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732b8359 DC |
1 | /* |
2 | * nss-icmp or libnss_icmp - GNU C Library NSS module to query host | |
3 | * names by ICMP. | |
4 | * Copyright (C) 2005 Fredrik Tolf <fredrik@dolda2000.com> | |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Library General Public | |
8 | * License as published by the Free Software Foundation; either | |
9 | * version 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Library General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Library General Public | |
17 | * License along with this library; if not, write to the Free | |
18 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
19 | * MA 02111-1307, USA | |
20 | */ | |
21 | ||
2dec74ab DC |
22 | #include <stdlib.h> |
23 | #include <stdio.h> | |
24 | #include <unistd.h> | |
25 | #include <string.h> | |
26 | #include <errno.h> | |
f0df8f66 | 27 | #include <time.h> |
2dec74ab DC |
28 | #include <sys/socket.h> |
29 | #include <netinet/in.h> | |
30 | #include <netdb.h> | |
31 | #include <arpa/inet.h> | |
32 | #include <nss.h> | |
33 | #include <sys/types.h> | |
34 | #include <fcntl.h> | |
35 | ||
15a913c2 | 36 | #define CONFIGFILE "/etc/nss-icmp.conf" |
78d913fb DC |
37 | #if 0 |
38 | #define DEBUGP(format...) fprintf(stderr, "nss-icmp: " format); | |
39 | #else | |
40 | #define DEBUGP(format...) | |
41 | #endif | |
15a913c2 DC |
42 | |
43 | struct cache { | |
44 | struct cache *next, *prev; | |
45 | char *addr; | |
46 | socklen_t addrlen; | |
47 | int af; | |
48 | int notfound; | |
49 | char **names; | |
f0df8f66 | 50 | time_t at, ttl; |
15a913c2 DC |
51 | }; |
52 | ||
53 | static int inited = 0; | |
54 | static int timeout = -1; | |
55 | static int usecache = 1; | |
f0df8f66 | 56 | static time_t nfttl = 300; |
15a913c2 DC |
57 | static struct cache *cache = NULL; |
58 | ||
59 | static void readconfig(void) | |
60 | { | |
61 | FILE *f; | |
62 | char linebuf[1024]; | |
63 | char *p, *p2; | |
64 | ||
65 | if((f = fopen(CONFIGFILE, "r")) == NULL) | |
66 | return; | |
67 | ||
68 | while(fgets(linebuf, sizeof(linebuf), f) != NULL) { | |
69 | if(linebuf[0] == '#') | |
70 | continue; | |
71 | if((p = strchr(linebuf, '\n')) != NULL) | |
72 | *p = 0; | |
73 | if((p = strchr(linebuf, ' ')) != NULL) { | |
74 | p2 = p + 1; | |
75 | *p = 0; | |
76 | } | |
77 | if(!strcmp(linebuf, "timeout")) { | |
78 | if(p2 == NULL) | |
79 | continue; | |
80 | timeout = atoi(p2); | |
81 | } | |
f0df8f66 DC |
82 | if(!strcmp(linebuf, "ttlnotfound")) { |
83 | if(p2 == NULL) | |
84 | continue; | |
85 | nfttl = atoi(p2); | |
86 | } | |
15a913c2 DC |
87 | if(!strcmp(linebuf, "nocache")) { |
88 | usecache = 0; | |
89 | } | |
90 | } | |
91 | ||
92 | fclose(f); | |
93 | } | |
94 | ||
95 | static void freecache(struct cache *cc) | |
96 | { | |
97 | int i; | |
98 | ||
99 | if(cc->next != NULL) | |
100 | cc->next->prev = cc->prev; | |
101 | if(cc->prev != NULL) | |
102 | cc->prev->next = cc->next; | |
103 | if(cc == cache) | |
104 | cache = cc->next; | |
105 | if(cc->addr != NULL) | |
106 | free(cc->addr); | |
107 | if(cc->names != NULL) { | |
108 | for(i = 0; cc->names[i] != NULL; i++) | |
