dhcp.c

lwip-1.4.0

        /* limit number of DNS servers */
        decode_len = LWIP_MIN(len, 4 * DNS_MAX_SERVERS);
        LWIP_ASSERT("len >= decode_len", len >= decode_len);
        decode_idx = DHCP_OPTION_IDX_DNS_SERVER;
        break;
      case(DHCP_OPTION_LEASE_TIME):
        LWIP_ASSERT("len == 4", len == 4);
        decode_idx = DHCP_OPTION_IDX_LEASE_TIME;
        break;
      case(DHCP_OPTION_OVERLOAD):
        LWIP_ASSERT("len == 1", len == 1);
        decode_idx = DHCP_OPTION_IDX_OVERLOAD;
        break;
      case(DHCP_OPTION_MESSAGE_TYPE):
        LWIP_ASSERT("len == 1", len == 1);
        decode_idx = DHCP_OPTION_IDX_MSG_TYPE;
        break;
      case(DHCP_OPTION_SERVER_ID):
        LWIP_ASSERT("len == 4", len == 4);
        decode_idx = DHCP_OPTION_IDX_SERVER_ID;
        break;
      case(DHCP_OPTION_T1):
        LWIP_ASSERT("len == 4", len == 4);
        decode_idx = DHCP_OPTION_IDX_T1;
        break;
      case(DHCP_OPTION_T2):
        LWIP_ASSERT("len == 4", len == 4);
        decode_idx = DHCP_OPTION_IDX_T2;
        break;
      default:
        decode_len = 0;
        LWIP_DEBUGF(DHCP_DEBUG, ("skipping option %"U16_F" in options\n", op));
        break;
    }
    offset += len + 2;
    if (decode_len > 0) {
      u32_t value = 0;
      u16_t copy_len;
decode_next:
      LWIP_ASSERT("check decode_idx", decode_idx >= 0 && decode_idx < DHCP_OPTION_IDX_MAX);
      LWIP_ASSERT("option already decoded", !dhcp_option_given(dhcp, decode_idx));
      copy_len = LWIP_MIN(decode_len, 4);
      pbuf_copy_partial(q, &value, copy_len, val_offset);
      if (decode_len > 4) {
        /* decode more than one u32_t */
        LWIP_ASSERT("decode_len % 4 == 0", decode_len % 4 == 0);
        dhcp_got_option(dhcp, decode_idx);
        dhcp_set_option_value(dhcp, decode_idx, htonl(value));
        decode_len -= 4;
        val_offset += 4;
        decode_idx++;
        goto decode_next;
      } else if (decode_len == 4) {
        value = ntohl(value);
      } else {
        LWIP_ASSERT("invalid decode_len", decode_len == 1);
        value = ((u8_t*)&value)[0];
      }
      dhcp_got_option(dhcp, decode_idx);
      dhcp_set_option_value(dhcp, decode_idx, value);
    }
    if (offset >= q->len) {
      offset -= q->len;
      offset_max -= q->len;
      q = q->next;
      options = (u8_t*)q->payload;
    }
  }
  /* is this an overloaded message? */
  if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_OVERLOAD)) {
    u32_t overload = dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_OVERLOAD);
    dhcp_clear_option(dhcp, DHCP_OPTION_IDX_OVERLOAD);
    if (overload == DHCP_OVERLOAD_FILE) {
      parse_file_as_options = 1;
      LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded file field\n"));
    } else if (overload == DHCP_OVERLOAD_SNAME) {
      parse_sname_as_options = 1;
      LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded sname field\n"));
    } else if (overload == DHCP_OVERLOAD_SNAME_FILE) {
      parse_sname_as_options = 1;
      parse_file_as_options = 1;
      LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded sname and file field\n"));
    } else {
      LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("invalid overload option: %d\n", (int)overload));
    }
#if LWIP_DHCP_BOOTP_FILE
    if (!parse_file_as_options) {
      /* only do this for ACK messages */
      if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_MSG_TYPE) &&
        (dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_MSG_TYPE) == DHCP_ACK))
      /* copy bootp file name, don't care for sname (server hostname) */
      pbuf_copy_partial(p, dhcp->boot_file_name, DHCP_FILE_LEN-1, DHCP_FILE_OFS);
      /* make sure the string is really NULL-terminated */
      dhcp->boot_file_name[DHCP_FILE_LEN-1] = 0;
    }
#endif /* LWIP_DHCP_BOOTP_FILE */
  }
  if (parse_file_as_options) {
    /* if both are overloaded, parse file first and then sname (RFC 2131 ch. 4.1) */
    parse_file_as_options = 0;
    options_idx = DHCP_FILE_OFS;
    options_idx_max = DHCP_FILE_OFS + DHCP_FILE_LEN;
    goto again;
  } else if (parse_sname_as_options) {
    parse_sname_as_options = 0;
    options_idx = DHCP_SNAME_OFS;
    options_idx_max = DHCP_SNAME_OFS + DHCP_SNAME_LEN;
    goto again;
  }
  return ERR_OK;
}

