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0cd2f407 MP |
1 | /* -*- c-file-style: "linux" -*- |
2 | ||
3 | rsync -- fast file replication program | |
4 | ||
5 | Copyright (C) 1992-2001 by Andrew Tridgell <tridge@samba.org> | |
6 | Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org> | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program; if not, write to the Free Software | |
20 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | */ | |
22 | ||
23 | /** | |
24 | * @file clientname.c | |
25 | * | |
26 | * Functions for looking up the remote name or addr of a socket. | |
27 | * | |
28 | * This file is now converted to use the new-style getaddrinfo() | |
29 | * interface, which supports IPv6 but is also supported on recent | |
30 | * IPv4-only machines. On systems that don't have that interface, we | |
31 | * emulate it using the KAME implementation. | |
32 | **/ | |
33 | ||
34 | #include "rsync.h" | |
35 | ||
36 | static const char default_name[] = "UNKNOWN"; | |
37 | ||
38 | ||
39 | /** | |
40 | * Return the IP addr of the client as a string | |
41 | **/ | |
42 | char *client_addr(int fd) | |
43 | { | |
44 | struct sockaddr_storage ss; | |
45 | socklen_t length = sizeof ss; | |
46 | static char addr_buf[100]; | |
47 | static int initialised; | |
48 | ||
49 | if (initialised) return addr_buf; | |
50 | ||
51 | initialised = 1; | |
52 | ||
53 | client_sockaddr(fd, &ss, &length); | |
54 | ||
55 | getnameinfo((struct sockaddr *)&ss, length, | |
56 | addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST); | |
57 | ||
58 | return addr_buf; | |
59 | } | |
60 | ||
61 | ||
62 | static int get_sockaddr_family(const struct sockaddr_storage *ss) | |
63 | { | |
64 | return ((struct sockaddr *) ss)->sa_family; | |
65 | } | |
66 | ||
67 | ||
68 | /** | |
69 | * Return the DNS name of the client. | |
70 | * | |
71 | * The name is statically cached so that repeated lookups are quick, | |
72 | * so there is a limit of one lookup per customer. | |
73 | * | |
74 | * If anything goes wrong, including the name->addr->name check, then | |
75 | * we just use "UNKNOWN", so you can use that value in hosts allow | |
76 | * lines. | |
6c92af20 MP |
77 | * |
78 | * After translation from sockaddr to name we do a forward lookup to | |
79 | * make sure nobody is spoofing PTR records. | |
0cd2f407 MP |
80 | **/ |
81 | char *client_name(int fd) | |
82 | { | |
83 | struct sockaddr_storage ss; | |
84 | socklen_t ss_len = sizeof ss; | |
85 | static char name_buf[100]; | |
86 | static char port_buf[100]; | |
87 | static int initialised; | |
88 | ||
89 | if (initialised) return name_buf; | |
90 | ||
91 | strcpy(name_buf, default_name); | |
92 | initialised = 1; | |
93 | ||
94 | client_sockaddr(fd, &ss, &ss_len); | |
95 | ||
6c92af20 MP |
96 | if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, |
97 | port_buf, sizeof port_buf)) | |
98 | check_name(fd, &ss, name_buf); | |
0cd2f407 MP |
99 | |
100 | return name_buf; | |
101 | } | |
102 | ||
103 | ||
104 | ||
105 | /** | |
af32f69e MP |
106 | * Get the sockaddr for the client. |
107 | * | |
108 | * If it comes in as an ipv4 address mapped into IPv6 format then we | |
109 | * convert it back to a regular IPv4. | |
0cd2f407 MP |
110 | **/ |
111 | void client_sockaddr(int fd, | |
112 | struct sockaddr_storage *ss, | |
