/* dhcpc.c
 *
 * udhcp DHCP client
 *
 * Russ Dill <Russ.Dill@asu.edu> July 2001
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

#include <sys/time.h>
#include <sys/file.h>
#include <unistd.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>

#include "common.h"
#include "dhcpd.h"
#include "dhcpc.h"
#include "options.h"
#include "clientpacket.h"
#include "clientsocket.h"
#include "script.h"
#include "socket.h"
#include "signalpipe.h"
#include "pidfile.h"


static int state;
static unsigned long requested_ip; /* = 0 */
static unsigned long server_addr;
static unsigned long timeout;
static int packet_num; /* = 0 */
static int fd = -1;

#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static int listen_mode;
static int re_execed = 0;

#ifndef HAVE_MMU
static int daemonize(int argc, char *argv[])
{
  int  fd;
  char **vfork_args;
  int a = 0;
  pid_t pid;
  
  
  close(0);
  close(1);
  close(2);

  fd = open("/dev/null", O_RDWR);
  while ((unsigned)fd < 2)
    fd = dup(fd);
    
  if(re_execed == 0)
  {
     pid = vfork();
    
    if ( pid < 0) {
      LOG(LOG_ERR, "vfork failed\n");
      exit(1);
    } 
    
    if (pid > 0) 
      exit(0);
  
     vfork_args = malloc(sizeof(char *) * (argc + 2));
     memset(vfork_args, 0, sizeof(char *) * (argc + 2));
     while (*argv) {
      vfork_args[a++] = *argv;
      argv++;
     }
    
     vfork_args[a] = "-D";
    
     execv(vfork_args[0], vfork_args);
    
     LOG(LOG_ERR, "Couldn't exec\n");
     _exit(1);
  
  }
  
  setsid();
  dup2(fd, 0);
  dup2(fd, 1);
  dup2(fd, 2);
  
  while (fd > 2)
    close(fd--);
  
  return 0;
}
#endif

struct client_config_t client_config = {
  /* Default options. */
  .abort_if_no_lease = 0,
  .foreground = 0,
  .quit_after_lease = 0,
  .background_if_no_lease = 0,
  .interface = "eth0",
  .pidfile = "/var/run/udhcpc.pid", // Modified by James Chen, Foxconn, 2010/08/30
  .script = DEFAULT_SCRIPT,
  .clientid = NULL,
  .vendorclass = NULL,
  .hostname = NULL,
  .fqdn = NULL,
  .ifindex = 0,
  .retries = 3,
  .timeout = 3,
  .arp = "\0\0\0\0\0\0",    /* appease gcc-3.0 */
};


static void show_usage(void)
{
  printf(
"Usage: udhcpc [OPTIONS]\n\n"
"  -c, --clientid=CLIENTID         Set client identifier - type is first char\n"
"  -C, --clientid-none             Suppress default client identifier\n"
"  -V, --vendorclass=CLASSID       Set vendor class identifier\n"
"  -H, --hostname=HOSTNAME         Client hostname\n"
"  -h                              Alias for -H\n"
"  -F, --fqdn=FQDN                 Client fully qualified domain name\n"
"  -f, --foreground                Do not fork after getting lease\n"
"  -b, --background                Fork to background if lease cannot be\n"
"                                  immediately negotiated.\n"
"  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
"  -n, --now                       Exit with failure if lease cannot be\n"
"                                  immediately negotiated.\n"
"  -p, --pidfile=file              Store process ID of daemon in file\n"
"  -q, --quit                      Quit after obtaining lease\n"
"  -r, --request=IP                IP address to request (default: none)\n"
"  -s, --script=file               Run file at dhcp events (default:\n"
"                                  " DEFAULT_SCRIPT ")\n"
"  -T, --timeout=seconds           Try to get the lease for the amount of\n"
"                                  seconds (default: 3)\n"
"  -v, --version                   Display version\n"
  );
  exit(0);
}



/* just a little helper */
static void change_mode(int new_mode)
{
  DEBUG(LOG_INFO, "entering %s listen mode",
    new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  if (fd >= 0) close(fd);

  fd = -1;
  listen_mode = new_mode;
}


/* perform a renew */
static void perform_renew(void)
{
  LOG(LOG_INFO, "Performing a DHCP renew");
  switch (state) {
  case BOUND:
    change_mode(LISTEN_KERNEL);
  case RENEWING:
  case REBINDING:
    state = RENEW_REQUESTED;
    break;
  case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
    run_script(NULL, "deconfig");
  case REQUESTING:
  case RELEASED:
    change_mode(LISTEN_RAW);
    state = INIT_SELECTING;
    break;
  case INIT_SELECTING:
    break;
  }

