libnetfilter_queue 1.0.5
ipv6.c
1/*
2 * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This code has been sponsored by Vyatta Inc. <http://www.vyatta.com>
10 */
11
12#include <stdio.h>
13#include <stddef.h>
14#include <stdbool.h>
15#include <arpa/inet.h>
16#include <netinet/ip6.h>
17
18#include <libnetfilter_queue/libnetfilter_queue.h>
19#include <libnetfilter_queue/libnetfilter_queue_ipv6.h>
20#include <libnetfilter_queue/pktbuff.h>
21
22#include "internal.h"
23
35EXPORT_SYMBOL
36struct ip6_hdr *nfq_ip6_get_hdr(struct pkt_buff *pktb)
37{
38 struct ip6_hdr *ip6h;
39 unsigned int pktlen = pktb_tail(pktb) - pktb->network_header;
40
41 /* Not enough room for IPv6 header. */
42 if (pktlen < sizeof(struct ip6_hdr))
43 return NULL;
44
45 ip6h = (struct ip6_hdr *)pktb->network_header;
46
47 /* Not IPv6 packet. */
48 if ((*(uint8_t *)ip6h & 0xf0) != 0x60)
49 return NULL;
50
51 return ip6h;
52}
53
63EXPORT_SYMBOL
64int nfq_ip6_set_transport_header(struct pkt_buff *pktb, struct ip6_hdr *ip6h,
65 uint8_t target)
66{
67 uint8_t nexthdr = ip6h->ip6_nxt;
68 uint8_t *cur = (uint8_t *)ip6h + sizeof(struct ip6_hdr);
69
70 while (nexthdr != target) {
71 struct ip6_ext *ip6_ext;
72 uint32_t hdrlen;
73
74 /* No more extensions, we're done. */
75 if (nexthdr == IPPROTO_NONE) {
76 cur = NULL;
77 break;
78 }
79 /* No room for extension, bad packet. */
80 if (pktb_tail(pktb) - cur < sizeof(struct ip6_ext)) {
81 cur = NULL;
82 break;
83 }
84 ip6_ext = (struct ip6_ext *)cur;
85
86 if (nexthdr == IPPROTO_FRAGMENT) {
87 uint16_t *frag_off;
88
89 /* No room for full fragment header, bad packet. */
90 if (pktb_tail(pktb) - cur < sizeof(struct ip6_frag)) {
91 cur = NULL;
92 break;
93 }
94
95 frag_off = (uint16_t *)cur +
96 offsetof(struct ip6_frag, ip6f_offlg);
97
98 /* Fragment offset is only 13 bits long. */
99 if (htons(*frag_off & ~0x7)) {
100 /* Not the first fragment, it does not contain
101 * any headers.
102 */
103 cur = NULL;
104 break;
105 }
106 hdrlen = sizeof(struct ip6_frag);
107 } else if (nexthdr == IPPROTO_AH)
108 hdrlen = (ip6_ext->ip6e_len + 2) << 2;
109 else
110 hdrlen = ip6_ext->ip6e_len;
111
112 nexthdr = ip6_ext->ip6e_nxt;
113 cur += hdrlen;
114 }
115 pktb->transport_header = cur;
116 return cur ? 1 : 0;
117}
118
130EXPORT_SYMBOL
131int nfq_ip6_mangle(struct pkt_buff *pktb, unsigned int dataoff,
132 unsigned int match_offset, unsigned int match_len,
133 const char *rep_buffer, unsigned int rep_len)
134{
135 struct ip6_hdr *ip6h = (struct ip6_hdr *)pktb->network_header;
136
137 if (!pktb_mangle(pktb, dataoff, match_offset, match_len, rep_buffer,
138 rep_len))
139 return 0;
140
141 /* Fix IPv6 hdr length information */
142 ip6h->ip6_plen =
143 htons(pktb_tail(pktb) - pktb->network_header - sizeof *ip6h);
144
145 return 1;
146}
147
157EXPORT_SYMBOL
158int nfq_ip6_snprintf(char *buf, size_t size, const struct ip6_hdr *ip6h)
159{
160 int ret;
161 char src[INET6_ADDRSTRLEN];
162 char dst[INET6_ADDRSTRLEN];
163
164 inet_ntop(AF_INET6, &ip6h->ip6_src, src, INET6_ADDRSTRLEN);
165 inet_ntop(AF_INET6, &ip6h->ip6_dst, dst, INET6_ADDRSTRLEN);
166
167 ret = snprintf(buf, size, "SRC=%s DST=%s LEN=%zu TC=0x%X "
168 "HOPLIMIT=%u FLOWLBL=%u ",
169 src, dst,
170 ntohs(ip6h->ip6_plen) + sizeof(struct ip6_hdr),
171 (ip6h->ip6_flow & 0x0ff00000) >> 20,
172 ip6h->ip6_hlim,
173 (ip6h->ip6_flow & 0x000fffff));
174
175 return ret;
176}
177
int nfq_ip6_snprintf(char *buf, size_t size, const struct ip6_hdr *ip6h)
Definition ipv6.c:158
int nfq_ip6_set_transport_header(struct pkt_buff *pktb, struct ip6_hdr *ip6h, uint8_t target)
Definition ipv6.c:64
int nfq_ip6_mangle(struct pkt_buff *pktb, unsigned int dataoff, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
Definition ipv6.c:131
struct ip6_hdr * nfq_ip6_get_hdr(struct pkt_buff *pktb)
Definition ipv6.c:36
int pktb_mangle(struct pkt_buff *pktb, int dataoff, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
Definition pktbuff.c:314