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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. | |
77 | **/ | |
78 | char *client_name(int fd) | |
79 | { | |
80 | struct sockaddr_storage ss; | |
81 | socklen_t ss_len = sizeof ss; | |
82 | static char name_buf[100]; | |
83 | static char port_buf[100]; | |
84 | static int initialised; | |
85 | ||
86 | if (initialised) return name_buf; | |
87 | ||
88 | strcpy(name_buf, default_name); | |
89 | initialised = 1; | |
90 | ||
91 | client_sockaddr(fd, &ss, &ss_len); | |
92 | ||
93 | if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, port_buf, sizeof port_buf)) | |
be8bd99a | 94 | check_name(fd, &ss, name_buf, port_buf); |
0cd2f407 MP |
95 | |
96 | return name_buf; | |
97 | } | |
98 | ||
99 | ||
100 | ||
101 | /** | |
af32f69e MP |
102 | * Get the sockaddr for the client. |
103 | * | |
104 | * If it comes in as an ipv4 address mapped into IPv6 format then we | |
105 | * convert it back to a regular IPv4. | |
0cd2f407 MP |
106 | **/ |
107 | void client_sockaddr(int fd, | |
108 | struct sockaddr_storage *ss, | |
109 | socklen_t *ss_len) | |
110 | { | |
111 | if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { | |
112 | /* FIXME: Can we really not continue? */ | |
113 | rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n", | |
114 | fd, strerror(errno)); | |
115 | exit_cleanup(RERR_SOCKETIO); | |
116 | } | |
117 | ||
118 | #ifdef INET6 | |
119 | if (get_sockaddr_family(ss) == AF_INET6 && | |
120 | IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { | |
121 | /* OK, so ss is in the IPv6 family, but it is really | |
122 | * an IPv4 address: something like | |
123 | * "::ffff:10.130.1.2". If we use it as-is, then the | |
124 | * reverse lookup might fail or perhaps something else | |
125 | * bad might happen. So instead we convert it to an | |
126 | * equivalent address in the IPv4 address family. */ | |
127 | struct sockaddr_in6 sin6; | |
128 | struct sockaddr_in *sin; | |
129 | ||
130 | memcpy(&sin6, ss, sizeof(sin6)); | |
131 | sin = (struct sockaddr_in *)ss; | |
132 | memset(sin, 0, sizeof(*sin)); | |
133 | sin->sin_family = AF_INET; | |
134 | *ss_len = sizeof(struct sockaddr_in); | |
135 | #ifdef HAVE_SOCKADDR_LEN | |
136 | sin->sin_len = *ss_len; | |
137 | #endif | |
138 | sin->sin_port = sin6.sin6_port; | |
139 | ||
140 | /* There is a macro to extract the mapped part | |
141 | * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem | |
142 | * to be present in the Linux headers. */ | |
143 | memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], | |
144 | sizeof(sin->sin_addr)); | |
145 | } | |
146 | #endif | |
147 | } | |
148 | ||
149 | ||
150 | /** | |
151 | * Look up a name from @p ss into @p name_buf. | |
152 | **/ | |
153 | int lookup_name(int fd, const struct sockaddr_storage *ss, | |
154 | socklen_t ss_len, | |
155 | char *name_buf, size_t name_buf_len, | |
156 | char *port_buf, size_t port_buf_len) | |
157 | { | |
158 | int name_err; | |
159 | ||
160 | /* reverse lookup */ | |
161 | name_err = getnameinfo((struct sockaddr *) ss, ss_len, | |
162 | name_buf, name_buf_len, | |
163 | port_buf, port_buf_len, | |
164 | NI_NAMEREQD | NI_NUMERICSERV); | |
165 | if (name_err != 0) { | |
166 | strcpy(name_buf, default_name); | |
167 | rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n", | |
168 | client_addr(fd), | |
169 | gai_strerror(name_err)); | |
170 | return name_err; | |
171 | } | |
172 | ||
173 | return 0; | |
174 | } | |
175 | ||
176 | ||
177 | ||
974f27e7 MP |
178 | /** |
179 | * Compare an addrinfo from the resolver to a sockinfo. | |
180 | * | |
181 | * Like strcmp, returns 0 for identical. | |
182 | **/ | |