  /* start things over */
  packet_num = 0;

  /* Kill any timeouts because the user wants this to hurry along */
  timeout = 0;
}


/* perform a release */
static void perform_release(void)
{
  char buffer[16];
  struct in_addr temp_addr;

  /* send release packet */
  if (state == BOUND || state == RENEWING || state == REBINDING) {
    temp_addr.s_addr = server_addr;
    sprintf(buffer, "%s", inet_ntoa(temp_addr));
    temp_addr.s_addr = requested_ip;
    LOG(LOG_INFO, "Unicasting a release of %s to %s",
        inet_ntoa(temp_addr), buffer);
    send_release(server_addr, requested_ip); /* unicast */
    run_script(NULL, "deconfig");
  }
  LOG(LOG_INFO, "Entering released state");

  change_mode(LISTEN_NONE);
  state = RELEASED;
  timeout = 0x7fffffff;
}

#ifdef HAVE_MMU
static void client_background(void)
{
  background(client_config.pidfile);
  client_config.foreground = 1; /* Do not fork again. */
  client_config.background_if_no_lease = 0;
}
#endif


#ifdef COMBINED_BINARY
int udhcpc_main(int argc, char *argv[])
#else
int main(int argc, char *argv[])
#endif
{
  uint8_t *temp, *message;
  unsigned long t1 = 0, t2 = 0, xid = 0;
  unsigned long start = 0, lease;
  fd_set rfds;
  int retval;
  struct timeval tv;
  int c, len;
  struct dhcpMessage packet;
  struct in_addr temp_addr;
  long now;
  int max_fd;
  int sig;
  int no_clientid = 0;

  static const struct option arg_options[] = {
    {"clientid",  required_argument,  0, 'c'},
    {"clientid-none", no_argument,    0, 'C'},
    {"vendorclass", required_argument,  0, 'V'},
    {"foreground",  no_argument,    0, 'f'},
    {"background",  no_argument,    0, 'b'},
    {"hostname",  required_argument,  0, 'H'},
    {"hostname",  required_argument,  0, 'h'},
    {"fqdn",  required_argument,  0, 'F'},
    {"interface", required_argument,  0, 'i'},
    {"now",   no_argument,    0, 'n'},
    {"pidfile", required_argument,  0, 'p'},
    {"quit",  no_argument,    0, 'q'},
    {"request", required_argument,  0, 'r'},
    {"script",  required_argument,  0, 's'},
    {"timeout", required_argument,  0, 'T'},
    {"version", no_argument,    0, 'v'},
    {"retries", required_argument,  0, 't'},    
    {0, 0, 0, 0}
  };

  /* get options */
  while (1) {
    int option_index = 0;
    c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qr:s:T:t:vD", arg_options, &option_index);
    if (c == -1) break;

    switch (c) {
    case 'c':
      if (no_clientid) show_usage();
      len = strlen(optarg) > 255 ? 255 : strlen(optarg);
      free(client_config.clientid);
      client_config.clientid = xmalloc(len + 2);
      client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
      client_config.clientid[OPT_LEN] = len;
      client_config.clientid[OPT_DATA] = '\0';
      strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
      break;
    case 'C':
      if (client_config.clientid) show_usage();
      no_clientid = 1;
      break;
    case 'V':
      len = strlen(optarg) > 255 ? 255 : strlen(optarg);
      free(client_config.vendorclass);
      client_config.vendorclass = xmalloc(len + 2);
      client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
      client_config.vendorclass[OPT_LEN] = len;
      strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
      break;
    case 'f':
      client_config.foreground = 1;
      break;
    case 'b':
      client_config.background_if_no_lease = 1;
      break;
    case 'h':
    case 'H':
      len = strlen(optarg) > 255 ? 255 : strlen(optarg);
      free(client_config.hostname);
      client_config.hostname = xmalloc(len + 2);
      client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
      client_config.hostname[OPT_LEN] = len;
      strncpy((char*)client_config.hostname + 2, optarg, len);
      break;
    case 'F':
      len = strlen(optarg) > 255 ? 255 : strlen(optarg);
      free(client_config.fqdn);
      client_config.fqdn = xmalloc(len + 5);
      client_config.fqdn[OPT_CODE] = DHCP_FQDN;
      client_config.fqdn[OPT_LEN] = len + 3;
      /* 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"
      N: 1 => Client requests Server to not update DNS
      */
      client_config.fqdn[OPT_LEN + 1] = 0x1;
      client_config.fqdn[OPT_LEN + 2] = 0;
      client_config.fqdn[OPT_LEN + 3] = 0;
      strncpy((char*)client_config.fqdn + 5, optarg, len);
      break;
    case 'i':
      client_config.interface =  optarg;
      break;
    case 'n':
      client_config.abort_if_no_lease = 1;
      break;
    case 'p':
      client_config.pidfile = optarg;
      break;
    case 'q':
      client_config.quit_after_lease = 1;
      break;
    case 'r':
      requested_ip = inet_addr(optarg);
      break;
    case 's':
      client_config.script = optarg;
      break;
    case 'T':
      client_config.timeout = atoi(optarg);
      break;
    case 't':
      client_config.retries = atoi(optarg);
      break;
    case 'D':
      re_execed = 1;
      break;
    case 'v':
      printf("udhcpc, UCI version %s\n\n", VERSION);
      return 0;
      break;
    default:
      show_usage();
    }
  }

