docs/logging_and_backgrounding.txt: new mini-doc
[oweals/busybox.git] / networking / udhcp / dhcpc.c
index 69c35ca506cea23aa4723975d27eec82d045b61a..e9f99e39c83e8d18573638cab3f2ec06e70b9831 100644 (file)
@@ -8,7 +8,6 @@
  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 
-#include <getopt.h>
 #include <syslog.h>
 
 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
@@ -19,9 +18,6 @@
 #include "options.h"
 
 
-static int timeout; /* = 0. Must be signed */
-static uint32_t requested_ip; /* = 0 */
-static uint32_t server_addr;
 static int sockfd = -1;
 
 #define LISTEN_NONE 0
@@ -29,6 +25,14 @@ static int sockfd = -1;
 #define LISTEN_RAW 2
 static smallint listen_mode;
 
+#define INIT_SELECTING  0
+#define REQUESTING      1
+#define BOUND           2
+#define RENEWING        3
+#define REBINDING       4
+#define INIT_REBOOT     5
+#define RENEW_REQUESTED 6
+#define RELEASED        7
 static smallint state;
 
 /* struct client_config_t client_config is in bb_common_bufsiz1 */
@@ -39,11 +43,17 @@ static void change_listen_mode(int new_mode)
 {
        DEBUG("entering %s listen mode",
                new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
+
+       listen_mode = new_mode;
        if (sockfd >= 0) {
                close(sockfd);
                sockfd = -1;
        }
-       listen_mode = new_mode;
+       if (new_mode == LISTEN_KERNEL)
+               sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
+       else if (new_mode != LISTEN_NONE)
+               sockfd = udhcp_raw_socket(client_config.ifindex);
+       /* else LISTEN_NONE: sockfd stay closed */
 }
 
 
@@ -72,7 +82,7 @@ static void perform_renew(void)
 
 
 /* perform a release */
-static void perform_release(void)
+static void perform_release(uint32_t requested_ip, uint32_t server_addr)
 {
        char buffer[sizeof("255.255.255.255")];
        struct in_addr temp_addr;
@@ -91,28 +101,18 @@ static void perform_release(void)
 
        change_listen_mode(LISTEN_NONE);
        state = RELEASED;
-       timeout = INT_MAX;
 }
 
 
+#if BB_MMU
 static void client_background(void)
 {
-#if !BB_MMU
-       bb_error_msg("cannot background in uclinux (yet)");
-/* ... mainly because udhcpc calls client_background()
- * in _the _middle _of _udhcpc _run_, not at the start!
- * If that will be properly disabled for NOMMU, client_background()
- * will work on NOMMU too */
-#else
        bb_daemonize(0);
        logmode &= ~LOGMODE_STDIO;
        /* rewrite pidfile, as our pid is different now */
        write_pidfile(client_config.pidfile);
-#endif
-       /* Do not fork again. */
-       client_config.foreground = 1;
-       client_config.background_if_no_lease = 0;
 }
+#endif
 
 
 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
@@ -129,66 +129,34 @@ static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 
 
 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int udhcpc_main(int argc, char **argv)
+int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 {
        uint8_t *temp, *message;
-       char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_A, *str_t;
+       char *str_c, *str_V, *str_h, *str_F, *str_r;
+       USE_FEATURE_UDHCP_PORT(char *str_P;)
        llist_t *list_O = NULL;
-#if ENABLE_FEATURE_UDHCPC_ARPING
-       char *str_W;
-#endif
        int tryagain_timeout = 20;
        int discover_timeout = 3;
        int discover_retries = 3;
+       uint32_t server_addr = server_addr; /* for compiler */
+       uint32_t requested_ip = 0;
        uint32_t xid = 0;
        uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
        int packet_num;
-       /* t1, t2... what a wonderful names... */
-       unsigned t1 = t1; /* for gcc */
-       unsigned t2 = t2;
-       unsigned timestamp_got_lease = timestamp_got_lease;
+       int timeout; /* must be signed */
+       unsigned already_waited_sec;
        unsigned opt;
        int max_fd;
        int retval;
-       int len;
        struct timeval tv;
-       struct in_addr temp_addr;
        struct dhcpMessage packet;
        fd_set rfds;
 
