| 1 | #include <stdlib.h> |
| 2 | #include <stdio.h> |
| 3 | #include <unistd.h> |
| 4 | #include <string.h> |
| 5 | #include <errno.h> |
| 6 | #include <time.h> |
| 7 | #include <sys/socket.h> |
| 8 | #include <netinet/in.h> |
| 9 | #include <netdb.h> |
| 10 | #include <arpa/inet.h> |
| 11 | #include <nss.h> |
| 12 | #include <sys/types.h> |
| 13 | #include <fcntl.h> |
| 14 | |
| 15 | #define CONFIGFILE "/etc/nss-icmp.conf" |
| 16 | |
| 17 | struct cache { |
| 18 | struct cache *next, *prev; |
| 19 | char *addr; |
| 20 | socklen_t addrlen; |
| 21 | int af; |
| 22 | int notfound; |
| 23 | char **names; |
| 24 | time_t at, ttl; |
| 25 | }; |
| 26 | |
| 27 | static int inited = 0; |
| 28 | static int timeout = -1; |
| 29 | static int usecache = 1; |
| 30 | static time_t nfttl = 300; |
| 31 | static struct cache *cache = NULL; |
| 32 | |
| 33 | static void readconfig(void) |
| 34 | { |
| 35 | FILE *f; |
| 36 | char linebuf[1024]; |
| 37 | char *p, *p2; |
| 38 | |
| 39 | if((f = fopen(CONFIGFILE, "r")) == NULL) |
| 40 | return; |
| 41 | |
| 42 | while(fgets(linebuf, sizeof(linebuf), f) != NULL) { |
| 43 | if(linebuf[0] == '#') |
| 44 | continue; |
| 45 | if((p = strchr(linebuf, '\n')) != NULL) |
| 46 | *p = 0; |
| 47 | if((p = strchr(linebuf, ' ')) != NULL) { |
| 48 | p2 = p + 1; |
| 49 | *p = 0; |
| 50 | } |
| 51 | if(!strcmp(linebuf, "timeout")) { |
| 52 | if(p2 == NULL) |
| 53 | continue; |
| 54 | timeout = atoi(p2); |
| 55 | } |
| 56 | if(!strcmp(linebuf, "ttlnotfound")) { |
| 57 | if(p2 == NULL) |
| 58 | continue; |
| 59 | nfttl = atoi(p2); |
| 60 | } |
| 61 | if(!strcmp(linebuf, "nocache")) { |
| 62 | usecache = 0; |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | fclose(f); |
| 67 | } |
| 68 | |
| 69 | static void freecache(struct cache *cc) |
| 70 | { |
| 71 | int i; |
| 72 | |
| 73 | if(cc->next != NULL) |
| 74 | cc->next->prev = cc->prev; |
| 75 | if(cc->prev != NULL) |
| 76 | cc->prev->next = cc->next; |
| 77 | if(cc == cache) |
| 78 | cache = cc->next; |
| 79 | if(cc->addr != NULL) |
| 80 | free(cc->addr); |
| 81 | if(cc->names != NULL) { |
| 82 | for(i = 0; cc->names[i] != NULL; i++) |
| 83 | free(cc->names[i]); |
| 84 | free(cc->names); |
| 85 | } |
| 86 | free(cc); |
| 87 | } |
| 88 | |
| 89 | static void cachenotfound(const void *addr, socklen_t len, int af, time_t ttl) |
| 90 | { |
| 91 | struct cache *cc; |
| 92 | |
| 93 | for(cc = cache; cc != NULL; cc = cc->next) { |
| 94 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) |
| 95 | break; |
| 96 | } |
| 97 | if(cc == NULL) { |
| 98 | if((cc = malloc(sizeof(*cc))) == NULL) |
| 99 | return; |
| 100 | memset(cc, 0, sizeof(*cc)); |
| 101 | if((cc->addr = malloc(len)) == NULL) { |
| 102 | freecache(cc); |
| 103 | return; |
| 104 | } |
| 105 | memcpy(cc->addr, addr, len); |
| 106 | cc->addrlen = len; |
| 107 | cc->af = af; |
| 108 | cc->at = time(NULL); |
| 109 | cc->ttl = ttl; |
| 110 | |
| 111 | cc->notfound = 1; |
| 112 | |
| 113 | cc->next = cache; |
| 114 | if(cache != NULL) |
| 115 | cache->prev = cc; |
| 116 | cache = cc; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | static void updatecache(const void *addr, socklen_t len, int af, char **names, time_t ttl) |
| 121 | { |
| 122 | int i; |
| 123 | struct cache *cc; |
| 124 | |
| 125 | for(cc = cache; cc != NULL; cc = cc->next) { |
| 126 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) |
| 127 | break; |
| 128 | } |
| 129 | if(cc == NULL) { |
