From 0fea0bf3f7982348fd6ec9d14ebd946c783445b0 Mon Sep 17 00:00:00 2001
From: Sergey Kandaurov <pluknet@nginx.com>
Date: Tue, 30 Jul 2013 15:04:46 +0400
Subject: [PATCH] Added safety belt for the case of sending header twice.

The aforementioned situation is abnormal per se and as such it now forces
request termination with appropriate error message.
---
 src/http/ngx_http_core_module.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index ffe7fb4fe..47e5ff789 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -1933,6 +1933,12 @@ ngx_http_send_response(ngx_http_request_t *r, ngx_uint_t status,
 ngx_int_t
 ngx_http_send_header(ngx_http_request_t *r)
 {
+    if (r->header_sent) {
+        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                      "header already sent");
+        return NGX_ERROR;
+    }
+
     if (r->err_status) {
         r->headers_out.status = r->err_status;
         r->headers_out.status_line.len = 0;