-       enum {
-               OPT_c = 1 << 0,
-               OPT_C = 1 << 1,
-               OPT_V = 1 << 2,
-               OPT_f = 1 << 3,
-               OPT_b = 1 << 4,
-               OPT_H = 1 << 5,
-               OPT_h = 1 << 6,
-               OPT_F = 1 << 7,
-               OPT_i = 1 << 8,
-               OPT_n = 1 << 9,
-               OPT_p = 1 << 10,
-               OPT_q = 1 << 11,
-               OPT_R = 1 << 12,
-               OPT_r = 1 << 13,
-               OPT_s = 1 << 14,
-               OPT_T = 1 << 15,
-               OPT_t = 1 << 16,
-               OPT_v = 1 << 17,
-               OPT_S = 1 << 18,
-               OPT_A = 1 << 19,
-#if ENABLE_FEATURE_UDHCPC_ARPING
-               OPT_a = 1 << 20,
-               OPT_W = 1 << 21,
-#endif
-       };
 #if ENABLE_GETOPT_LONG
        static const char udhcpc_longopts[] ALIGN1 =
                "clientid\0"       Required_argument "c"
                "clientid-none\0"  No_argument       "C"
                "vendorclass\0"    Required_argument "V"
-               "foreground\0"     No_argument       "f"
-               "background\0"     No_argument       "b"
                "hostname\0"       Required_argument "H"
                "fqdn\0"           Required_argument "F"
                "interface\0"      Required_argument "i"
@@ -203,40 +171,71 @@ int udhcpc_main(int argc, char **argv)
                "retries\0"        Required_argument "t"
                "tryagain\0"       Required_argument "A"
                "syslog\0"         No_argument       "S"
-#if ENABLE_FEATURE_UDHCPC_ARPING
-               "arping\0"         No_argument       "a"
-#endif
                "request-option\0" Required_argument "O"
+               "no-default-options\0" No_argument   "o"
+               "foreground\0"     No_argument       "f"
+               "background\0"     No_argument       "b"
+               USE_FEATURE_UDHCPC_ARPING("arping\0"    No_argument       "a")
+               USE_FEATURE_UDHCP_PORT("client-port\0"  Required_argument "P")
                ;
 #endif
+       enum {
+               OPT_c = 1 << 0,
+               OPT_C = 1 << 1,
+               OPT_V = 1 << 2,
+               OPT_H = 1 << 3,
+               OPT_h = 1 << 4,
+               OPT_F = 1 << 5,
+               OPT_i = 1 << 6,
+               OPT_n = 1 << 7,
+               OPT_p = 1 << 8,
+               OPT_q = 1 << 9,
+               OPT_R = 1 << 10,
+               OPT_r = 1 << 11,
+               OPT_s = 1 << 12,
+               OPT_T = 1 << 13,
+               OPT_t = 1 << 14,
+               OPT_v = 1 << 15,
+               OPT_S = 1 << 16,
+               OPT_A = 1 << 17,
+               OPT_O = 1 << 18,
+               OPT_o = 1 << 19,
+               OPT_f = 1 << 20,
+/* The rest has variable bit positions, need to be clever */
+               OPTBIT_f = 20,
+               USE_FOR_MMU(              OPTBIT_b,)
+               USE_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
+               USE_FEATURE_UDHCP_PORT(   OPTBIT_P,)
+               USE_FOR_MMU(              OPT_b = 1 << OPTBIT_b,)
+               USE_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
+               USE_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
+       };
+
        /* Default options. */
+       USE_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
+       USE_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
        client_config.interface = "eth0";
        client_config.script = DEFAULT_SCRIPT;
 
