icerrok.c

来自「TCP-IP红宝书源代码」· C语言 代码 · 共 40 行

/* icerrok.c - icerrok */

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

/*------------------------------------------------------------------------
 *  icerrok -  is it ok to send an error response?
 *------------------------------------------------------------------------
 */
Bool
icerrok(struct ep *pep)
{
	struct	ip	*pip = (struct ip *)pep->ep_data;
	struct	icmp	*pic = (struct icmp *)pip->ip_data;

	/* don't send errors about error packets... */

	if (pip->ip_proto == IPT_ICMP)
		switch(pic->ic_type) {
		case ICT_DESTUR:
		case ICT_REDIRECT:
		case ICT_SRCQ:
		case ICT_TIMEX:
		case ICT_PARAMP:
			return FALSE;
		default:
			break;
		}
	/* ...or other than the first of a fragment */

	if (pip->ip_fragoff & IP_FRAGOFF)
		return FALSE;
	/* ...or broadcast or multicast packets */

	if (isbrc(pip->ip_dst) || IP_CLASSD(pip->ip_dst))
		return FALSE;
	return TRUE;
}