ip.c

嵌入式TCpip协议栈 开源代码

	     avaliable data in the pbuf is given by the q->len
	     variable. */
	  DEBUGF(IP_REASS_DEBUG, ("ip_reass: bcopy from %p (%d) to %p, %d bytes\n",
				  &ip_reassbuf[i], i, q->payload, q->len > ip_reasslen - i? ip_reasslen - i: q->len));
	  bcopy(&ip_reassbuf[i], q->payload,
		q->len > ip_reasslen - i? ip_reasslen - i: q->len);
	  i += q->len;
	}
      }
      DEBUGF(IP_REASS_DEBUG, ("ip_reass: p %p\n", p));
      return p;
    }
  }

 nullreturn:
  pbuf_free(p);
  return NULL;
}
#endif /* IP_REASSEMBLY */
/*-----------------------------------------------------------------------------------*/
/* ip_input:
 *
 * This function is called by the network interface device driver when
 * an IP packet is received. The function does the basic checks of the
 * IP header such as packet size being at least larger than the header
 * size etc. If the packet was not destined for us, the packet is
 * forwarded (using ip_forward). The IP checksum is always checked.
 *
 * Finally, the packet is sent to the upper layer protocol input function.
 */
/*-----------------------------------------------------------------------------------*/
err_t
ip_input(struct pbuf *p, struct netif *inp) {
  static struct ip_hdr *iphdr;
  static struct netif *netif;
  static u8_t hl;

  
  
#ifdef IP_STATS
  ++stats.ip.recv;
#endif /* IP_STATS */

  /* identify the IP header */
  iphdr = p->payload;
  if(IPH_V(iphdr) != 4) {
    DEBUGF(IP_DEBUG, ("IP packet dropped due to bad version number %d\n", IPH_V(iphdr)));
#if IP_DEBUG
    ip_debug_print(p);
#endif /* IP_DEBUG */
    pbuf_free(p);
#ifdef IP_STATS
    ++stats.ip.err;
    ++stats.ip.drop;
#endif /* IP_STATS */
    return ERR_OK;
  }
  
  hl = IPH_HL(iphdr);
  
  if(hl * 4 > p->len) {
    DEBUGF(IP_DEBUG, ("IP packet dropped due to too short packet %d\n", p->len));

    pbuf_free(p);
#ifdef IP_STATS
    ++stats.ip.lenerr;
    ++stats.ip.drop;
#endif /* IP_STATS */
    return ERR_OK;
  }

  /* verify checksum */
  if(inet_chksum(iphdr, hl * 4) != 0) {

    DEBUGF(IP_DEBUG, ("IP packet dropped due to failing checksum 0x%x\n", inet_chksum(iphdr, hl * 4)));
#if IP_DEBUG
    ip_debug_print(p);
#endif /* IP_DEBUG */
    pbuf_free(p);
#ifdef IP_STATS
    ++stats.ip.chkerr;
    ++stats.ip.drop;
#endif /* IP_STATS */
    return ERR_OK;
  }
  
  /* Trim pbuf. This should have been done at the netif layer,
     but we'll do it anyway just to be sure that its done. */
  pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));

  /* is this packet for us? */
  for(netif = netif_list; netif != NULL; netif = netif->next) {

    DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%lx netif->ip_addr 0x%lx (0x%lx, 0x%lx, 0x%lx)\n",
		      iphdr->dest.addr, netif->ip_addr.addr,
		      iphdr->dest.addr & netif->netmask.addr,
		      netif->ip_addr.addr & netif->netmask.addr,
		      iphdr->dest.addr & ~(netif->netmask.addr)));

    if(ip_addr_isany(&(netif->ip_addr)) ||
       ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
       (ip_addr_isbroadcast(&(iphdr->dest), &(netif->netmask)) &&
	ip_addr_maskcmp(&(iphdr->dest), &(netif->ip_addr), &(netif->netmask))) ||
       ip_addr_cmp(&(iphdr->dest), IP_ADDR_BROADCAST)) {
      break;
    }
  }