109 | free(cc->names[i]); | |
110 | free(cc->names); | |
111 | } | |
112 | free(cc); | |
113 | } | |
114 | ||
f0df8f66 | 115 | static void cachenotfound(const void *addr, socklen_t len, int af, time_t ttl) |
15a913c2 DC |
116 | { |
117 | struct cache *cc; | |
118 | ||
119 | for(cc = cache; cc != NULL; cc = cc->next) { | |
120 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) | |
121 | break; | |
122 | } | |
123 | if(cc == NULL) { | |
124 | if((cc = malloc(sizeof(*cc))) == NULL) | |
125 | return; | |
126 | memset(cc, 0, sizeof(*cc)); | |
127 | if((cc->addr = malloc(len)) == NULL) { | |
128 | freecache(cc); | |
129 | return; | |
130 | } | |
131 | memcpy(cc->addr, addr, len); | |
132 | cc->addrlen = len; | |
133 | cc->af = af; | |
f0df8f66 DC |
134 | cc->at = time(NULL); |
135 | cc->ttl = ttl; | |
15a913c2 DC |
136 | |
137 | cc->notfound = 1; | |
138 | ||
139 | cc->next = cache; | |
140 | if(cache != NULL) | |
141 | cache->prev = cc; | |
142 | cache = cc; | |
143 | } | |
144 | } | |
145 | ||
f0df8f66 | 146 | static void updatecache(const void *addr, socklen_t len, int af, char **names, time_t ttl) |
15a913c2 DC |
147 | { |
148 | int i; | |
149 | struct cache *cc; | |
150 | ||
151 | for(cc = cache; cc != NULL; cc = cc->next) { | |
f0df8f66 | 152 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) |
15a913c2 DC |
153 | break; |
154 | } | |
155 | if(cc == NULL) { | |
156 | if((cc = malloc(sizeof(*cc))) == NULL) | |
157 | return; | |
158 | memset(cc, 0, sizeof(*cc)); | |
f0df8f66 | 159 | if((cc->addr = malloc(len)) == NULL) { |
15a913c2 DC |
160 | freecache(cc); |
161 | return; | |
162 | } | |
f0df8f66 DC |
163 | memcpy(cc->addr, addr, len); |
164 | cc->addrlen = len; | |
165 | cc->af = af; | |
166 | cc->at = time(NULL); | |
167 | cc->ttl = ttl; | |
15a913c2 | 168 | |
f0df8f66 | 169 | for(i = 0; names[i] != NULL; i++); |
15a913c2 DC |
170 | if((cc->names = malloc(sizeof(*(cc->names)) * (i + 1))) == NULL) { |
171 | freecache(cc); | |
172 | return; | |
173 | } | |
174 | memset(cc->names, 0, sizeof(*(cc->names)) * (i + 1)); | |
f0df8f66 DC |
175 | for(i = 0; names[i] != NULL; i++) { |
176 | if((cc->names[i] = malloc(strlen(names[i]) + 1)) == NULL) { | |
15a913c2 DC |
177 | freecache(cc); |
178 | return; | |
179 | } | |
f0df8f66 | 180 | strcpy(cc->names[i], names[i]); |
15a913c2 DC |
181 | } |
182 | ||
183 | cc->next = cache; | |
184 | if(cache != NULL) | |
185 | cache->prev = cc; | |
186 | cache = cc; | |
187 | } | |
188 | } | |
189 | ||
f0df8f66 DC |
190 | static void expirecache(void) |
191 | { | |
192 | struct cache *cc, *next; | |
193 | time_t now; | |
194 | ||
195 | now = time(NULL); | |
196 | for(cc = cache; cc != NULL; cc = next) { | |
197 | next = cc->next; | |
198 | if(now - cc->at > cc->ttl) { | |
199 | freecache(cc); | |
200 | continue; | |
201 | } | |
202 | } | |
203 | } | |
204 | ||
2dec74ab DC |
205 | enum nss_status _nss_icmp_gethostbyaddr_r(const void *addr, socklen_t len, int af, struct hostent *result, char *buffer, size_t buflen, int *errnop, int *h_errnop) |
206 | { | |
15a913c2 | 207 | int i, ret; |
2dec74ab DC |
208 | struct retstruct { |
209 | char *aliaslist[16]; | |
