text: /**
   * @file
   *
   * lwIP network interface abstraction
   */
  
  /*
   * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  
  #include "lwip/opt.h"
  
  #include "lwip/def.h"
  #include "lwip/ip_addr.h"
  #include "lwip/netif.h"
  #include "lwip/tcp.h"
  
  struct netif *netif_list = NULL;
  struct netif *netif_default = NULL;
  
  /**
   * Add a network interface to the list of lwIP netifs.
   *
   * @param netif a pre-allocated netif structure
   * @param ipaddr IP address for the new netif
   * @param netmask network mask for the new netif
   * @param gw default gateway IP address for the new netif
   * @param state opaque data passed to the new netif
   * @param init callback function that initializes the interface
   * @param input callback function that is called to pass
   * ingress packets up in the protocol layer stack.
   *
   * @return netif, or NULL if failed.
   */
  struct netif *
  netif_add(struct netif *netif, struct ip_addr *ipaddr, struct ip_addr *netmask,
    struct ip_addr *gw,
    void *state,
    err_t (* init)(struct netif *netif),
    err_t (* input)(struct pbuf *p, struct netif *netif))
  {
    static s16_t netifnum = 0;
    
  #if LWIP_DHCP
    /* netif not under DHCP control by default */
    netif->dhcp = NULL;
  #endif
    /* remember netif specific state information data */
    netif->state = state;
    netif->num = netifnum++;
    netif->input = input;
  
    netif_set_addr(netif, ipaddr, netmask, gw);
  
    /* call user specified initialization function for netif */
    if (init(netif) != ERR_OK) {
      return NULL;
    }
  
    /* add this netif to the list */
    netif->next = netif_list;
    netif_list = netif;
    LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP addr ",
      netif->name[0], netif->name[1]));
    ip_addr_debug_print(NETIF_DEBUG, ipaddr);
    LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
    ip_addr_debug_print(NETIF_DEBUG, netmask);
    LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
    ip_addr_debug_print(NETIF_DEBUG, gw);
    LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
    return netif;
  }
  
  void
  netif_set_addr(struct netif *netif,struct ip_addr *ipaddr, struct ip_addr *netmask,
      struct ip_addr *gw)
  {
    netif_set_ipaddr(netif, ipaddr);
    netif_set_netmask(netif, netmask);
    netif_set_gw(netif, gw);
  }
  
  void netif_remove(struct netif * netif)
  {
    if ( netif == NULL ) return;
  
    /*  is it the first netif? */
    if (netif_list == netif) {
      netif_list = netif->next;
    }
    else {
      /*  look for netif further down the list */
      struct netif * tmpNetif;
      for (tmpNetif = netif_list; tmpNetif != NULL; tmpNetif = tmpNetif->next) {
        if (tmpNetif->next == netif) {
          tmpNetif->next = netif->next;
          break;
          }
      }
      if (tmpNetif == NULL)
        return; /*  we didn't find any netif today */
    }
    /* this netif is default? */
    if (netif_default == netif)
      /* reset default netif */
      netif_default = NULL;
    LWIP_DEBUGF( NETIF_DEBUG, ("netif_remove: removed netif\n") );
  }
  
  struct netif *
  netif_find(char *name)
  {
    struct netif *netif;
    u8_t num;
  
    if (name == NULL) {
      return NULL;
    }
  
    num = name[2] - '0';
  
    for(netif = netif_list; netif != NULL; netif = netif->next) {
      if (num == netif->num &&
         name[0] == netif->name[0] &&
         name[1] == netif->name[1]) {
        LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: found %c%c\n", name[0], name[1]));
        return netif;
      }
    }
    LWIP_DEBUGF(NETIF_DEBUG, ("netif_find: didn't find %c%c\n", name[0], name[1]));
    return NULL;
  }
  
  void
  netif_set_ipaddr(struct netif *netif, struct ip_addr *ipaddr)
  {
    /* TODO: Handling of obsolete pcbs */
    /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
  #if LWIP_TCP
    struct tcp_pcb *pcb;
    struct tcp_pcb_listen *lpcb;
  