#if LWIP_DHCP
  /* If a DHCP packet has arrived on the interface, we pass it up the
     stack regardless of destination IP address. The reason is that
     DHCP replies are sent to the IP adress that will be given to this
     node (as recommended by RFC 1542 section 3.1.1, referred by RFC
     2131). */
  if(IPH_PROTO(iphdr) == IP_PROTO_UDP &&
     ((struct udp_hdr *)((u8_t *)iphdr + IPH_HL(iphdr) * 4/sizeof(u8_t)))->src ==
     DHCP_SERVER_PORT) {
    netif = inp;
  }  
#endif /* LWIP_DHCP */
	  
  if(netif == NULL) {
    /* packet not for us, route or discard */
    DEBUGF(IP_DEBUG, ("ip_input: packet not for us.\n"));
#if IP_FORWARD
    if(!ip_addr_isbroadcast(&(iphdr->dest), &(inp->netmask))) {
      ip_forward(p, iphdr, inp);
    }
#endif /* IP_FORWARD */
    pbuf_free(p);
    return ERR_OK;
  }

#if IP_REASSEMBLY
  if((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
    p = ip_reass(p);
    if(p == NULL) {
      return ERR_OK;
    }
    iphdr = p->payload;
  }
#else /* IP_REASSEMBLY */
  if((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
    pbuf_free(p);
    DEBUGF(IP_DEBUG, ("IP packet dropped since it was fragmented (0x%x).\n",
		      ntohs(IPH_OFFSET(iphdr))));
#ifdef IP_STATS
    ++stats.ip.opterr;
    ++stats.ip.drop;
#endif /* IP_STATS */
    return ERR_OK;
  }
#endif /* IP_REASSEMBLY */
  
#if IP_OPTIONS == 0
  if(hl * 4 > IP_HLEN) {
    DEBUGF(IP_DEBUG, ("IP packet dropped since there were IP options.\n"));

    pbuf_free(p);    
#ifdef IP_STATS
    ++stats.ip.opterr;
    ++stats.ip.drop;
#endif /* IP_STATS */
    return ERR_OK;
  }  
#endif /* IP_OPTIONS == 0 */


  /* send to upper layers */
#if IP_DEBUG
  DEBUGF(IP_DEBUG, ("ip_input: \n"));
  ip_debug_print(p);
  DEBUGF(IP_DEBUG, ("ip_input: p->len %d p->tot_len %d\n", p->len, p->tot_len));
#endif /* IP_DEBUG */   

  switch(IPH_PROTO(iphdr)) {
#if LWIP_UDP > 0    
  case IP_PROTO_UDP:
    udp_input(p, inp);
    break;
#endif /* LWIP_UDP */
#if LWIP_TCP > 0    
  case IP_PROTO_TCP:
    tcp_input(p, inp);
    break;
#endif /* LWIP_TCP */
  case IP_PROTO_ICMP:
    icmp_input(p, inp);
    break;
  default:
    /* send ICMP destination protocol unreachable unless is was a broadcast */
    if(!ip_addr_isbroadcast(&(iphdr->dest), &(inp->netmask)) &&
       !ip_addr_ismulticast(&(iphdr->dest))) {
      p->payload = iphdr;
      icmp_dest_unreach(p, ICMP_DUR_PROTO);
    }
    pbuf_free(p);

    DEBUGF(IP_DEBUG, ("Unsupported transportation protocol %d\n", IPH_PROTO(iphdr)));

#ifdef IP_STATS
    ++stats.ip.proterr;
    ++stats.ip.drop;
#endif /* IP_STATS */

  }
  return ERR_OK;
}

/*-----------------------------------------------------------------------------------*/
/* ip_output_if:
 *
 * Sends an IP packet on a network interface. This function constructs
 * the IP header and calculates the IP header checksum. If the source
 * IP address is NULL, the IP address of the outgoing network
 * interface is filled in as source address.
 */
/*-----------------------------------------------------------------------------------*/
err_t
ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
	     u8_t ttl,
	     u8_t proto, struct netif *netif)
{
  static struct ip_hdr *iphdr;
  static u16_t ip_id = 0;

  
  
  if(dest != IP_HDRINCL) {
    if(pbuf_header(p, IP_HLEN)) {
      DEBUGF(IP_DEBUG, ("ip_output: not enough room for IP header in pbuf\n"));
      
