From cdf3e5b04eea80e49e8ae5a540ca921f62914e66 Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Mon, 28 Sep 2020 13:31:38 -0700
Subject: [PATCH] retry isc_nm_udpconnect() if it fails

On FreeBSD, we sometimes see spurious transient EADDRINUSE errors
when connecting to a UDP socket. We now try a few times to ensure
the error is real before giving up.

This commit also fixes a memory leak that occurred if an error was
encountered in isc__nm_async_udpconnect().
---
 bin/dig/dighost.c    | 16 ++++++++++++----
 lib/isc/netmgr/udp.c |  9 +++------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index 6edb456940..e28ea8db7e 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -2918,7 +2918,8 @@ static void
 start_udp(dig_query_t *query) {
 	dig_lookup_t *l = NULL;
 	isc_result_t result;
-	dig_query_t *next;
+	dig_query_t *next = NULL;
+	int i = 0;
 
 	REQUIRE(DIG_VALID_QUERY(query));
 
@@ -2971,9 +2972,16 @@ start_udp(dig_query_t *query) {
 		}
 	}
 
-	result = isc_nm_udpconnect(netmgr, (isc_nmiface_t *)&localaddr,
-				   (isc_nmiface_t *)&query->sockaddr, udp_ready,
-				   query, 0);
+	do {
+		/*
+		 * On FreeBSD the UDP connect() call sometimes results
+		 * in a spurious transient EADDRINUSE. Try a few more times
+		 * before giving up.
+		 */
+		result = isc_nm_udpconnect(netmgr, (isc_nmiface_t *)&localaddr,
+					   (isc_nmiface_t *)&query->sockaddr,
+					   udp_ready, query, 0);
+	} while (result != ISC_R_SUCCESS && i++ < 2);
 	check_result(result, "isc_nm_udpconnect");
 }
 
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 4e88be7e3f..6ba07098de 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -607,7 +607,6 @@ isc__nm_async_udpconnect(isc__networker_t *worker, isc__netievent_t *ev0) {
 	uv_udp_init(&worker->loop, &sock->uv_handle.udp);
 	uv_handle_set_data(&sock->uv_handle.handle, NULL);
 	uv_handle_set_data(&sock->uv_handle.handle, sock);
-	handle = isc__nmhandle_get(sock, &ievent->peer, &sock->iface->addr);
 
 	r = uv_udp_open(&sock->uv_handle.udp, sock->fd);
 	if (r != 0) {
@@ -654,16 +653,17 @@ isc__nm_async_udpconnect(isc__networker_t *worker, isc__netievent_t *ev0) {
 	atomic_store(&sock->connected, true);
 	sock->result = ISC_R_SUCCESS;
 
-done:
 	cb = sock->connect_cb;
 	cbarg = sock->connect_cbarg;
 
+	handle = isc__nmhandle_get(sock, &ievent->peer, &sock->iface->addr);
 	cb(handle, sock->result, cbarg);
 
 	LOCK(&sock->lock);
 	SIGNAL(&sock->cond);
 	UNLOCK(&sock->lock);
 
+done:
 	isc__nmsocket_detach(&sock);
 }
 
@@ -743,10 +743,7 @@ isc_nm_udpconnect(isc_nm_t *mgr, isc_nmiface_t *local, isc_nmiface_t *peer,
 		UNLOCK(&sock->lock);
 	}
 
-	if (sock->result != ISC_R_SUCCESS) {
-		result = sock->result;
-		isc__nmsocket_detach(&sock);
-	}
+	sock->result = result;
 
 	isc__nmsocket_detach(&tmp);