dhcp.c

来自「Keil下移植好的lwip基于c166」· C语言 代码 · 共 1,329 行 · 第 1/4 页

  /* did not get response to renew request? */
  else if (dhcp->state == DHCP_RENEWING) {
    DEBUGF(DHCP_DEBUG, ("dhcp_timeout(): RENEWING, DHCP request timed out"));
    /* just retry renewal */ 
    /* note that the rebind timer will eventually time-out if renew does not work */
    dhcp_renew(netif);
  /* did not get response to rebind request? */
  } else if (dhcp->state == DHCP_REBINDING) {
    DEBUGF(DHCP_DEBUG, ("dhcp_timeout(): REBINDING, DHCP request timed out"));
    if (dhcp->tries <= 8) {
      dhcp_rebind(netif);
    } else {
      DEBUGF(DHCP_DEBUG, ("dhcp_timeout(): RELEASING, DISCOVERING"));
      dhcp_release(netif);
      dhcp_discover(netif);
    }
  }
}

/**
 * The renewal period has timed out.
 *
 * @param dhcp pointer to DHCP state structure
 */
static void dhcp_t1_timeout(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  DEBUGF(DHCP_DEBUG, ("dhcp_t1_timeout()"));
  if ((dhcp->state == DHCP_REQUESTING) || (dhcp->state == DHCP_BOUND) || (dhcp->state == DHCP_RENEWING)) {
    /* just retry to renew */
    /* note that the rebind timer will eventually time-out if renew does not work */
    DEBUGF(DHCP_DEBUG, ("dhcp_t1_timeout(): must renew"));
    dhcp_renew(netif);
  }
}

/**
 * The rebind period has timed out.
 *
 */
static void dhcp_t2_timeout(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  DEBUGF(DHCP_DEBUG, ("dhcp_t2_timeout()"));
  if ((dhcp->state == DHCP_REQUESTING) || (dhcp->state == DHCP_BOUND) || (dhcp->state == DHCP_RENEWING)) {
    /* just retry to rebind */
    DEBUGF(DHCP_DEBUG, ("dhcp_t2_timeout(): must rebind"));
    dhcp_rebind(netif);
  }
}

/**
 * Extract options from the server ACK message.
 *
 * @param dhcp pointer to DHCP state structure
 */
static void dhcp_handle_ack(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  u8_t *option_ptr;
  /* clear options we might not get from the ACK */
  dhcp->offered_sn_mask.addr = 0;
  dhcp->offered_gw_addr.addr = 0;
  dhcp->offered_bc_addr.addr = 0;

  /* lease time given? */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_LEASE_TIME);
  if (option_ptr != NULL) {
    /* remember offered lease time */
    dhcp->offered_t0_lease = dhcp_get_option_long(option_ptr + 2);
  }
  /* renewal period given? */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_T1);
  if (option_ptr != NULL) {
    /* remember given renewal period */
    dhcp->offered_t1_renew = dhcp_get_option_long(option_ptr + 2);
  } else {
    /* calculate safe periods for renewal */
    dhcp->offered_t1_renew = dhcp->offered_t0_lease / 2;
  }

  /* renewal period given? */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_T2);
  if (option_ptr != NULL) {
    /* remember given rebind period */
    dhcp->offered_t2_rebind = dhcp_get_option_long(option_ptr + 2);
  } else {
    /* calculate safe periods for rebinding */
    dhcp->offered_t2_rebind = dhcp->offered_t0_lease;
  }

  /* (y)our internet address */
  ip_addr_set(&dhcp->offered_ip_addr, &dhcp->msg_in->yiaddr);

  /* subnet mask */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_SUBNET_MASK);
  /* subnet mask given? */
  if (option_ptr != NULL) {
    dhcp->offered_sn_mask.addr = htonl(dhcp_get_option_long(&option_ptr[2]));
  }

  /* gateway router */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_ROUTER);
  if (option_ptr != NULL) {
    dhcp->offered_gw_addr.addr = htonl(dhcp_get_option_long(&option_ptr[2]));
  }

  /* broadcast address */
  option_ptr = dhcp_get_option_ptr(dhcp, DHCP_OPTION_BROADCAST);
  if (option_ptr != NULL) {
    dhcp->offered_bc_addr.addr = htonl(dhcp_get_option_long(&option_ptr[2]));
  }
}