        /* Parse command line */
-       opt_complementary = "c--C:C--c:O::"; // Cc: mutually exclusive; O: list
-#if ENABLE_GETOPT_LONG
-       applet_long_options = udhcpc_longopts;
-#endif
-       opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
-               USE_FEATURE_UDHCPC_ARPING("aW:")
-               "O:"
+       /* Cc: mutually exclusive; O: list; -T,-t,-A take numeric param */
+       opt_complementary = "c--C:C--c:O::T+:t+:A+";
+       USE_GETOPT_LONG(applet_long_options = udhcpc_longopts;)
+       opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:vSA:O:of"
+               USE_FOR_MMU("b")
+               USE_FEATURE_UDHCPC_ARPING("a")
+               USE_FEATURE_UDHCP_PORT("P:")
                , &str_c, &str_V, &str_h, &str_h, &str_F
-               , &client_config.interface, &client_config.pidfile, &str_r
-               , &client_config.script, &str_T, &str_t, &str_A
-               USE_FEATURE_UDHCPC_ARPING(, &str_W)
+               , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
+               , &client_config.script /* s */
+               , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
                , &list_O
+               USE_FEATURE_UDHCP_PORT(, &str_P)
                );
-
        if (opt & OPT_c)
                client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
-       //if (opt & OPT_C)
        if (opt & OPT_V)
                client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
-       if (opt & OPT_f)
-               client_config.foreground = 1;
-       if (opt & OPT_b)
-               client_config.background_if_no_lease = 1;
        if (opt & (OPT_h|OPT_H))
                client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
        if (opt & OPT_F) {
@@ -244,50 +243,50 @@ int udhcpc_main(int argc, char **argv)
                /* Flags: 0000NEOS
                S: 1 => Client requests Server to update A RR in DNS as well as PTR
                O: 1 => Server indicates to client that DNS has been updated regardless
-               E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
+               E: 1 => Name data is DNS format, i.e. <4>host<6>domain<3>com<0> not "host.domain.com"
                N: 1 => Client requests Server to not update DNS
                */
                client_config.fqdn[OPT_DATA + 0] = 0x1;
                /* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
                /* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
        }
-       // if (opt & OPT_i) client_config.interface = ...
-       if (opt & OPT_n)
-               client_config.abort_if_no_lease = 1;
-       // if (opt & OPT_p) client_config.pidfile = ...
-       if (opt & OPT_q)
-               client_config.quit_after_lease = 1;
-       if (opt & OPT_R)
-               client_config.release_on_quit = 1;
        if (opt & OPT_r)
                requested_ip = inet_addr(str_r);
-       // if (opt & OPT_s) client_config.script = ...
-       if (opt & OPT_T)
-               discover_timeout = xatoi_u(str_T);
-       if (opt & OPT_t)
-               discover_retries = xatoi_u(str_t);
-       if (opt & OPT_A)
-               tryagain_timeout = xatoi_u(str_A);
        if (opt & OPT_v) {
                puts("version "BB_VER);
                return 0;
        }
-       if (opt & OPT_S) {
-               openlog(applet_name, LOG_PID, LOG_LOCAL0);
-               logmode |= LOGMODE_SYSLOG;
+#if ENABLE_FEATURE_UDHCP_PORT
+       if (opt & OPT_P) {
+               CLIENT_PORT = xatou16(str_P);
+               SERVER_PORT = CLIENT_PORT - 1;
        }
+#endif
+       if (opt & OPT_o)
+               client_config.no_default_options = 1;
        while (list_O) {
-               int n = index_in_strings(dhcp_option_strings, list_O->data);
+               char *optstr = llist_pop(&list_O);
+               int n = index_in_strings(dhcp_option_strings, optstr);
                if (n < 0)
-                       bb_error_msg_and_die("unknown option '%s'", list_O->data);
+                       bb_error_msg_and_die("unknown option '%s'", optstr);
                n = dhcp_options[n].code;
                client_config.opt_mask[n >> 3] |= 1 << (n & 7);
-               list_O = list_O->link;
        }
 
