ethernetif.c

lwip 是一个嵌入式TCP/IP协议

/*
 * Copyright (c) 2001-2003 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 <[e-mail]>
 *
 */

/*
 * This file is a skeleton for developing Ethernet network interface
 * drivers for lwIP. Add code to the low_level functions and do a
 * search-and-replace for the word "ethernetif" to replace it with
 * something that better describes your network interface.
 *
 * THIS CODE NEEDS TO BE FIXED - IT IS NOT In SYNC WITH CURRENT ETHARP API
 */

#include "lwip/opt.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/pbuf.h"
#include "lwip/sys.h"

#include "netif/arp.h"

/* Define those to better describe your network interface. */
#define IFNAME0 'e'
#define IFNAME1 't'

struct ethernetif {
  struct eth_addr *ethaddr;
  /* Add whatever per-interface state that is needed here. */
};

static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};

/* Forward declarations. */
static void  ethernetif_input(struct netif *netif);
static err_t ethernetif_output(struct netif *netif, struct pbuf *p,
             struct ip_addr *ipaddr);


static void
low_level_init(struct netif *netif)
{
  struct ethernetif *ethernetif;

  ethernetif = netif->state;
  
  /* set MAC hardware address length */
  netif->hwaddr_len = 6;

  /* set MAC hardware address */
  netif->hwaddr[0] = ;
  ...
  netif->hwaddr[6] = ;

  /* maximum transfer unit */
  netif->mtu = 1500;
  
  /* broadcast capability */
  netif->flags = NETIF_FLAG_BROADCAST;
 
  /* Do whatever else is needed to initialize interface. */  
}

/*
 * low_level_output():
 *
 * Should do the actual transmission of the packet. The packet is
 * contained in the pbuf that is passed to the function. This pbuf
 * might be chained.
 *
 */


static err_t
low_level_output(struct ethernetif *ethernetif, struct pbuf *p)
{
  struct pbuf *q;

  initiate transfer();
  
  for(q = p; q != NULL; q = q->next) {
    /* Send the data from the pbuf to the interface, one pbuf at a
       time. The size of the data in each pbuf is kept in the ->len
       variable. */
    send data from(q->payload, q->len);
  }

  signal that packet should be sent();
  
#ifdef LINK_STATS
  lwip_stats.link.xmit++;
#endif /* LINK_STATS */      

  return ERR_OK;
}

/*
 * low_level_input():
 *
 * Should allocate a pbuf and transfer the bytes of the incoming
 * packet from the interface into the pbuf.
 *
 */

static struct pbuf *
low_level_input(struct ethernetif *ethernetif)
{
  struct pbuf *p, *q;
  u16_t len;

  /* Obtain the size of the packet and put it into the "len"
     variable. */
  len = ;

  /* We allocate a pbuf chain of pbufs from the pool. */
  p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
  
  if (p != NULL) {
    /* We iterate over the pbuf chain until we have read the entire
       packet into the pbuf. */
    for(q = p; q != NULL; q = q->next) {
      /* Read enough bytes to fill this pbuf in the chain. The
         available data in the pbuf is given by the q->len
         variable. */
      read data into(q->payload, q->len);
    }
    acknowledge that packet has been read();
#ifdef LINK_STATS
    lwip_stats.link.recv++;
#endif /* LINK_STATS */      
  } else {
    drop packet();
#ifdef LINK_STATS
    lwip_stats.link.memerr++;
    lwip_stats.link.drop++;
#endif /* LINK_STATS */      
  }

  return p;  
}

/*
 * ethernetif_output():
 *
 * This function is called by the TCP/IP stack when an IP packet
 * should be sent. It calls the function called low_level_output() to
 * do the actuall transmission of the packet.
 *
 */

static err_t
ethernetif_output(struct netif *netif, struct pbuf *p,
      struct ip_addr *ipaddr)
{
  struct ethernetif *ethernetif;
  struct pbuf *q;
  struct eth_hdr *ethhdr;
  struct eth_addr *dest, mcastaddr;
  struct ip_addr *queryaddr;
  err_t err;
  u8_t i;
  
  ethernetif = netif->state;

