[nginx] svn commit: r5023 - trunk/src/event

[vbart at nginx.com]

Author: vbart
Date: 2013-01-28 15:40:25 +0000 (Mon, 28 Jan 2013)
New Revision: 5023
URL: http://trac.nginx.org/nginx/changeset/5023/nginx

Log:
SSL: avoid calling SSL_write() with zero data size.

According to documentation, calling SSL_write() with num=0 bytes to be sent
results in undefined behavior.

We don't currently call ngx_ssl_send_chain() with empty chain and buffer.
This check handles the case of a chain with total data size that is
a multiple of NGX_SSL_BUFSIZE, and with the special buffer at the end.

In practice such cases resulted in premature connection close and critical
error "SSL_write() failed (SSL:)" in the error log.



Modified:
   trunk/src/event/ngx_event_openssl.c

Modified: trunk/src/event/ngx_event_openssl.c
===================================================================
--- trunk/src/event/ngx_event_openssl.c	2013-01-28 15:38:36 UTC (rev 5022)
+++ trunk/src/event/ngx_event_openssl.c	2013-01-28 15:40:25 UTC (rev 5023)
@@ -1213,6 +1213,12 @@
 
         size = buf->last - buf->pos;
 
+        if (size == 0) {
+            buf->flush = 0;
+            c->buffered &= ~NGX_SSL_BUFFERED;
+            return in;
+        }
+
         n = ngx_ssl_write(c, buf->pos, size);
 
         if (n == NGX_ERROR) {