-       if (read_interface(client_config.interface, &client_config.ifindex,
+       if (udhcp_read_interface(client_config.interface, &client_config.ifindex,
                           NULL, client_config.arp))
                return 1;
+#if !BB_MMU
+       /* on NOMMU reexec (i.e., background) early */
+       if (!(opt & OPT_f)) {
+               bb_daemonize_or_rexec(0 /* flags */, argv);
+               logmode = LOGMODE_NONE;
+       }
+#endif
+       if (opt & OPT_S) {
+               openlog(applet_name, LOG_PID, LOG_DAEMON);
+               logmode |= LOGMODE_SYSLOG;
+       }
 
        /* Make sure fd 0,1,2 are open */
        bb_sanitize_stdio();
@@ -296,9 +295,8 @@ int udhcpc_main(int argc, char **argv)
 
        /* Create pidfile */
        write_pidfile(client_config.pidfile);
-       /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
 
-       /* Goes to stdout and possibly syslog */
+       /* Goes to stdout (unless NOMMU) and possibly syslog */
        bb_info_msg("%s (v"BB_VER") started", applet_name);
 
        /* if not set, and not suppressed, setup the default client ID */
@@ -318,65 +316,79 @@ int udhcpc_main(int argc, char **argv)
        udhcp_run_script(NULL, "deconfig");
        change_listen_mode(LISTEN_RAW);
        packet_num = 0;
+       timeout = 0;
+       already_waited_sec = 0;
 
        /* Main event loop. select() waits on signal pipe and possibly
         * on sockfd.
         * "continue" statements in code below jump to the top of the loop.
         */
        for (;;) {
-               tv.tv_sec = timeout;
-               tv.tv_usec = 0;
+               /* silence "uninitialized!" warning */
+               unsigned timestamp_before_wait = timestamp_before_wait;
+
+               //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
+
+               /* Was opening raw or udp socket here
+                * if (listen_mode != LISTEN_NONE && sockfd < 0),
+                * but on fast network renew responses return faster
+                * than we open sockets. Thus this code is moved
+                * to change_listen_mode(). Thus we open listen socket
+                * BEFORE we send renew request (see "case BOUND:"). */
 
-               if (listen_mode != LISTEN_NONE && sockfd < 0) {
-                       if (listen_mode == LISTEN_KERNEL)
-                               sockfd = listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
-                       else
-                               sockfd = raw_socket(client_config.ifindex);
-               }
                max_fd = udhcp_sp_fd_set(&rfds, sockfd);
 
+               tv.tv_sec = timeout - already_waited_sec;
+               tv.tv_usec = 0;
                retval = 0; /* If we already timed out, fall through, else... */
                if (tv.tv_sec > 0) {
+                       timestamp_before_wait = (unsigned)monotonic_sec();
                        DEBUG("Waiting on select...");
                        retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
-               }
-
-               if (retval < 0) {
-                       /* EINTR? signal was caught, don't panic */
-                       if (errno != EINTR) {
+                       if (retval < 0) {
+                               /* EINTR? A signal was caught, don't panic */
+                               if (errno == EINTR)
+                                       continue;
                                /* Else: an error occured, panic! */
                                bb_perror_msg_and_die("select");
                        }
-                       continue;
                }
 
                /* If timeout dropped to zero, time to become active:
                 * resend discover/renew/whatever
                 */
                if (retval == 0) {
+                       /* We will restart the wait in any case */
+                       already_waited_sec = 0;
+
                        switch (state) {
                        case INIT_SELECTING:
                                if (packet_num < discover_retries) {
                                        if (packet_num == 0)
                                                xid = random_xid();
 
-                                       /* send discover packet */
                                        send_discover(xid, requested_ip); /* broadcast */
 
