Mail: fixed SMTP pipelining to send the response immediately.

Previously, if there were some pipelined SMTP data in the buffer when
a proxied connection with the backend was established, nginx called
ngx_mail_proxy_handler() to send these data, and not tried to send the
response to the last command.  In most cases, this response was later sent
along with the response to the pipelined command, but if for some reason
client decides to wait for the response before finishing the next command
this might result in a connection hang.

Fix is to always call ngx_mail_proxy_handler() to send the response, and
additionally post an event to send the pipelined data if needed.

diff --git a/src/mail/ngx_mail_proxy_module.c b/src/mail/ngx_mail_proxy_module.c
index 66aa0ba0981d12dbe68f904c1bb70faaf258034f..38164af95567a3e75805a3fedd0f66212da22fc1 100644 (file)
--- a/src/mail/ngx_mail_proxy_module.c
+++ b/src/mail/ngx_mail_proxy_module.c
@@ -813,13 +813,12 @@ ngx_mail_proxy_smtp_handler(ngx_event_t *rev)
         c->log->action = NULL;
         ngx_log_error(NGX_LOG_INFO, c->log, 0, "client logged in");
 
-        if (s->buffer->pos == s->buffer->last) {
-            ngx_mail_proxy_handler(s->connection->write);
-
-        } else {
-            ngx_mail_proxy_handler(c->write);
+        if (s->buffer->pos < s->buffer->last) {
+            ngx_post_event(c->write, &ngx_posted_events);
         }
 
+        ngx_mail_proxy_handler(s->connection->write);
+
         return;
 
     default: