udhcpc[6]: close listening socket more eagerly (e.g. across script runs)

function                                             old     new   delta
udhcpc6_main                                        2571    2600     +29
udhcpc_main                                         2588    2566     -22
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 29/-22)              Total: 7 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 45 insertions, 28 deletions

diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index c68dc8c4f..b2df9f091 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -1090,6 +1090,8 @@ static void change_listen_mode(int new_mode)
 
 static void perform_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
 {
+        change_listen_mode(LISTEN_NONE);
+
         /* send release packet */
         if (client_data.state == BOUND
          || client_data.state == RENEWING
@@ -1107,7 +1109,6 @@ static void perform_d6_release(struct in6_addr *server_ipv6, struct in6_addr *ou
  * of the states above.
  */
         d6_run_script_no_option("deconfig");
-        change_listen_mode(LISTEN_NONE);
         client_data.state = RELEASED;
 }
 
@@ -1311,7 +1312,6 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
 
         client_data.state = INIT_SELECTING;
         d6_run_script_no_option("deconfig");
-        change_listen_mode(LISTEN_RAW);
         packet_num = 0;
         timeout = 0;
         lease_remaining = 0;
@@ -1387,8 +1387,10 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                         switch (client_data.state) {
                         case INIT_SELECTING:
                                 if (!discover_retries || packet_num < discover_retries) {
-                                        if (packet_num == 0)
+                                        if (packet_num == 0) {
+                                                change_listen_mode(LISTEN_RAW);
                                                 xid = random_xid();
+                                        }
                                         /* multicast */
                                         if (opt & OPT_l)
                                                 send_d6_info_request(xid);
@@ -1399,6 +1401,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                         continue;
                                 }
  leasefail:
+                                change_listen_mode(LISTEN_NONE);
                                 d6_run_script_no_option("leasefail");
 #if BB_MMU /* -b is not supported on NOMMU */
                                 if (opt & OPT_b) { /* background if no lease */
@@ -1435,7 +1438,6 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                  * "discover...select...discover..." loops
                                  * were seen in the wild. Treat them similarly
                                  * to "no response to discover" case */
-                                change_listen_mode(LISTEN_RAW);
                                 client_data.state = INIT_SELECTING;
                                 goto leasefail;
                         case BOUND:
@@ -1470,11 +1472,11 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                 /* Timed out, enter rebinding state */
                                 log1s("entering rebinding state");
                                 client_data.state = REBINDING;
+                                /* Switch to bcast receive */
+                                change_listen_mode(LISTEN_RAW);
                                 packet_num = 0;
                                 /* fall right through */
                         case REBINDING:
-                                /* Switch to bcast receive */
-                                change_listen_mode(LISTEN_RAW);
                                 /* Lease is *really* about to run out,
                                  * try to find DHCP server using broadcast */
                                 if (lease_remaining > 0 && packet_num < 3) {
@@ -1487,6 +1489,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                         continue;
                                 }
                                 /* Timed out, enter init state */
+                                change_listen_mode(LISTEN_NONE);
                                 bb_simple_info_msg("lease lost, entering init state");
                                 d6_run_script_no_option("deconfig");
                                 client_data.state = INIT_SELECTING;
@@ -1522,12 +1525,15 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
 