                                        timeout = discover_timeout;
                                        packet_num++;
                                        continue;
                                }
+ leasefail:
                                udhcp_run_script(NULL, "leasefail");
-                               if (client_config.background_if_no_lease) {
+#if BB_MMU /* -b is not supported on NOMMU */
+                               if (opt & OPT_b) { /* background if no lease */
                                        bb_info_msg("No lease, forking to background");
                                        client_background();
-                               } else if (client_config.abort_if_no_lease) {
+                                       /* do not background again! */
+                                       opt = ((opt & ~OPT_b) | OPT_f);
+                               } else
+#endif
+                               if (opt & OPT_n) { /* abort if no lease */
                                        bb_info_msg("No lease, failing");
                                        retval = 1;
                                        goto ret;
                                }
-                               /* wait to try again */
+                               /* wait before trying again */
                                timeout = tryagain_timeout;
                                packet_num = 0;
                                continue;
@@ -384,11 +396,12 @@ int udhcpc_main(int argc, char **argv)
                        case REQUESTING:
                                if (packet_num < discover_retries) {
                                        /* send request packet */
-                                       if (state == RENEW_REQUESTED)
-                                               send_renew(xid, server_addr, requested_ip); /* unicast */
-                                       else send_selecting(xid, server_addr, requested_ip); /* broadcast */
+                                       if (state == RENEW_REQUESTED) /* unicast */
+                                               send_renew(xid, server_addr, requested_ip);
+                                       else /* broadcast */
+                                               send_select(xid, server_addr, requested_ip);
 
-                                       timeout = ((packet_num == 2) ? 10 : 2);
+                                       timeout = discover_timeout;
                                        packet_num++;
                                        continue;
                                }
@@ -396,38 +409,41 @@ int udhcpc_main(int argc, char **argv)
                                if (state == RENEW_REQUESTED)
                                        udhcp_run_script(NULL, "deconfig");
                                change_listen_mode(LISTEN_RAW);
+                               /* "discover...select...discover..." loops
+                                * were seen in the wild. Treat them similarly
+                                * to "no response to discover" case */
+                               if (state == REQUESTING) {
+                                       state = INIT_SELECTING;
+                                       goto leasefail;
+                               }
                                state = INIT_SELECTING;
                                timeout = 0;
                                packet_num = 0;
                                continue;
                        case BOUND:
-                               /* Lease is starting to run out, time to enter renewing state */
+                               /* Half of the lease passed, time to enter renewing state */
                                change_listen_mode(LISTEN_KERNEL);
                                DEBUG("Entering renew state");
                                state = RENEWING;
                                /* fall right through */
                        case RENEWING:
-                               /* Either set a new T1, or enter REBINDING state */
-                               if ((t2 - t1) > (lease_seconds / (4*60*60) + 1)) {
+                               if (timeout > 60) {
                                        /* send a request packet */
                                        send_renew(xid, server_addr, requested_ip); /* unicast */
-                                       t1 += (t2 - t1) / 2;
-                                       timeout = t1 - ((int)monotonic_sec() - timestamp_got_lease);
+                                       timeout >>= 1;
                                        continue;
                                }
                                /* Timed out, enter rebinding state */
                                DEBUG("Entering rebinding state");
                                state = REBINDING;
-                               timeout = (t2 - t1);
-                               continue;
+                               /* fall right through */
                        case REBINDING:
                                /* Lease is *really* about to run out,
                                 * try to find DHCP server using broadcast */
-                               if ((lease_seconds - t2) > (lease_seconds / (4*60*60) + 1)) {
+                               if (timeout > 0) {
                                        /* send a request packet */
-                                       send_renew(xid, 0, requested_ip); /* broadcast */
-                                       t2 += (lease_seconds - t2) / 2;
-                                       timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
+                                       send_renew(xid, 0 /*INADDR_ANY*/, requested_ip); /* broadcast */
+                                       timeout >>= 1;
                                        continue;
                                }
                                /* Timed out, enter init state */
@@ -435,7 +451,7 @@ int udhcpc_main(int argc, char **argv)
                                udhcp_run_script(NULL, "deconfig");
                                change_listen_mode(LISTEN_RAW);
                                state = INIT_SELECTING;
-                               timeout = 0;
+                               /*timeout = 0; - already is */
                                packet_num = 0;
                                continue;
                        /* case RELEASED: */
@@ -446,22 +462,29 @@ int udhcpc_main(int argc, char **argv)
                }
 
