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- /*
- * mod_ip_ttl.c
- *
- * Copyright (c) 2001 Dug Song <dugsong@monkey.org>
- *
- * $Id$
- */
- #include "config.h"
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include "argv.h"
- #include "mod.h"
- #include "pkt.h"
- struct ip_ttl_data {
- int ttl;
- };
- void *
- ip_ttl_close(void *d)
- {
- if (d != NULL)
- free(d);
- return (NULL);
- }
- void *
- ip_ttl_open(int argc, char *argv[])
- {
- struct ip_ttl_data *data;
- if (argc != 2)
- return (NULL);
- if ((data = calloc(1, sizeof(*data))) == NULL)
- return (NULL);
- if ((data->ttl = atoi(argv[1])) <= 0 || data->ttl > 255)
- return (ip_ttl_close(data));
- return (data);
- }
- int
- ip_ttl_apply(void *d, struct pktq *pktq)
- {
- struct ip_ttl_data *data = (struct ip_ttl_data *)d;
- struct pkt *pkt;
- int ttldec;
- TAILQ_FOREACH(pkt, pktq, pkt_next) {
- uint16_t eth_type = htons(pkt->pkt_eth->eth_type);
- if (eth_type == ETH_TYPE_IP) {
- ttldec = pkt->pkt_ip->ip_ttl - data->ttl;
- pkt->pkt_ip->ip_ttl = data->ttl;
- if (pkt->pkt_ip->ip_sum >= htons(0xffff - (ttldec << 8)))
- pkt->pkt_ip->ip_sum += htons(ttldec << 8) + 1;
- else
- pkt->pkt_ip->ip_sum += htons(ttldec << 8);
- } else if (eth_type == ETH_TYPE_IPV6) {
- pkt->pkt_ip6->ip6_hlim = data->ttl;
- }
- }
- return (0);
- }
- struct mod mod_ip_ttl = {
- "ip_ttl", /* name */
- "ip_ttl <ttl>", /* usage */
- ip_ttl_open, /* open */
- ip_ttl_apply, /* apply */
- ip_ttl_close /* close */
- };
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