dhcpc.c

這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU

        }

      optptr += optptr[1] + 2;
    }
  return type;
}

/****************************************************************************
 * Name: dhcpc_parsemsg
 ****************************************************************************/

static uint8 dhcpc_parsemsg(struct dhcpc_state_s *pdhcpc, int buflen,
                            struct dhcpc_state *presult)
{
  if (pdhcpc->packet.op == DHCP_REPLY &&
      memcmp(pdhcpc->packet.xid, xid, sizeof(xid)) == 0 &&
      memcmp(pdhcpc->packet.chaddr, pdhcpc->ds_macaddr, pdhcpc->ds_maclen) == 0)
    {
      memcpy(&presult->ipaddr.s_addr, pdhcpc->packet.yiaddr, 4);
      return dhcpc_parseoptions(presult, &pdhcpc->packet.options[4], buflen);
    }
  return 0;
}

/****************************************************************************
 * Global Functions
 ****************************************************************************/

/****************************************************************************
 * Name: dhcpc_open
 ****************************************************************************/

void *dhcpc_open(const void *macaddr, int maclen)
{
  struct dhcpc_state_s *pdhcpc;
  struct sockaddr_in addr;
  struct timeval tv;

  dbg("MAC: %02x:%02x:%02x:%02x:%02x:%02x\n",
      ((uint8*)macaddr)[0], ((uint8*)macaddr)[1], ((uint8*)macaddr)[2],
      ((uint8*)macaddr)[3], ((uint8*)macaddr)[4], ((uint8*)macaddr)[5]);

  /* Allocate an internal DHCP structure */

  pdhcpc = (struct dhcpc_state_s *)malloc(sizeof(struct dhcpc_state_s));
  if (pdhcpc)
    {
      /* Initialize the allocated structure */

      memset(pdhcpc, 0, sizeof(struct dhcpc_state_s));
      pdhcpc->ds_macaddr = macaddr;
      pdhcpc->ds_maclen  = maclen;

      /* Create a UDP socket */

      pdhcpc->sockfd    = socket(PF_INET, SOCK_DGRAM, 0);
      if (pdhcpc->sockfd < 0)
        {
          free(pdhcpc);
          return NULL;
        }

      /* bind the socket */

      addr.sin_family      = AF_INET;
      addr.sin_port        = HTONS(DHCPC_CLIENT_PORT);
      addr.sin_addr.s_addr = INADDR_ANY;

      if (bind(pdhcpc->sockfd, (struct sockaddr*)&addr, sizeof(struct sockaddr_in)) < 0)
        {
          close(pdhcpc->sockfd);
          free(pdhcpc);
          return NULL;
        }

      /* Configure for read timeouts */

      tv.tv_sec  = 10;
      tv.tv_usec = 0;
      if (setsockopt(pdhcpc->sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(struct timeval)) < 0)
        {
          close(pdhcpc->sockfd);
          free(pdhcpc);
          return NULL;
        }
    }

  return (void*)pdhcpc;
}

/****************************************************************************
 * Name: dhcpc_close
 ****************************************************************************/

void dhcpc_close(void *handle)
{
  struct dchcpc_state_internal *pdhcpc = (struct dchcpc_state_internal *)handle;
  if (pdhcpc)
    {
      free(pdhcpc);
    }
}

/****************************************************************************
 * Name: dhcpc_request
 ****************************************************************************/

int dhcpc_request(void *handle, struct dhcpc_state *presult)
{
  struct dhcpc_state_s *pdhcpc = (struct dhcpc_state_s *)handle;
  struct in_addr oldaddr;
  struct in_addr newaddr;
  ssize_t result;
  uint8   msgtype;
  int     retries;
  int     state;

  /* Save the currently assigned IP address (should be INADDR_ANY) */

  oldaddr.s_addr = 0;
  uip_gethostaddr("eth0", &oldaddr);

  /* Loop until we receive the lease (or an error occurs) */

  do
    {
      /* Set the IP address to INADDR_ANY. */

      newaddr.s_addr = INADDR_ANY;
      (void)uip_sethostaddr("eth0", &newaddr);

      /* Loop sending DISCOVER until we receive an OFFER from a DHCP
       * server.  We will lock on to the first OFFER and decline any
       * subsequent offers (which will happen if there are more than one
       * DHCP servers on the network.
       */

      state = STATE_INITIAL;
      do
        {
          /* Send the DISCOVER command */

          dbg("Broadcast DISCOVER\n");
          if (dhcpc_sendmsg(pdhcpc, presult, DHCPDISCOVER) < 0)
            {
              return ERROR;
            }

