Repair --multihome on FreeBSD for IPv4 sockets.

The code in link_socket_write_udp_posix_sendmsg() for the IP_RECVDESTADDR
case was sending a too-large control message (sizeof openvpn_pktinfo,
which is a union for IPv4+IPv6) instead of just openvpn_in4_pktinfo,
leading to sendmsg() refusing to send the packet.

Use RFC 2292 macros for alignment + size calculation.

Fix trac#327

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Lazy-Ack-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1390164697-1590-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/8250

diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index ed4bc6fd9801c9070addc8cb28ea8886e223872f..0b3d7ade60973fcdb7b8ffea32fb70d89116cd9d 100644 (file)
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -3004,11 +3004,11 @@ link_socket_write_udp_posix_sendmsg (struct link_socket *sock,
         mesg.msg_name = &to->dest.addr.sa;
         mesg.msg_namelen = sizeof (struct sockaddr_in);
         mesg.msg_control = &opi;
-        mesg.msg_controllen = sizeof (struct openvpn_in4_pktinfo);
         mesg.msg_flags = 0;
+#ifdef HAVE_IN_PKTINFO
+        mesg.msg_controllen = sizeof (struct openvpn_in4_pktinfo);
         cmsg = CMSG_FIRSTHDR (&mesg);
         cmsg->cmsg_len = sizeof (struct openvpn_in4_pktinfo);
-#ifdef HAVE_IN_PKTINFO
         cmsg->cmsg_level = SOL_IP;
         cmsg->cmsg_type = IP_PKTINFO;
        {
@@ -3019,6 +3019,10 @@ link_socket_write_udp_posix_sendmsg (struct link_socket *sock,
         pkti->ipi_addr.s_addr = 0;
        }
 #elif defined(IP_RECVDSTADDR)
+       ASSERT( CMSG_SPACE(sizeof (struct in_addr)) <= sizeof(opi) );
+        mesg.msg_controllen = CMSG_SPACE(sizeof (struct in_addr));
+        cmsg = CMSG_FIRSTHDR (&mesg);
+        cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
         cmsg->cmsg_level = IPPROTO_IP;
         cmsg->cmsg_type = IP_RECVDSTADDR;
         *(struct in_addr *) CMSG_DATA (cmsg) = to->pi.in4;