[master] 36a1f756a For backends with PROXYv1, send UNKNOWN in a probe if the backend's address family is neither of AF_INET or AF_INET6.

[Geoff Simmons]

commit 36a1f756ae2825e1f0091a023efc85becb0c48b5
Author: Geoff Simmons <geoff at uplex.de>
Date:   Mon Jul 2 00:13:12 2018 +0200

    For backends with PROXYv1, send UNKNOWN in a probe if the backend's
    address family is neither of AF_INET or AF_INET6.
    
    This means that UNKNOWN is sent in probes to UDS backends when
    .proxy_header=1 is set.
    
    Also verify that a UDS backend receives PROXY LOCAL in a probe when
    .proxy_header=2 is set.
    
    Fixes #2702
    Closes #2726

diff --git a/bin/varnishd/cache/cache_backend_probe.c b/bin/varnishd/cache/cache_backend_probe.c
index e63cd02c4..026a8928c 100644
--- a/bin/varnishd/cache/cache_backend_probe.c
+++ b/bin/varnishd/cache/cache_backend_probe.c
@@ -269,8 +269,9 @@ vbp_write_proxy_v1(struct vbp_target *vt, int *sock)
 	else if (ss.ss_family == AF_INET)
 		VSB_printf(&vsb, " TCP4 ");
 	else
-		WRONG("Unknown family");
-	VSB_printf(&vsb, "%s %s %s %s\r\n", addr, addr, port, port);
+		VSB_printf(&vsb, " UNKNOWN\r\n");
+	if (ss.ss_family == AF_INET6 || ss.ss_family == AF_INET)
+		VSB_printf(&vsb, "%s %s %s %s\r\n", addr, addr, port, port);
 	AZ(VSB_finish(&vsb));
 
 	return (vbp_write(vt, sock, VSB_data(&vsb), VSB_len(&vsb)));
diff --git a/bin/varnishtest/tests/r02702.vtc b/bin/varnishtest/tests/r02702.vtc
new file mode 100644
index 000000000..6208f0c07
--- /dev/null
+++ b/bin/varnishtest/tests/r02702.vtc
@@ -0,0 +1,74 @@
+varnishtest "probes to UDS backends with .proxy_header in [12]"
+
+# Since we can only reliably forward IP addresses via PROXY with
+# Varnish, we can't use the trick from o00002.vtc (use a Varnish
+# instance listening for PROXY as a backend) to verify PROXYv1 (but
+# the PROXY header can be viewed in the test log).
+
+# We just verify that the probe is good (and that Varnish doesn't
+# crash with WRONG).
+
+server s1 -listen "${tmpdir}/s1.sock" {
+	rxreq
+	txresp
+} -start
+
+# For PROXYv1 with a UDS backend, we send PROXY UNKNOWN in the probe.
+varnish v1 -vcl {
+	backend s1 {
+		.path = "${s1_sock}";
+		.proxy_header = 1;
+
+		.probe = {
+			.window = 1;
+			.threshold = 1;
+			.interval = 0.5s;
+		}
+	}
+} -start
+
+delay 1
+
+varnish v1 -cliexpect "vcl1.s1[ ]+probe[ ]+1/1[ ]+good" backend.list
+
+# For PROXYv2, we apply a trick similar to o0000[24].vtc, since
+# Varnish accepts (and ignores) PROXY LOCAL.
+
+server s2 {
+	rxreq
+	expect req.http.Host == "v2"
+	expect req.http.X-Forwarded-For == "0.0.0.0"
+	txresp
+} -start
+
+varnish v2 -arg "-a ${tmpdir}/v2.sock,PROXY" -vcl {
+	backend s2 { .host = "${s2_addr}"; .port = "${s2_port}"; }
+} -start
+
+varnish v3 -vcl {
+	backend bp {
+		.path = "${v2_addr}";
+		.host_header = "v2";
+		.proxy_header = 2;
+
+		.probe = {
+			.window = 1;
+			.threshold = 1;
+			.interval = 0.5s;
+		}
+	}
+} -start
+
+server s1 -wait
+
+delay 1
+
+varnish v3 -cliexpect "vcl1.bp[ ]+probe[ ]+1/1[ ]+good" backend.list
+
+# Verify in the v2 log that PROXY LOCAL was sent.
+
+logexpect l1 -v v2 -d 1 -g session -q "Proxy" {
+	expect 0 * Begin sess
+	expect * = Proxy {^\d+ local local local local$}
+	expect * = End
+} -run