1 /* 2 * Copyright (c) 1985 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #if defined(LIBC_SCCS) && !defined(lint) 8 static char sccsid[] = "@(#)gethostnamadr.c 6.23 (Berkeley) 08/03/87"; 9 #endif LIBC_SCCS and not lint 10 11 #include <sys/param.h> 12 #include <sys/socket.h> 13 #include <netinet/in.h> 14 #include <ctype.h> 15 #include <netdb.h> 16 #include <stdio.h> 17 #include <errno.h> 18 #include <arpa/inet.h> 19 #include <arpa/nameser.h> 20 #include <resolv.h> 21 22 #define MAXALIASES 35 23 #define MAXADDRS 35 24 25 static char *h_addr_ptrs[MAXADDRS + 1]; 26 27 static struct hostent host; 28 static char *host_aliases[MAXALIASES]; 29 static char hostbuf[BUFSIZ+1]; 30 static struct in_addr host_addr; 31 static char HOSTDB[] = "/etc/hosts"; 32 static FILE *hostf = NULL; 33 static char line[BUFSIZ+1]; 34 static char hostaddr[MAXADDRS]; 35 static char *host_addrs[2]; 36 static int stayopen = 0; 37 static char *any(); 38 39 typedef union { 40 HEADER qb1; 41 char qb2[PACKETSZ]; 42 } querybuf; 43 44 static union { 45 long al; 46 char ac; 47 } align; 48 49 50 int h_errno; 51 extern errno; 52 53 static struct hostent * 54 getanswer(msg, msglen, iquery) 55 char *msg; 56 int msglen, iquery; 57 { 58 register HEADER *hp; 59 register char *cp; 60 register int n; 61 querybuf answer; 62 char *eom, *bp, **ap; 63 int type, class, buflen, ancount, qdcount; 64 int haveanswer, getclass = C_ANY; 65 char **hap; 66 67 n = res_send(msg, msglen, (char *)&answer, sizeof(answer)); 68 if (n < 0) { 69 #ifdef DEBUG 70 int terrno; 71 terrno = errno; 72 if (_res.options & RES_DEBUG) 73 printf("res_send failed\n"); 74 errno = terrno; 75 #endif 76 h_errno = TRY_AGAIN; 77 return (NULL); 78 } 79 eom = (char *)&answer + n; 80 /* 81 * find first satisfactory answer 82 */ 83 hp = (HEADER *) &answer; 84 ancount = ntohs(hp->ancount); 85 qdcount = ntohs(hp->qdcount); 86 if (hp->rcode != NOERROR || ancount == 0) { 87 #ifdef DEBUG 88 if (_res.options & RES_DEBUG) 89 printf("rcode = %d, ancount=%d\n", hp->rcode, ancount); 90 #endif 91 switch (hp->rcode) { 92 case NXDOMAIN: 93 /* Check if it's an authoritive answer */ 94 if (hp->aa) 95 h_errno = HOST_NOT_FOUND; 96 else 97 h_errno = TRY_AGAIN; 98 break; 99 case SERVFAIL: 100 h_errno = TRY_AGAIN; 101 break; 102 case NOERROR: 103 h_errno = NO_ADDRESS; 104 break; 105 case FORMERR: 106 case NOTIMP: 107 case REFUSED: 108 h_errno = NO_RECOVERY; 109 } 110 return (NULL); 111 } 112 bp = hostbuf; 113 buflen = sizeof(hostbuf); 114 cp = (char *)&answer + sizeof(HEADER); 115 if (qdcount) { 116 if (iquery) { 117 if ((n = dn_expand((char *)&answer, eom, 118 cp, bp, buflen)) < 0) { 119 h_errno = NO_RECOVERY; 120 return (NULL); 121 } 122 cp += n + QFIXEDSZ; 123 host.h_name = bp; 124 n = strlen(bp) + 1; 125 bp += n; 126 buflen -= n; 127 } else 128 cp += dn_skip(cp) + QFIXEDSZ; 129 while (--qdcount > 0) 130 cp += dn_skip(cp) + QFIXEDSZ; 131 } else if (iquery) { 132 if (hp->aa) 133 h_errno = HOST_NOT_FOUND; 134 else 135 h_errno = TRY_AGAIN; 136 return (NULL); 137 } 138 ap = host_aliases; 139 host.h_aliases = host_aliases; 140 hap = h_addr_ptrs; 141 #if BSD >= 43 142 host.h_addr_list = h_addr_ptrs; 143 #endif 144 haveanswer = 0; 145 while (--ancount >= 0 && cp < eom) { 146 if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0) 147 break; 148 cp += n; 149 type = _getshort(cp); 150 cp += sizeof(u_short); 151 class = _getshort(cp); 152 cp += sizeof(u_short) + sizeof(u_long); 153 n = _getshort(cp); 154 cp += sizeof(u_short); 155 if (type == T_CNAME) { 156 cp += n; 157 if (ap >= &host_aliases[MAXALIASES-1]) 158 continue; 159 *ap++ = bp; 160 n = strlen(bp) + 1; 161 bp += n; 162 buflen -= n; 163 continue; 164 } 165 if (type == T_PTR) { 166 if ((n = dn_expand((char *)&answer, eom, 167 cp, bp, buflen)) < 0) { 168 cp += n; 169 continue; 170 } 171 cp += n; 172 host.h_name = bp; 173 return(&host); 174 } 175 if (type != T_A) { 176 #ifdef DEBUG 177 if (_res.options & RES_DEBUG) 178 printf("unexpected answer type %d, size %d\n", 179 type, n); 180 #endif 181 cp += n; 182 continue; 183 } 184 if (haveanswer) { 185 if (n != host.h_length) { 186 cp += n; 187 continue; 188 } 189 if (class != getclass) { 190 cp += n; 191 continue; 192 } 193 } else { 194 host.h_length = n; 195 getclass = class; 196 host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC; 197 if (!iquery) { 198 host.h_name = bp; 199 bp += strlen(bp) + 1; 200 } 201 } 202 203 bp += sizeof(align) - ((u_long)bp % sizeof(align)); 204 205 if (bp + n >= &hostbuf[sizeof(hostbuf)]) { 206 #ifdef DEBUG 207 if (_res.options & RES_DEBUG) 208 printf("size (%d) too big\n", n); 209 #endif 210 break; 211 } 212 bcopy(cp, *hap++ = bp, n); 213 bp +=n; 214 cp += n; 215 haveanswer++; 216 } 217 if (haveanswer) { 218 *ap = NULL; 219 #if BSD >= 43 220 *hap = NULL; 221 #else 222 host.h_addr = h_addr_ptrs[0]; 223 #endif 224 return (&host); 225 } else { 226 h_errno = TRY_AGAIN; 227 return (NULL); 228 } 229 } 230 231 struct hostent * 232 gethostbyname(name) 233 char *name; 234 { 235 register char *cp, **domain; 236 int n; 237 struct hostent *hp, *gethostdomain(); 238 char *hostalias(); 239 extern struct hostent *_gethtbyname(); 240 241 if (!(_res.options & RES_INIT) && res_init() == -1) 242 return (NULL); 243 if (isdigit(name[0])) { 244 h_errno = HOST_NOT_FOUND; 245 return (NULL); 246 247 } 248 errno = 0; 249 for (cp = name, n = 0; *cp; cp++) 250 if (*cp == '.') 251 n++; 252 if ((n && *--cp == '.') || (_res.options & RES_DEFNAMES) == 0) { 253 if (n && *cp == '.') 254 *cp = 0; 255 hp = gethostdomain(name, (char *)NULL); 256 if (n && cp == 0) 257 *cp = '.'; 258 return (hp); 259 } 260 if (n == 0 && (cp = hostalias(name))) 261 return (gethostdomain(cp, (char *)NULL)); 262 for (domain = _res.dnsrch; *domain; domain++) { 263 hp = gethostdomain(name, *domain); 264 if (hp) 265 return (hp); 266 /* 267 * If no server present, use host table. 268 * If host isn't found in this domain, 269 * keep trying higher domains in the search list 270 * (if that's enabled). 271 * On a NO_ADDRESS error, keep trying, 272 * or a wildcard MX entry could keep us from finding 273 * host entries higher in the domain. 274 */ 275 if (errno == ECONNREFUSED) 276 return (_gethtbyname(name)); 277 if ((h_errno != HOST_NOT_FOUND && 278 h_errno != NO_ADDRESS) || 279 (_res.options & RES_DNSRCH) == 0) 280 return (NULL); 281 h_errno = 0; 282 } 283 return (gethostdomain(name, (char *)NULL)); 284 } 285 286 static struct hostent * 287 gethostdomain(name, domain) 288 char *name, *domain; 289 { 290 querybuf buf; 291 char nbuf[2*MAXDNAME+2]; 292 int n; 293 294 if (domain == NULL) 295 sprintf(nbuf, "%.*s", MAXDNAME, name); 296 else 297 sprintf(nbuf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain); 298 n = res_mkquery(QUERY, nbuf, C_IN, T_A, (char *)NULL, 0, NULL, 299 (char *)&buf, sizeof(buf)); 300 if (n < 0) { 301 #ifdef DEBUG 302 if (_res.options & RES_DEBUG) 303 printf("res_mkquery failed\n"); 304 #endif 305 return (NULL); 306 } 307 return (getanswer((char *)&buf, n, 0)); 308 } 309 310 struct hostent * 311 gethostbyaddr(addr, len, type) 312 char *addr; 313 int len, type; 314 { 315 int n; 316 querybuf buf; 317 register struct hostent *hp; 318 char qbuf[MAXDNAME]; 319 extern struct hostent *_gethtbyaddr(); 320 321 if (type != AF_INET) 322 return (NULL); 323 (void)sprintf(qbuf, "%d.%d.%d.