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- /* Kernel module to match packet length. */
- /* (C) 1999-2001 James Morris <jmorros@intercode.com.au>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/ipv6.h>
- #include <net/ip.h>
- #include <linux/netfilter/xt_length.h>
- #include <linux/netfilter/x_tables.h>
- MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
- MODULE_DESCRIPTION("IP tables packet length matching module");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS("ipt_length");
- MODULE_ALIAS("ip6t_length");
- static int
- match(const struct sk_buff *skb,
- const struct net_device *in,
- const struct net_device *out,
- const struct xt_match *match,
- const void *matchinfo,
- int offset,
- unsigned int protoff,
- int *hotdrop)
- {
- const struct xt_length_info *info = matchinfo;
- u_int16_t pktlen = ntohs(skb->nh.iph->tot_len);
- return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
- }
- static int
- match6(const struct sk_buff *skb,
- const struct net_device *in,
- const struct net_device *out,
- const struct xt_match *match,
- const void *matchinfo,
- int offset,
- unsigned int protoff,
- int *hotdrop)
- {
- const struct xt_length_info *info = matchinfo;
- u_int16_t pktlen = ntohs(skb->nh.ipv6h->payload_len) + sizeof(struct ipv6hdr);
- return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
- }
- static struct xt_match xt_length_match[] = {
- {
- .name = "length",
- .family = AF_INET,
- .match = match,
- .matchsize = sizeof(struct xt_length_info),
- .me = THIS_MODULE,
- },
- {
- .name = "length",
- .family = AF_INET6,
- .match = match6,
- .matchsize = sizeof(struct xt_length_info),
- .me = THIS_MODULE,
- },
- };
- static int __init xt_length_init(void)
- {
- return xt_register_matches(xt_length_match,
- ARRAY_SIZE(xt_length_match));
- }
- static void __exit xt_length_fini(void)
- {
- xt_unregister_matches(xt_length_match, ARRAY_SIZE(xt_length_match));
- }
- module_init(xt_length_init);
- module_exit(xt_length_fini);
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