/**
 * Start DHCP negotiation for a network interface.
 *
 * If no DHCP client instance was attached to this interface,
 * a new client is created first. If a DHCP client instance
 * was already present, it restarts negotiation.
 *
 * @param netif The lwIP network interface 
 * @return The DHCP client state, which must be passed for 
 * all subsequential dhcp_*() calls. NULL means there is
 * no (longer a) DHCP client attached to the interface
 * (due to unavailable memory or network resources).
 *
 */
err_t dhcp_start(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  err_t result = ERR_OK;

  DEBUGF(DHCP_DEBUG, ("dhcp_start(netif=%c%c%u)", netif->name[0], netif->name[1], netif->num));

  if (dhcp == NULL) {
    DEBUGF(DHCP_DEBUG, ("dhcp_start(): starting new DHCP client"));
    dhcp = mem_malloc(sizeof(struct dhcp));
    if (dhcp == NULL) {
      DEBUGF(DHCP_DEBUG, ("dhcp_start(): could not allocate dhcp"));
      netif->flags &= ~NETIF_FLAG_DHCP;
      return ERR_MEM;
    }
    /* clear data structure */
    memset(dhcp, 0, sizeof(struct dhcp));
    DEBUGF(DHCP_DEBUG, ("dhcp_start(): allocated dhcp"));
    dhcp->pcb = udp_new();
    if (dhcp->pcb == NULL) {
      DEBUGF(DHCP_DEBUG, ("dhcp_start(): could not obtain pcb"));
      mem_free((void *)dhcp);
      dhcp = NULL;
      netif->flags &= ~NETIF_FLAG_DHCP;
      return ERR_MEM;
    }
    /* store this dhcp client in the netif */
    netif->dhcp = dhcp;
    DEBUGF(DHCP_DEBUG, ("dhcp_start(): created new udp pcb"));
    DEBUGF(DHCP_DEBUG, ("dhcp_start(): starting DHCP configuration"));
  } else {
    DEBUGF(DHCP_DEBUG, ("dhcp_start(): restarting DHCP configuration"));
  }
  /* (re)start the DHCP negotiation */
  result = dhcp_discover(netif);
  if (result != ERR_OK) {
    /* free resources allocated above */
    dhcp_stop(netif);
  }
  return result;
}

/**
 * Inform a DHCP server of our manual configuration.
 * 
 * This informs DHCP servers of our fixed IP address configuration
 * by sending an INFORM message. It does not involve DHCP address
 * configuration, it is just here to be nice to the network.
 *
 * @param netif The lwIP network interface 
 *
 */ 
void dhcp_inform(struct netif *netif)
{
  struct dhcp *dhcp;
  err_t result = ERR_OK;
  dhcp = mem_malloc(sizeof(struct dhcp));
  if (dhcp == NULL) {
    DEBUGF(DHCP_DEBUG, ("dhcp_inform(): could not allocate dhcp"));
    return;
  }  
  memset(dhcp, 0, sizeof(struct dhcp));

  DEBUGF(DHCP_DEBUG, ("dhcp_inform(): allocated dhcp"));
  dhcp->pcb = udp_new();
  if (dhcp->pcb == NULL) {
    DEBUGF(DHCP_DEBUG, ("dhcp_inform(): could not obtain pcb"));
    mem_free((void *)dhcp);
    return;
  }
  DEBUGF(DHCP_DEBUG, ("dhcp_inform(): created new udp pcb"));
  /* create and initialize the DHCP message header */
  result = dhcp_create_request(netif);
  if (result == ERR_OK) {

    dhcp_option(dhcp, DHCP_OPTION_MESSAGE_TYPE, DHCP_OPTION_MESSAGE_TYPE_LEN);
    dhcp_option_byte(dhcp, DHCP_INFORM);

    dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
    /* TODO: use netif->mtu ?! */
    dhcp_option_short(dhcp, 576);

    dhcp_option_trailer(dhcp);

    pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);

    udp_bind(dhcp->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
    udp_connect(dhcp->pcb, IP_ADDR_BROADCAST, DHCP_SERVER_PORT);
    udp_send(dhcp->pcb, dhcp->p_out);
    udp_connect(dhcp->pcb, IP_ADDR_ANY, DHCP_SERVER_PORT);
    dhcp_delete_request(netif);
  }

  if (dhcp != NULL)
  {
    if (dhcp->pcb != NULL) udp_remove(dhcp->pcb);
    dhcp->pcb = NULL;
    mem_free((void *)dhcp);
  }
}