%d.in-addr.arpa", 324 ((unsigned)addr[3] & 0xff), 325 ((unsigned)addr[2] & 0xff), 326 ((unsigned)addr[1] & 0xff), 327 ((unsigned)addr[0] & 0xff)); 328 n = res_mkquery(QUERY, qbuf, C_IN, T_PTR, (char *)NULL, 0, NULL, 329 (char *)&buf, sizeof(buf)); 330 if (n < 0) { 331 #ifdef DEBUG 332 if (_res.options & RES_DEBUG) 333 printf("res_mkquery failed\n"); 334 #endif 335 return (NULL); 336 } 337 hp = getanswer((char *)&buf, n, 1); 338 if (hp == NULL && errno == ECONNREFUSED) 339 hp = _gethtbyaddr(addr, len, type); 340 if (hp == NULL) 341 return(NULL); 342 hp->h_addrtype = type; 343 hp->h_length = len; 344 h_addr_ptrs[0] = (char *)&host_addr; 345 h_addr_ptrs[1] = (char *)0; 346 host_addr = *(struct in_addr *)addr; 347 return(hp); 348 } 349 350 char * 351 hostalias(name) 352 register char *name; 353 { 354 register char *C1, *C2; 355 FILE *fp; 356 char *file, *getenv(), *strcpy(), *strncpy(); 357 char buf[BUFSIZ]; 358 static char abuf[MAXDNAME]; 359 360 file = getenv("HOSTALIASES"); 361 if (file == NULL || (fp = fopen(file, "r")) == NULL) 362 return (NULL); 363 buf[sizeof(buf) - 1] = '\0'; 364 while (fgets(buf, sizeof(buf), fp)) { 365 for (C1 = buf; *C1 && !isspace(*C1); ++C1); 366 if (!*C1 || *C1 == '\n') 367 break; 368 if (!strncasecmp(buf, name, C1 - buf)) { 369 while (isspace(*++C1)); 370 if (!*C1) 371 break; 372 for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2); 373 abuf[sizeof(abuf) - 1] = *C2 = '\0'; 374 (void)strncpy(abuf, C1, sizeof(abuf) - 1); 375 fclose(fp); 376 return (abuf); 377 } 378 } 379 fclose(fp); 380 return (NULL); 381 } 382 383 _sethtent(f) 384 int f; 385 { 386 if (hostf == NULL) 387 hostf = fopen(HOSTDB, "r" ); 388 else 389 rewind(hostf); 390 stayopen |= f; 391 } 392 393 _endhtent() 394 { 395 if (hostf && !stayopen) { 396 (void) fclose(hostf); 397 hostf = NULL; 398 } 399 } 400 401 struct hostent * 402 _gethtent() 403 { 404 char *p; 405 register char *cp, **q; 406 407 if (hostf == NULL && (hostf = fopen(HOSTDB, "r" )) == NULL) 408 return (NULL); 409 again: 410 if ((p = fgets(line, BUFSIZ, hostf)) == NULL) 411 return (NULL); 412 if (*p == '#') 413 goto again; 414 cp = any(p, "#\n"); 415 if (cp == NULL) 416 goto again; 417 *cp = '\0'; 418 cp = any(p, " \t"); 419 if (cp == NULL) 420 goto again; 421 *cp++ = '\0'; 422 /* THIS STUFF IS INTERNET SPECIFIC */ 423 #if BSD >= 43 424 host.h_addr_list = host_addrs; 425 #endif 426 host.h_addr = hostaddr; 427 *((u_long *)host.h_addr) = inet_addr(p); 428 host.h_length = sizeof (u_long); 429 host.h_addrtype = AF_INET; 430 while (*cp == ' ' || *cp == '\t') 431 cp++; 432 host.h_name = cp; 433 q = host.h_aliases = host_aliases; 434 cp = any(cp, " \t"); 435 if (cp != NULL) 436 *cp++ = '\0'; 437 while (cp && *cp) { 438 if (*cp == ' ' || *cp == '\t') { 439 cp++; 440 continue; 441 } 442 if (q < &host_aliases[MAXALIASES - 1]) 443 *q++ = cp; 444 cp = any(cp, " \t"); 445 if (cp != NULL) 446 *cp++ = '\0'; 447 } 448 *q = NULL; 449 return (&host); 450 } 451 452 static char * 453 any(cp, match) 454 register char *cp; 455 char *match; 456 { 457 register char *mp, c; 458 459 while (c = *cp) { 460 for (mp = match; *mp; mp++) 461 if (*mp == c) 462 return (cp); 463 cp++; 464 } 465 return ((char *)0); 466 } 467 468 struct hostent * 469 _gethtbyname(name) 470 char *name; 471 { 472 register struct hostent *p; 473 register char **cp; 474 475 _sethtent(0); 476 while (p = _gethtent()) { 477 if (strcasecmp(p->h_name, name) == 0) 478 break; 479 for (cp = p->h_aliases; *cp != 0; cp++) 480 if (strcasecmp(*cp, name) == 0) 481 goto found; 482 } 483 found: 484 _endhtent(); 485 return (p); 486 } 487 488 struct hostent * 489 _gethtbyaddr(addr, len, type) 490 char *addr; 491 int len, type; 492 { 493 register struct hostent *p; 494 495 _sethtent(0); 496 while (p = _gethtent()) 497 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len)) 498 break; 499 _endhtent(); 500 return (p); 501 } 502