                /* select() didn't timeout, something did happen. */
-               /* Is is a packet? */
+               /* Is it a packet? */
                if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
+                       int len;
                        /* A packet is ready, read it */
 
                        if (listen_mode == LISTEN_KERNEL)
-                               len = udhcp_get_packet(&packet, sockfd);
-                       else len = get_raw_packet(&packet, sockfd);
-
-                       if (len == -1 && errno != EINTR) {
+                               len = udhcp_recv_kernel_packet(&packet, sockfd);
+                       else
+                               len = udhcp_recv_raw_packet(&packet, sockfd);
+                       if (len == -1) { /* error is severe, reopen socket */
                                DEBUG("error on read, %s, reopening socket", strerror(errno));
+                               sleep(discover_timeout); /* 3 seconds by default */
                                change_listen_mode(listen_mode); /* just close and reopen */
                        }
-                       if (len < 0) continue;
+                       /* If this packet will turn out to be unrelated/bogus,
+                        * we will go back and wait for next one.
+                        * Be sure timeout is properly decreased. */
+                       already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
+                       if (len < 0)
+                               continue;
 
                        if (packet.xid != xid) {
-                               DEBUG("Ignoring XID %x (our xid is %x)",
+                               DEBUG("Ignoring xid %x (our xid is %x)",
                                        (unsigned)packet.xid, (unsigned)xid);
                                continue;
                        }
@@ -489,8 +512,8 @@ int udhcpc_main(int argc, char **argv)
                                                continue;
                                                /* still selecting - this server looks bad */
                                        }
-                                       /* can be misaligned, thus memcpy */
-                                       memcpy(&server_addr, temp, 4);
+                                       /* it IS unaligned sometimes, don't "optimize" */
+                                       move_from_unaligned32(server_addr, temp);
                                        xid = packet.xid;
                                        requested_ip = packet.yiaddr;
 
@@ -498,6 +521,7 @@ int udhcpc_main(int argc, char **argv)
                                        state = REQUESTING;
                                        timeout = 0;
                                        packet_num = 0;
+                                       already_waited_sec = 0;
                                }
                                continue;
                        case RENEW_REQUESTED:
@@ -510,12 +534,24 @@ int udhcpc_main(int argc, char **argv)
                                                bb_error_msg("no lease time with ACK, using 1 hour lease");
                                                lease_seconds = 60 * 60;
                                        } else {
-                                               /* can be misaligned, thus memcpy */
-                                               memcpy(&lease_seconds, temp, 4);
+                                               /* it IS unaligned sometimes, don't "optimize" */
+                                               move_from_unaligned32(lease_seconds, temp);
                                                lease_seconds = ntohl(lease_seconds);
+                                               lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
+                                               if (lease_seconds < 10) /* and not too small */
+                                                       lease_seconds = 10;
                                        }
 #if ENABLE_FEATURE_UDHCPC_ARPING
                                        if (opt & OPT_a) {
+/* RFC 2131 3.1 paragraph 5:
+ * "The client receives the DHCPACK message with configuration
+ * parameters. The client SHOULD perform a final check on the
+ * parameters (e.g., ARP for allocated network address), and notes
+ * the duration of the lease specified in the DHCPACK message. At this
+ * point, the client is configured. If the client detects that the
+ * address is already in use (e.g., through the use of ARP),
+ * the client MUST send a DHCPDECLINE message to the server and restarts
+ * the configuration process..." */
                                                if (!arpping(packet.yiaddr,
                                                            (uint32_t) 0,
                                                            client_config.arp,
@@ -523,7 +559,7 @@ int udhcpc_main(int argc, char **argv)
                                                ) {
                                                        bb_info_msg("offered address is in use "
                                                                "(got ARP reply), declining");
-                                                       send_decline(xid, server_addr);
+                                                       send_decline(xid, server_addr, packet.yiaddr);
 
