Make it possible to test for the non-definition of a http header.

Fixes #1062

bin/varnishtest/tests/a00012.vtc

+varnishtest "Ensure that we can test non-existence of headers (#1062)"
+
+server s1 {
+        rxreq
+        txresp
+} -start
+
+client c1 -connect ${s1_sock} {
+        txreq
+        rxresp
+        expect resp.http.X-Test == <undef>
+} -run
+

bin/varnishtest/tests/c00016.vtc

@@ -8,7 +8,7 @@ server s1 {
 
 	rxreq
 	expect req.url == "/bar"
-	expect req.http.Foo == "req.http.Foo"
+	expect req.http.Foo == <undef>
 	txresp -hdr "Bar: fnry,glyf, FOO ,brok" -hdr "Connection: bar" -body "foobar" 
 } -start
 
@@ -21,5 +21,5 @@ client c1 {
 
 	txreq -url "/bar" -hdr "Foo: bar2" -hdr "Connection: foo, close"
 	rxresp
-	expect req.http.Bar == "req.http.Bar"
+	expect req.http.Bar == <undef>
 } -run

bin/varnishtest/tests/e00024.vtc

@@ -81,7 +81,7 @@ client c1 {
 
 	txreq 
 	rxresp
-	expect resp.http.content-encoding == resp.http.content-encoding
+	expect resp.http.content-encoding == <undef>
 	expect resp.status == 200
 	expect resp.bodylen == 252
 } -run

bin/varnishtest/tests/e00025.vtc

@@ -18,7 +18,7 @@ client c1 {
 
 	txreq 
 	rxresp
-	expect resp.http.content-encoding == resp.http.content-encoding
+	expect resp.http.content-encoding == <undef>
 	expect resp.status == 200
 	expect resp.bodylen == 3
 } -run

bin/varnishtest/tests/g00001.vtc

@@ -13,7 +13,7 @@ client c1 {
 	txreq 
 	rxresp
 	expect resp.bodylen == "3"
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 
 	txreq -hdr "Accept-encoding: gzip;q=0.1"
 	rxresp
@@ -26,13 +26,13 @@ client c1 {
 	txreq -proto HTTP/1.0
 	rxresp
 	expect resp.bodylen == "3"
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 } -run
 
 client c1 {
 	txreq -req HEAD
 	rxresp -no_obj
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 
 	txreq -req HEAD -hdr "Accept-encoding: gzip;q=0.1"
 	rxresp -no_obj

bin/varnishtest/tests/g00002.vtc

@@ -39,12 +39,12 @@ client c1 {
 	# See varnish can gunzip it.
 	txreq -url /foo -hdr "Accept-Encoding: null"
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 4100
 
 	# See varnish can gunzip it, inside ESI
 	txreq -url /bar -hdr "Accept-Encoding: null"
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 4109
 } -run

bin/varnishtest/tests/g00003.vtc

@@ -30,12 +30,12 @@ varnish v1 -cliok "param.set http_gzip_support true" -vcl+backend {
 client c1 {
 	txreq -url /foo -hdr "Accept-Encoding: gzip"
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 41
 
 	txreq -url /bar -hdr "Accept-Encoding: gzip"
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 42
 
 	txreq -url /foobar -hdr "Accept-Encoding: gzip"
@@ -46,6 +46,6 @@ client c1 {
 
 	txreq -url /foobar 
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 43
 } -run

bin/varnishtest/tests/r00292.vtc

@@ -6,11 +6,11 @@ varnishtest "Header deletion test"
 server s1 {
 	rxreq
 	expect req.url == "/foo"
-	expect req.http.hdr1 == "req.http.hdr1"
+	expect req.http.hdr1 == <undef>
 	expect req.http.hdr2 == "2"
-	expect req.http.hdr3 == "req.http.hdr3"
+	expect req.http.hdr3 == <undef>
 	expect req.http.hdr4 == "4"
-	expect req.http.hdr5 == "req.http.hdr5"
+	expect req.http.hdr5 == <undef>
 	expect req.http.hdr6 == "6"
 	txresp -body "foobar"
 } -start

bin/varnishtest/tests/r00466.vtc

@@ -3,7 +3,7 @@ varnishtest "Check Range forwarding to backend"
 server s1 {
 	rxreq 
 	expect req.url == "/foo"
-	expect req.http.range == "req.http.range"
+	expect req.http.range == <undef>
 	txresp \
 		-hdr "Foobar: _barf_" \
 		-body "012345\n"

bin/varnishtest/tests/r00494.vtc

@@ -19,6 +19,6 @@ client c1 {
 	txreq
 	rxresp
 	expect resp.http.bar == "bar,  barf: fail"
-	expect resp.http.barf == resp.http.barf
-	expect resp.http.foo == resp.http.foo
+	expect resp.http.barf == <undef>
+	expect resp.http.foo == <undef>
 } -run

bin/varnishtest/tests/r00693.vtc

@@ -4,11 +4,11 @@ feature 64bit
 
 server s1 {
 	rxreq
-	expect req.http.baz == "req.http.baz"
+	expect req.http.baz == <undef>
 	txresp -status 201
 
 	rxreq
-	expect req.http.baz == "req.http.baz"
+	expect req.http.baz == <undef>
 	txresp -status 202
 
 	rxreq
@@ -52,7 +52,7 @@ varnish v1 -arg "-p sess_workspace=1024" -vcl+backend {
 			"0123456789abcdef" + "0123456789abcdef" +
 			"0123456789abcdef" + "0123456789abcdef" +
 			"0123456789abcdef" +
-			"01234567";
+			"0123456";
 		set req.http.baz = "BAZ";
 		return (pass);
 	}

bin/varnishtest/tests/r00861.vtc

@@ -34,12 +34,12 @@ varnish v1 \
 client c1 {
 	txreq -url "/1"
 	rxresp
-	expect resp.http.Content-Encoding == resp.http.Content-Encoding
+	expect resp.http.Content-Encoding == <undef>
 	expect resp.bodylen == 22
 
 	txreq -url "/barf" -hdr "Accept-Encoding: gzip"
 	rxresp
-	expect resp.http.Content-Encoding == resp.http.Content-Encoding
+	expect resp.http.Content-Encoding == <undef>
 	expect resp.bodylen == 909
 
 	txreq -url "/2" -hdr "Accept-Encoding: gzip"

bin/varnishtest/tests/r00980.vtc

@@ -24,6 +24,6 @@ client c1 {
 
 	txreq -url /foobar 
 	rxresp
-	expect resp.http.content-encoding == "resp.http.content-encoding"
+	expect resp.http.content-encoding == <undef>
 	expect resp.bodylen == 43
 } -run

bin/varnishtest/vtc_http.c

@@ -175,7 +175,7 @@ http_find_header(char * const *hh, const char *hdr)
  * Expect
  */
 
-static char *
+static const char *
 cmd_var_resolve(struct http *hp, char *spec)
 {
 	char **hh, *hdr;
@@ -207,16 +207,16 @@ cmd_var_resolve(struct http *hp, char *spec)
 	hdr = http_find_header(hh, hdr);
 	if (hdr != NULL)
 		return (hdr);
-	return (spec);
+	return ("<undef>");
 }
 
 static void
 cmd_http_expect(CMD_ARGS)
 {
 	struct http *hp;
-	char *lhs;
+	const char *lhs;
 	char *cmp;
-	char *rhs;
+	const char *rhs;
 
 	(void)cmd;
 	(void)vl;