113 | socklen_t *ss_len) | |
114 | { | |
115 | if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { | |
116 | /* FIXME: Can we really not continue? */ | |
117 | rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n", | |
118 | fd, strerror(errno)); | |
119 | exit_cleanup(RERR_SOCKETIO); | |
120 | } | |
121 | ||
122 | #ifdef INET6 | |
123 | if (get_sockaddr_family(ss) == AF_INET6 && | |
124 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { | |
125 | /* OK, so ss is in the IPv6 family, but it is really | |
126 | * an IPv4 address: something like | |
127 | * "::ffff:10.130.1.2". If we use it as-is, then the | |
128 | * reverse lookup might fail or perhaps something else | |
129 | * bad might happen. So instead we convert it to an | |
130 | * equivalent address in the IPv4 address family. */ | |
131 | struct sockaddr_in6 sin6; | |
132 | struct sockaddr_in *sin; | |
133 | ||
134 | memcpy(&sin6, ss, sizeof(sin6)); | |
135 | sin = (struct sockaddr_in *)ss; | |
136 | memset(sin, 0, sizeof(*sin)); | |
137 | sin->sin_family = AF_INET; | |
138 | *ss_len = sizeof(struct sockaddr_in); | |
139 | #ifdef HAVE_SOCKADDR_LEN | |
140 | sin->sin_len = *ss_len; | |
141 | #endif | |
142 | sin->sin_port = sin6.sin6_port; | |
143 | ||
144 | /* There is a macro to extract the mapped part | |
145 | * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem | |
146 | * to be present in the Linux headers. */ | |
147 | memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], | |
148 | sizeof(sin->sin_addr)); | |
149 | } | |
150 | #endif | |
151 | } | |
152 | ||
153 | ||
154 | /** | |
155 | * Look up a name from @p ss into @p name_buf. | |
6c92af20 MP |
156 | * |
157 | * @param fd file descriptor for client socket. | |
0cd2f407 MP |
158 | **/ |
159 | int lookup_name(int fd, const struct sockaddr_storage *ss, | |
160 | socklen_t ss_len, | |
161 | char *name_buf, size_t name_buf_len, | |
162 | char *port_buf, size_t port_buf_len) | |
163 | { | |
164 | int name_err; | |
165 | ||
166 | /* reverse lookup */ | |
167 | name_err = getnameinfo((struct sockaddr *) ss, ss_len, | |
168 | name_buf, name_buf_len, | |
169 | port_buf, port_buf_len, | |
170 | NI_NAMEREQD | NI_NUMERICSERV); | |
171 | if (name_err != 0) { | |
172 | strcpy(name_buf, default_name); | |
173 | rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n", | |
174 | client_addr(fd), | |
175 | gai_strerror(name_err)); | |
176 | return name_err; | |
177 | } | |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | ||
183 | ||
974f27e7 MP |
184 | /** |
185 | * Compare an addrinfo from the resolver to a sockinfo. | |
186 | * | |
187 | * Like strcmp, returns 0 for identical. | |
188 | **/ | |
189 | int compare_addrinfo_sockaddr(const struct addrinfo *ai, | |
190 | const struct sockaddr_storage *ss) | |
191 | { | |
192 | int ss_family = get_sockaddr_family(ss); | |
193 | const char fn[] = "compare_addrinfo_sockaddr"; | |
194 | ||
195 | if (ai->ai_family != ss_family) { | |
196 | rprintf(FERROR, | |
197 | "%s: response family %d != %d\n", | |
198 | fn, ai->ai_family, ss_family); | |
199 | return 1; | |
200 | } | |
201 | ||
39e01d2d MP |
202 | /* The comparison method depends on the particular AF. */ |
203 | if (ss_family == AF_INET) { | |
204 | const struct sockaddr_in *sin1, *sin2; | |
205 | ||