/**
 * If an incoming DHCP message is in response to us, then trigger the state machine
 */
static void
dhcp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t port)
{
  struct netif *netif = (struct netif *)arg;
  struct dhcp *dhcp = netif->dhcp;
  struct dhcp_msg *reply_msg = (struct dhcp_msg *)p->payload;
  u8_t msg_type;
  u8_t i;
  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_recv(pbuf = %p) from DHCP server %"U16_F".%"U16_F".%"U16_F".%"U16_F" port %"U16_F"\n", (void*)p,
    ip4_addr1_16(addr), ip4_addr2_16(addr), ip4_addr3_16(addr), ip4_addr4_16(addr), port));
  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->len = %"U16_F"\n", p->len));
  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->tot_len = %"U16_F"\n", p->tot_len));
  /* prevent warnings about unused arguments */
  LWIP_UNUSED_ARG(pcb);
  LWIP_UNUSED_ARG(addr);
  LWIP_UNUSED_ARG(port);

  LWIP_ASSERT("reply wasn't freed", dhcp->msg_in == NULL);

  if (p->len < DHCP_MIN_REPLY_LEN) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("DHCP reply message or pbuf too short\n"));
    goto free_pbuf_and_return;
  }

  if (reply_msg->op != DHCP_BOOTREPLY) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("not a DHCP reply message, but type %"U16_F"\n", (u16_t)reply_msg->op));
    goto free_pbuf_and_return;
  }
  /* iterate through hardware address and match against DHCP message */
  for (i = 0; i < netif->hwaddr_len; i++) {
    if (netif->hwaddr[i] != reply_msg->chaddr[i]) {
      LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
        ("netif->hwaddr[%"U16_F"]==%02"X16_F" != reply_msg->chaddr[%"U16_F"]==%02"X16_F"\n",
        (u16_t)i, (u16_t)netif->hwaddr[i], (u16_t)i, (u16_t)reply_msg->chaddr[i]));
      goto free_pbuf_and_return;
    }
  }
  /* match transaction ID against what we expected */
  if (ntohl(reply_msg->xid) != dhcp->xid) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
      ("transaction id mismatch reply_msg->xid(%"X32_F")!=dhcp->xid(%"X32_F")\n",ntohl(reply_msg->xid),dhcp->xid));
    goto free_pbuf_and_return;
  }
  /* option fields could be unfold? */
  if (dhcp_parse_reply(dhcp, p) != ERR_OK) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
      ("problem unfolding DHCP message - too short on memory?\n"));
    goto free_pbuf_and_return;
  }

  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("searching DHCP_OPTION_MESSAGE_TYPE\n"));
  /* obtain pointer to DHCP message type */
  if (!dhcp_option_given(dhcp, DHCP_OPTION_IDX_MSG_TYPE)) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("DHCP_OPTION_MESSAGE_TYPE option not found\n"));
    goto free_pbuf_and_return;
  }

