 1;
 
             goto next;
         }
@@ -343,6 +346,7 @@ ngx_event_recvmsg(ngx_event_t *ev)
         rev = c->read;
         wev = c->write;
 
+        rev->active = 1;
         wev->ready = 1;
 
         rev->log = log;
@@ -453,7 +457,9 @@ ngx_udp_shared_recv(ngx_connection_t *c, u_char *buf, size_t size)
     ngx_memcpy(buf, b->pos, n);
 
     c->udp->buffer = NULL;
+
     c->read->ready = 0;
+    c->read->active = 1;
 
     return n;
 }

diff --git a/src/stream/ngx_stream_proxy_module.c b/src/stream/ngx_stream_proxy_module.c
index 09493135539d1b86cf508bc9d887589d5308182b..ccb54188b112806164892d1d148b64f4056a8e37 100644 (file)
--- a/src/stream/ngx_stream_proxy_module.c
+++ b/src/stream/ngx_stream_proxy_module.c
@@ -1667,13 +1667,13 @@ ngx_stream_proxy_process(ngx_stream_session_t *s, ngx_uint_t from_upstream,
 
     flags = src->read->eof ? NGX_CLOSE_EVENT : 0;
 
-    if (!src->shared && ngx_handle_read_event(src->read, flags) != NGX_OK) {
+    if (ngx_handle_read_event(src->read, flags) != NGX_OK) {
         ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
         return;
     }
 
     if (dst) {
-        if (!dst->shared && ngx_handle_write_event(dst->write, 0) != NGX_OK) {
+        if (ngx_handle_write_event(dst->write, 0) != NGX_OK) {
             ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
             return;
         }