210 | char *addrlist[2]; | |
211 | char retaddr[16]; | |
212 | } *retbuf; | |
213 | char addrbuf[1024]; | |
f0df8f66 | 214 | int an, thislen, ttl; |
2dec74ab DC |
215 | char *p, *p2, *p3; |
216 | u_int8_t *ap; | |
217 | pid_t child; | |
218 | int pfd[2]; | |
219 | int rl; | |
15a913c2 DC |
220 | struct cache *cc; |
221 | ||
222 | if(!inited) { | |
223 | readconfig(); | |
224 | inited = 1; | |
225 | } | |
2dec74ab DC |
226 | |
227 | retbuf = (struct retstruct *)buffer; | |
228 | if((buflen < sizeof(*retbuf)) || (len > sizeof(retbuf->retaddr))) { | |
229 | *errnop = ENOMEM; | |
230 | *h_errnop = NETDB_INTERNAL; | |
231 | return(NSS_STATUS_UNAVAIL); | |
232 | } | |
233 | ||
78d913fb DC |
234 | DEBUGP("starting lookup\n"); |
235 | ||
f416a8cd | 236 | if(usecache) { |
f0df8f66 | 237 | expirecache(); |
f416a8cd DC |
238 | for(cc = cache; cc != NULL; cc = cc->next) { |
239 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) | |
240 | break; | |
241 | } | |
242 | } else { | |
243 | cc = NULL; | |
2dec74ab DC |
244 | } |
245 | ||
15a913c2 | 246 | if(cc == NULL) { |
78d913fb | 247 | DEBUGP("address not in cache, looking up for real\n"); |
15a913c2 DC |
248 | ap = (u_int8_t *)addr; |
249 | if(inet_ntop(af, addr, addrbuf, sizeof(addrbuf)) == NULL) { | |
2dec74ab DC |
250 | *errnop = errno; |
251 | *h_errnop = NETDB_INTERNAL; | |
2dec74ab DC |
252 | return(NSS_STATUS_UNAVAIL); |
253 | } | |
78d913fb | 254 | DEBUGP("address is %s\n", addrbuf); |
15a913c2 DC |
255 | |
256 | if(pipe(pfd)) { | |
257 | *errnop = errno; | |
2dec74ab | 258 | *h_errnop = NETDB_INTERNAL; |
2dec74ab DC |
259 | return(NSS_STATUS_UNAVAIL); |
260 | } | |
15a913c2 DC |
261 | /* I honestly don't know if it is considered OK to fork in other |
262 | * people's programs. We need a SUID worker, though, so there's | |
263 | * little choice that I can see. */ | |
264 | if((child = fork()) < 0) { | |
265 | *errnop = errno; | |
2dec74ab DC |
266 | *h_errnop = NETDB_INTERNAL; |
267 | return(NSS_STATUS_UNAVAIL); | |
268 | } | |
15a913c2 DC |
269 | |
270 | if(child == 0) { | |
271 | int i, fd; | |
272 | char timeoutbuf[128]; | |
273 | ||
274 | if((fd = open("/dev/null", O_WRONLY)) < 0) | |
275 | exit(127); | |
276 | close(pfd[0]); | |
277 | dup2(pfd[1], 1); | |
278 | dup2(fd, 2); | |
279 | for(i = 3; i < FD_SETSIZE; i++) | |
280 | close(i); | |
281 | ||
282 | if(timeout != -1) { | |
283 | snprintf(timeoutbuf, sizeof(timeoutbuf), "%i", timeout); | |
f0df8f66 | 284 | execlp("idnlookup", "idnlookup", "-Tt", timeoutbuf, addrbuf, NULL); |
15a913c2 | 285 | } else { |
f0df8f66 | 286 | execlp("idnlookup", "idnlookup", "-T", addrbuf, NULL); |
15a913c2 DC |
287 | } |
288 | exit(127); | |
289 | } | |
290 | ||
291 | close(pfd[1]); | |
292 | ||
293 | rl = 0; | |
294 | do { | |
295 | ret = read(pfd[0], addrbuf + rl, sizeof(addrbuf) - rl); | |
296 | if(ret < 0) { | |
297 | *errnop = errno; | |
298 | *h_errnop = NETDB_INTERNAL; | |
299 | close(pfd[0]); | |
300 | return(NSS_STATUS_UNAVAIL); | |
301 | } | |
302 | rl += ret; | |
303 | if(rl >= sizeof(addrbuf) - 1) { | |
304 | *errnop = ENOMEM; | |
305 | *h_errnop = NETDB_INTERNAL; | |
306 | close(pfd[0]); | |
