# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1621383192 -10800
# Node ID c72d8839f427d4e026bc09e91916d46833640c30
# Parent  b3f4d83d6fd0299ca5db6636d35e0a7d217149ba
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
--- a/src/mail/ngx_mail_proxy_module.c
+++ b/src/mail/ngx_mail_proxy_module.c
@@ -813,12 +813,11 @@ ngx_mail_proxy_smtp_handler(ngx_event_t 
         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);
+        if (s->buffer->pos < s->buffer->last) {
+            ngx_post_event(c->write, &ngx_posted_events);
+        }
 
-        } else {
-            ngx_mail_proxy_handler(c->write);
-        }
+        ngx_mail_proxy_handler(s->connection->write);
 
         return;