[PATCH] Added logging to PROXY protocol write buffer check

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1667891773 -10800
#      Tue Nov 08 10:16:13 2022 +0300
# Node ID 22c65e5f1c372f251e2cefdd7aae743794ecfa9e
# Parent  17d6a537fb1bb587e4de22961bf5be5f0c648fa8
Added logging to PROXY protocol write buffer check.

The check is not expected to fail unless there is a bug in the calling
code.  But given the check is here, it should log an alert if it fails
instead of silently closing the connection.

diff --git a/src/core/ngx_proxy_protocol.c b/src/core/ngx_proxy_protocol.c
--- a/src/core/ngx_proxy_protocol.c
+++ b/src/core/ngx_proxy_protocol.c
@@ -282,6 +282,8 @@ ngx_proxy_protocol_write(ngx_connection_
     ngx_uint_t  port, lport;
 
     if (last - buf < NGX_PROXY_PROTOCOL_V1_MAX_HEADER) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                      "too small buffer for PROXY protocol");
         return NULL;
     }