rtfifoif.c

rtlinux-3.2源码

  char buf[1500];
  char *bufptr;
  unsigned char size_of_packet[4];
  int packet_size;

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

  rtf_get(rtfifoif->readfd, &size_of_packet, 4);
  
  packet_size = size_of_packet[0] + size_of_packet[1] + size_of_packet[2] + size_of_packet[3];

  /* Wait for a packet to arrive. */
  while(rtf_isempty(rtfifoif->readfd)){
    usleep(10);
  }

  len = rtf_get(rtfifoif->readfd, buf,(int) packet_size);


  /* We allocate a pbuf chain of pbufs from the pool. */
  p = pbuf_alloc(PBUF_LINK, len, PBUF_POOL);
  
  if(p != NULL) {
    /* We iterate over the pbuf chain until we have read the entire
       packet into the pbuf. */
    bufptr = &buf[0];
    for(q = p; q != NULL; q = q->next) {
      /* Read enough bytes to fill this pbuf in the chain. The
         avaliable data in the pbuf is given by the q->len
         variable. */
      /* read data into(q->payload, q->len); */
      bcopy(bufptr, q->payload, q->len);
      bufptr += q->len;
    }
    /* acknowledge that packet has been read(); */
  } else {
    rtl_printf("rtfifoif: Can't allocate memory for pbuf\n");
  }

  return p;  
}

/*-----------------------------------------------------------------------------------*/
/*
 * fifoif_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
rtfifoif_output(struct netif *netif, struct pbuf *p,
		  struct ip_addr *ipaddr)
{
  struct rtfifoif *rtfifoif;
  struct pbuf *q;
  struct eth_hdr *ethhdr;
  struct eth_addr *dest, mcastaddr;
  struct ip_addr *queryaddr;
  err_t err;
  u8_t i;
  
  rtfifoif = netif->state;

  /* Make room for Ethernet header. */
  if(pbuf_header(p, sizeof(struct eth_hdr)) != 0) {
    /* The pbuf_header() call shouldn't fail, but we allocate an extra
       pbuf just in case. */
    q = pbuf_alloc(PBUF_LINK, sizeof(struct eth_hdr), PBUF_RAM);
    if(q == NULL) {
      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, rtfifoif->ethaddr, queryaddr);
    if(q != NULL) {
      err = low_level_output(rtfifoif, q);
      pbuf_free(q);
      return err;
    }
    return ERR_MEM;
  }
  ethhdr = p->payload;
  
  for(i = 0; i < 6; i++) {
    ethhdr->dest.addr[i] = dest->addr[i];
    ethhdr->src.addr[i] = rtfifoif->ethaddr->addr[i];
  }
  
  ethhdr->type = htons(ETHTYPE_IP);
  
  return low_level_output(rtfifoif, p);

}
/*-----------------------------------------------------------------------------------*/
/*
 * rtfifoif_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
rtfifoif_input(struct netif *netif)
{
  struct rtfifoif *rtfifoif;
  struct eth_hdr *ethhdr;
  struct pbuf *p;


  rtfifoif = netif->state;
  
  p = low_level_input(rtfifoif);
  
  if(p == NULL) {
    return;
  }
  ethhdr = p->payload;

  switch(htons(ethhdr->type)) {
  case ETHTYPE_IP:
    arp_ip_input(netif, p);
    pbuf_header(p, -14);
    if(ip_lookup(p->payload, netif)) {
      netif->input(p, netif);
    }
    break;
  case ETHTYPE_ARP:

    p = arp_arp_input(netif, rtfifoif->ethaddr, p);
    if(p != NULL) {
      low_level_output(rtfifoif, p);
      pbuf_free(p);
    }
    break;
  default:
    pbuf_free(p);
    break;
  }
}
/*-----------------------------------------------------------------------------------*/
static void
arp_timer(void *arg)
{
  arp_tmr();
  sys_timeout(ARP_TMR_INTERVAL, (sys_timeout_handler)arp_timer, NULL);
}
/*-----------------------------------------------------------------------------------*/
/*
 * rtfifoif_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
rtfifoif_init(struct netif *netif)
{
  struct rtfifoif *rtfifoif;
    
  rtfifoif = mem_malloc(sizeof(struct rtfifoif));
  netif->state = rtfifoif;
  netif->name[0] = IFNAME0;
  netif->name[1] = IFNAME1;
  netif->output = rtfifoif_output;
  netif->linkoutput = low_level_output;
  
  rtfifoif->ethaddr = (struct eth_addr *)&(netif->hwaddr[0]);
  
  low_level_init(netif);
  arp_init();
  
  _timeout(ARP_TMR_INTERVAL, (sys_timeout_handler)arp_timer, NULL);
}
/*-----------------------------------------------------------------------------------*/
#endif //__RTFIFOOPTS__