dhcp-network: enable IP_FREEBIND for UDP sockets

[elogind.git] / src / libsystemd-network / dhcp-network.c

diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c
index f119cae7ffd63805963d872ff3574760753ed3fe..29276c0559b07a90213a95da9cb5395ff26d5b41 100644 (file)
--- a/src/libsystemd-network/dhcp-network.c
+++ b/src/libsystemd-network/dhcp-network.c
@@ -41,8 +41,12 @@ int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link,
             BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0),                /* IP protocol == UDP ? */
             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
+            BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags */
+            BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x20),                             /* A <- A & 0x20 (More Fragments bit) */
+            BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                          /* A == 0 ? */
+            BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
             BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */
-            BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff),                           /* A <- A & 0x1fff */
+            BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff),                           /* A <- A & 0x1fff (Fragment offset) */
             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                          /* A == 0 ? */
             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
             BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)),    /* A <- UDP destination port */
@@ -122,7 +126,7 @@ int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
                 .in.sin_addr.s_addr = address,
         };
         _cleanup_close_ int s = -1;
-        int r, tos = IPTOS_CLASS_CS6;
+        int r, on = 1, tos = IPTOS_CLASS_CS6;
 
         s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
         if (s < 0)
@@ -132,13 +136,11 @@ int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
         if (r < 0)
                 return -errno;
 
-        if (address == INADDR_ANY) {
-                int on = 1;
-
-                r = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
-                if (r < 0)
-                        return -errno;
+        r = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+        if (r < 0)
+                return -errno;
 
+        if (address == INADDR_ANY) {
                 r = setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
                 if (r < 0)
                         return -errno;
@@ -146,6 +148,10 @@ 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)
+                        return -errno;
         }
 
         r = bind(s, &src.sa, sizeof(src.in));