#ifndef HAVE_MMU

  if(!client_config.foreground)
    daemonize(argc, argv);
  
#endif

  /* Start the log, sanitize fd's, and write a pid file */
  start_log_and_pid("udhcpc", client_config.pidfile);

  if (read_interface(client_config.interface, &client_config.ifindex,
         NULL, client_config.arp) < 0)
    return 1;

  /* if not set, and not suppressed, setup the default client ID */
  if (!client_config.clientid && !no_clientid) {
    client_config.clientid = xmalloc(6 + 3);
    client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
    client_config.clientid[OPT_LEN] = 7;
    client_config.clientid[OPT_DATA] = 1;
    memcpy(client_config.clientid + 3, client_config.arp, 6);
  }

  if (!client_config.vendorclass) {
    client_config.vendorclass = xmalloc(sizeof("udhcp "VERSION) + 2);
    client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
    client_config.vendorclass[OPT_LEN] = sizeof("udhcp "VERSION) - 1;
    client_config.vendorclass[OPT_DATA] = 1;
    memcpy(&client_config.vendorclass[OPT_DATA],
      "udhcp "VERSION, sizeof("udhcp "VERSION) - 1);
  }


  /* setup the signal pipe */
  udhcp_sp_setup();

  state = INIT_SELECTING;
  run_script(NULL, "deconfig");
  change_mode(LISTEN_RAW);

  for (;;) {

    tv.tv_sec = timeout - uptime();
    tv.tv_usec = 0;

    if (listen_mode != LISTEN_NONE && fd < 0) {
      if (listen_mode == LISTEN_KERNEL)
        fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
      else
        fd = raw_socket(client_config.ifindex);
      if (fd < 0) {
        LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
        return 0;
      }
    }
    max_fd = udhcp_sp_fd_set(&rfds, fd);

    if (tv.tv_sec > 0) {
      DEBUG(LOG_INFO, "Waiting on select...");
      retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
    } else retval = 0; /* If we already timed out, fall through */

    now = uptime();
    if (retval == 0) {
      /* timeout dropped to zero */
      switch (state) {
      case INIT_SELECTING:
        if (packet_num < client_config.retries) {
          if (packet_num == 0)
            xid = random_xid();

          /* send discover packet */
          send_discover(xid, requested_ip); /* broadcast */

          timeout = now + client_config.timeout;
          packet_num++;
        } else {
          run_script(NULL, "leasefail");
#ifdef HAVE_MMU
          if (client_config.background_if_no_lease) {
            LOG(LOG_INFO, "No lease, forking to background.");
            client_background();
          } else 
#endif          
          if (client_config.abort_if_no_lease) {
            LOG(LOG_INFO, "No lease, failing.");
            return 1;
          }
          /* wait to try again */
          packet_num = 0;
          timeout = now + 60;
        }
        break;
      case RENEW_REQUESTED:
      case REQUESTING:
        if (packet_num < client_config.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 */