                         /* Start things over */
                         case RENEW_REQUESTED: /* two or more SIGUSR1 received */
+                                change_listen_mode(LISTEN_NONE);
                                 d6_run_script_no_option("deconfig");
-                        /* case REQUESTING: break; */
-                        /* case RELEASED: break; */
-                        /* case INIT_SELECTING: break; */
+
+                        default:
+                        /* case REQUESTING: */
+                        /* case RELEASED: */
+                        /* case INIT_SELECTING: */
+                                change_listen_mode(LISTEN_NONE);
                         }
-                        change_listen_mode(LISTEN_RAW);
                         client_data.state = INIT_SELECTING;
                         packet_num = 0;
                         /* Kill any timeouts, user wants this to hurry along */
@@ -1535,6 +1541,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                         continue;
                 case SIGUSR2:
                         perform_d6_release(&srv6_buf, requested_ipv6);
+                        /* ^^^ switches to LISTEN_NONE */
                         timeout = INT_MAX;
                         continue;
                 case SIGTERM:
@@ -1592,6 +1599,8 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                 unsigned address_timeout;
                                 unsigned prefix_timeout;
  type_is_ok:
+                                change_listen_mode(LISTEN_NONE);
+
                                 address_timeout = 0;
                                 prefix_timeout = 0;
                                 option = d6_find_option(packet.d6_options, packet_end, D6_OPT_STATUS_CODE);
@@ -1602,7 +1611,6 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                                         packet_end, "nak");
                                         if (client_data.state != REQUESTING)
                                                 d6_run_script_no_option("deconfig");
-                                        change_listen_mode(LISTEN_RAW);
                                         sleep(3); /* avoid excessive network traffic */
                                         client_data.state = INIT_SELECTING;
                                         client_data.first_secs = 0; /* make secs field count from 0 */
@@ -1624,6 +1632,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                                 client6_data.server_id = option;
                                 if (packet.d6_msg_type == D6_MSG_ADVERTISE) {
                                         /* enter requesting state */
+                                        change_listen_mode(LISTEN_RAW);
                                         client_data.state = REQUESTING;
                                         timeout = 0;
                                         packet_num = 0;
@@ -1826,7 +1835,6 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
 // BOUND_for_half_lease:
                                 timeout = (unsigned)lease_remaining / 2;
                                 client_data.state = BOUND;
-                                change_listen_mode(LISTEN_NONE);
                                 packet_num = 0;
                                 continue; /* back to main loop */
                         }
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index ab669d2b5..5fb96c2d8 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -1122,6 +1122,8 @@ static void perform_release(uint32_t server_addr, uint32_t requested_ip)
         char buffer[sizeof("255.255.255.255")];
         struct in_addr temp_addr;
 
+        change_listen_mode(LISTEN_NONE);
+
         /* send release packet */
         if (client_data.state == BOUND
          || client_data.state == RENEWING
@@ -1143,8 +1145,6 @@ static void perform_release(uint32_t server_addr, uint32_t requested_ip)
  * of the states above.
  */
         udhcp_run_script(NULL, "deconfig");
-
-        change_listen_mode(LISTEN_NONE);
         client_data.state = RELEASED;
 }
 
@@ -1343,6 +1343,10 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                 clientid_mac_ptr += OPT_DATA + 1; /* skip option code, len, ethernet */
         }
 
