1 /*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 * icmp.c - convenience functions for translating ICMP and ICMPv6 packets.
17 */
18
19 #include <netinet/in.h>
20 #include <netinet/ip_icmp.h>
21 #include <netinet/icmp6.h>
22 #include <linux/icmp.h>
23
24 #include "logging.h"
25 #include "icmp.h"
26
27 /* function: icmp_guess_ttl
28 * Guesses the number of hops a received packet has traversed based on its TTL.
29 * ttl - the ttl of the received packet.
30 */
icmp_guess_ttl(uint8_t ttl)31 uint8_t icmp_guess_ttl(uint8_t ttl) {
32 if (ttl > 128) {
33 return 255 - ttl;
34 } else if (ttl > 64) {
35 return 128 - ttl;
36 } else if (ttl > 32) {
37 return 64 - ttl;
38 } else {
39 return 32 - ttl;
40 }
41 }
42
43 /* function: is_icmp_error
44 * Determines whether an ICMP type is an error message.
45 * type: the ICMP type
46 */
is_icmp_error(uint8_t type)47 int is_icmp_error(uint8_t type) {
48 return type == 3 || type == 11 || type == 12;
49 }
50
51 /* function: is_icmp6_error
52 * Determines whether an ICMPv6 type is an error message.
53 * type: the ICMPv6 type
54 */
is_icmp6_error(uint8_t type)55 int is_icmp6_error(uint8_t type) {
56 return type < 128;
57 }
58
59 /* function: icmp_to_icmp6_type
60 * Maps ICMP types to ICMPv6 types. Partial implementation of RFC 6145, section 4.2.
61 * type - the ICMPv6 type
62 */
icmp_to_icmp6_type(uint8_t type,uint8_t code)63 uint8_t icmp_to_icmp6_type(uint8_t type, uint8_t code) {
64 switch (type) {
65 case ICMP_ECHO:
66 return ICMP6_ECHO_REQUEST;
67
68 case ICMP_ECHOREPLY:
69 return ICMP6_ECHO_REPLY;
70
71 case ICMP_TIME_EXCEEDED:
72 return ICMP6_TIME_EXCEEDED;
73
74 case ICMP_DEST_UNREACH:
75 // These two types need special translation which we don't support yet.
76 if (code != ICMP_UNREACH_PROTOCOL && code != ICMP_UNREACH_NEEDFRAG) {
77 return ICMP6_DST_UNREACH;
78 }
79 }
80
81 // We don't understand this ICMP type. Return parameter problem so the caller will bail out.
82 logmsg_dbg(ANDROID_LOG_DEBUG, "icmp_to_icmp6_type: unhandled ICMP type %d", type);
83 return ICMP6_PARAM_PROB;
84 }
85
86 /* function: icmp_to_icmp6_code
87 * Maps ICMP codes to ICMPv6 codes. Partial implementation of RFC 6145, section 4.2.
88 * type - the ICMP type
89 * code - the ICMP code
90 */
icmp_to_icmp6_code(uint8_t type,uint8_t code)91 uint8_t icmp_to_icmp6_code(uint8_t type, uint8_t code) {
92 switch (type) {
93 case ICMP_ECHO:
94 case ICMP_ECHOREPLY:
95 return 0;
96
97 case ICMP_TIME_EXCEEDED:
98 return code;
99
100 case ICMP_DEST_UNREACH:
101 switch (code) {
102 case ICMP_UNREACH_NET:
103 case ICMP_UNREACH_HOST:
104 return ICMP6_DST_UNREACH_NOROUTE;
105
106 case ICMP_UNREACH_PORT:
107 return ICMP6_DST_UNREACH_NOPORT;
108
109 case ICMP_UNREACH_NET_PROHIB:
110 case ICMP_UNREACH_HOST_PROHIB:
111 case ICMP_UNREACH_FILTER_PROHIB:
112 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
113 return ICMP6_DST_UNREACH_ADMIN;
114
115 // Otherwise, we don't understand this ICMP type/code combination. Fall through.
116 }
117 }
118 logmsg_dbg(ANDROID_LOG_DEBUG, "icmp_to_icmp6_code: unhandled ICMP type/code %d/%d", type, code);
119 return 0;
120 }
121
122 /* function: icmp6_to_icmp_type
123 * Maps ICMPv6 types to ICMP types. Partial implementation of RFC 6145, section 5.2.
124 * type - the ICMP type
125 */
icmp6_to_icmp_type(uint8_t type,uint8_t code)126 uint8_t icmp6_to_icmp_type(uint8_t type, uint8_t code) {
127 switch (type) {
128 case ICMP6_ECHO_REQUEST:
129 return ICMP_ECHO;
130
131 case ICMP6_ECHO_REPLY:
132 return ICMP_ECHOREPLY;
133
134 case ICMP6_DST_UNREACH:
135 return ICMP_DEST_UNREACH;
136
137 case ICMP6_TIME_EXCEEDED:
138 return ICMP_TIME_EXCEEDED;
139 }
140
141 // We don't understand this ICMP type. Return parameter problem so the caller will bail out.
142 logmsg_dbg(ANDROID_LOG_DEBUG, "icmp6_to_icmp_type: unhandled ICMP type/code %d/%d", type, code);
143 return ICMP_PARAMETERPROB;
144 }
145
146 /* function: icmp6_to_icmp_code
147 * Maps ICMPv6 codes to ICMP codes. Partial implementation of RFC 6145, section 5.2.
148 * type - the ICMPv6 type
149 * code - the ICMPv6 code
150 */
icmp6_to_icmp_code(uint8_t type,uint8_t code)151 uint8_t icmp6_to_icmp_code(uint8_t type, uint8_t code) {
152 switch (type) {
153 case ICMP6_ECHO_REQUEST:
154 case ICMP6_ECHO_REPLY:
155 case ICMP6_TIME_EXCEEDED:
156 return code;
157
158 case ICMP6_DST_UNREACH:
159 switch (code) {
160 case ICMP6_DST_UNREACH_NOROUTE:
161 return ICMP_UNREACH_HOST;
162
163 case ICMP6_DST_UNREACH_ADMIN:
164 return ICMP_UNREACH_HOST_PROHIB;
165
166 case ICMP6_DST_UNREACH_BEYONDSCOPE:
167 return ICMP_UNREACH_HOST;
168
169 case ICMP6_DST_UNREACH_ADDR:
170 return ICMP_HOST_UNREACH;
171
172 case ICMP6_DST_UNREACH_NOPORT:
173 return ICMP_UNREACH_PORT;
174
175 // Otherwise, we don't understand this ICMPv6 type/code combination. Fall through.
176 }
177 }
178
179 logmsg_dbg(ANDROID_LOG_DEBUG, "icmp6_to_icmp_code: unhandled ICMP type/code %d/%d", type, code);
180 return 0;
181 }
182