          /* Get the DHCPOFFER response */

          result = recv(pdhcpc->sockfd, &pdhcpc->packet, sizeof(struct dhcp_msg), 0);
          if (result >= 0)
            {
              msgtype = dhcpc_parsemsg(pdhcpc, result, presult);
              if (msgtype == DHCPOFFER)
                {
                  /* Save the servid from the presult so that it is not clobbered
                   * by a new OFFER.
                   */

                  dbg("Received OFFER from %08x\n", ntohl(presult->serverid.s_addr));
                  pdhcpc->ipaddr.s_addr   = presult->ipaddr.s_addr;
                  pdhcpc->serverid.s_addr = presult->serverid.s_addr;

                  /* Temporarily use the address offered by the server and break
                   * out of the loop.
                   */

                  (void)uip_sethostaddr("eth0", &presult->ipaddr);
                  state = STATE_HAVE_OFFER;
                }
            }

          /* An error has occurred.  If this was a timeout error (meaning that
           * nothing was received on this socket for a long period of time).
           * Then loop and send the DISCOVER command again.
           */

          else if (*get_errno_ptr() != EAGAIN)
            {
              /* An error other than a timeout was received -- error out */

              return ERROR;
            }
        }
      while (state == STATE_INITIAL);


      /* Loop sending the REQUEST up to three times (if there is no response) */

      retries = 0;
      do
        {
          /* Send the REQUEST message to obtain the lease that was offered to us. */

          dbg("Send REQUEST\n");
          if (dhcpc_sendmsg(pdhcpc, presult, DHCPREQUEST) < 0)
            {
              return ERROR;
            }
          retries++;

          /* Get the ACK/NAK response to the REQUEST (or timeout) */

          result = recv(pdhcpc->sockfd, &pdhcpc->packet, sizeof(struct dhcp_msg), 0);
          if (result >= 0)
            {
              /* Parse the response */

              msgtype = dhcpc_parsemsg(pdhcpc, result, presult);

              /* The ACK response means that the server has accepted our request
               * and we have the lease.
               */

              if (msgtype == DHCPACK)
                {
                  dbg("Received ACK\n");
                  state = STATE_HAVE_LEASE;
                }

              /* NAK means the the server has refused our request.  Break out of
               * this loop with state == STATE_HAVE_OFFER and send DISCOVER again
               */

              else if (msgtype == DHCPNAK)
                {
                  dbg("Received NAK\n");
                  break;
                }

              /* If we get any OFFERs from other servers, then decline them now
               * and continue waiting for the ACK from the server that we
               * requested from.
               */

              else if (msgtype == DHCPOFFER)
                {
                  dbg("Received another OFFER, send DECLINE\n");
                  (void)dhcpc_sendmsg(pdhcpc, presult, DHCPDECLINE);
                }

              /* Otherwise, it is something that we do not recognize */

              else
                {
                  dbg("Ignoring msgtype=%d\n", msgtype);
                }
            }

          /* An error has occurred.  If this was a timeout error (meaning
           * that nothing was received on this socket for a long period of time).
           * Then break out and send the DISCOVER command again (at most
           * 3 times).
           */

          else if (*get_errno_ptr() != EAGAIN)
            {
              /* An error other than a timeout was received */

              (void)uip_sethostaddr("eth0", &oldaddr);
              return ERROR;
            }
        }
      while (state == STATE_HAVE_OFFER && retries < 3);
    }
  while (state != STATE_HAVE_LEASE);

  dbg("Got IP address %d.%d.%d.%d\n",
      (presult->ipaddr.s_addr >> 24 ) & 0xff,
      (presult->ipaddr.s_addr >> 16 ) & 0xff,
      (presult->ipaddr.s_addr >> 8  ) & 0xff,
      (presult->ipaddr.s_addr       ) & 0xff);
  dbg("Got netmask %d.%d.%d.%d\n",
      (presult->netmask.s_addr >> 24 ) & 0xff,
      (presult->netmask.s_addr >> 16 ) & 0xff,
      (presult->netmask.s_addr >> 8  ) & 0xff,
      (presult->netmask.s_addr       ) & 0xff);
  dbg("Got DNS server %d.%d.%d.%d\n",
      (presult->dnsaddr.s_addr >> 24 ) & 0xff,
      (presult->dnsaddr.s_addr >> 16 ) & 0xff,
      (presult->dnsaddr.s_addr >> 8  ) & 0xff,
      (presult->dnsaddr.s_addr       ) & 0xff);
  dbg("Got default router %d.%d.%d.%d\n",
      (presult->default_router.s_addr >> 24 ) & 0xff,
      (presult->default_router.s_addr >> 16 ) & 0xff,
      (presult->default_router.s_addr >> 8  ) & 0xff,
      (presult->default_router.s_addr       ) & 0xff);
  dbg("Lease expires in %ld seconds\n",
      ntohs(presult->lease_time[0])*65536ul + ntohs(presult->lease_time[1]));
  return OK;
}