  /* read DHCP message type */
  msg_type = (u8_t)dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_MSG_TYPE);
  /* message type is DHCP ACK? */
  if (msg_type == DHCP_ACK) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_ACK received\n"));
    /* in requesting state? */
    if (dhcp->state == DHCP_REQUESTING) {
      dhcp_handle_ack(netif);
#if DHCP_DOES_ARP_CHECK
      /* check if the acknowledged lease address is already in use */
      dhcp_check(netif);
#else
      /* bind interface to the acknowledged lease address */
      dhcp_bind(netif);
#endif
    }
    /* already bound to the given lease address? */
    else if ((dhcp->state == DHCP_REBOOTING) || (dhcp->state == DHCP_REBINDING) || (dhcp->state == DHCP_RENEWING)) {
      dhcp_bind(netif);
    }
  }
  /* received a DHCP_NAK in appropriate state? */
  else if ((msg_type == DHCP_NAK) &&
    ((dhcp->state == DHCP_REBOOTING) || (dhcp->state == DHCP_REQUESTING) ||
     (dhcp->state == DHCP_REBINDING) || (dhcp->state == DHCP_RENEWING  ))) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_NAK received\n"));
    dhcp_handle_nak(netif);
  }
  /* received a DHCP_OFFER in DHCP_SELECTING state? */
  else if ((msg_type == DHCP_OFFER) && (dhcp->state == DHCP_SELECTING)) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_OFFER received in DHCP_SELECTING state\n"));
    dhcp->request_timeout = 0;
    /* remember offered lease */
    dhcp_handle_offer(netif);
  }
free_pbuf_and_return:
  dhcp->msg_in = NULL;
  pbuf_free(p);
}

/**
 * Create a DHCP request, fill in common headers
 *
 * @param netif the netif under DHCP control
 * @param dhcp dhcp control struct
 * @param message_type message type of the request
 */
static err_t
dhcp_create_msg(struct netif *netif, struct dhcp *dhcp, u8_t message_type)
{
  u16_t i;
#ifndef DHCP_GLOBAL_XID
  /** default global transaction identifier starting value (easy to match
   *  with a packet analyser). We simply increment for each new request.
   *  Predefine DHCP_GLOBAL_XID to a better value or a function call to generate one
   *  at runtime, any supporting function prototypes can be defined in DHCP_GLOBAL_XID_HEADER */
  static u32_t xid = 0xABCD0000;
#else
  static u32_t xid;
  static u8_t xid_initialised = 0;
  if (!xid_initialised) {
    xid = DHCP_GLOBAL_XID;
    xid_initialised = !xid_initialised;
  }
#endif
  LWIP_ERROR("dhcp_create_msg: netif != NULL", (netif != NULL), return ERR_ARG;);
  LWIP_ERROR("dhcp_create_msg: dhcp != NULL", (dhcp != NULL), return ERR_VAL;);
  LWIP_ASSERT("dhcp_create_msg: dhcp->p_out == NULL", dhcp->p_out == NULL);
  LWIP_ASSERT("dhcp_create_msg: dhcp->msg_out == NULL", dhcp->msg_out == NULL);
  dhcp->p_out = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcp_msg), PBUF_RAM);
  if (dhcp->p_out == NULL) {
    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
      ("dhcp_create_msg(): could not allocate pbuf\n"));
    return ERR_MEM;
  }
  LWIP_ASSERT("dhcp_create_msg: check that first pbuf can hold struct dhcp_msg",
           (dhcp->p_out->len >= sizeof(struct dhcp_msg)));

  /* reuse transaction identifier in retransmissions */
  if (dhcp->tries == 0) {
      xid++;
  }
  dhcp->xid = xid;
  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE,
              ("transaction id xid(%"X32_F")\n", xid));

  dhcp->msg_out = (struct dhcp_msg *)dhcp->p_out->payload;

