Open UDP sockets for *.*.*.*:bootpc and $ip_address:bootpc

diff --git a/dhcp.c b/dhcp.c
index 2423301f08f9dfb67afe4acd87234e9e806360b9..ef00d97eae2587f259fc252d0c10e4e4da582d5f 100644 (file)
--- a/dhcp.c
+++ b/dhcp.c
@@ -124,6 +124,7 @@ struct udp_dhcp_packet
 struct dhcp_opt *dhcp_opts = NULL;
 size_t dhcp_opts_len = 0;
 
+static int udp_fd = -1;
 static const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);
 
 static int dhcp_open(struct interface *);
@@ -1356,7 +1357,7 @@ dhcp_close(struct interface *ifp)
 }
 
 static int
-dhcp_openudp(struct interface *iface)
+dhcp_openudp(struct interface *ifp)
 {
        int s;
        struct sockaddr_in sin;
@@ -1374,26 +1375,34 @@ dhcp_openudp(struct interface *iface)
        if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &n, sizeof(n)) == -1)
                goto eexit;
 #ifdef SO_BINDTODEVICE
-       memset(&ifr, 0, sizeof(ifr));
-       strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
-       /* We can only bind to the real device */
-       p = strchr(ifr.ifr_name, ':');
-       if (p)
-           *p = '\0';
-       if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, &ifr,
+       if (ifp) {
+               memset(&ifr, 0, sizeof(ifr));
+               strlcpy(ifr.ifr_name, ifp->name, sizeof(ifr.ifr_name));
+               /* We can only bind to the real device */
+               p = strchr(ifr.ifr_name, ':');
+               if (p)
+                       *p = '\0';
+               if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, &ifr,
                    sizeof(ifr)) == -1)
-               goto eexit;
+                       goto eexit;
+       }
 #endif
-       state = D_STATE(iface);
        memset(&sin, 0, sizeof(sin));
        sin.sin_family = AF_INET;
        sin.sin_port = htons(DHCP_CLIENT_PORT);
-       sin.sin_addr.s_addr = state->addr.s_addr;
+       if (ifp) {
+               state = D_STATE(ifp);
+               sin.sin_addr.s_addr = state->addr.s_addr;
+       } else
+               state = NULL; /* appease gcc */
        if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) == -1)
                goto eexit;
 
-       state->udp_fd = s;
        set_cloexec(s);
+       if (ifp)
+               state->udp_fd = s;
+       else
+               udp_fd = s;
        return 0;
 
 eexit:
@@ -2060,6 +2069,20 @@ dhcp_drop(struct interface *ifp, const char *reason)
        state->auth.replay = 0;
        free(state->auth.reconf);
        state->auth.reconf = NULL;
+
+       /* If we don't have any more DHCP enabled interfaces,
+        * close the global socket */
+       if (ifaces) {
+               TAILQ_FOREACH(ifp, ifaces, next) {
+                       if (D_STATE(ifp))
+                               break;
+               }
+       }
+       if (ifp == NULL && udp_fd != -1) {
+               close(udp_fd);
+               eloop_event_delete(udp_fd);
+               udp_fd = -1;
+       }
 }
 
 static void
@@ -2604,7 +2627,10 @@ dhcp_open(struct interface *ifp)
                eloop_event_add(state->raw_fd, dhcp_handlepacket, ifp);
        }
        if (state->udp_fd == -1 &&
-           ifp->options->options & DHCPCD_DHCP)
+           state->addr.s_addr != 0 &&
+           state->new != NULL &&
+           (state->new->cookie == htonl(MAGIC_COOKIE) ||
+           ifp->options->options & DHCPCD_INFORM))
        {
                if (dhcp_openudp(ifp) == -1 && errno != EADDRINUSE) {
                        syslog(LOG_ERR, "%s: dhcp_openudp: %m", ifp->name);
@@ -2682,6 +2708,11 @@ dhcp_init(struct interface *ifp)
        const struct if_options *ifo;
        size_t len;
 
+       /* Listen on *.*.*.*:bootpc so that the kernel never sends an
+        * ICMP port unreachable message back to the DHCP server */
+       if (udp_fd == -1 && dhcp_openudp(NULL) != -1)
+               eloop_event_add(udp_fd, dhcp_handleudp, NULL);
+
        state = D_STATE(ifp);
        if (state == NULL) {
                ifp->if_data[IF_DATA_DHCP] = calloc(1, sizeof(*state));