udp.c

网络服务器上实现操作系统和嵌入式协议栈的 结合

/**
 * @file
 * User Datagram Protocol module
 *
 */
/*
 * 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]>
 *
 */

/*-----------------------------------------------------------------------------------*/
/* udp.c
 *
 * The code for the User Datagram Protocol UDP.
 *
 */
/*-----------------------------------------------------------------------------------*/
#include "lwip/opt.h"

#include "lwip/def.h"
#include "lwip/memp.h"
#include "lwip/inet.h"
#include "lwip/netif.h"
#include "lwip/udp.h"
#include "lwip/icmp.h"
#include "lwip/ip_addr.h"

#include "lwip/stats.h"

#include "arch/perf.h"
#include "lwip/snmp.h"
//added by dy
#include <string.h>


//#undef DEBUGF
//#define DEBUGF(x,y) { page_printf("\f"); page_printf y; };

/* The list of UDP PCBs */
#if LWIP_UDP
/* was static, but we may want to access this from a socket layer */
struct udp_pcb *udp_pcbs = NULL;

static struct udp_pcb *pcb_cache = NULL;

#if UDP_DEBUG
int udp_debug_print(struct udp_hdr *udphdr);
#endif /* UDP_DEBUG */
	  
/*-----------------------------------------------------------------------------------*/
void
udp_init(void)
{
  udp_pcbs = pcb_cache = NULL;
}

/*-----------------------------------------------------------------------------------*/
/* udp_lookup:
 *
 * An experimental feature that will be changed in future versions. Do
 * not depend on it yet...
 */
/*-----------------------------------------------------------------------------------*/
#ifdef LWIP_DEBUG
u8_t
udp_lookup(struct ip_hdr *iphdr, struct netif *inp)
{
  struct udp_pcb *pcb;
  struct udp_hdr *udphdr;
  u16_t src, dest;

    PERF_START;
  (void)inp;

    udphdr = (struct udp_hdr *)(u8_t *)iphdr + IPH_HL(iphdr) * 4;

  src = ntohs(udphdr->src);
  dest = ntohs(udphdr->dest);

    pcb = pcb_cache;
  if(pcb != NULL &&
    pcb->remote_port == src &&
    pcb->local_port == dest &&
    (ip_addr_isany(&pcb->remote_ip) ||
    ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
    (ip_addr_isany(&pcb->local_ip) ||
    ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
    return 1;
  }
  else {  
    for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
      if(pcb->remote_port == src &&
	 pcb->local_port == dest &&
	 (ip_addr_isany(&pcb->remote_ip) ||
	  ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
	 (ip_addr_isany(&pcb->local_ip) ||
	  ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
	pcb_cache = pcb;
        break;
        }
    }

    if(pcb == NULL) {
      for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
	if(pcb->remote_port == 0 &&
	   pcb->local_port == dest &&
	   (ip_addr_isany(&pcb->remote_ip) ||
	    ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
	   (ip_addr_isany(&pcb->local_ip) ||
	    ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
	      break;
        }
      }
    }
  }

  PERF_STOP("udp_lookup");

  if(pcb != NULL) {
    return 1;
  }
  else {  
    return 1;
  }
}
#endif /* LWIP_DEBUG */
/**
 * Process an incoming UDP datagram.
 *
 * Given an incoming UDP datagram (as a chain of pbufs) this function
 * finds a corresponding UDP PCB and
 *
 * @param pbuf pbuf to be demultiplexed to a UDP PCB.
 * @param netif network interface on which the datagram was received.
 *
 * @see udp_disconnect()
 */
void
udp_input(struct pbuf *p, struct netif *inp)
{
  struct udp_hdr *udphdr;  
  struct udp_pcb *pcb;
  struct ip_hdr *iphdr;
  u16_t src, dest;
  
  PERF_START;
  
#ifdef UDP_STATS
  ++lwip_stats.udp.recv;
#endif /* UDP_STATS */

  iphdr = p->payload;

  pbuf_header(p, -((s16_t)(UDP_HLEN + IPH_HL(iphdr) * 4)));

  udphdr = (struct udp_hdr *)((u8_t *)p->payload - UDP_HLEN);
  
  DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %u\n", p->tot_len));
	
  src = ntohs(udphdr->src);
  dest = ntohs(udphdr->dest);

#if UDP_DEBUG
  udp_debug_print(udphdr);
#endif /* UDP_DEBUG */

  /* print the UDP source and destination */
  DEBUGF(UDP_DEBUG, ("udp (%u.%u.%u.%u, %u) <-- (%u.%u.%u.%u, %u)\n",
    ip4_addr1(&iphdr->dest), ip4_addr2(&iphdr->dest),
    ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
    ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
    ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));
  /* Iterate through the UDP pcb list for a fully matching pcb */
  for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
    /* print the PCB local and remote address */
    DEBUGF(UDP_DEBUG, ("pcb (%u.%u.%u.%u, %u) --- (%u.%u.%u.%u, %u)\n",
      ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
      ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
      ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
      ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));

