+static void ipv4ll_start(GDHCPClient *dhcp_client)
+{
+ guint timeout;
+ int seed;
+
+ if (dhcp_client->timeout > 0) {
+ g_source_remove(dhcp_client->timeout);
+ dhcp_client->timeout = 0;
+ }
+
+ switch_listening_mode(dhcp_client, L_NONE);
+ dhcp_client->type = G_DHCP_IPV4LL;
+ dhcp_client->retry_times = 0;
+ dhcp_client->requested_ip = 0;
+
+ /*try to start with a based mac address ip*/
+ seed = (dhcp_client->mac_address[4] << 8 | dhcp_client->mac_address[4]);
+ dhcp_client->requested_ip = ipv4ll_random_ip(seed);
+
+ /*first wait a random delay to avoid storm of arp request on boot*/
+ timeout = ipv4ll_random_delay_ms(PROBE_WAIT);
+
+ dhcp_client->retry_times++;
+ dhcp_client->timeout = g_timeout_add_full(G_PRIORITY_HIGH,
+ timeout,
+ send_probe_packet,
+ dhcp_client,
+ NULL);
+}
+
+static void ipv4ll_stop(GDHCPClient *dhcp_client)
+{
+
+ switch_listening_mode(dhcp_client, L_NONE);
+
+ if (dhcp_client->timeout > 0)
+ g_source_remove(dhcp_client->timeout);
+
+ if (dhcp_client->listener_watch > 0) {
+ g_source_remove(dhcp_client->listener_watch);
+ dhcp_client->listener_watch = 0;
+ }
+
+ dhcp_client->state = IPV4LL_PROBE;
+ dhcp_client->retry_times = 0;
+ dhcp_client->requested_ip = 0;
+
+ g_free(dhcp_client->assigned_ip);
+ dhcp_client->assigned_ip = NULL;
+}
+
+static int ipv4ll_recv_arp_packet(GDHCPClient *dhcp_client)
+{
+ int bytes;
+ struct ether_arp arp;
+ uint32_t ip_requested;
+ int source_conflict;
+ int target_conflict;
+
+ memset(&arp, 0, sizeof(arp));
+ bytes = 0;
+ bytes = read(dhcp_client->listener_sockfd, &arp, sizeof(arp));
+ if (bytes < 0)
+ return bytes;
+
+ if (arp.arp_op != htons(ARPOP_REPLY) &&
+ arp.arp_op != htons(ARPOP_REQUEST))
+ return -EINVAL;
+
+ ip_requested = ntohl(dhcp_client->requested_ip);
+ source_conflict = !memcmp(arp.arp_spa, &ip_requested,
+ sizeof(ip_requested));
+
+ target_conflict = !memcmp(arp.arp_tpa, &ip_requested,
+ sizeof(ip_requested));
+
+ if (!source_conflict && !target_conflict)
+ return 0;
+
+ dhcp_client->conflicts++;
+
+ debug(dhcp_client, "IPV4LL conflict detected");
+
+ if (dhcp_client->state == IPV4LL_MONITOR) {
+ if (!source_conflict)
+ return 0;
+ dhcp_client->state = IPV4LL_DEFEND;
+ debug(dhcp_client, "DEFEND mode conflicts : %d",
+ dhcp_client->conflicts);
+ /*Try to defend with a single announce*/
+ send_announce_packet(dhcp_client);
+ return 0;
+ }
+
+ if (dhcp_client->state == IPV4LL_DEFEND) {
+ if (!source_conflict)
+ return 0;
+ else if (dhcp_client->ipv4ll_lost_cb != NULL)
+ dhcp_client->ipv4ll_lost_cb(dhcp_client,
+ dhcp_client->ipv4ll_lost_data);
+ }
+
+ ipv4ll_stop(dhcp_client);
+
+ if (dhcp_client->conflicts < MAX_CONFLICTS) {
+ /*restart whole state machine*/
+ dhcp_client->retry_times++;
+ dhcp_client->timeout =
+ g_timeout_add_full(G_PRIORITY_HIGH,
+ ipv4ll_random_delay_ms(PROBE_WAIT),
+ send_probe_packet,
+ dhcp_client,
+ NULL);
+ }
+ /* Here we got a lot of conflicts, RFC3927 states that we have
+ * to wait RATE_LIMIT_INTERVAL before retrying,
+ * but we just report failure.
+ */
+ else if (dhcp_client->no_lease_cb != NULL)
+ dhcp_client->no_lease_cb(dhcp_client,
+ dhcp_client->no_lease_data);
+
+ return 0;
+}
+