//如果是time_exceeded，那么icmpdata中包含iphdr+icmphdr数据（源ICMP数据包）.
int CSocketIcmp::icmp_time_exceeded(int code,const char *icmpdata,int len)
{
if (len <=0)
{
DEBUG("icmp_time_exceeded :data len %d!\n",len);
return -1;
}
int ret = 0;
switch(code)
{
case ICMP_EXC_TTL:
{
DEBUG("time exceeded code [%d]:ICMP_EXC_TTL!\n",code);
if(0 != time_exceeded(icmp_data,len))
{
ret = -3;
}
break;
}
case ICMP_EXC_FRAGTIME:
{
DEBUG("time exceeded code [%d]:ICMP_EXC_FRAGTIME!\n",code);
if (0 != time_exceeded(icmp_data,len))
{
ret = -4;
}
break;
}
default :
{
DEBUG("Unknow icmp code [%d]\n",code);
ret = -5;
break;
}
}
return ret;
}
/*------------------------------------------------------------------------------*/
u8_t
uip_fw_forward(void)
{
struct fwcache_entry *fw;
/* First check if the packet is destined for ourselves and return 0
to indicate that the packet should be processed locally. */
if(BUF->destipaddr[0] == uip_hostaddr[0] &&
BUF->destipaddr[1] == uip_hostaddr[1]) {
return UIP_FW_LOCAL;
}
/* If we use ping IP address configuration, and our IP address is
not yet configured, we should intercept all ICMP echo packets. */
#if UIP_PINGADDRCONF
if((uip_hostaddr[0] | uip_hostaddr[1]) == 0 &&
BUF->proto == UIP_PROTO_ICMP &&
ICMPBUF->type == ICMP_ECHO) {
return UIP_FW_LOCAL;
}
#endif /* UIP_PINGADDRCONF */
/* Check if the packet is in the forwarding cache already, and if so
we drop it. */
for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
if(fw->timer != 0 &&
#if UIP_REASSEMBLY > 0
fw->len == BUF->len &&
fw->offset == BUF->ipoffset &&
#endif
fw->ipid == BUF->ipid &&
fw->srcipaddr[0] == BUF->srcipaddr[0] &&
fw->srcipaddr[1] == BUF->srcipaddr[1] &&
fw->destipaddr[0] == BUF->destipaddr[0] &&
fw->destipaddr[1] == BUF->destipaddr[1] &&
#if notdef
fw->payload[0] == BUF->srcport &&
fw->payload[1] == BUF->destport &&
#endif
fw->proto == BUF->proto) {
/* Drop packet. */
return UIP_FW_FORWARDED;
}
}
/* If the TTL reaches zero we produce an ICMP time exceeded message
in the uip_buf buffer and forward that packet back to the sender
of the packet. */
if(BUF->ttl <= 1) {
/* No time exceeded for broadcasts and multicasts! */
if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
return UIP_FW_LOCAL;
}
time_exceeded();
}
/* Decrement the TTL (time-to-live) value in the IP header */
BUF->ttl = BUF->ttl - 1;
/* Update the IP checksum. */
if(BUF->ipchksum >= HTONS(0xffff - 0x0100)) {
BUF->ipchksum = BUF->ipchksum + HTONS(0x0100) + 1;
} else {
BUF->ipchksum = BUF->ipchksum + HTONS(0x0100);
}
if(uip_len > 0) {
uip_appdata = &uip_buf[UIP_LLH_LEN + UIP_TCPIP_HLEN];
uip_fw_output();
}
#if UIP_BROADCAST
if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
return UIP_FW_LOCAL;
}
#endif /* UIP_BROADCAST */
/* Return non-zero to indicate that the packet was forwarded and that no
other processing should be made. */
return UIP_FW_FORWARDED;
}
