From 6fab2f80c95959b17adb2f81656e9abf003e1717 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Thu, 21 Jul 2011 01:40:50 +0000
Subject: [PATCH] 3135.   [port]          FreeBSD: workaround broken
 IPV6_USE_MIN_MTU processing.                         See
 http://www.freebsd.org/cgi/query-pr.cgi?pr=158307                         [RT
 #24950]

---
 CHANGES               |  4 ++++
 lib/isc/unix/socket.c | 44 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/CHANGES b/CHANGES
index 7f3dc8f11a..a5e65a2562 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+3135.	[port]		FreeBSD: workaround broken IPV6_USE_MIN_MTU processing.
+			See http://www.freebsd.org/cgi/query-pr.cgi?pr=158307
+			[RT #24950]
+
 3134.	[bug]		Improve the accuracy of dnssec-signzone's signing
 			statistics. [RT #16030]
 
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 9d47f72403..90be778a4b 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.c,v 1.338 2011/03/11 06:11:26 marka Exp $ */
+/* $Id: socket.c,v 1.339 2011/07/21 01:40:50 marka Exp $ */
 
 /*! \file */
 
@@ -1364,6 +1364,9 @@ build_msghdr_send(isc__socket_t *sock, isc_socketevent_t *dev,
 #if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
 	if ((sock->type == isc_sockettype_udp)
 	    && ((dev->attributes & ISC_SOCKEVENTATTR_PKTINFO) != 0)) {
+#if defined(IPV6_USE_MIN_MTU)
+		int use_min_mtu = 1;	/* -1, 0, 1 */
+#endif
 		struct cmsghdr *cmsgp;
 		struct in6_pktinfo *pktinfop;
 
@@ -1382,6 +1385,22 @@ build_msghdr_send(isc__socket_t *sock, isc_socketevent_t *dev,
 		cmsgp->cmsg_len = cmsg_len(sizeof(struct in6_pktinfo));
 		pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
 		memcpy(pktinfop, &dev->pktinfo, sizeof(struct in6_pktinfo));
+#if defined(IPV6_USE_MIN_MTU)
+		/*
+		 * Set IPV6_USE_MIN_MTU as a per packet option as FreeBSD
+		 * ignores setsockopt(IPV6_USE_MIN_MTU) when IPV6_PKTINFO 
+		 * is used.
+		 */
+		cmsgp = (struct cmsghdr *)(sock->sendcmsgbuf +
+					   msg->msg_controllen);
+		msg->msg_controllen += cmsg_space(sizeof(use_min_mtu));
+		INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
+
+		cmsgp->cmsg_level = IPPROTO_IPV6;
+		cmsgp->cmsg_type = IPV6_USE_MIN_MTU;
+		cmsgp->cmsg_len = cmsg_len(sizeof(use_min_mtu));
+		memcpy(CMSG_DATA(cmsgp), &use_min_mtu, sizeof(use_min_mtu));
+#endif
 	}
 #endif /* USE_CMSG && ISC_PLATFORM_HAVEIPV6 */
 #else /* ISC_NET_BSD44MSGHDR */
@@ -2053,6 +2072,13 @@ allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
 	cmsgbuflen = 0;
 #if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
 	cmsgbuflen += cmsg_space(sizeof(struct in6_pktinfo));
+#if defined(IPV6_USE_MIN_MTU)
+	/*
+	 * Provide space for working around FreeBSD's broken IPV6_USE_MIN_MTU
+	 * support.
+	 */
+	cmsgbuflen += cmsg_space(sizeof(int));
+#endif
 #endif
 	sock->sendcmsgbuflen = cmsgbuflen;
 	if (sock->sendcmsgbuflen != 0U) {
@@ -2402,10 +2428,18 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock) {
 #endif /* ISC_PLATFORM_HAVEIN6PKTINFO */
 #ifdef IPV6_USE_MIN_MTU        /* RFC 3542, not too common yet*/
 		/* use minimum MTU */
-		if (sock->pf == AF_INET6) {
-			(void)setsockopt(sock->fd, IPPROTO_IPV6,
-					 IPV6_USE_MIN_MTU,
-					 (void *)&on, sizeof(on));
+		if (sock->pf == AF_INET6 &&
+		    setsockopt(sock->fd, IPPROTO_IPV6, IPV6_USE_MIN_MTU,
+			       (void *)&on, sizeof(on)) < 0) {
+			isc__strerror(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IPV6_USE_MIN_MTU) "
+					 "%s: %s", sock->fd,
+					 isc_msgcat_get(isc_msgcat,
+							ISC_MSGSET_GENERAL,
+							ISC_MSG_FAILED,
+							"failed"),
+					 strbuf);
 		}
 #endif
 #if defined(IPV6_MTU)