Function IcmpAliasIn1

freebsd/netinet/libalias/alias.c:288–331

static int	TcpAliasOut(struct libalias *, struct ip *, int, int create);

static int
IcmpAliasIn1(struct libalias *la, struct ip *pip)
{

	LIBALIAS_LOCK_ASSERT(la);
/*
    De-alias incoming echo and timestamp replies.
    Alias incoming echo and timestamp requests.
*/
	struct alias_link *lnk;
	struct icmp *ic;

	ic = (struct icmp *)ip_next(pip);

/* Get source address from ICMP data field and restore original data */
	lnk = FindIcmpIn(la, pip->ip_src, pip->ip_dst, ic->icmp_id, 1);
	if (lnk != NULL) {
		u_short original_id;
		int accumulate;

		original_id = GetOriginalPort(lnk);

/* Adjust ICMP checksum */
		accumulate = ic->icmp_id;
		accumulate -= original_id;
		ADJUST_CHECKSUM(accumulate, ic->icmp_cksum);

/* Put original sequence number back in */
		ic->icmp_id = original_id;

/* Put original address back into IP header */
		{
			struct in_addr original_address;

			original_address = GetOriginalAddress(lnk);
			DifferentialChecksum(&pip->ip_sum,
			    &original_address, &pip->ip_dst, 2);
			pip->ip_dst = original_address;
		}

		return (PKT_ALIAS_OK);
	}
	return (PKT_ALIAS_IGNORED);
}

static int
IcmpAliasIn2(struct libalias *la, struct ip *pip)