From 78c125f954893b3a828f258e37f31aec204e8c45 Mon Sep 17 00:00:00 2001
From: Erich Hoover <ehoover@mines.edu>
Date: Sat, 8 May 2010 16:14:00 -0600
Subject: server: Ensure Async ReadFile does not wake up on packets with an interface mismatch.

---
 server/sock.c |   67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/server/sock.c b/server/sock.c
index e0d2706..98585d5 100644
--- a/server/sock.c
+++ b/server/sock.c
@@ -38,6 +38,9 @@
 #ifdef HAVE_SYS_SOCKET_H
 # include <sys/socket.h>
 #endif
+#ifdef HAVE_NETINET_IN_H
+# include <netinet/in.h>
+#endif
 #ifdef HAVE_SYS_IOCTL_H
 #include <sys/ioctl.h>
 #endif
@@ -89,6 +92,10 @@
 /* Constants for WSAIoctl() */
 #define WSA_FLAG_OVERLAPPED        0x01
 
+#if defined(HAVE_NETINET_IN_H) && !defined(HAVE_STRUCT_MSGHDR_MSG_ACCRIGHTS)
+#    define USE_IP_PKTINFO_FILTER
+#endif
+
 struct sock
 {
     struct object       obj;         /* object header */
@@ -322,6 +329,57 @@ static inline int sock_error( struct fd *fd )
     return optval;
 }
 
+/* Test for IP_PKTINFO filtered packets that are requested using
+ * ReadFile instead of WSARecv.  If the packet does not match
+ * for this socket's interface then throw it away.
+ */
+static int accept_read_poll( struct fd *fd )
+{
+#ifdef USE_IP_PKTINFO_FILTER
+    struct sock *sock = get_fd_user( fd );
+    unsigned int check_iface, optlen;
+    int handle = get_unix_fd ( fd );
+    struct msghdr hdr;
+    char pktbuf[512];
+
+    memset(&hdr, 0, sizeof(struct msghdr));
+    hdr.msg_control = pktbuf;
+    hdr.msg_controllen = sizeof(pktbuf);
+    hdr.msg_flags = 0;
+
+    check_iface = 0;
+    optlen = sizeof(check_iface);
+    getsockopt(handle, IPPROTO_IP, IP_PKTINFO, (void *) &check_iface, &optlen);
+    if (check_iface)
+    {
+        /* Peek at the packet to check its interface */
+        if ( recvmsg(handle, &hdr, MSG_PEEK|MSG_DONTWAIT) != -1 )
+        {
+            int iface_index = sock->iface_index;
+            struct in_pktinfo *pktinfo = NULL;
+            struct cmsghdr *cmsg;
+
+            for (cmsg = CMSG_FIRSTHDR(&hdr); cmsg != NULL;
+                 cmsg = CMSG_NXTHDR(&hdr, cmsg))
+            {
+                if (cmsg->cmsg_level == IPPROTO_IP && cmsg->cmsg_type == IP_PKTINFO)
+                    pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsg);
+            }
+            if (pktinfo && pktinfo->ipi_ifindex != iface_index)
+            {
+                if ( recvmsg(handle, &hdr, MSG_DONTWAIT) != -1 )
+                    return FALSE;
+                else
+                    fprintf(stderr, "Failed to throw away packet with interface mismatch! %m\n");
+            }
+        }
+        else
+            fprintf(stderr, "Failed to peek at message header! %m\n");
+    }
+#endif /* USE_IP_PKTINFO_FILTER */
+    return TRUE;
+}
+
 static void sock_poll_event( struct fd *fd, int event )
 {
     struct sock *sock = get_fd_user( fd );
@@ -414,9 +472,12 @@ static void sock_poll_event( struct fd *fd, int event )
         }
         else if ( event & POLLIN ) /* POLLIN for non-stream socket */
         {
-            sock->pmask |= FD_READ;
-            sock->hmask |= (FD_READ|FD_CLOSE);
-            sock->errors[FD_READ_BIT] = 0;
+            if (accept_read_poll(fd))
+            {
+                sock->pmask |= FD_READ;
+                sock->hmask |= (FD_READ|FD_CLOSE);
+                sock->errors[FD_READ_BIT] = 0;
+            }
             if (debug_level)
                 fprintf(stderr, "socket %p is readable\n", sock );
 
-- 
1.7.0.4