Return HTTP response to RX_OVERFLOW

bin/varnishd/http1/cache_http1_fsm.c

@@ -327,6 +327,10 @@ HTTP1_Session(struct worker *wrk, struct req *req)
 			    cache_param->http_req_size);
 			assert(!WS_IsReserved(req->htc->ws));
 			if (hs < HTC_S_EMPTY) {
+				if (FEATURE(FEATURE_OVERFLOW_HTTP_RESP) && hs == HTC_S_OVERFLOW) {
+					(void)req->transport->minimal_response(req,
+								cache_param->req_overflow_status);
+				}
 				req->acct.req_hdrbytes +=
 				    req->htc->rxbuf_e - req->htc->rxbuf_b;
 				Req_AcctLogCharge(wrk->stats, req);

bin/varnishtest/tests/b00092.vtc

@@ -0,0 +1,28 @@
+varnishtest "HTTP response to RX_OVERFLOW"
+
+# server s1 {} -start
+
+varnish v1 -cliok "param.set http_req_size 500b" -vcl {
+	backend default none;
+} -start
+
+client c1 {
+	txreq -url "/world?hello=world${string,repeat,100,&hello=world}"
+	expect_close
+} -run
+
+varnish v1 -cliok "param.set feature +overflow_http_resp"
+
+client c1 {
+	txreq -url "/world?hello=world${string,repeat,100,&hello=world}"
+	rxresp
+	expect resp.status == 413
+} -run
+
+varnish v1 -cliok "param.set req_overflow_status 414"
+
+client c1 {
+	txreq -url "/world?hello=world${string,repeat,100,_hello-world}"
+	rxresp
+	expect resp.status == 414
+} -run

include/tbl/feature_bits.h

@@ -96,6 +96,10 @@ FEATURE_BIT(VCL_REQ_RESET,			vcl_req_reset,
     "When this happens MAIN.req_reset is incremented."
 )
 
+FEATURE_BIT(OVERFLOW_HTTP_RESP,			overflow_http_resp,
+    "Send an HTTP response instead of silently closing the socket"
+    "in case of RX_OVERFLOW.")
+
 #undef FEATURE_BIT
 
 /*lint -restore */

include/tbl/params.h

@@ -855,6 +855,17 @@ PARAM_SIMPLE(
 	"IPv4 and IPv6 addresses."
 )
 
+PARAM_SIMPLE(
+	/* name */	req_overflow_status,
+	/* type */	uint,
+	/* min */	"400",
+	/* max */	"499",
+	/* def */	"413",
+	/* units */	"HTTP code",
+	/* descr */
+	"HTTP code to be returned in case of a request overflow."
+)
+
 PARAM_SIMPLE(
 	/* name */	rush_exponent,
 	/* type */	uint,