  dhcp->msg_out->op = DHCP_BOOTREQUEST;
  /* TODO: make link layer independent */
  dhcp->msg_out->htype = DHCP_HTYPE_ETH;
  dhcp->msg_out->hlen = netif->hwaddr_len;
  dhcp->msg_out->hops = 0;
  dhcp->msg_out->xid = htonl(dhcp->xid);
  dhcp->msg_out->secs = 0;
  /* we don't need the broadcast flag since we can receive unicast traffic
     before being fully configured! */
  dhcp->msg_out->flags = 0;
  ip_addr_set_zero(&dhcp->msg_out->ciaddr);
  /* set ciaddr to netif->ip_addr based on message_type and state */
  if ((message_type == DHCP_INFORM) || (message_type == DHCP_DECLINE) ||
      ((message_type == DHCP_REQUEST) && /* DHCP_BOUND not used for sending! */
       ((dhcp->state==DHCP_RENEWING) || dhcp->state==DHCP_REBINDING))) {
    ip_addr_copy(dhcp->msg_out->ciaddr, netif->ip_addr);
  }
  ip_addr_set_zero(&dhcp->msg_out->yiaddr);
  ip_addr_set_zero(&dhcp->msg_out->siaddr);
  ip_addr_set_zero(&dhcp->msg_out->giaddr);
  for (i = 0; i < DHCP_CHADDR_LEN; i++) {
    /* copy netif hardware address, pad with zeroes */
    dhcp->msg_out->chaddr[i] = (i < netif->hwaddr_len) ? netif->hwaddr[i] : 0/* pad byte*/;
  }
  for (i = 0; i < DHCP_SNAME_LEN; i++) {
    dhcp->msg_out->sname[i] = 0;
  }
  for (i = 0; i < DHCP_FILE_LEN; i++) {
    dhcp->msg_out->file[i] = 0;
  }
  dhcp->msg_out->cookie = PP_HTONL(DHCP_MAGIC_COOKIE);
  dhcp->options_out_len = 0;
  /* fill options field with an incrementing array (for debugging purposes) */
  for (i = 0; i < DHCP_OPTIONS_LEN; i++) {
    dhcp->msg_out->options[i] = (u8_t)i; /* for debugging only, no matter if truncated */
  }
  /* Add option MESSAGE_TYPE */
  dhcp_option(dhcp, DHCP_OPTION_MESSAGE_TYPE, DHCP_OPTION_MESSAGE_TYPE_LEN);
  dhcp_option_byte(dhcp, message_type);
  return ERR_OK;
}

/**
 * Free previously allocated memory used to send a DHCP request.
 *
 * @param dhcp the dhcp struct to free the request from
 */
static void
dhcp_delete_msg(struct dhcp *dhcp)
{
  LWIP_ERROR("dhcp_delete_msg: dhcp != NULL", (dhcp != NULL), return;);
  LWIP_ASSERT("dhcp_delete_msg: dhcp->p_out != NULL", dhcp->p_out != NULL);
  LWIP_ASSERT("dhcp_delete_msg: dhcp->msg_out != NULL", dhcp->msg_out != NULL);
  if (dhcp->p_out != NULL) {
    pbuf_free(dhcp->p_out);
  }
  dhcp->p_out = NULL;
  dhcp->msg_out = NULL;
}

/**
 * Add a DHCP message trailer
 *
 * Adds the END option to the DHCP message, and if
 * necessary, up to three padding bytes.
 *
 * @param dhcp DHCP state structure
 */
static void
dhcp_option_trailer(struct dhcp *dhcp)
{
  LWIP_ERROR("dhcp_option_trailer: dhcp != NULL", (dhcp != NULL), return;);
  LWIP_ASSERT("dhcp_option_trailer: dhcp->msg_out != NULL\n", dhcp->msg_out != NULL);
  LWIP_ASSERT("dhcp_option_trailer: dhcp->options_out_len < DHCP_OPTIONS_LEN\n", dhcp->options_out_len < DHCP_OPTIONS_LEN);
  dhcp->msg_out->options[dhcp->options_out_len++] = DHCP_OPTION_END;
  /* packet is too small, or not 4 byte aligned? */
  while ((dhcp->options_out_len < DHCP_MIN_OPTIONS_LEN) || (dhcp->options_out_len & 3)) {
    /* LWIP_DEBUGF(DHCP_DEBUG,("dhcp_option_trailer:dhcp->options_out_len=%"U16_F", DHCP_OPTIONS_LEN=%"U16_F, dhcp->options_out_len, DHCP_OPTIONS_LEN)); */
    LWIP_ASSERT("dhcp_option_trailer: dhcp->options_out_len < DHCP_OPTIONS_LEN\n", dhcp->options_out_len < DHCP_OPTIONS_LEN);
    /* add a fill/padding byte */
    dhcp->msg_out->options[dhcp->options_out_len++] = 0;
  }
}

#endif /* LWIP_DHCP */