vrt_var: req.ttl and req.grace is NAN when not set

Since VCL is not prepared to deal with NAN, the accessor function
converts NAN to 0.

As a side effect, we are no longer able to determine whether req.ttl and
req.grace are set.

Author: AlveElde

bin/varnishd/cache/cache_expire.c

@@ -73,7 +73,7 @@ EXP_Ttl(const struct req *req, const struct objcore *oc)
 	CHECK_OBJ_NOTNULL(oc, OBJCORE_MAGIC);
 
 	r = oc->ttl;
-	if (req != NULL && req->d_ttl >= 0. && req->d_ttl < r)
+	if (req != NULL && !isnan(req->d_ttl) && req->d_ttl < r)
 		r = req->d_ttl;
 	return (oc->t_origin + r);
 }
@@ -91,7 +91,7 @@ EXP_Ttl_grace(const struct req *req, const struct objcore *oc)
 	CHECK_OBJ_NOTNULL(oc, OBJCORE_MAGIC);
 
 	g = oc->grace;
-	if (req != NULL && req->d_grace >= 0. && req->d_grace < g)
+	if (req != NULL && !isnan(req->d_grace) && req->d_grace < g)
 		g = req->d_grace;
 	return (EXP_Ttl(req, oc) + g);
 }

bin/varnishd/cache/cache_req_fsm.c

@@ -891,8 +891,8 @@ cnt_recv_prep(struct req *req, const char *ci)
 		VRT_Assign_Backend(&req->director_hint,
 		    VCL_DefaultDirector(req->vcl));
 
-		req->d_ttl = -1;
-		req->d_grace = -1;
+		req->d_ttl = NAN;
+		req->d_grace = NAN;
 		req->disable_esi = 0;
 		req->hash_always_miss = 0;
 		req->hash_ignore_busy = 0;

bin/varnishd/cache/cache_vrt_var.c

@@ -566,14 +566,17 @@ VRT_l_req_##nm(VRT_CTX, type arg)					\
 	ctx->req->elem = arg;						\
 }
 
-#define REQ_VAR_R(nm, elem, type)					\
+#define REQ_VAR_R(nm, elem, type, extra)				\
 									\
 type									\
 VRT_r_req_##nm(VRT_CTX)							\
 {									\
+	type e;								\
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);				\
 	CHECK_OBJ_NOTNULL(ctx->req, REQ_MAGIC);				\
-	return (ctx->req->elem);					\
+	e = ctx->req->elem; 						\
+	extra;								\
+	return (e);							\
 }
 
 #define REQ_VAR_U(nm, elem, val)					\
@@ -586,14 +589,14 @@ VRT_u_req_##nm(VRT_CTX)							\
 	ctx->req->elem = val;						\
 }
 
-REQ_VAR_R(backend_hint, director_hint, VCL_BACKEND)
+REQ_VAR_R(backend_hint, director_hint, VCL_BACKEND, )
 
 REQ_VAR_L(ttl, d_ttl, VCL_DURATION, if (!(arg>0.0)) arg = 0;)
-REQ_VAR_R(ttl, d_ttl, VCL_DURATION)
-REQ_VAR_U(ttl, d_ttl, -1)
+REQ_VAR_R(ttl, d_ttl, VCL_DURATION, if (isnan(e)) e = 0;)
+REQ_VAR_U(ttl, d_ttl, NAN)
 REQ_VAR_L(grace, d_grace, VCL_DURATION, if (!(arg>0.0)) arg = 0;)
-REQ_VAR_R(grace, d_grace, VCL_DURATION)
-REQ_VAR_U(grace, d_grace, -1)
+REQ_VAR_R(grace, d_grace, VCL_DURATION, if (isnan(e)) e = 0;)
+REQ_VAR_U(grace, d_grace, NAN)
 
 VCL_VOID
 VRT_l_req_backend_hint(VRT_CTX, VCL_BACKEND be)

bin/varnishtest/tests/b00064.vtc

@@ -84,7 +84,7 @@ client c2 {
 	expect resp.status == 200
 	expect resp.body == "1"
 	expect resp.http.X-grace == "60.000"
-	expect resp.http.X-req-grace < 0.
+	expect resp.http.X-req-grace == "0.000"
 	expect resp.http.X-was-bgfetch == <undef>
 } -run
 
@@ -118,7 +118,7 @@ client c4 {
 	# We should get what c1 got in the very beginning
 	expect resp.body == "1"
 	expect resp.http.X-grace == "60.000"
-	expect resp.http.X-req-grace < 0.
+	expect resp.http.X-req-grace == "0.000"
 	expect resp.http.X-was-bgfetch == <undef>
 } -start
 

bin/varnishtest/tests/b00086.vtc

@@ -2,12 +2,12 @@ varnishtest "unset req.ttl and req.grace"
 
 server s1 {
 	rxreq
-	expect req.http.ttl-initial == -1.000
-	expect req.http.grace-initial == -1.000
+	expect req.http.ttl-initial == 0.000
+	expect req.http.grace-initial == 0.000
 	expect req.http.ttl-set == 0.000
 	expect req.http.grace-set == 0.000
-	expect req.http.ttl-unset == -1.000
-	expect req.http.grace-unset == -1.000
+	expect req.http.ttl-unset == 0.000
+	expect req.http.grace-unset == 0.000
 	txresp
 } -start