dhcp: Try to reuse the IP address we had last time.

This fix will cause the DHCP_REQUESTED_IP option to be sent to
the server.

Fixes BMC #21068

4 files changed, 39 insertions, 7 deletions

diff --git a/gdhcp/client.c b/gdhcp/client.c
index 0cf39cd7..8ea75d65 100644
--- a/gdhcp/client.c
+++ b/gdhcp/client.c
@@ -109,6 +109,7 @@ struct _GDHCPClient {
 	gpointer address_conflict_data;
 	GDHCPDebugFunc debug_func;
 	gpointer debug_data;
+	char *last_address;
 };
 
 static inline void debug(GDHCPClient *client, const char *format, ...)
@@ -879,7 +880,7 @@ static void restart_dhcp(GDHCPClient *dhcp_client, int retry_times)
 	dhcp_client->requested_ip = 0;
 	switch_listening_mode(dhcp_client, L2);
 
-	g_dhcp_client_start(dhcp_client);
+	g_dhcp_client_start(dhcp_client, dhcp_client->last_address);
 }
 
 static gboolean start_rebound_timeout(gpointer user_data)
@@ -1240,7 +1241,12 @@ static gboolean discover_timeout(gpointer user_data)
 
 	dhcp_client->retry_times++;
 
-	g_dhcp_client_start(dhcp_client);
+	/*
+	 * We do not send the REQUESTED IP option if we are retrying because
+	 * if the server is non-authoritative it will ignore the request if the
+	 * option is present.
+	 */
+	g_dhcp_client_start(dhcp_client, NULL);
 
 	return FALSE;
 }
@@ -1306,9 +1312,10 @@ static gboolean ipv4ll_probe_timeout(gpointer dhcp_data)
 	return FALSE;
 }
 
-int g_dhcp_client_start(GDHCPClient *dhcp_client)
+int g_dhcp_client_start(GDHCPClient *dhcp_client, const char *last_address)
 {
 	int re;
+	uint32_t addr;
 
 	if (dhcp_client->retry_times == DISCOVER_RETRIES) {
 		ipv4ll_start(dhcp_client);
@@ -1327,7 +1334,18 @@ int g_dhcp_client_start(GDHCPClient *dhcp_client)
 		dhcp_client->xid = rand();
 	}
 
-	send_discover(dhcp_client, 0);
+	if (last_address == NULL) {
+		addr = 0;
+	} else {
+		addr = inet_addr(last_address);
+		if (addr == 0xFFFFFFFF) {
+			addr = 0;
+		} else {
+			g_free(dhcp_client->last_address);
+			dhcp_client->last_address = g_strdup(last_address);
+		}
+	}
+	send_discover(dhcp_client, addr);
 
 	dhcp_client->timeout = g_timeout_add_seconds_full(G_PRIORITY_HIGH,
 							DISCOVER_TIMEOUT,
@@ -1505,6 +1523,7 @@ void g_dhcp_client_unref(GDHCPClient *dhcp_client)
 
 	g_free(dhcp_client->interface);
 	g_free(dhcp_client->assigned_ip);
+	g_free(dhcp_client->last_address);
 
 	g_list_free(dhcp_client->request_list);
 	g_list_free(dhcp_client->require_list);
diff --git a/gdhcp/gdhcp.h b/gdhcp/gdhcp.h
index 4f583ff7..d89446e2 100644
--- a/gdhcp/gdhcp.h
+++ b/gdhcp/gdhcp.h
@@ -73,7 +73,7 @@ typedef void (*GDHCPDebugFunc)(const char *str, gpointer user_data);
 GDHCPClient *g_dhcp_client_new(GDHCPType type, int index,
 						GDHCPClientError *error);
 
-int g_dhcp_client_start(GDHCPClient *client);
+int g_dhcp_client_start(GDHCPClient *client, const char *last_address);
 void g_dhcp_client_stop(GDHCPClient *client);
 
 GDHCPClient *g_dhcp_client_ref(GDHCPClient *client);
diff --git a/src/dhcp.c b/src/dhcp.c
index 39f4eeb5..10e14031 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -103,6 +103,10 @@ static void dhcp_invalidate(struct connman_dhcp *dhcp, connman_bool_t callback)
 		}
 	}
 
+	__connman_ipconfig_set_dhcp_address(ipconfig,
+				__connman_ipconfig_get_local(ipconfig));
+	DBG("last address %s", __connman_ipconfig_get_dhcp_address(ipconfig));
+
 	__connman_ipconfig_address_remove(ipconfig);
 
 	__connman_ipconfig_set_local(ipconfig, NULL);
@@ -205,6 +209,9 @@ static void lease_available_cb(GDHCPClient *dhcp_client, gpointer user_data)
 
 	address = g_dhcp_client_get_address(dhcp_client);
 
+	__connman_ipconfig_set_dhcp_address(ipconfig, address);
+	DBG("last address %s", address);
+
 	option = g_dhcp_client_get_option(dhcp_client, G_DHCP_SUBNET);
 	if (option != NULL)
 		netmask = g_strdup(option->data);
@@ -365,6 +372,8 @@ static void dhcp_debug(const char *str, void *data)
 
 static int dhcp_request(struct connman_dhcp *dhcp)
 {
+	struct connman_service *service;
+	struct connman_ipconfig *ipconfig;
 	GDHCPClient *dhcp_client;
 	GDHCPClientError error;
 	const char *hostname;
@@ -412,7 +421,11 @@ static int dhcp_request(struct connman_dhcp *dhcp)
 
 	dhcp->dhcp_client = dhcp_client;
 
-	return g_dhcp_client_start(dhcp_client);
+	service = __connman_service_lookup_from_network(dhcp->network);
+	ipconfig = __connman_service_get_ip4config(service);
+
+	return g_dhcp_client_start(dhcp_client,
+				__connman_ipconfig_get_dhcp_address(ipconfig));
 }
 
 static int dhcp_release(struct connman_dhcp *dhcp)
diff --git a/tools/dhcp-test.c b/tools/dhcp-test.c
index 1fbf1f9d..18527c88 100644
--- a/tools/dhcp-test.c
+++ b/tools/dhcp-test.c
@@ -170,7 +170,7 @@ int main(int argc, char *argv[])
 
 	timer = g_timer_new();
 
-	g_dhcp_client_start(dhcp_client);
+	g_dhcp_client_start(dhcp_client, NULL);
 
 	memset(&sa, 0, sizeof(sa));
 	sa.sa_handler = sig_term;