307 | return(NSS_STATUS_UNAVAIL); | |
308 | } | |
309 | } while(ret != 0); | |
310 | addrbuf[rl] = 0; | |
311 | close(pfd[0]); | |
f0df8f66 DC |
312 | |
313 | if((p = strchr(addrbuf, '\n')) == NULL) { | |
314 | if(usecache) | |
315 | cachenotfound(addr, len, af, nfttl); | |
316 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ | |
317 | return(NSS_STATUS_NOTFOUND); | |
318 | } | |
319 | *(p++) = 0; | |
320 | ttl = atoi(addrbuf); | |
321 | ||
15a913c2 | 322 | an = 0; |
15a913c2 DC |
323 | p3 = buffer + sizeof(*retbuf); |
324 | while((p2 = strchr(p, '\n')) != NULL) { | |
325 | *p2 = 0; | |
326 | thislen = p2 - p; | |
327 | if(thislen == 0) | |
328 | continue; | |
329 | if((p3 - buffer) + thislen + 1 > buflen) { | |
330 | *errnop = ENOMEM; | |
331 | *h_errnop = NETDB_INTERNAL; | |
332 | return(NSS_STATUS_UNAVAIL); | |
333 | } | |
334 | memcpy(p3, p, thislen + 1); | |
335 | retbuf->aliaslist[an] = p3; | |
336 | p3 += thislen + 1; | |
337 | p = p2 + 1; | |
338 | if(++an == 16) { | |
339 | *errnop = ENOMEM; | |
340 | *h_errnop = NETDB_INTERNAL; | |
341 | return(NSS_STATUS_UNAVAIL); | |
342 | } | |
343 | } | |
344 | if(an == 0) { | |
f416a8cd | 345 | if(usecache) |
f0df8f66 | 346 | cachenotfound(addr, len, af, nfttl); |
15a913c2 DC |
347 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ |
348 | return(NSS_STATUS_NOTFOUND); | |
349 | } | |
350 | retbuf->aliaslist[an] = NULL; | |
f0df8f66 DC |
351 | |
352 | if(usecache) | |
353 | updatecache(addr, len, af, retbuf->aliaslist, ttl); | |
15a913c2 | 354 | } else { |
78d913fb | 355 | DEBUGP("address found in cache\n"); |
15a913c2 DC |
356 | if(cc->notfound) { |
357 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ | |
358 | return(NSS_STATUS_NOTFOUND); | |
359 | } | |
360 | ||
361 | p3 = buffer + sizeof(*retbuf); | |
362 | for(i = 0; cc->names[i] != NULL; i++) { | |
363 | thislen = strlen(cc->names[i]); | |
78d913fb | 364 | DEBUGP("filling in address %s, length %i\n", cc->names[i], thislen); |
15a913c2 DC |
365 | if((p3 - buffer) + thislen + 1 > buflen) { |
366 | *errnop = ENOMEM; | |
367 | *h_errnop = NETDB_INTERNAL; | |
368 | return(NSS_STATUS_UNAVAIL); | |
369 | } | |
370 | memcpy(p3, cc->names[i], thislen + 1); | |
78d913fb | 371 | retbuf->aliaslist[i] = p3; |
15a913c2 | 372 | p3 += thislen + 1; |
2dec74ab | 373 | } |
78d913fb | 374 | retbuf->aliaslist[i] = NULL; |
2dec74ab | 375 | } |
2dec74ab | 376 | |
78d913fb | 377 | DEBUGP("returning hostent\n"); |
2dec74ab DC |
378 | memcpy(retbuf->retaddr, addr, len); |
379 | retbuf->addrlist[0] = retbuf->retaddr; | |
380 | retbuf->addrlist[1] = NULL; | |
381 | result->h_name = retbuf->aliaslist[0]; | |
382 | result->h_aliases = retbuf->aliaslist; | |
383 | result->h_addr_list = retbuf->addrlist; | |
384 | result->h_addrtype = af; | |
385 | result->h_length = len; | |
386 | ||
387 | *h_errnop = NETDB_SUCCESS; | |
78d913fb | 388 | DEBUGP("returning\n"); |
2dec74ab DC |
389 | return(NSS_STATUS_SUCCESS); |
390 | } | |
732b8359 DC |
391 | |
392 | /* | |
393 | * Local Variables: | |
394 | * compile-command: "gcc -shared -Wall -g -o libnss_icmp.so.2 nss-icmp.c" | |
395 | * End: | |
396 | */ |