While compiling varnish 3.0.5, I have detected a possible bug at
getsockopt when TCP_NODELAY is used as parameter. The issue is caused
because at cygwin it returns a BOOL, instead returning INT value like at
Linux.
At varnish 3.0.5, the following code at "sock_test(int fd)" uses getsockopt:
-
https://www.varnish-cache.org/trac/browser/bin/varnishd/cache_acceptor.c?rev=dec9098a2ac760d7ba4765a9a1a1091103b6eb05
l = sizeof tcp_nodelay;
i = getsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &tcp_nodelay, &l);
if (i) {
VTCP_Assert(i);
return;
}
assert(l == sizeof tcp_nodelay);
if (!tcp_nodelay)
need_tcpnodelay = 1;
The problem is that at cygwin, this ASSERT fails:
- assert(l == sizeof tcp_nodelay);
Because before function call, the initial tcp_nodelay variable size is
INT, but after funtion call, it returns a pointer to a BOOL variable, so
assert (sizeof INT == sizeof BOOL) fails.
After some investigations I have seen that at windows, its getsockopt
function, returns BOOL for TCP_NODELAY:
-
http://msdn.microsoft.com/en-us/library/windows/desktop/ms738544%28v=vs.85%29.aspx
But at Unix, the correct behaviour is to return INT:
- http://www.yolinux.com/TUTORIALS/Sockets.html
I suppose that the cygwin getsockopt internally calls to Windows
getsockopt, and no type conversion of variables is done. I think the
solution would be to wrap getsockopt response and change it from bool
size variable to a int size variable.
As a temporary workaround for varnish 3.0.5 I have changed the variable
types to bool, but I think It would be better to directly fix it at
cygwin layer, to avoid modifications to original Linux code:
--- origsrc/varnish-3.0.5/bin/varnishd/cache_acceptor.c 2013-12-02
08:48:15.000000000 +0100
+++ src/varnish-3.0.5/bin/varnishd/cache_acceptor.c 2014-04-17
21:31:12.555512600 +0200
@@ -36,6 +36,9 @@
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
+#if defined(__CYGWIN__)
+#include <stdbool.h>
+#endif
#include <sys/uio.h>
#include <sys/types.h>
@@ -105,7 +108,12 @@ sock_test(int fd)
struct linger lin;
struct timeval tv;
socklen_t l;
- int i, tcp_nodelay;
+ int i;
+ #if defined(__CYGWIN__)
+ bool tcp_nodelay;
+ #else
+ int tcp_nodelay;
+ #endif
l = sizeof lin;
i = getsockopt(fd, SOL_SOCKET, SO_LINGER, &lin, &l);
@@ -172,7 +180,11 @@ VCA_Prep(struct sess *sp)
{
char addr[VTCP_ADDRBUFSIZE];
char port[VTCP_PORTBUFSIZE];
+ #if defined(__CYGWIN__)
+ bool tcp_nodelay = true;
+ #else
int tcp_nodelay = 1;
+ #endif
VTCP_name(sp->sockaddr, sp->sockaddrlen,
addr, sizeof addr, port, sizeof port);
Thank you
Jorge
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