From 3e7b9f76f56db77fa1e8a09b543176c7ddd136de Mon Sep 17 00:00:00 2001
From: 27o <27o@users.noreply.github.com>
Date: Wed, 7 Dec 2016 02:00:05 +0100
Subject: dhcp: bind udp sockets to interfaces (#4822)

---
 src/libsystemd-network/dhcp-network.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'src/libsystemd-network/dhcp-network.c')

diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c
index 3c85bb0b54..65405dcce0 100644
--- a/src/libsystemd-network/dhcp-network.c
+++ b/src/libsystemd-network/dhcp-network.c
@@ -19,6 +19,7 @@
 
 #include <errno.h>
 #include <net/ethernet.h>
+#include <net/if.h>
 #include <net/if_arp.h>
 #include <stdio.h>
 #include <string.h>
@@ -156,13 +157,14 @@ int dhcp_network_bind_raw_socket(int ifindex, union sockaddr_union *link,
                                 bcast_addr, &eth_mac, arp_type, dhcp_hlen, port);
 }
 
-int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
+int dhcp_network_bind_udp_socket(int ifindex, be32_t address, uint16_t port) {
         union sockaddr_union src = {
                 .in.sin_family = AF_INET,
                 .in.sin_port = htobe16(port),
                 .in.sin_addr.s_addr = address,
         };
         _cleanup_close_ int s = -1;
+        char ifname[IF_NAMESIZE] = "";
         int r, on = 1, tos = IPTOS_CLASS_CS6;
 
         s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
@@ -177,6 +179,15 @@ int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
         if (r < 0)
                 return -errno;
 
+        if (ifindex > 0) {
+                if (if_indextoname(ifindex, ifname) == 0)
+                        return -errno;
+
+                r = setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
+                if (r < 0)
+                        return -errno;
+        }
+
         if (address == INADDR_ANY) {
                 r = setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
                 if (r < 0)
@@ -185,6 +196,7 @@ int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
                 r = setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on));
                 if (r < 0)
                         return -errno;
+
         } else {
                 r = setsockopt(s, IPPROTO_IP, IP_FREEBIND, &on, sizeof(on));
                 if (r < 0)
-- 
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