          timeout = now + ((packet_num == 2) ? 10 : 2);
          packet_num++;
        } else {
          /* timed out, go back to init state */
          if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
          state = INIT_SELECTING;
          timeout = now;
          packet_num = 0;
          change_mode(LISTEN_RAW);
        }
        break;
      case BOUND:
        /* Lease is starting to run out, time to enter renewing state */
        state = RENEWING;
        change_mode(LISTEN_KERNEL);
        DEBUG(LOG_INFO, "Entering renew state");
        /* fall right through */
      case RENEWING:
        /* Either set a new T1, or enter REBINDING state */
        if ((t2 - t1) <= (lease / 14400 + 1)) {
          /* timed out, enter rebinding state */
          state = REBINDING;
          timeout = now + (t2 - t1);
          DEBUG(LOG_INFO, "Entering rebinding state");
        } else {
          /* send a request packet */
          send_renew(xid, server_addr, requested_ip); /* unicast */

          t1 = (t2 - t1) / 2 + t1;
          timeout = t1 + start;
        }
        break;
      case REBINDING:
        /* Either set a new T2, or enter INIT state */
        if ((lease - t2) <= (lease / 14400 + 1)) {
          /* timed out, enter init state */
          state = INIT_SELECTING;
          LOG(LOG_INFO, "Lease lost, entering init state");
          run_script(NULL, "deconfig");
          timeout = now;
          packet_num = 0;
          change_mode(LISTEN_RAW);
        } else {
          /* send a request packet */
          send_renew(xid, 0, requested_ip); /* broadcast */

          t2 = (lease - t2) / 2 + t2;
          timeout = t2 + start;
        }
        break;
      case RELEASED:
        /* yah, I know, *you* say it would never happen */
        timeout = 0x7fffffff;
        break;
      }
    } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
      /* a packet is ready, read it */

      if (listen_mode == LISTEN_KERNEL)
        len = get_packet(&packet, fd);
      else len = get_raw_packet(&packet, fd);

      if (len == -1 && errno != EINTR) {
        DEBUG(LOG_INFO, "error on read, %m, reopening socket");
        change_mode(listen_mode); /* just close and reopen */
      }
      if (len < 0) continue;

      if (packet.xid != xid) {
        DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
          (unsigned long) packet.xid, xid);
        continue;
      }
      /* Ignore packets that aren't for us */
      if (memcmp(packet.chaddr, client_config.arp, 6)) {
        DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
        continue;
      }

      if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
        DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
        continue;
      }

      switch (state) {
      case INIT_SELECTING:
        /* Must be a DHCPOFFER to one of our xid's */
        if (*message == DHCPOFFER) {
          if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
            memcpy(&server_addr, temp, 4);
            xid = packet.xid;
            requested_ip = packet.yiaddr;

            /* enter requesting state */
            state = REQUESTING;
            timeout = now;
            packet_num = 0;
          } else {
            DEBUG(LOG_ERR, "No server ID in message");
          }
        }
        break;
      case RENEW_REQUESTED:
      case REQUESTING:
      case RENEWING:
      case REBINDING:
        if (*message == DHCPACK) {
          if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
            LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
            lease = 60 * 60;
          } else {
            memcpy(&lease, temp, 4);
            lease = ntohl(lease);
          }

          /* enter bound state */
          t1 = lease / 2;

          /* little fixed point for n * .875 */
          t2 = (lease * 0x7) >> 3;
          temp_addr.s_addr = packet.yiaddr;
          LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
            inet_ntoa(temp_addr), lease);
          start = now;
          timeout = t1 + start;
          requested_ip = packet.yiaddr;
          run_script(&packet,
               ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));

          state = BOUND;
          change_mode(LISTEN_NONE);
          
          if (client_config.quit_after_lease)
            return 0;

#ifdef HAVE_MMU   
          if (!client_config.foreground)
            client_background();
#endif

        } else if (*message == DHCPNAK) {
          /* return to init state */
          LOG(LOG_INFO, "Received DHCP NAK");
          run_script(&packet, "nak");
          if (state != REQUESTING)
            run_script(NULL, "deconfig");
          state = INIT_SELECTING;
          timeout = now;
          requested_ip = 0;
          packet_num = 0;
          change_mode(LISTEN_RAW);
          sleep(3); /* avoid excessive network traffic */
        }
        break;
      /* case BOUND, RELEASED: - ignore all packets */
      }
    } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
      switch (sig) {
      case SIGUSR1:
        perform_renew();
        break;
      case SIGUSR2:
        perform_release();
        break;
      case SIGTERM:
        LOG(LOG_INFO, "Received SIGTERM");
        remove_pid(client_config.pidfile); // Added by James Chen, Foxconn, 2010/08/30
        return 0;
      }
    } else if (retval == -1 && errno == EINTR) {
      /* a signal was caught */
    } else {
      /* An error occured */
      DEBUG(LOG_ERR, "Error on select");
    }

  }
  return 0;
}
