The vcl_purge{} method can return synth or restart.

(Remember to change the "PURGE" to "GET" if you do this.)

Fixes #1493

bin/varnishd/cache/cache_req_fsm.c

@@ -830,7 +830,16 @@ cnt_purge(struct worker *wrk, struct req *req)
 	AZ(HSH_DerefObjCore(&wrk->stats, &boc));
 
 	VCL_purge_method(req->vcl, wrk, req, NULL, req->http->ws);
-	req->req_step = R_STP_SYNTH;
+	switch (wrk->handling) {
+	case VCL_RET_RESTART:
+		req->req_step = R_STP_RESTART;
+		break;
+	case VCL_RET_SYNTH:
+		req->req_step = R_STP_SYNTH;
+		break;
+	default:
+		WRONG("Illegal return from vcl_purge{}");
+	}
 	return (REQ_FSM_MORE);
 }
 

bin/varnishtest/tests/r01493.vtc

+varnishtest "restart in vcl_purge"
+
+server s1 {
+	rxreq
+	txresp
+} -start
+
+varnish v1 -vcl+backend {
+	sub vcl_recv {
+		if (req.method == "PURGE") {
+			return (purge);
+		}
+	}
+	sub vcl_purge {
+		set req.method = "GET";
+		return (restart);
+	}
+} -start
+
+client c1 {
+	txreq -req PURGE
+	rxresp
+	expect resp.status == 200
+} -run

lib/libvcc/generate.py

@@ -100,7 +100,7 @@ returns =(
 	),
 	('purge',
 		"C",
-		('synth', 'fetch',)
+		('synth', 'restart',)
 	),
 	('miss',
 		"C",