+        /* Not really necessary (we redo it on every iteration)
+         * but allows early (before daemonization) detection
+         * of bad interface name.
+         */
         if (udhcp_read_interface(client_data.interface,
                         &client_data.ifindex,
                         NULL,
@@ -1372,7 +1376,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 
         client_data.state = INIT_SELECTING;
         udhcp_run_script(NULL, "deconfig");
-        change_listen_mode(LISTEN_RAW);
         packet_num = 0;
         timeout = 0;
         lease_remaining = 0;
@@ -1446,8 +1449,10 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                         switch (client_data.state) {
                         case INIT_SELECTING:
                                 if (!discover_retries || packet_num < discover_retries) {
-                                        if (packet_num == 0)
+                                        if (packet_num == 0) {
+                                                change_listen_mode(LISTEN_RAW);
                                                 xid = random_xid();
+                                        }
                                         /* broadcast */
                                         send_discover(xid, requested_ip);
                                         timeout = discover_timeout;
@@ -1455,6 +1460,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                         continue;
                                 }
  leasefail:
+                                change_listen_mode(LISTEN_NONE);
                                 udhcp_run_script(NULL, "leasefail");
 #if BB_MMU /* -b is not supported on NOMMU */
                                 if (opt & OPT_b) { /* background if no lease */
@@ -1491,7 +1497,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                  * "discover...select...discover..." loops
                                  * were seen in the wild. Treat them similarly
                                  * to "no response to discover" case */
-                                change_listen_mode(LISTEN_RAW);
                                 client_data.state = INIT_SELECTING;
                                 goto leasefail;
                         case BOUND:
@@ -1528,17 +1533,17 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                 }
 //TODO: if 3 renew's failed (no reply) but remaining lease is large enough,
 //it might make sense to go back to BOUND and try later? a-la
-// if (lease_remaining > 30) goto BOUND_for_half_lease;
+// if (lease_remaining > 30) change_listen_mode(LISTEN_NONE) + goto BOUND_for_half_lease;
 //If we do that, "packet_num < 3" test below might be superfluous
 //(lease_remaining will run out anyway)
                                 /* Timed out or error, enter rebinding state */
                                 log1s("entering rebinding state");
                                 client_data.state = REBINDING;
+                                /* Switch to bcast receive */
+                                change_listen_mode(LISTEN_RAW);
                                 packet_num = 0;
                                 /* fall right through */
                         case REBINDING:
-                                /* Switch to bcast receive */
-                                change_listen_mode(LISTEN_RAW);
                                 /* Lease is *really* about to run out,
                                  * try to find DHCP server using broadcast */
                                 if (lease_remaining > 0 && packet_num < 3) {
@@ -1549,6 +1554,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                         continue;
                                 }
                                 /* Timed out, enter init state */
+                                change_listen_mode(LISTEN_NONE);
                                 bb_simple_info_msg("lease lost, entering init state");
                                 udhcp_run_script(NULL, "deconfig");
                                 client_data.state = INIT_SELECTING;
@@ -1584,12 +1590,15 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 
                         /* Start things over */
                         case RENEW_REQUESTED: /* two or more SIGUSR1 received */
+                                change_listen_mode(LISTEN_NONE);
                                 udhcp_run_script(NULL, "deconfig");
-                        /* case REQUESTING: break; */
-                        /* case RELEASED: break; */
-                        /* case INIT_SELECTING: break; */
+
+                        default:
+                        /* case REQUESTING: */
+                        /* case RELEASED: */
+                        /* case INIT_SELECTING: */
+                                change_listen_mode(LISTEN_NONE);
                         }
-                        change_listen_mode(LISTEN_RAW);
                         client_data.state = INIT_SELECTING;
                         packet_num = 0;
                         /* Kill any timeouts, user wants this to hurry along */
@@ -1597,6 +1606,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                         continue;
                 case SIGUSR2:
                         perform_release(server_addr, requested_ip);
+                        /* ^^^ switches to LISTEN_NONE */
                         timeout = INT_MAX;
                         continue;
                 case SIGTERM:
@@ -1706,6 +1716,8 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                 char server_str[sizeof("255.255.255.255")];
                                 uint8_t *temp;
 
+                                change_listen_mode(LISTEN_NONE);
+
                                 temp_addr.s_addr = server_addr;
                                 strcpy(server_str, inet_ntoa(temp_addr));
                                 temp_addr.s_addr = packet.yiaddr;
@@ -1758,7 +1770,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 
                                                 if (client_data.state != REQUESTING)
                                                         udhcp_run_script(NULL, "deconfig");
-                                                change_listen_mode(LISTEN_RAW);
                                                 client_data.state = INIT_SELECTING;
                                                 client_data.first_secs = 0; /* make secs field count from 0 */
                                                 requested_ip = 0;
@@ -1768,7 +1779,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                         }
                                 }
 #endif
-
                                 /* enter bound state */
                                 start = monotonic_sec();
                                 udhcp_run_script(&packet, client_data.state == REQUESTING ? "bound" : "renew");
@@ -1791,7 +1801,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 // BOUND_for_half_lease:
                                 timeout = (unsigned)lease_remaining / 2;
                                 client_data.state = BOUND;
-                                change_listen_mode(LISTEN_NONE);
                                 /* make future renew packets use different xid */
                                 /* xid = random_xid(); ...but why bother? */
                                 packet_num = 0;
@@ -1818,11 +1827,11 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                                 goto non_matching_svid;
                                 }
                                 /* return to init state */
+                                change_listen_mode(LISTEN_NONE);
                                 bb_info_msg("received %s", "DHCP NAK");
                                 udhcp_run_script(&packet, "nak");
                                 if (client_data.state != REQUESTING)
                                         udhcp_run_script(NULL, "deconfig");
-                                change_listen_mode(LISTEN_RAW);
                                 sleep(3); /* avoid excessive network traffic */
                                 client_data.state = INIT_SELECTING;
                                 client_data.first_secs = 0; /* make secs field count from 0 */