  /* Make room for Ethernet header. */
  if (pbuf_header(p, 14) != 0) {
    /* The pbuf_header() call shouldn't fail, but we allocate an extra
       pbuf just in case. */
    q = pbuf_alloc(PBUF_LINK, 14, PBUF_RAM);
    if (q == NULL) {
#ifdef LINK_STATS
      lwip_stats.link.drop++;
      lwip_stats.link.memerr++;
#endif /* LINK_STATS */      
      return ERR_MEM;
    }
    pbuf_chain(q, p);
    p = q;
  }

  /* Construct Ethernet header. Start with looking up deciding which
     MAC address to use as a destination address. Broadcasts and
     multicasts are special, all other addresses are looked up in the
     ARP table. */
  queryaddr = ipaddr;
  if (ip_addr_isany(ipaddr) ||
     ip_addr_isbroadcast(ipaddr, &(netif->netmask))) {
    dest = (struct eth_addr *)&ethbroadcast;
  } else if (ip_addr_ismulticast(ipaddr)) {
    /* Hash IP multicast address to MAC address. */
    mcastaddr.addr[0] = 0x01;
    mcastaddr.addr[1] = 0x0;
    mcastaddr.addr[2] = 0x5e;
    mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
    mcastaddr.addr[4] = ip4_addr3(ipaddr);
    mcastaddr.addr[5] = ip4_addr4(ipaddr);
    dest = &mcastaddr;
  } else {

    if (ip_addr_maskcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
      /* Use destination IP address if the destination is on the same
         subnet as we are. */
      queryaddr = ipaddr;
    } else {
      /* Otherwise we use the default router as the address to send
         the Ethernet frame to. */
      queryaddr = &(netif->gw);
    }
    dest = arp_lookup(queryaddr);
  }


  /* If the arp_lookup() didn't find an address, we send out an ARP
     query for the IP address. */
  if (dest == NULL) {
    q = arp_query(netif, ethernetif->ethaddr, queryaddr);
    if (q != NULL) {
      err = low_level_output(ethernetif, q);
      pbuf_free(q);
      return err;
    }
#ifdef LINK_STATS
    lwip_stats.link.drop++;
    lwip_stats.link.memerr++;
#endif /* LINK_STATS */          
    return ERR_MEM;
  }
  ethhdr = p->payload;

  for(i = 0; i < 6; i++) {
    ethhdr->dest.addr[i] = dest->addr[i];
    ethhdr->src.addr[i] = ethernetif->ethaddr->addr[i];
  }
  
  ethhdr->type = htons(ETHTYPE_IP);
  
  return low_level_output(ethernetif, p);

}

/*
 * ethernetif_input():
 *
 * This function should be called when a packet is ready to be read
 * from the interface. It uses the function low_level_input() that
 * should handle the actual reception of bytes from the network
 * interface.
 *
 */

static void
ethernetif_input(struct netif *netif)
{
  struct ethernetif *ethernetif;
  struct eth_hdr *ethhdr;
  struct pbuf *p;


  ethernetif = netif->state;
  
  p = low_level_input(ethernetif);

  if (p != NULL) {

#ifdef LINK_STATS
    lwip_stats.link.recv++;
#endif /* LINK_STATS */

    ethhdr = p->payload;
    
    switch (htons(ethhdr->type)) {
    case ETHTYPE_IP:
      arp_ip_input(netif, p);
      pbuf_header(p, -14);
      netif->input(p, netif);
      break;
    case ETHTYPE_ARP:
      p = arp_arp_input(netif, ethernetif->ethaddr, p);
      if (p != NULL) {
  low_level_output(ethernetif, p);
  pbuf_free(p);
      }
      break;
    default:
      pbuf_free(p);
      break;
    }
  }
}

static void
arp_timer(void *arg)
{
  arp_tmr();
  sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
}

/*
 * ethernetif_init():
 *
 * Should be called at the beginning of the program to set up the
 * network interface. It calls the function low_level_init() to do the
 * actual setup of the hardware.
 *
 */

void
ethernetif_init(struct netif *netif)
{
  struct ethernetif *ethernetif;
    
  ethernetif = mem_malloc(sizeof(struct ethernetif));
  netif->state = ethernetif;
  netif->name[0] = IFNAME0;
  netif->name[1] = IFNAME1;
  netif->output = ethernetif_output;
  netif->linkoutput = low_level_output;
  
  ethernetif->ethaddr = (struct eth_addr *)&(netif->hwaddr[0]);
  
  low_level_init(netif);
  arp_init();

  sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
}