                                                        if (state != REQUESTING)
                                                                udhcp_run_script(NULL, "deconfig");
@@ -532,34 +568,38 @@ int udhcpc_main(int argc, char **argv)
                                                        requested_ip = 0;
                                                        timeout = tryagain_timeout;
                                                        packet_num = 0;
+                                                       already_waited_sec = 0;
                                                        continue; /* back to main loop */
                                                }
                                        }
 #endif
                                        /* enter bound state */
-                                       t1 = lease_seconds / 2;
-
-                                       /* little fixed point for n * .875 */
-                                       t2 = (lease_seconds * 7) >> 3;
-                                       temp_addr.s_addr = packet.yiaddr;
-                                       bb_info_msg("Lease of %s obtained, lease time %u",
-                                               inet_ntoa(temp_addr), (unsigned)lease_seconds);
-                                       timestamp_got_lease = monotonic_sec();
-                                       timeout = t1;
+                                       timeout = lease_seconds / 2;
+                                       {
+                                               struct in_addr temp_addr;
+                                               temp_addr.s_addr = packet.yiaddr;
+                                               bb_info_msg("Lease of %s obtained, lease time %u",
+                                                       inet_ntoa(temp_addr), (unsigned)lease_seconds);
+                                       }
                                        requested_ip = packet.yiaddr;
                                        udhcp_run_script(&packet,
-                                                  ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
+                                                       ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 
                                        state = BOUND;
                                        change_listen_mode(LISTEN_NONE);
-                                       if (client_config.quit_after_lease) {
-                                               if (client_config.release_on_quit)
-                                                       perform_release();
+                                       if (opt & OPT_q) { /* quit after lease */
+                                               if (opt & OPT_R) /* release on quit */
+                                                       perform_release(requested_ip, server_addr);
                                                goto ret0;
                                        }
-                                       if (!client_config.foreground)
+#if BB_MMU /* NOMMU case backgrounded earlier */
+                                       if (!(opt & OPT_f)) {
                                                client_background();
-
+                                               /* do not background again! */
+                                               opt = ((opt & ~OPT_b) | OPT_f);
+                                       }
+#endif
+                                       already_waited_sec = 0;
                                        continue; /* back to main loop */
                                }
                                if (*message == DHCPNAK) {
@@ -574,6 +614,7 @@ int udhcpc_main(int argc, char **argv)
                                        requested_ip = 0;
                                        timeout = 0;
                                        packet_num = 0;
+                                       already_waited_sec = 0;
                                }
                                continue;
                        /* case BOUND, RELEASED: - ignore all packets */
@@ -594,12 +635,13 @@ int udhcpc_main(int argc, char **argv)
                                timeout = 0;
                                break;
                        case SIGUSR2:
-                               perform_release();
+                               perform_release(requested_ip, server_addr);
+                               timeout = INT_MAX;
                                break;
                        case SIGTERM:
                                bb_info_msg("Received SIGTERM");
-                               if (client_config.release_on_quit)
-                                       perform_release();
+                               if (opt & OPT_R) /* release on quit */
+                                       perform_release(requested_ip, server_addr);
                                goto ret0;
                        }
                }
@@ -608,7 +650,7 @@ int udhcpc_main(int argc, char **argv)
  ret0:
        retval = 0;
  ret:
-       /*if (client_config.pidfile) - remove_pidfile has it's own check */
+       /*if (client_config.pidfile) - remove_pidfile has its own check */
                remove_pidfile(client_config.pidfile);
        return retval;
 }