1 files changed, 17 insertions, 1 deletions

diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 51374646d..4d8e005d4 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -189,7 +189,8 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
 /* Let the kernel do all the work for packet generation */
 int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
                 uint32_t source_nip, int source_port,
-                uint32_t dest_nip, int dest_port)
+                uint32_t dest_nip, int dest_port,
+                const char *ifname)
 {
         struct sockaddr_in sa;
         unsigned padding;
@@ -204,6 +205,21 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
         }
         setsockopt_reuseaddr(fd);
 
+        /* If interface carrier goes down, unless we
+         * bind socket to a particular netdev, the packet
+         * can go out through another interface, eg. via
+         * default route despite being bound to a specific
+         * source IP. As such, bind to device hard and fail
+         * otherwise. Sending renewal packets on foreign
+         * interfaces makes no sense.
+         */
+        if (ifname) {
+                if (setsockopt_bindtodevice(fd, ifname) < 0) {
+                        msg = "bindtodevice";
+                        goto ret_close;
+                }
+        }
+
         memset(&sa, 0, sizeof(sa));
         sa.sin_family = AF_INET;
         sa.sin_port = htons(source_port);