tcpok.c,v

来自「TCP-IP红宝书源代码」· C,V 代码 · 共 89 行

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1.2
date	97.09.21.19.29.52;	author dls;	state Dist;
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1.1
date	94.01.14.03.51.20;	author dls;	state v2e1;
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@pre-3e code
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@/* tcpok.c - tcpok */

#include <conf.h>
#include <kernel.h>
#include <network.h>

/*------------------------------------------------------------------------
 *  tcpok -  determine if a received segment is acceptable
 *------------------------------------------------------------------------
 */
int tcpok(ptcb, pep)
struct	tcb	*ptcb;
struct	ep	*pep;
{
	struct	ip	*pip = (struct ip *)pep->ep_data;
	struct	tcp	*ptcp = (struct tcp *) pip->ip_data;
	int		seglen, rwindow;
	tcpseq		wlast, slast, sup;
	Bool		rv;

	if (ptcb->tcb_state < TCPS_SYNRCVD)
		return TRUE;
	seglen = pip->ip_len - IP_HLEN(pip) - TCP_HLEN(ptcp);

	/* add SYN and FIN */
	if (ptcp->tcp_code & TCPF_SYN)
		++seglen;
	if (ptcp->tcp_code & TCPF_FIN)
		++seglen;
	rwindow = ptcb->tcb_rbsize - ptcb->tcb_rbcount; 
	if (rwindow == 0 && seglen == 0)
		return ptcp->tcp_seq == ptcb->tcb_rnext;
	wlast = ptcb->tcb_rnext + rwindow - 1;
	rv = (ptcp->tcp_seq - ptcb->tcb_rnext) >= 0 &&
		(ptcp->tcp_seq - wlast) <= 0;
	if (seglen == 0)
		return rv;
	slast = ptcp->tcp_seq + seglen - 1;
	rv |= (slast - ptcb->tcb_rnext) >= 0 && (slast - wlast) <= 0;

	/* If no window, strip data but keep ACK, RST and URG		*/
	if (rwindow == 0)
		pip->ip_len = IP_HLEN(pip) + TCP_HLEN(ptcp);
	return rv;
}
@


1.1
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@Initial revision
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@d17 2
a18 1
	int		seglen, wlast, slast, rwindow;
a32 2
	if (ptcp->tcp_code & TCPF_URG)
		(void) tcprcvurg(ptcb, pep);
@