tcp.bak

是TCPIP程序

void tcp_handler(in_Header xdata *ip)
{
        eth_Header xdata *peth;
	tcp_Header xdata *tp;
	tcp_PseudoHeader xdata *ph;
	int xdata len;
	int xdata diff;
	uint flags;
	long xdata diffticks;
        long xdata ldiff;	/* 注意必须有符号 */

	if ( ip->destination !=local_ip)
		return;
        len =((ip.hd_ver)&0x0f)*4;
	tp = (tcp_Header xdata *)((uchar xdata *)ip + len);	/* TCP帧指针 */
        ph=ETH_RECV_ADDR-sizeof(tcp_PseudoHeader);
	len =  ip->length  - len;		/* TCP数据长度 */
	flags =tp->flags;
	if ( s->hisaddr != 0 && tp->dstPort != s->myport )return;
        if ( s->hisaddr != 0 && tp->srcPort != s->hisport)return;
        if ( s->hisaddr != 0 && ip->source  != s->hisaddr)return;

        if( s->hisaddr==0 && tp->dstPort != s->myport && tp->dstPort != HTTPPORT)return;
	ph.src = ip->source;	/* 已经本地字节序(Intel) */
	ph.dst = ip->destination;
	ph.mbz = 0;
	ph.protocol = TCP_PROTO;
	ph.length =  len ;
	ph.checksum =  checksum((uchar xdata *)tp, len);
	if ( checksum((uchar xdata *)ph, sizeof(tcp_PseudoHeader)) != 0xffff )
	{
        	return;
	}

       /* RESET code */
	if ( flags & tcp_FlagRST )
	{
                s->rdatalen=0;
		s->state = tcp_StateCLOSED;
                s->safetysig=FALSE;
		return;
	}

        curr_conf.type  =TCP_PROTO;
        curr_conf.dst_ip=ip.source;
        curr_conf.timer =ARP_KEEP_TIME;

	switch ( s->state )
	{
   	case tcp_StateLISTEN:	/* 接收SYN */
                peth=((eth_Header xdata *)ip)-1;

                curr_conf.dst_mac=peth.source;

		if ( flags & tcp_FlagSYN )
		{
			s->acknum =  tp->seqnum  + 1;
                        s->myport =  tp->dstPort;
                        s->hisport=  tp->srcPort;
			s->hisaddr = ip->source ;
			s->flags = tcp_FlagSYN | tcp_FlagACK;
			s->state = tcp_StateSYNREC;
			s->unhappy = TRUE;
			tcp_send();    /* 立即相应 */

			s->timeout = set_timeout( tcp_TIMEOUT );
		}
		else
			tcp_rst( ip , tp ); /* 是个错误RESET之 */

		return;

        case tcp_StateSYNSENT:
	    if ( flags & tcp_FlagSYN )
	    {
			s->flags = tcp_FlagACK;
			s->timeout = set_timeout( tcp_TIMEOUT );
			/* FlagACK 意味着连接已经建立, 否则就是 SYNREC */
			if ( flags & tcp_FlagACK)
			{
				/* 判断是不是当前对话的 */
				if (tp->acknum == s->seqnum + 1)
				{
					s->state = tcp_StateESTAB;
					s->seqnum++;
					s->acknum = tp->seqnum + 1;
					tcp_ProcessData( tp, len, ph);
					s->unhappy = TRUE;
					tcp_send( );
				}
				else
				{
					/* 错误的SEQNUM,RESET之,重发SYN */
					s->flags = tcp_FlagRST;
					s->unhappy = TRUE;
					tcp_send( );
					s->flags = tcp_FlagSYN;
					tcp_send( );
				}
			}
			else
			{
				s->acknum++;
				s->state = tcp_StateSYNREC;
				return;
			}
		}
		else
			tcp_rst( ip, tp );

		break;

	case tcp_StateSYNREC:	/* recSYNSENT, sentACK, waiting  EST */
		if ( flags & tcp_FlagSYN )
		{
			s->flags = tcp_FlagSYN | tcp_FlagACK;
			s->unhappy = TRUE;
			tcp_send();
			s->timeout = set_timeout( tcp_TIMEOUT );
			return;
		}
		if ( (flags & tcp_FlagACK) && ( tp->acknum  == s->seqnum + 1))
		{
			s->flags = tcp_FlagACK;
			s->state = tcp_StateESTAB;
			s->seqnum++;
			s->timeout = set_timeout(0);     /* never timeout 在我这里按说是不可能的 ,得要加上窗口探测