From 643abfbba7fe9eb7e2000ee3015c7e680cc590a2 Mon Sep 17 00:00:00 2001
From: Aram Sargsyan <aram@isc.org>
Date: Mon, 12 Dec 2022 11:55:09 +0000
Subject: [PATCH] Synchronize dns_request_createraw() and dns_request_create()
 UDP timeout

The dns_request_createraw() function, unlike dns_request_create(), when
calculating the UDP timeout value, doesn't check that 'udpretries' is
not zero, and that is the more logical behavior, because the calculation
formula uses division to 'udpretries + 1', where '1' is the first try.

Change the dns_request_create() function to remove the 'udpretries != 0'
condition.

Add a 'REQUIRE(udpretries != UINT_MAX)' check to protect from a division
by zero.

Make the 'request->udpcount' field to represent the number of tries,
instead of the number of retries.
---
 lib/dns/request.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/lib/dns/request.c b/lib/dns/request.c
index f78a57d7a3..977b2ebaad 100644
--- a/lib/dns/request.c
+++ b/lib/dns/request.c
@@ -421,6 +421,8 @@ dns_request_createraw(dns_requestmgr_t *requestmgr, isc_buffer_t *msgbuf,
 	REQUIRE(cb != NULL);
 	REQUIRE(requestp != NULL && *requestp == NULL);
 	REQUIRE(timeout > 0);
+	REQUIRE(udpretries != UINT_MAX);
+
 	if (srcaddr != NULL) {
 		REQUIRE(isc_sockaddr_pf(srcaddr) == isc_sockaddr_pf(destaddr));
 	}
@@ -447,7 +449,7 @@ dns_request_createraw(dns_requestmgr_t *requestmgr, isc_buffer_t *msgbuf,
 	request->cb = cb;
 	request->arg = arg;
 	request->result = ISC_R_FAILURE;
-	request->udpcount = udpretries;
+	request->udpcount = udpretries + 1;
 
 	isc_buffer_usedregion(msgbuf, &r);
 	if (r.length < DNS_MESSAGE_HEADERLEN || r.length > 65535) {
@@ -460,7 +462,7 @@ dns_request_createraw(dns_requestmgr_t *requestmgr, isc_buffer_t *msgbuf,
 		request->timeout = timeout * 1000;
 	} else {
 		if (udptimeout == 0) {
-			udptimeout = timeout / (udpretries + 1);
+			udptimeout = timeout / request->udpcount;
 		}
 		if (udptimeout == 0) {
 			udptimeout = 1;
@@ -569,6 +571,7 @@ dns_request_create(dns_requestmgr_t *requestmgr, dns_message_t *message,
 	REQUIRE(cb != NULL);
 	REQUIRE(requestp != NULL && *requestp == NULL);
 	REQUIRE(timeout > 0);
+	REQUIRE(udpretries != UINT_MAX);
 
 	mctx = requestmgr->mctx;
 
@@ -598,9 +601,7 @@ dns_request_create(dns_requestmgr_t *requestmgr, dns_message_t *message,
 	request->cb = cb;
 	request->arg = arg;
 	request->result = ISC_R_FAILURE;
-	request->udpcount = udpretries;
-
-	request->udpcount = udpretries;
+	request->udpcount = udpretries + 1;
 
 	if (key != NULL) {
 		dns_tsigkey_attach(key, &request->tsigkey);
@@ -615,8 +616,8 @@ dns_request_create(dns_requestmgr_t *requestmgr, dns_message_t *message,
 		tcp = true;
 		request->timeout = timeout * 1000;
 	} else {
-		if (udptimeout == 0 && udpretries != 0) {
-			udptimeout = timeout / (udpretries + 1);
+		if (udptimeout == 0) {
+			udptimeout = timeout / request->udpcount;
 		}
 		if (udptimeout == 0) {
 			udptimeout = 1;
@@ -973,7 +974,7 @@ req_response(isc_result_t result, isc_region_t *region, void *arg) {
 
 	if (result == ISC_R_TIMEDOUT) {
 		LOCK(&request->requestmgr->locks[request->hash]);
-		if (request->udpcount != 0) {
+		if (request->udpcount > 1) {
 			request->udpcount -= 1;
 			dns_dispatch_resume(request->dispentry,
 					    request->timeout);