    /* address is actually being changed? */
    if ((ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0)
    {
      /* extern struct tcp_pcb *tcp_active_pcbs; defined by tcp.h */
      LWIP_DEBUGF(NETIF_DEBUG | 1, ("netif_set_ipaddr: netif address being changed\n"));
      pcb = tcp_active_pcbs;
      while (pcb != NULL) {
        /* PCB bound to current local interface address? */
        if (ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
          /* this connection must be aborted */
          struct tcp_pcb *next = pcb->next;
          LWIP_DEBUGF(NETIF_DEBUG | 1, ("netif_set_ipaddr: aborting TCP pcb %p\n", (void *)pcb));
          tcp_abort(pcb);
          pcb = next;
        } else {
          pcb = pcb->next;
        }
      }
      for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
        /* PCB bound to current local interface address? */
        if (ip_addr_cmp(&(lpcb->local_ip), &(netif->ip_addr))) {
          /* The PCB is listening to the old ipaddr and
           * is set to listen to the new one instead */
          ip_addr_set(&(lpcb->local_ip), ipaddr);
        }
      }
    }
  #endif
    ip_addr_set(&(netif->ip_addr), ipaddr);
  #if 0 /* only allowed for Ethernet interfaces TODO: how can we check? */
    /** For Ethernet network interfaces, we would like to send a
     *  "gratuitous ARP"; this is an ARP packet sent by a node in order
     *  to spontaneously cause other nodes to update an entry in their
     *  ARP cache. From RFC 3220 "IP Mobility Support for IPv4" section 4.6.
     */ 
    etharp_query(netif, ipaddr, NULL);
  #endif
    LWIP_DEBUGF(NETIF_DEBUG | DBG_TRACE | DBG_STATE | 3, ("netif: IP address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      netif->name[0], netif->name[1],
      ip4_addr1(&netif->ip_addr),
      ip4_addr2(&netif->ip_addr),
      ip4_addr3(&netif->ip_addr),
      ip4_addr4(&netif->ip_addr)));
  }
  
  void
  netif_set_gw(struct netif *netif, struct ip_addr *gw)
  {
    ip_addr_set(&(netif->gw), gw);
    LWIP_DEBUGF(NETIF_DEBUG | DBG_TRACE | DBG_STATE | 3, ("netif: GW address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      netif->name[0], netif->name[1],
      ip4_addr1(&netif->gw),
      ip4_addr2(&netif->gw),
      ip4_addr3(&netif->gw),
      ip4_addr4(&netif->gw)));
  }
  
  void
  netif_set_netmask(struct netif *netif, struct ip_addr *netmask)
  {
    ip_addr_set(&(netif->netmask), netmask);
    LWIP_DEBUGF(NETIF_DEBUG | DBG_TRACE | DBG_STATE | 3, ("netif: netmask of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      netif->name[0], netif->name[1],
      ip4_addr1(&netif->netmask),
      ip4_addr2(&netif->netmask),
      ip4_addr3(&netif->netmask),
      ip4_addr4(&netif->netmask)));
  }
  
  void
  netif_set_default(struct netif *netif)
  {
    netif_default = netif;
    LWIP_DEBUGF(NETIF_DEBUG, ("netif: setting default interface %c%c\n",
             netif ? netif->name[0] : '\'', netif ? netif->name[1] : '\''));
  }
  
  /**
   * Bring an interface up, available for processing
   * traffic.
   * 
   * @note: Enabling DHCP on a down interface will make it come
   * up once configured.
   * 
   * @see dhcp_start()
   */ 
  void netif_set_up(struct netif *netif)
  {
    netif->flags |= NETIF_FLAG_UP;
  }
  
  /**
   * Ask if an interface is up
   */ 
  u8_t netif_is_up(struct netif *netif)
  {
    return (netif->flags & NETIF_FLAG_UP)?1:0;
  }
  
  /**
   * Bring an interface down, disabling any traffic processing.
   *
   * @note: Enabling DHCP on a down interface will make it come
   * up once configured.
   * 
   * @see dhcp_start()
   */ 
  void netif_set_down(struct netif *netif)
  {
    netif->flags &= ~NETIF_FLAG_UP;
  }
  
  void
  netif_init(void)
  {
    netif_list = netif_default = NULL;
  }
  
  