Make regsub() return an empty string if it gets no input.

Fixes ticket 251 (regression test added)



git-svn-id: http://www.varnish-cache.org/svn/trunk@2743 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache_vrt_re.c

@@ -115,6 +115,8 @@ VRT_regsub(const struct sess *sp, int all, const char *str, void *re, const char
 	unsigned u, x;
 
 	AN(re);
+	if (str == NULL)
+		return ("");
 	t = re;
 	i = regexec(t, str, 10, pm, 0);
 

bin/varnishtest/tests/r00251.vtc

+# $Id$
+
+test "Regression test for #251: segfault on regsub on missing http header"
+
+server s1 {
+	rxreq 
+	txresp \
+		-hdr "Foobar: _barf_" \
+		-hdr "Connection: close" \
+		-body "012345\n"
+}
+
+varnish v1 -vcl+backend { 
+	sub vcl_fetch {
+		set obj.http.Snafu1 =
+		    "zoom"
+		    regsub(obj.http.Foomble, "ar", "\0\0")
+		    "box";
+	}
+} -start 
+
+server s1 -start 
+
+client c1 {
+	txreq -url "/"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.X-Varnish == "1001"
+	expect resp.http.foobar == "_barf_"
+	expect resp.http.snafu1 == "zoombox"
+}
+
+client c1 -run