183 | int compare_addrinfo_sockaddr(const struct addrinfo *ai, | |
184 | const struct sockaddr_storage *ss) | |
185 | { | |
186 | int ss_family = get_sockaddr_family(ss); | |
187 | const char fn[] = "compare_addrinfo_sockaddr"; | |
188 | ||
189 | if (ai->ai_family != ss_family) { | |
190 | rprintf(FERROR, | |
191 | "%s: response family %d != %d\n", | |
192 | fn, ai->ai_family, ss_family); | |
193 | return 1; | |
194 | } | |
195 | ||
39e01d2d MP |
196 | /* The comparison method depends on the particular AF. */ |
197 | if (ss_family == AF_INET) { | |
198 | const struct sockaddr_in *sin1, *sin2; | |
199 | ||
200 | sin1 = (const struct sockaddr_in *) ss; | |
201 | sin2 = (const struct sockaddr_in *) ai->ai_addr; | |
202 | ||
6780f720 MP |
203 | return memcmp(&sin1->sin_addr, &sin2->sin_addr, |
204 | sizeof sin1->sin_addr); | |
39e01d2d | 205 | } |
974f27e7 | 206 | #ifdef INET6 |
39e01d2d | 207 | else if (ss_family == AF_INET6) { |
6780f720 MP |
208 | const struct sockaddr_in6 *sin1, *sin2; |
209 | ||
210 | sin1 = (const struct sockaddr_in6 *) ss; | |
211 | sin2 = (const struct sockaddr_in6 *) ai->ai_addr; | |
212 | ||
213 | return memcmp(&sin1->sin6_addr, &sin2->sin6_addr, | |
214 | sizeof sin1->sin6_addr); | |
39e01d2d MP |
215 | } |
216 | #endif /* INET6 */ | |
217 | else { | |
218 | /* don't know */ | |
974f27e7 MP |
219 | return 1; |
220 | } | |
221 | } | |
222 | ||
223 | ||
af32f69e MP |
224 | /** |
225 | * Do a forward lookup on @p name_buf and make sure it corresponds to | |
226 | * @p ss -- otherwise we may be being spoofed. If we suspect we are, | |
227 | * then we don't abort the connection but just emit a warning, and | |
228 | * change @p name_buf to be "UNKNOWN". | |
229 | **/ | |
0cd2f407 MP |
230 | int check_name(int fd, |
231 | const struct sockaddr_storage *ss, | |
0cd2f407 MP |
232 | char *name_buf, |
233 | const char *port_buf) | |
234 | { | |
235 | struct addrinfo hints, *res, *res0; | |
236 | int error; | |
237 | int ss_family = get_sockaddr_family(ss); | |
238 | ||
239 | memset(&hints, 0, sizeof(hints)); | |
39e01d2d MP |
240 | hints.ai_family = ss_family; |
241 | hints.ai_flags = AI_CANONNAME; | |
0cd2f407 MP |
242 | hints.ai_socktype = SOCK_STREAM; |
243 | error = getaddrinfo(name_buf, port_buf, &hints, &res0); | |
244 | if (error) { | |
245 | rprintf(FERROR, | |
af32f69e MP |
246 | RSYNC_NAME ": forward name lookup for %s failed: %s\n", |
247 | name_buf, gai_strerror(error)); | |
0cd2f407 MP |
248 | strcpy(name_buf, default_name); |
249 | return error; | |
250 | } | |
251 | ||
252 | ||
974f27e7 MP |
253 | /* Given all these results, we expect that one of them will be |
254 | * the same as ss. The comparison is a bit complicated. */ | |
0cd2f407 | 255 | for (res = res0; res; res = res->ai_next) { |
974f27e7 MP |
256 | if (!compare_addrinfo_sockaddr(res, ss)) |
257 | break; /* OK, identical */ | |
0cd2f407 MP |
258 | } |
259 | ||
260 | if (!res0) { | |
261 | /* We hit the end of the list without finding an | |
262 | * address that was the same as ss. */ | |
263 | rprintf(FERROR, RSYNC_NAME | |
264 | ": no known address for \"%s\": " | |
265 | "spoofed address?\n", | |
266 | name_buf); | |
267 | strcpy(name_buf, default_name); | |
974f27e7 | 268 | } else if (res == NULL) { |
0cd2f407 MP |
269 | /* We hit the end of the list without finding an |
270 | * address that was the same as ss. */ | |
271 | rprintf(FERROR, RSYNC_NAME | |
272 | ": %s is not a known address for \"%s\": " | |
273 | "spoofed address?\n", | |
274 | client_addr(fd), | |
275 | name_buf); | |
276 | strcpy(name_buf, default_name); | |
277 | } | |
278 | ||
279 | freeaddrinfo(res0); | |
280 | return 0; | |
281 | } | |
282 |