From: Witold Kręcicki <wpk@isc.org>
Date: Tue, 21 Jul 2020 11:29:14 +0000 (+0200)
Subject: netmgr: retry binding with IP_FREEBIND when EADDRNOTAVAIL is returned.
X-Git-Tag: v9.17.4~20^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a0f7d28967f95c904614bbe44efde789e430a80e;p=thirdparty%2Fbind9.git

netmgr: retry binding with IP_FREEBIND when EADDRNOTAVAIL is returned.

When a new IPv6 interface/address appears it's first in a tentative
state - in which we cannot bind to it, yet it's already being reported
by the route socket. Because of that BIND9 is unable to listen on any
newly detected IPv6 addresses. Fix it by setting IP_FREEBIND option (or
equivalent option on other OSes) and then retrying bind() call.
---

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index 277601d5ab8..b5593a7f59f 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -821,3 +821,9 @@ isc__nm_decstats(isc_nm_t *mgr, isc_statscounter_t counterid);
 /*%<
  * Decrement socket-related statistics counters.
  */
+
+isc_result_t
+isc__nm_socket_freebind(const uv_handle_t *handle);
+/*%<
+ * Set the IP_FREEBIND (or equivalent) socket option on the uv_handle
+ */
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 0cdf5b3e9cd..30260afb294 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -1519,3 +1519,54 @@ isc__nm_decstats(isc_nm_t *mgr, isc_statscounter_t counterid) {
 		isc_stats_decrement(mgr->stats, counterid);
 	}
 }
+
+#define setsockopt_on(socket, level, name) \
+	setsockopt(socket, level, name, &(int){ 1 }, sizeof(int))
+
+isc_result_t
+isc__nm_socket_freebind(const uv_handle_t *handle) {
+	/*
+	 * Set the IP_FREEBIND (or equivalent option) on the uv_handle.
+	 */
+	isc_result_t result = ISC_R_SUCCESS;
+	uv_os_fd_t fd;
+	if (uv_fileno(handle, &fd) != 0) {
+		return (ISC_R_FAILURE);
+	}
+#ifdef IP_FREEBIND
+	if (setsockopt_on(fd, IPPROTO_IP, IP_FREEBIND) == -1) {
+		return (ISC_R_FAILURE);
+	}
+#elif defined(IP_BINDANY) || defined(IPV6_BINDANY)
+	struct sockaddr_in sockfd;
+
+	if (getsockname(fd, (struct sockaddr *)&sockfd,
+			&(socklen_t){ sizeof(sockfd) }) == -1)
+	{
+		return (ISC_R_FAILURE);
+	}
+#if defined(IP_BINDANY)
+	if (sockfd.sin_family == AF_INET) {
+		if (setsockopt_on(fd, IPPROTO_IP, IP_BINDANY) == -1) {
+			return (ISC_R_FAILURE);
+		}
+	}
+#endif
+#if defined(IPV6_BINDANY)
+	if (sockfd.sin_family == AF_INET6) {
+		if (setsockopt_on(fd, IPPROTO_IPV6, IPV6_BINDANY) == -1) {
+			return (ISC_R_FAILURE);
+		}
+	}
+#endif
+#elif defined(SO_BINDANY)
+	if (setsockopt_on(fd, SOL_SOCKET, SO_BINDANY) == -1) {
+		return (ISC_R_FAILURE);
+	}
+#else
+	UNUSED(handle);
+	UNUSED(fd);
+	result = ISC_R_NOTIMPLEMENTED;
+#endif
+	return (result);
+}
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 430616355b8..558b685caf9 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -340,6 +340,19 @@ isc__nm_async_tcplisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 
 	r = uv_tcp_bind(&sock->uv_handle.tcp, &sock->iface->addr.type.sa,
 			flags);
+	if (r == UV_EADDRNOTAVAIL &&
+	    isc__nm_socket_freebind(&sock->uv_handle.handle) == ISC_R_SUCCESS)
+	{
+		/*
+		 * Retry binding with IP_FREEBIND (or equivalent option) if the
+		 * address is not available. This helps with IPv6 tentative
+		 * addresses which are reported by the route socket, although
+		 * named is not yet able to properly bind to them.
+		 */
+		r = uv_tcp_bind(&sock->uv_handle.tcp,
+				&sock->iface->addr.type.sa, flags);
+	}
+
 	if (r != 0) {
 		isc__nm_incstats(sock->mgr, sock->statsindex[STATID_BINDFAIL]);
 		uv_close(&sock->uv_handle.handle, tcp_close_cb);
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 0e782f5cdec..544a967ae94 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -168,6 +168,20 @@ isc__nm_async_udplisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 
 	r = uv_udp_bind(&sock->uv_handle.udp,
 			&sock->parent->iface->addr.type.sa, uv_bind_flags);
+	if (r == UV_EADDRNOTAVAIL &&
+	    isc__nm_socket_freebind(&sock->uv_handle.handle) == ISC_R_SUCCESS)
+	{
+		/*
+		 * Retry binding with IP_FREEBIND (or equivalent option) if the
+		 * address is not available. This helps with IPv6 tentative
+		 * addresses which are reported by the route socket, although
+		 * named is not yet able to properly bind to them.
+		 */
+		r = uv_udp_bind(&sock->uv_handle.udp,
+				&sock->parent->iface->addr.type.sa,
+				uv_bind_flags);
+	}
+
 	if (r < 0) {
 		isc__nm_incstats(sock->mgr, sock->statsindex[STATID_BINDFAIL]);
 	}