libnetfilter_queue 1.0.5
udp.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 <stdbool.h>
14#include <arpa/inet.h>
15#include <netinet/ip.h>
16#include <netinet/ip6.h>
17#define _GNU_SOURCE
18#include <netinet/udp.h>
19
20#include <libnetfilter_queue/libnetfilter_queue.h>
21#include <libnetfilter_queue/libnetfilter_queue_udp.h>
22#include <libnetfilter_queue/libnetfilter_queue_ipv4.h>
23#include <libnetfilter_queue/libnetfilter_queue_ipv6.h>
24#include <libnetfilter_queue/pktbuff.h>
25
26#include "internal.h"
27
42EXPORT_SYMBOL
43struct udphdr *nfq_udp_get_hdr(struct pkt_buff *pktb)
44{
45 if (pktb->transport_header == NULL)
46 return NULL;
47
48 /* No room for the UDP header. */
49 if (pktb_tail(pktb) - pktb->transport_header < sizeof(struct udphdr))
50 return NULL;
51
52 return (struct udphdr *)pktb->transport_header;
53}
54
61EXPORT_SYMBOL
62void *nfq_udp_get_payload(struct udphdr *udph, struct pkt_buff *pktb)
63{
64 uint16_t len = ntohs(udph->len);
65
66 /* the UDP packet is too short. */
67 if (len < sizeof(struct udphdr))
68 return NULL;
69
70 /* malformed UDP packet. */
71 if (pktb->transport_header + len > pktb_tail(pktb))
72 return NULL;
73
74 return pktb->transport_header + sizeof(struct udphdr);
75}
76
83EXPORT_SYMBOL
84unsigned int nfq_udp_get_payload_len(struct udphdr *udph, struct pkt_buff *pktb)
85{
86 return pktb_tail(pktb) - pktb->transport_header - sizeof(struct udphdr);
87}
88
107EXPORT_SYMBOL
108void nfq_udp_compute_checksum_ipv4(struct udphdr *udph, struct iphdr *iph)
109{
110 /* checksum field in header needs to be zero for calculation. */
111 udph->check = 0;
112 udph->check = nfq_checksum_tcpudp_ipv4(iph, IPPROTO_UDP);
113}
114
125EXPORT_SYMBOL
126void nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h)
127{
128 /* checksum field in header needs to be zero for calculation. */
129 udph->check = 0;
130 udph->check = nfq_checksum_tcpudp_ipv6(ip6h, udph, IPPROTO_UDP);
131}
132
149EXPORT_SYMBOL
150int nfq_udp_mangle_ipv4(struct pkt_buff *pktb,
151 unsigned int match_offset, unsigned int match_len,
152 const char *rep_buffer, unsigned int rep_len)
153{
154 struct iphdr *iph;
155 struct udphdr *udph;
156
157 iph = (struct iphdr *)pktb->network_header;
158 udph = (struct udphdr *)(pktb->network_header + iph->ihl*4);
159
160 udph->len = htons(ntohs(udph->len) + rep_len - match_len);
161
162 if (!nfq_ip_mangle(pktb, iph->ihl*4 + sizeof(struct udphdr),
163 match_offset, match_len, rep_buffer, rep_len))
164 return 0;
165
167
168 return 1;
169}
170
183EXPORT_SYMBOL
184int nfq_udp_mangle_ipv6(struct pkt_buff *pktb,
185 unsigned int match_offset, unsigned int match_len,
186 const char *rep_buffer, unsigned int rep_len)
187{
188 struct ip6_hdr *ip6h;
189 struct udphdr *udph;
190
191 ip6h = (struct ip6_hdr *)pktb->network_header;
192 udph = (struct udphdr *)(pktb->transport_header);
193 if (!udph)
194 return 0;
195
196 udph->len = htons(ntohs(udph->len) + rep_len - match_len);
197
198 if (!nfq_ip6_mangle(pktb,
199 pktb->transport_header - pktb->network_header +
200 sizeof(struct udphdr),
201 match_offset, match_len, rep_buffer, rep_len))
202 return 0;
203
205
206 return 1;
207}
208
219EXPORT_SYMBOL
220int nfq_udp_snprintf(char *buf, size_t size, const struct udphdr *udph)
221{
222 return snprintf(buf, size, "SPT=%u DPT=%u ",
223 htons(udph->source), htons(udph->dest));
224}
225
int nfq_ip_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: ipv4.c:127
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
void nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h)
Definition: udp.c:126
void nfq_udp_compute_checksum_ipv4(struct udphdr *udph, struct iphdr *iph)
Definition: udp.c:108
void * nfq_udp_get_payload(struct udphdr *udph, struct pkt_buff *pktb)
Definition: udp.c:62
int nfq_udp_mangle_ipv6(struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
Definition: udp.c:184
int nfq_udp_snprintf(char *buf, size_t size, const struct udphdr *udph)
Definition: udp.c:220
unsigned int nfq_udp_get_payload_len(struct udphdr *udph, struct pkt_buff *pktb)
Definition: udp.c:84
struct udphdr * nfq_udp_get_hdr(struct pkt_buff *pktb)
Definition: udp.c:43
int nfq_udp_mangle_ipv4(struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
Definition: udp.c:150