206 | sin1 = (const struct sockaddr_in *) ss; | |
207 | sin2 = (const struct sockaddr_in *) ai->ai_addr; | |
208 | ||
6780f720 MP |
209 | return memcmp(&sin1->sin_addr, &sin2->sin_addr, |
210 | sizeof sin1->sin_addr); | |
39e01d2d | 211 | } |
974f27e7 | 212 | #ifdef INET6 |
39e01d2d | 213 | else if (ss_family == AF_INET6) { |
6780f720 MP |
214 | const struct sockaddr_in6 *sin1, *sin2; |
215 | ||
216 | sin1 = (const struct sockaddr_in6 *) ss; | |
217 | sin2 = (const struct sockaddr_in6 *) ai->ai_addr; | |
218 | ||
219 | return memcmp(&sin1->sin6_addr, &sin2->sin6_addr, | |
220 | sizeof sin1->sin6_addr); | |
39e01d2d MP |
221 | } |
222 | #endif /* INET6 */ | |
223 | else { | |
224 | /* don't know */ | |
974f27e7 MP |
225 | return 1; |
226 | } | |
227 | } | |
228 | ||
229 | ||
af32f69e MP |
230 | /** |
231 | * Do a forward lookup on @p name_buf and make sure it corresponds to | |
232 | * @p ss -- otherwise we may be being spoofed. If we suspect we are, | |
233 | * then we don't abort the connection but just emit a warning, and | |
234 | * change @p name_buf to be "UNKNOWN". | |
6c92af20 MP |
235 | * |
236 | * We don't do anything with the service when checking the name, | |
237 | * because it doesn't seem that it could be spoofed in any way, and | |
238 | * getaddrinfo on random service names seems to cause problems on AIX. | |
af32f69e | 239 | **/ |
0cd2f407 MP |
240 | int check_name(int fd, |
241 | const struct sockaddr_storage *ss, | |
6c92af20 | 242 | char *name_buf) |
0cd2f407 MP |
243 | { |
244 | struct addrinfo hints, *res, *res0; | |
245 | int error; | |
246 | int ss_family = get_sockaddr_family(ss); | |
247 | ||
248 | memset(&hints, 0, sizeof(hints)); | |
39e01d2d MP |
249 | hints.ai_family = ss_family; |
250 | hints.ai_flags = AI_CANONNAME; | |
0cd2f407 | 251 | hints.ai_socktype = SOCK_STREAM; |
6c92af20 | 252 | error = getaddrinfo(name_buf, NULL, &hints, &res0); |
0cd2f407 MP |
253 | if (error) { |
254 | rprintf(FERROR, | |
af32f69e MP |
255 | RSYNC_NAME ": forward name lookup for %s failed: %s\n", |
256 | name_buf, gai_strerror(error)); | |
0cd2f407 MP |
257 | strcpy(name_buf, default_name); |
258 | return error; | |
259 | } | |
260 | ||
261 | ||
974f27e7 MP |
262 | /* Given all these results, we expect that one of them will be |
263 | * the same as ss. The comparison is a bit complicated. */ | |
0cd2f407 | 264 | for (res = res0; res; res = res->ai_next) { |
974f27e7 MP |
265 | if (!compare_addrinfo_sockaddr(res, ss)) |
266 | break; /* OK, identical */ | |
0cd2f407 MP |
267 | } |
268 | ||
269 | if (!res0) { | |
270 | /* We hit the end of the list without finding an | |
271 | * address that was the same as ss. */ | |
272 | rprintf(FERROR, RSYNC_NAME | |
273 | ": no known address for \"%s\": " | |
274 | "spoofed address?\n", | |
275 | name_buf); | |
276 | strcpy(name_buf, default_name); | |
974f27e7 | 277 | } else if (res == NULL) { |
0cd2f407 MP |
278 | /* We hit the end of the list without finding an |
279 | * address that was the same as ss. */ | |
280 | rprintf(FERROR, RSYNC_NAME | |
281 | ": %s is not a known address for \"%s\": " | |
282 | "spoofed address?\n", | |
283 | client_addr(fd), | |
284 | name_buf); | |
285 | strcpy(name_buf, default_name); | |
286 | } | |
287 | ||
288 | freeaddrinfo(res0); | |
289 | return 0; | |
290 | } | |
291 |