| 130 | if((cc = malloc(sizeof(*cc))) == NULL) |
| 131 | return; |
| 132 | memset(cc, 0, sizeof(*cc)); |
| 133 | if((cc->addr = malloc(len)) == NULL) { |
| 134 | freecache(cc); |
| 135 | return; |
| 136 | } |
| 137 | memcpy(cc->addr, addr, len); |
| 138 | cc->addrlen = len; |
| 139 | cc->af = af; |
| 140 | cc->at = time(NULL); |
| 141 | cc->ttl = ttl; |
| 142 | |
| 143 | for(i = 0; names[i] != NULL; i++); |
| 144 | if((cc->names = malloc(sizeof(*(cc->names)) * (i + 1))) == NULL) { |
| 145 | freecache(cc); |
| 146 | return; |
| 147 | } |
| 148 | memset(cc->names, 0, sizeof(*(cc->names)) * (i + 1)); |
| 149 | for(i = 0; names[i] != NULL; i++) { |
| 150 | if((cc->names[i] = malloc(strlen(names[i]) + 1)) == NULL) { |
| 151 | freecache(cc); |
| 152 | return; |
| 153 | } |
| 154 | strcpy(cc->names[i], names[i]); |
| 155 | } |
| 156 | |
| 157 | cc->next = cache; |
| 158 | if(cache != NULL) |
| 159 | cache->prev = cc; |
| 160 | cache = cc; |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | static void expirecache(void) |
| 165 | { |
| 166 | struct cache *cc, *next; |
| 167 | time_t now; |
| 168 | |
| 169 | now = time(NULL); |
| 170 | for(cc = cache; cc != NULL; cc = next) { |
| 171 | next = cc->next; |
| 172 | if(now - cc->at > cc->ttl) { |
| 173 | freecache(cc); |
| 174 | continue; |
| 175 | } |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | 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) |
| 180 | { |
| 181 | int i, ret; |
| 182 | struct retstruct { |
| 183 | char *aliaslist[16]; |
| 184 | char *addrlist[2]; |
| 185 | char retaddr[16]; |
| 186 | } *retbuf; |
| 187 | char addrbuf[1024]; |
| 188 | int an, thislen, ttl; |
| 189 | char *p, *p2, *p3; |
| 190 | u_int8_t *ap; |
| 191 | pid_t child; |
| 192 | int pfd[2]; |
| 193 | int rl; |
| 194 | struct cache *cc; |
| 195 | |
| 196 | if(!inited) { |
| 197 | readconfig(); |
| 198 | inited = 1; |
| 199 | } |
| 200 | |
| 201 | retbuf = (struct retstruct *)buffer; |
| 202 | if((buflen < sizeof(*retbuf)) || (len > sizeof(retbuf->retaddr))) { |
| 203 | *errnop = ENOMEM; |
| 204 | *h_errnop = NETDB_INTERNAL; |
| 205 | return(NSS_STATUS_UNAVAIL); |
| 206 | } |
| 207 | |
| 208 | if(usecache) { |
| 209 | expirecache(); |
| 210 | for(cc = cache; cc != NULL; cc = cc->next) { |
| 211 | if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len)) |
| 212 | break; |
| 213 | } |
| 214 | } else { |
| 215 | cc = NULL; |
| 216 | } |
| 217 | |
| 218 | if(cc == NULL) { |
| 219 | ap = (u_int8_t *)addr; |
| 220 | if(inet_ntop(af, addr, addrbuf, sizeof(addrbuf)) == NULL) { |
| 221 | *errnop = errno; |
| 222 | *h_errnop = NETDB_INTERNAL; |
| 223 | return(NSS_STATUS_UNAVAIL); |
| 224 | } |
| 225 | |
| 226 | if(pipe(pfd)) { |
| 227 | *errnop = errno; |
| 228 | *h_errnop = NETDB_INTERNAL; |
| 229 | return(NSS_STATUS_UNAVAIL); |
| 230 | } |
| 231 | /* I honestly don't know if it is considered OK to fork in other |
| 232 | * people's programs. We need a SUID worker, though, so there's |
| 233 | * little choice that I can see. */ |
| 234 | if((child = fork()) < 0) { |
| 235 | *errnop = errno; |
| 236 | *h_errnop = NETDB_INTERNAL; |
| 237 | return(NSS_STATUS_UNAVAIL); |
| 238 | } |
| 239 | |
| 240 | if(child == 0) { |
| 241 | int i, fd; |
| 242 | char timeoutbuf[128]; |
| 243 | |
| 244 | if((fd = open("/dev/null", O_WRONLY)) < 0) |
| 245 | exit(127); |
| 246 | close(pfd[0]); |
| 247 | dup2(pfd[1], 1); |
| 248 | dup2(fd, 2); |
| 249 | for(i = 3; i < FD_SETSIZE; i++) |