#ifdef IP_STATS
      ++stats.ip.err;
#endif /* IP_STATS */
      pbuf_free(p);
      return ERR_BUF;
    }
    
    iphdr = p->payload;
    
    IPH_TTL_SET(iphdr, ttl);
    IPH_PROTO_SET(iphdr, proto);
    
    ip_addr_set(&(iphdr->dest), dest);

    IPH_VHLTOS_SET(iphdr, 4, IP_HLEN / 4, 0);
    IPH_LEN_SET(iphdr, htons(p->tot_len));
    IPH_OFFSET_SET(iphdr, htons(IP_DF));
    IPH_ID_SET(iphdr, htons(++ip_id));

    if(ip_addr_isany(src)) {
      ip_addr_set(&(iphdr->src), &(netif->ip_addr));
    } else {
      ip_addr_set(&(iphdr->src), src);
    }

    IPH_CHKSUM_SET(iphdr, 0);
    IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
  } else {
    iphdr = p->payload;
    dest = &(iphdr->dest);
  }

#ifdef IP_STATS
  stats.ip.xmit++;
#endif /* IP_STATS */
  DEBUGF(IP_DEBUG, ("ip_output_if: %c%c ", netif->name[0], netif->name[1]));
#if IP_DEBUG
  ip_debug_print(p);
#endif /* IP_DEBUG */


  return netif->output(netif, p, dest);  
}
/*-----------------------------------------------------------------------------------*/
/* ip_output:
 *
 * Simple interface to ip_output_if. It finds the outgoing network
 * interface and calls upon ip_output_if to do the actual work.
 */
/*-----------------------------------------------------------------------------------*/
err_t
ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
	  u8_t ttl, u8_t proto)
{
  static struct netif *netif;

  
  if((netif = ip_route(dest)) == NULL) {
    DEBUGF(IP_DEBUG, ("ip_output: No route to 0x%lx\n", dest->addr));

#ifdef IP_STATS
    ++stats.ip.rterr;
#endif /* IP_STATS */
    pbuf_free(p);
    return ERR_RTE;
  }

  return ip_output_if(p, src, dest, ttl, proto, netif);
}
/*-----------------------------------------------------------------------------------*/
#if IP_DEBUG
void
ip_debug_print(struct pbuf *p)
{
  struct ip_hdr *iphdr = p->payload;
  u8_t *payload;

  payload = (u8_t *)iphdr + IP_HLEN/sizeof(u8_t);
  
  DEBUGF(IP_DEBUG, ("IP header:\n"));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  DEBUGF(IP_DEBUG, ("|%2d |%2d |   %2d  |      %4d     | (v, hl, tos, len)\n",
		    IPH_V(iphdr),
		    IPH_HL(iphdr),
		    IPH_TOS(iphdr),
		    ntohs(IPH_LEN(iphdr))));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  DEBUGF(IP_DEBUG, ("|    %5d      |%d%d%d|    %4d   | (id, flags, offset)\n",
		    ntohs(IPH_ID(iphdr)),
		    ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
		    ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
		    ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
		    ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  DEBUGF(IP_DEBUG, ("|   %2d  |   %2d  |    0x%04x     | (ttl, proto, chksum)\n",
		    IPH_TTL(iphdr),
		    IPH_PROTO(iphdr),
		    ntohs(IPH_CHKSUM(iphdr))));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  DEBUGF(IP_DEBUG, ("|  %3ld  |  %3ld  |  %3ld  |  %3ld  | (src)\n",
		    ntohl(iphdr->src.addr) >> 24 & 0xff,
		    ntohl(iphdr->src.addr) >> 16 & 0xff,
		    ntohl(iphdr->src.addr) >> 8 & 0xff,
		    ntohl(iphdr->src.addr) & 0xff));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  DEBUGF(IP_DEBUG, ("|  %3ld  |  %3ld  |  %3ld  |  %3ld  | (dest)\n",
		    ntohl(iphdr->dest.addr) >> 24 & 0xff,
		    ntohl(iphdr->dest.addr) >> 16 & 0xff,
		    ntohl(iphdr->dest.addr) >> 8 & 0xff,
		    ntohl(iphdr->dest.addr) & 0xff));
  DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
}
#endif /* IP_DEBUG */
/*-----------------------------------------------------------------------------------*/