2005-04-16 22:20:36 +00:00
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/* Kernel module to match Hop-by-Hop and Destination parameters. */
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/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <linux/types.h>
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#include <net/checksum.h>
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#include <net/ipv6.h>
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#include <asm/byteorder.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/netfilter_ipv6/ip6t_opts.h>
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#define HOPBYHOP 1
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MODULE_LICENSE("GPL");
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#if HOPBYHOP
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MODULE_DESCRIPTION("IPv6 HbH match");
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#else
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MODULE_DESCRIPTION("IPv6 DST match");
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#endif
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MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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/*
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2006-01-17 10:39:39 +00:00
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* (Type & 0xC0) >> 6
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* 0 -> ignorable
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* 1 -> must drop the packet
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* 2 -> send ICMP PARM PROB regardless and drop packet
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* 3 -> Send ICMP if not a multicast address and drop packet
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2005-04-16 22:20:36 +00:00
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* (Type & 0x20) >> 5
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2006-01-17 10:39:39 +00:00
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* 0 -> invariant
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* 1 -> can change the routing
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2005-04-16 22:20:36 +00:00
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* (Type & 0x1F) Type
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2006-01-17 10:39:39 +00:00
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* 0 -> Pad1 (only 1 byte!)
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* 1 -> PadN LENGTH info (total length = length + 2)
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* C0 | 2 -> JUMBO 4 x x x x ( xxxx > 64k )
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* 5 -> RTALERT 2 x x
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2005-04-16 22:20:36 +00:00
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*/
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static int
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match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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2006-03-21 02:02:56 +00:00
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const struct xt_match *match,
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2005-04-16 22:20:36 +00:00
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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2006-01-17 10:39:39 +00:00
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struct ipv6_opt_hdr _optsh, *oh;
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const struct ip6t_opts *optinfo = matchinfo;
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unsigned int temp;
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unsigned int ptr;
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unsigned int hdrlen = 0;
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unsigned int ret = 0;
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u8 _opttype, *tp = NULL;
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u8 _optlen, *lp = NULL;
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unsigned int optlen;
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2005-04-16 22:20:36 +00:00
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#if HOPBYHOP
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2006-01-05 20:21:16 +00:00
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if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP, NULL) < 0)
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2005-04-16 22:20:36 +00:00
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#else
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2006-01-05 20:21:16 +00:00
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if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST, NULL) < 0)
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2005-04-16 22:20:36 +00:00
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#endif
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2005-09-19 22:34:40 +00:00
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return 0;
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2005-04-16 22:20:36 +00:00
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2006-01-17 10:39:39 +00:00
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oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh);
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if (oh == NULL) {
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*hotdrop = 1;
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return 0;
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}
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hdrlen = ipv6_optlen(oh);
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if (skb->len - ptr < hdrlen) {
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/* Packet smaller than it's length field */
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return 0;
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}
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DEBUGP("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen);
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DEBUGP("len %02X %04X %02X ",
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optinfo->hdrlen, hdrlen,
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(!(optinfo->flags & IP6T_OPTS_LEN) ||
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((optinfo->hdrlen == hdrlen) ^
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!!(optinfo->invflags & IP6T_OPTS_INV_LEN))));
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ret = (oh != NULL) &&
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(!(optinfo->flags & IP6T_OPTS_LEN) ||
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((optinfo->hdrlen == hdrlen) ^
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!!(optinfo->invflags & IP6T_OPTS_INV_LEN)));
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ptr += 2;
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hdrlen -= 2;
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if (!(optinfo->flags & IP6T_OPTS_OPTS)) {
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return ret;
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2005-04-16 22:20:36 +00:00
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} else if (optinfo->flags & IP6T_OPTS_NSTRICT) {
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DEBUGP("Not strict - not implemented");
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} else {
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DEBUGP("Strict ");
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2006-01-17 10:39:39 +00:00
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DEBUGP("#%d ", optinfo->optsnr);
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for (temp = 0; temp < optinfo->optsnr; temp++) {
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2005-04-16 22:20:36 +00:00
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/* type field exists ? */
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if (hdrlen < 1)
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break;
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tp = skb_header_pointer(skb, ptr, sizeof(_opttype),
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&_opttype);
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if (tp == NULL)
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break;
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/* Type check */
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2006-01-17 10:39:39 +00:00
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if (*tp != (optinfo->opts[temp] & 0xFF00) >> 8) {
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2005-04-16 22:20:36 +00:00
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DEBUGP("Tbad %02X %02X\n",
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*tp,
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2006-01-17 10:39:39 +00:00
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(optinfo->opts[temp] & 0xFF00) >> 8);
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2005-04-16 22:20:36 +00:00
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return 0;
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} else {
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DEBUGP("Tok ");
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}
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/* Length check */
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if (*tp) {
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u16 spec_len;
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/* length field exists ? */
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if (hdrlen < 2)
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break;
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lp = skb_header_pointer(skb, ptr + 1,
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sizeof(_optlen),
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&_optlen);
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if (lp == NULL)
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break;
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spec_len = optinfo->opts[temp] & 0x00FF;
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if (spec_len != 0x00FF && spec_len != *lp) {
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DEBUGP("Lbad %02X %04X\n", *lp,
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spec_len);
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return 0;
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}
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DEBUGP("Lok ");
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optlen = *lp + 2;
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} else {
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DEBUGP("Pad1\n");
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optlen = 1;
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}
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/* Step to the next */
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DEBUGP("len%04X \n", optlen);
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if ((ptr > skb->len - optlen || hdrlen < optlen) &&
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(temp < optinfo->optsnr - 1)) {
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DEBUGP("new pointer is too large! \n");
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break;
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}
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ptr += optlen;
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hdrlen -= optlen;
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}
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if (temp == optinfo->optsnr)
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return ret;
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2006-01-17 10:39:39 +00:00
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else
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return 0;
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2005-04-16 22:20:36 +00:00
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}
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return 0;
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}
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/* Called when user tries to insert an entry of this type. */
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static int
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checkentry(const char *tablename,
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2006-01-17 10:39:39 +00:00
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const void *entry,
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2006-03-21 02:02:56 +00:00
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const struct xt_match *match,
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2006-01-17 10:39:39 +00:00
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void *matchinfo,
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unsigned int matchinfosize,
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unsigned int hook_mask)
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2005-04-16 22:20:36 +00:00
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{
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2006-01-17 10:39:39 +00:00
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const struct ip6t_opts *optsinfo = matchinfo;
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if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) {
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DEBUGP("ip6t_opts: unknown flags %X\n", optsinfo->invflags);
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return 0;
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}
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return 1;
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2005-04-16 22:20:36 +00:00
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}
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static struct ip6t_match opts_match = {
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#if HOPBYHOP
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.name = "hbh",
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#else
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.name = "dst",
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#endif
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2006-03-21 02:01:43 +00:00
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.match = match,
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.matchsize = sizeof(struct ip6t_opts),
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.checkentry = checkentry,
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2005-04-16 22:20:36 +00:00
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.me = THIS_MODULE,
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};
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static int __init init(void)
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{
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2006-01-17 10:39:39 +00:00
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return ip6t_register_match(&opts_match);
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2005-04-16 22:20:36 +00:00
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}
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static void __exit cleanup(void)
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{
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2006-01-17 10:39:39 +00:00
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ip6t_unregister_match(&opts_match);
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2005-04-16 22:20:36 +00:00
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}
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module_init(init);
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module_exit(cleanup);
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