| 250 | close(i); |
| 251 | |
| 252 | if(timeout != -1) { |
| 253 | snprintf(timeoutbuf, sizeof(timeoutbuf), "%i", timeout); |
| 254 | execlp("idnlookup", "idnlookup", "-Tt", timeoutbuf, addrbuf, NULL); |
| 255 | } else { |
| 256 | execlp("idnlookup", "idnlookup", "-T", addrbuf, NULL); |
| 257 | } |
| 258 | exit(127); |
| 259 | } |
| 260 | |
| 261 | close(pfd[1]); |
| 262 | |
| 263 | rl = 0; |
| 264 | do { |
| 265 | ret = read(pfd[0], addrbuf + rl, sizeof(addrbuf) - rl); |
| 266 | if(ret < 0) { |
| 267 | *errnop = errno; |
| 268 | *h_errnop = NETDB_INTERNAL; |
| 269 | close(pfd[0]); |
| 270 | return(NSS_STATUS_UNAVAIL); |
| 271 | } |
| 272 | rl += ret; |
| 273 | if(rl >= sizeof(addrbuf) - 1) { |
| 274 | *errnop = ENOMEM; |
| 275 | *h_errnop = NETDB_INTERNAL; |
| 276 | close(pfd[0]); |
| 277 | return(NSS_STATUS_UNAVAIL); |
| 278 | } |
| 279 | } while(ret != 0); |
| 280 | addrbuf[rl] = 0; |
| 281 | close(pfd[0]); |
| 282 | |
| 283 | if((p = strchr(addrbuf, '\n')) == NULL) { |
| 284 | if(usecache) |
| 285 | cachenotfound(addr, len, af, nfttl); |
| 286 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ |
| 287 | return(NSS_STATUS_NOTFOUND); |
| 288 | } |
| 289 | *(p++) = 0; |
| 290 | ttl = atoi(addrbuf); |
| 291 | |
| 292 | an = 0; |
| 293 | p3 = buffer + sizeof(*retbuf); |
| 294 | while((p2 = strchr(p, '\n')) != NULL) { |
| 295 | *p2 = 0; |
| 296 | thislen = p2 - p; |
| 297 | if(thislen == 0) |
| 298 | continue; |
| 299 | if((p3 - buffer) + thislen + 1 > buflen) { |
| 300 | *errnop = ENOMEM; |
| 301 | *h_errnop = NETDB_INTERNAL; |
| 302 | return(NSS_STATUS_UNAVAIL); |
| 303 | } |
| 304 | memcpy(p3, p, thislen + 1); |
| 305 | retbuf->aliaslist[an] = p3; |
| 306 | p3 += thislen + 1; |
| 307 | p = p2 + 1; |
| 308 | if(++an == 16) { |
| 309 | *errnop = ENOMEM; |
| 310 | *h_errnop = NETDB_INTERNAL; |
| 311 | return(NSS_STATUS_UNAVAIL); |
| 312 | } |
| 313 | } |
| 314 | if(an == 0) { |
| 315 | if(usecache) |
| 316 | cachenotfound(addr, len, af, nfttl); |
| 317 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ |
| 318 | return(NSS_STATUS_NOTFOUND); |
| 319 | } |
| 320 | retbuf->aliaslist[an] = NULL; |
| 321 | |
| 322 | if(usecache) |
| 323 | updatecache(addr, len, af, retbuf->aliaslist, ttl); |
| 324 | } else { |
| 325 | if(cc->notfound) { |
| 326 | *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */ |
| 327 | return(NSS_STATUS_NOTFOUND); |
| 328 | } |
| 329 | |
| 330 | p3 = buffer + sizeof(*retbuf); |
| 331 | for(i = 0; cc->names[i] != NULL; i++) { |
| 332 | thislen = strlen(cc->names[i]); |
| 333 | if((p3 - buffer) + thislen + 1 > buflen) { |
| 334 | *errnop = ENOMEM; |
| 335 | *h_errnop = NETDB_INTERNAL; |
| 336 | return(NSS_STATUS_UNAVAIL); |
| 337 | } |
| 338 | memcpy(p3, cc->names[i], thislen + 1); |
| 339 | retbuf->aliaslist[an] = p3; |
| 340 | p3 += thislen + 1; |
| 341 | if(++an == 16) { |
| 342 | *errnop = ENOMEM; |
| 343 | *h_errnop = NETDB_INTERNAL; |
| 344 | return(NSS_STATUS_UNAVAIL); |
| 345 | } |
| 346 | } |
| 347 | } |
| 348 | |
| 349 | memcpy(retbuf->retaddr, addr, len); |
| 350 | retbuf->addrlist[0] = retbuf->retaddr; |
| 351 | retbuf->addrlist[1] = NULL; |
| 352 | result->h_name = retbuf->aliaslist[0]; |
| 353 | result->h_aliases = retbuf->aliaslist; |
| 354 | result->h_addr_list = retbuf->addrlist; |
| 355 | result->h_addrtype = af; |
| 356 | result->h_length = len; |
| 357 | |
| 358 | *h_errnop = NETDB_SUCCESS; |
| 359 | return(NSS_STATUS_SUCCESS); |
| 360 | } |