1 /* Copyright (C) 2007-2013 Open Information Security Foundation
2 *
3 * You can copy, redistribute or modify this Program under the terms of
4 * the GNU General Public License version 2 as published by the Free
5 * Software Foundation.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * version 2 along with this program; if not, write to the Free Software
14 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15 * 02110-1301, USA.
16 */
17
18 /**
19 * \file
20 *
21 * \author Victor Julien <victor@inliniac.net>
22 */
23
24 #ifndef __DECODE_UDP_H__
25 #define __DECODE_UDP_H__
26
27 #define UDP_HEADER_LEN 8
28
29 /* XXX RAW* needs to be really 'raw', so no SCNtohs there */
30 #define UDP_GET_RAW_LEN(udph) SCNtohs((udph)->uh_len)
31 #define UDP_GET_RAW_SRC_PORT(udph) SCNtohs((udph)->uh_sport)
32 #define UDP_GET_RAW_DST_PORT(udph) SCNtohs((udph)->uh_dport)
33 #define UDP_GET_RAW_SUM(udph) SCNtohs((udph)->uh_sum)
34
35 #define UDP_GET_LEN(p) UDP_GET_RAW_LEN(p->udph)
36 #define UDP_GET_SRC_PORT(p) UDP_GET_RAW_SRC_PORT(p->udph)
37 #define UDP_GET_DST_PORT(p) UDP_GET_RAW_DST_PORT(p->udph)
38 #define UDP_GET_SUM(p) UDP_GET_RAW_SUM(p->udph)
39
40 /* UDP header structure */
41 typedef struct UDPHdr_
42 {
43 uint16_t uh_sport; /* source port */
44 uint16_t uh_dport; /* destination port */
45 uint16_t uh_len; /* length */
46 uint16_t uh_sum; /* checksum */
47 } __attribute__((__packed__)) UDPHdr;
48
49 #define CLEAR_UDP_PACKET(p) do { \
50 (p)->level4_comp_csum = -1; \
51 (p)->udph = NULL; \
52 } while (0)
53
54 void DecodeUDPV4RegisterTests(void);
55
56 /** ------ Inline function ------ */
57 static inline uint16_t UDPV4Checksum(uint16_t *, uint16_t *, uint16_t, uint16_t);
58 static inline uint16_t UDPV6Checksum(uint16_t *, uint16_t *, uint16_t, uint16_t);
59
60 /**
61 * \brief Calculate or valid the checksum for the UDP packet
62 *
63 * \param shdr Pointer to source address field from the IP packet. Used as a
64 * part of the psuedoheader for computing the checksum
65 * \param pkt Pointer to the start of the UDP packet
66 * \param hlen Total length of the UDP packet(header + payload)
67 * \param init For validation this is the UDP checksum, for calculation this
68 * value should be set to 0.
69 *
70 * \retval csum For validation 0 will be returned for success, for calculation
71 * this will be the checksum.
72 */
UDPV4Checksum(uint16_t * shdr,uint16_t * pkt,uint16_t tlen,uint16_t init)73 static inline uint16_t UDPV4Checksum(uint16_t *shdr, uint16_t *pkt,
74 uint16_t tlen, uint16_t init)
75 {
76 uint16_t pad = 0;
77 uint32_t csum = init;
78
79 csum += shdr[0] + shdr[1] + shdr[2] + shdr[3] + htons(17) + htons(tlen);
80
81 csum += pkt[0] + pkt[1] + pkt[2];
82
83 tlen -= 8;
84 pkt += 4;
85
86 while (tlen >= 32) {
87 csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
88 pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] +
89 pkt[14] + pkt[15];
90 tlen -= 32;
91 pkt += 16;
92 }
93
94 while(tlen >= 8) {
95 csum += pkt[0] + pkt[1] + pkt[2] + pkt[3];
96 tlen -= 8;
97 pkt += 4;
98 }
99
100 while(tlen >= 4) {
101 csum += pkt[0] + pkt[1];
102 tlen -= 4;
103 pkt += 2;
104 }
105
106 while (tlen > 1) {
107 csum += pkt[0];
108 pkt += 1;
109 tlen -= 2;
110 }
111
112 if (tlen == 1) {
113 *(uint8_t *)(&pad) = (*(uint8_t *)pkt);
114 csum += pad;
115 }
116
117 csum = (csum >> 16) + (csum & 0x0000FFFF);
118 csum += (csum >> 16);
119
120 uint16_t csum_u16 = (uint16_t)~csum;
121 if (init == 0 && csum_u16 == 0)
122 return 0xFFFF;
123 else
124 return csum_u16;
125 }
126
127 /**
128 * \brief Calculate or valid the checksum for the UDP packet
129 *
130 * \param shdr Pointer to source address field from the IPV6 packet. Used as a
131 * part of the psuedoheader for computing the checksum
132 * \param pkt Pointer to the start of the UDP packet
133 * \param tlen Total length of the UDP packet(header + payload)
134 * \param init For validation this is the UDP checksum, for calculation this
135 * value should be set to 0.
136 *
137 * \retval csum For validation 0 will be returned for success, for calculation
138 * this will be the checksum.
139 */
UDPV6Checksum(uint16_t * shdr,uint16_t * pkt,uint16_t tlen,uint16_t init)140 static inline uint16_t UDPV6Checksum(uint16_t *shdr, uint16_t *pkt,
141 uint16_t tlen, uint16_t init)
142 {
143 uint16_t pad = 0;
144 uint32_t csum = init;
145
146 csum += shdr[0] + shdr[1] + shdr[2] + shdr[3] + shdr[4] + shdr[5] + shdr[6] +
147 shdr[7] + shdr[8] + shdr[9] + shdr[10] + shdr[11] + shdr[12] +
148 shdr[13] + shdr[14] + shdr[15] + htons(17) + htons(tlen);
149
150 csum += pkt[0] + pkt[1] + pkt[2];
151
152 tlen -= 8;
153 pkt += 4;
154
155 while (tlen >= 32) {
156 csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
157 pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] +
158 pkt[14] + pkt[15];
159 tlen -= 32;
160 pkt += 16;
161 }
162
163 while(tlen >= 8) {
164 csum += pkt[0] + pkt[1] + pkt[2] + pkt[3];
165 tlen -= 8;
166 pkt += 4;
167 }
168
169 while(tlen >= 4) {
170 csum += pkt[0] + pkt[1];
171 tlen -= 4;
172 pkt += 2;
173 }
174
175 while (tlen > 1) {
176 csum += pkt[0];
177 pkt += 1;
178 tlen -= 2;
179 }
180
181 if (tlen == 1) {
182 *(uint8_t *)(&pad) = (*(uint8_t *)pkt);
183 csum += pad;
184 }
185
186 csum = (csum >> 16) + (csum & 0x0000FFFF);
187 csum += (csum >> 16);
188
189 uint16_t csum_u16 = (uint16_t)~csum;
190 if (init == 0 && csum_u16 == 0)
191 return 0xFFFF;
192 else
193 return csum_u16;
194 }
195
196
197 #endif /* __DECODE_UDP_H__ */
198