       /* PCB remote port matches UDP source port? */
    if((pcb->remote_port == src) &&
       /* PCB local port matches UDP destination port? */
       (pcb->local_port == dest) &&
       /* accepting from any remote (source) IP address? or... */
       (ip_addr_isany(&pcb->remote_ip) ||
       /* PCB remote IP address matches UDP source IP address? */
      	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
       /* accepting on any local (netif) IP address? or... */
       (ip_addr_isany(&pcb->local_ip) ||
       /* PCB local IP address matches UDP destination IP address? */
      	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
      break;
    }
  }
  /* no fully matching pcb found? then look for an unconnected pcb */
  if (pcb == NULL) {
    /* Iterate through the UDP PCB list for a pcb that matches
       the local address. */
    for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
      DEBUGF(UDP_DEBUG, ("pcb (%u.%u.%u.%u, %u) --- (%u.%u.%u.%u, %u)\n",
        ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
        ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
        ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
        ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));
      /* unconnected? */
      if(((pcb->flags & UDP_FLAGS_CONNECTED) == 0) &&
     	  /* destination port matches? */
	      (pcb->local_port == dest) &&
	      /* not bound to a specific (local) interface address? or... */
	      (ip_addr_isany(&pcb->local_ip) ||
	      /* ...matching interface address? */
	      ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
	       break;
      }      
    }
  }

  /* Check checksum if this is a match or if it was directed at us. */
  if(pcb != NULL  || ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) 
    {
    DEBUGF(UDP_DEBUG | DBG_TRACE, ("udp_input: calculating checksum\n"));
    pbuf_header(p, UDP_HLEN);    
#ifdef IPv6
    if(iphdr->nexthdr == IP_PROTO_UDPLITE) {    
#else
    if(IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {    
#endif /* IPv4 */
      /* Do the UDP Lite checksum */
      if(inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
			   (struct ip_addr *)&(iphdr->dest),
			   IP_PROTO_UDPLITE, ntohs(udphdr->len)) != 0) {
	DEBUGF(UDP_DEBUG | 2, ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
#ifdef UDP_STATS
	++lwip_stats.udp.chkerr;
	++lwip_stats.udp.drop;
#endif /* UDP_STATS */
  snmp_inc_udpinerrors();
	pbuf_free(p);
	goto end;
      }
    } else {
      if(udphdr->chksum != 0) {
	if(inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
			 (struct ip_addr *)&(iphdr->dest),
			  IP_PROTO_UDP, p->tot_len) != 0) {
	  DEBUGF(UDP_DEBUG | 2, ("udp_input: UDP datagram discarded due to failing checksum\n"));
	  
#ifdef UDP_STATS
	  ++lwip_stats.udp.chkerr;
	  ++lwip_stats.udp.drop;
#endif /* UDP_STATS */
    snmp_inc_udpinerrors();
	  pbuf_free(p);
	  goto end;
	}
      }
    }
    pbuf_header(p, -UDP_HLEN);    
    if(pcb != NULL) {
      snmp_inc_udpindatagrams();
      pcb->recv(pcb->recv_arg, pcb, p, &(iphdr->src), src);
    } else {
      DEBUGF(UDP_DEBUG | DBG_TRACE, ("udp_input: not for us.\n"));
      
      /* No match was found, send ICMP destination port unreachable unless
	 destination address was broadcast/multicast. */
      
      if(!ip_addr_isbroadcast(&iphdr->dest, &inp->netmask) &&
	 !ip_addr_ismulticast(&iphdr->dest)) {
	
	/* adjust pbuf pointer */
	p->payload = (void*)iphdr;
	icmp_dest_unreach(p, ICMP_DUR_PORT);
      }
#ifdef UDP_STATS
      ++lwip_stats.udp.proterr;
      ++lwip_stats.udp.drop;
#endif /* UDP_STATS */
    snmp_inc_udpnoports();
      pbuf_free(p);
    }
  } else {
    pbuf_free(p);
  }
  end:
    
  PERF_STOP("udp_input");
}
/**
 * Send data using UDP. 
 *
 * @param pcb UDP PCB used to send the data.
 * @param pbuf chain of pbuf's to be sent.
 *
 * @return lwIP error code.
 * - ERR_OK. Successful. No error occured.
 * - ERR_MEM. Out of memory.
 * - ERR_USE. The specified ipaddr and port are already bound to by
 * another UDP PCB.
 * 
 * @see udp_disconnect()
 */
err_t
udp_send(struct udp_pcb *pcb, struct pbuf *p)
{
  struct udp_hdr *udphdr;
  struct netif *netif;
  struct ip_addr *src_ip;
  err_t err;