[master] 9bc756d Add VCL var sess.xid (VCL >= 4.1).

[Geoff Simmons]

commit 9bc756d0cc4981624ce8c1d933ef52c82d6e1731
Author: Geoff Simmons <geoff at uplex.de>
Date:   Wed Mar 7 15:22:48 2018 +0100

    Add VCL var sess.xid (VCL >= 4.1).

diff --git a/bin/varnishd/cache/cache_vrt_var.c b/bin/varnishd/cache/cache_vrt_var.c
index f5f305f..05f058a 100644
--- a/bin/varnishd/cache/cache_vrt_var.c
+++ b/bin/varnishd/cache/cache_vrt_var.c
@@ -648,7 +648,7 @@ VRT_DO_AGE_R(obj, ctx->req->objcore)
 VRT_DO_AGE_R(beresp, ctx->bo->fetch_objcore)
 
 /*--------------------------------------------------------------------
- * [be]req.xid
+ * [[be]req|sess].xid
  */
 
 VCL_STRING
@@ -673,6 +673,20 @@ VRT_r_bereq_xid(VRT_CTX)
 	    VXID(ctx->bo->vsl->wid)));
 }
 
+VCL_STRING
+VRT_r_sess_xid(VRT_CTX)
+{
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+
+	if (VALID_OBJ(ctx->req, REQ_MAGIC))
+		return (WS_Printf(ctx->req->http->ws, "%u",
+		    VXID(ctx->req->sp->vxid)));
+
+	CHECK_OBJ_NOTNULL(ctx->bo, BUSYOBJ_MAGIC);
+	return (WS_Printf(ctx->bo->bereq->ws, "%u",
+	    VXID(ctx->bo->sp->vxid)));
+}
+
 /*--------------------------------------------------------------------
  * req fields
  */
diff --git a/bin/varnishtest/tests/t02000.vtc b/bin/varnishtest/tests/t02000.vtc
index cb7dc75..b3cbc1a 100644
--- a/bin/varnishtest/tests/t02000.vtc
+++ b/bin/varnishtest/tests/t02000.vtc
@@ -7,6 +7,10 @@ server s1 {
 		-hdr "H234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789I: foo" \
 		-hdr "Foo: H234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789I" \
 		-bodylen 10
+	rxreq
+	txresp
+	rxreq
+	txresp
 } -start
 
 varnish v1 -vcl+backend {
@@ -65,3 +69,34 @@ process p1 -stop
 # shell {cat ${tmpdir}/vlog}
 shell -match {1001 H2TxHdr        c \[000006040000000000\]} \
 	{cat ${tmpdir}/vlog}
+
+# While we're here, test sess.xid over H2 as well
+
+varnish v1 -syntax 4.1 -vcl+backend {
+	sub vcl_backend_response {
+		set beresp.http.B-Sess-XID = sess.xid;
+	}
+
+	sub vcl_deliver {
+		set resp.http.C-Sess-XID = sess.xid;
+	}
+}
+
+client c1 {
+	stream 7 {
+		txreq -url "/uncached"
+		rxresp
+		expect resp.status == 200
+		expect resp.http.C-Sess-XID ~ "^[0-9]+$"
+		expect resp.http.B-Sess-XID ~ "^[0-9]+$"
+		expect resp.http.C-Sess-XID == resp.http.B-Sess-XID
+	} -run
+	stream 9 {
+		txreq -url "/still_not_cached"
+		rxresp
+		expect resp.status == 200
+		expect resp.http.C-Sess-XID ~ "^[0-9]+$"
+		expect resp.http.B-Sess-XID ~ "^[0-9]+$"
+		expect resp.http.C-Sess-XID == resp.http.B-Sess-XID
+	} -run
+} -run
diff --git a/bin/varnishtest/tests/v00025.vtc b/bin/varnishtest/tests/v00025.vtc
index 544240b..9a20422 100644
--- a/bin/varnishtest/tests/v00025.vtc
+++ b/bin/varnishtest/tests/v00025.vtc
@@ -3,6 +3,8 @@ varnishtest "More VCL coverage"
 server s1 {
 	rxreq
 	txresp
+	rxreq
+	txresp
 } -start
 
 varnish v1 -syntax 4.0 -arg "-i J.F.Nobody" -vcl+backend {
@@ -91,3 +93,34 @@ client c1 {
 	txreq
 	rxresp
 } -run
+
+varnish v1 -syntax 4.0 -errvcl {Symbol not found: 'sess.xid' (Only available when 4.1 <= VCL syntax)} {
+	sub vcl_recv {
+		set req.http.Sess-XID = sess.xid;
+	}
+}
+
+varnish v1 -syntax 4.0 -errvcl {Symbol not found: 'sess.xid' (Only available when 4.1 <= VCL syntax)} {
+	sub vcl_backend_fetch {
+		set bereq.http.Sess-XID = sess.xid;
+	}
+}
+
+varnish v1 -syntax 4.1 -vcl+backend {
+	sub vcl_backend_response {
+		set beresp.http.B-Sess-XID = sess.xid;
+	}
+
+	sub vcl_deliver {
+		set resp.http.C-Sess-XID = sess.xid;
+	}
+}
+
+client c1 {
+	txreq -url "/uncached"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.C-Sess-XID ~ "^[0-9]+$"
+	expect resp.http.B-Sess-XID ~ "^[0-9]+$"
+	expect resp.http.C-Sess-XID == resp.http.B-Sess-XID
+} -run
diff --git a/doc/sphinx/reference/vcl_var.rst b/doc/sphinx/reference/vcl_var.rst
index 37e88c9..7c18b36 100644
--- a/doc/sphinx/reference/vcl_var.rst
+++ b/doc/sphinx/reference/vcl_var.rst
@@ -1120,7 +1120,23 @@ now
 
 	When converted to STRING in expressions it returns
 	a formatted timestamp like `Tue, 20 Feb 2018 09:30:31 GMT`
-	
+
+sess
+~~~~
+
+A session corresponds to the "conversation" that Varnish has with a
+single client connection, over which one or more request/response
+transactions may take place. It may comprise the traffic over an
+HTTP/1 keep-alive connection, or the multiplexed traffic over an
+HTTP/2 connection.
+
+sess.xid	``VCL >= 4.1``
+
+	Type: STRING
+
+	Readable from: client, backend
+
+	Unique ID of this session.
 
 storage
 ~~~~~~~