tcprmss.c,v

来自「TCP-IP红宝书源代码」· C,V 代码 · 共 71 行

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

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

/*------------------------------------------------------------------------
 *  tcprmss - set receive MSS option
 *------------------------------------------------------------------------
 */
int tcprmss(ptcb, pip)
struct	tcb	*ptcb;
struct	ip	*pip;
{
	struct	tcp	*ptcp = (struct tcp *)pip->ip_data;
	int		mss, hlen, olen, i;

	hlen = TCP_HLEN(ptcp);
	olen = 2 + sizeof(short);
	pip->ip_data[hlen] = TPO_MSS;		/* option kind		*/
	pip->ip_data[hlen+1] = olen;		/* option length	*/
	mss = ptcb->tcb_rmss;
	for (i=olen-1; i>1; i--) {
		pip->ip_data[hlen+i] = mss & LOWBYTE;
		mss >>= 8;
	}
	hlen += olen + 3;	/* +3 for proper rounding below */
	/* header length is high 4 bits of tcp_offset, in longs	*/
	ptcp->tcp_offset = ((hlen<<2) & 0xf0) | ptcp->tcp_offset & 0xf;
}
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@Initial revision
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	mss = hs2net((short)ptcb->tcb_smss);
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