#if DHCP_DOES_ARP_CHECK
/**
 * Match an ARP reply with the offered IP address.
 *
 * @param addr The IP address we received a reply from
 *
 */
void dhcp_arp_reply(struct netif *netif, struct ip_addr *addr)
{
  DEBUGF(DHCP_DEBUG, ("dhcp_arp_reply()"));
  /* is this DHCP client doing an ARP check? */
  if ((netif->dhcp != NULL) && (netif->dhcp->state == DHCP_CHECKING)) {
    DEBUGF(DHCP_DEBUG, ("dhcp_arp_reply(): CHECKING, arp reply for 0x%08lx", addr->addr));
    /* did a host respond with the address we
       were offered by the DHCP server? */
    if (ip_addr_cmp(addr, &netif->dhcp->offered_ip_addr)) {
      /* we will not accept the offered address */
      DEBUGF(DHCP_DEBUG, ("dhcp_arp_reply(): arp reply matched with offered address, declining"));
      dhcp_decline(netif);
    }
  }
}

/** 
 * Decline an offered lease.
 *
 * Tell the DHCP server we do not accept the offered address.
 * One reason to decline the lease is when we find out the address
 * is already in use by another host (through ARP).
 */
static err_t dhcp_decline(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  err_t result = ERR_OK;
  u16_t msecs;
  DEBUGF(DHCP_DEBUG, ("dhcp_decline()"));
  dhcp_set_state(dhcp, DHCP_BACKING_OFF);
  /* create and initialize the DHCP message header */
  result = dhcp_create_request(netif);
  if (result == ERR_OK)
  {
    dhcp_option(dhcp, DHCP_OPTION_MESSAGE_TYPE, DHCP_OPTION_MESSAGE_TYPE_LEN);
    dhcp_option_byte(dhcp, DHCP_DECLINE);

    dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
    dhcp_option_short(dhcp, 576);

    dhcp_option_trailer(dhcp);
    /* resize pbuf to reflect true size of options */
    pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);

    udp_bind(dhcp->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
    udp_connect(dhcp->pcb, &dhcp->server_ip_addr, DHCP_SERVER_PORT);
    udp_send(dhcp->pcb, dhcp->p_out);
    dhcp_delete_request(netif);
  }
  dhcp->tries++;
  msecs = 10*1000;
  dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
   DEBUGF(DHCP_DEBUG, ("dhcp_decline(): set request timeout %u msecs", msecs));
  return result;
}
#endif


/**
 * Start the DHCP process, discover a DHCP server.
 *
 */
static err_t dhcp_discover(struct netif *netif)
{
  struct dhcp *dhcp = netif->dhcp;
  err_t result = ERR_OK;
  u16_t msecs;
  DEBUGF(DHCP_DEBUG, ("dhcp_discover()"));
  ip_addr_set(&dhcp->offered_ip_addr, IP_ADDR_ANY);
  /* create and initialize the DHCP message header */
  result = dhcp_create_request(netif);
  if (result == ERR_OK)
  {
    dhcp_option(dhcp, DHCP_OPTION_MESSAGE_TYPE, DHCP_OPTION_MESSAGE_TYPE_LEN);
    dhcp_option_byte(dhcp, DHCP_DISCOVER);

    dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
    dhcp_option_short(dhcp, 576);

    dhcp_option(dhcp, DHCP_OPTION_PARAMETER_REQUEST_LIST, 3);
    dhcp_option_byte(dhcp, DHCP_OPTION_SUBNET_MASK);
    dhcp_option_byte(dhcp, DHCP_OPTION_ROUTER);
    dhcp_option_byte(dhcp, DHCP_OPTION_BROADCAST);

    dhcp_option_trailer(dhcp);

    pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);

    /* set receive callback function with netif as user data */
    udp_recv(dhcp->pcb, dhcp_recv, netif);
    udp_bind(dhcp->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
    udp_connect(dhcp->pcb, IP_ADDR_BROADCAST, DHCP_SERVER_PORT);

    udp_send(dhcp->pcb, dhcp->p_out);
    udp_bind(dhcp->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
    udp_connect(dhcp->pcb, IP_ADDR_ANY, DHCP_SERVER_PORT);
    dhcp_delete_request(netif);