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 6.22 (Berkeley) 07/27/87"; 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 errno = 0; 244 for (cp = name, n = 0; *cp; cp++) 245 if (*cp == '.') 246 n++; 247 if ((n && *--cp == '.') || (_res.options & RES_DEFNAMES) == 0) { 248 if (n && *cp == '.') 249 *cp = 0; 250 hp = gethostdomain(name, (char *)NULL); 251 if (n && cp == 0) 252 *cp = '.'; 253 return (hp); 254 } 255 if (n == 0 && (cp = hostalias(name))) 256 return (gethostdomain(cp, (char *)NULL)); 257 for (domain = _res.dnsrch; *domain; domain++) { 258 hp = gethostdomain(name, *domain); 259 if (hp) 260 return (hp); 261 /* 262 * If no server present, use host table. 263 * If host isn't found in this domain, 264 * keep trying higher domains in the search list 265 * (if that's enabled). 266 * On a NO_ADDRESS error, keep trying, 267 * or a wildcard MX entry could keep us from finding 268 * host entries higher in the domain. 269 */ 270 if (errno == ECONNREFUSED) 271 return (_gethtbyname(name)); 272 if ((h_errno != HOST_NOT_FOUND && 273 h_errno != NO_ADDRESS) || 274 (_res.options & RES_DNSRCH) == 0) 275 return (NULL); 276 h_errno = 0; 277 } 278 return (gethostdomain(name, (char *)NULL)); 279 } 280 281 static struct hostent * 282 gethostdomain(name, domain) 283 char *name, *domain; 284 { 285 querybuf buf; 286 char nbuf[2*MAXDNAME+2]; 287 int n; 288 289 if (domain == NULL) 290 sprintf(nbuf, "%.*s", MAXDNAME, name); 291 else 292 sprintf(nbuf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain); 293 n = res_mkquery(QUERY, nbuf, C_IN, T_A, (char *)NULL, 0, NULL, 294 (char *)&buf, sizeof(buf)); 295 if (n < 0) { 296 #ifdef DEBUG 297 if (_res.options & RES_DEBUG) 298 printf("res_mkquery failed\n"); 299 #endif 300 return (NULL); 301 } 302 return (getanswer((char *)&buf, n, 0)); 303 } 304 305 struct hostent * 306 gethostbyaddr(addr, len, type) 307 char *addr; 308 int len, type; 309 { 310 int n; 311 querybuf buf; 312 register struct hostent *hp; 313 char qbuf[MAXDNAME]; 314 extern struct hostent *_gethtbyaddr(); 315 316 if (type != AF_INET) 317 return (NULL); 318 (void)sprintf(qbuf, "%d.%d.%d.%d.in-addr.arpa", 319 ((unsigned)addr[3] & 0xff), 320 ((unsigned)addr[2] & 0xff), 321 ((unsigned)addr[1] & 0xff), 322 ((unsigned)addr[0] & 0xff)); 323 n = res_mkquery(QUERY, qbuf, C_IN, T_PTR, (char *)NULL, 0, NULL, 324 (char *)&buf, sizeof(buf)); 325 if (n < 0) { 326 #ifdef DEBUG 327 if (_res.options & RES_DEBUG) 328 printf("res_mkquery failed\n"); 329 #endif 330 return (NULL); 331 } 332 hp = getanswer((char *)&buf, n, 1); 333 if (hp == NULL && errno == ECONNREFUSED) 334 hp = _gethtbyaddr(addr, len, type); 335 if (hp == NULL) 336 return(NULL); 337 hp->h_addrtype = type; 338 hp->h_length = len; 339 h_addr_ptrs[0] = (char *)&host_addr; 340 h_addr_ptrs[1] = (char *)0; 341 host_addr = *(struct in_addr *)addr; 342 return(hp); 343 } 344 345 char * 346 hostalias(name) 347 register char *name; 348 { 349 register char *C1, *C2; 350 FILE *fp; 351 char *file, *getenv(), *strcpy(), *strncpy(); 352 char buf[BUFSIZ]; 353 static char abuf[MAXDNAME]; 354 355 file = getenv("HOSTALIASES"); 356 if (file == NULL || (fp = fopen(file, "r")) == NULL) 357 return (NULL); 358 buf[sizeof(buf) - 1] = '\0'; 359 while (fgets(buf, sizeof(buf), fp)) { 360 for (C1 = buf; *C1 && !isspace(*C1); ++C1); 361 if (!*C1 || *C1 == '\n') 362 break; 363 if (!strcasencmp(buf, name, C1 - buf)) { 364 while (isspace(*++C1)); 365 if (!*C1) 366 break; 367 for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2); 368 abuf[sizeof(abuf) - 1] = *C2 = '\0'; 369 (void)strncpy(abuf, C1, sizeof(abuf) - 1); 370 fclose(fp); 371 return (abuf); 372 } 373 } 374 fclose(fp); 375 return (NULL); 376 } 377 378 _sethtent(f) 379 int f; 380 { 381 if (hostf == NULL) 382 hostf = fopen(HOSTDB, "r" ); 383 else 384 rewind(hostf); 385 stayopen |= f; 386 } 387 388 _endhtent() 389 { 390 if (hostf && !stayopen) { 391 (void) fclose(hostf); 392 hostf = NULL; 393 } 394 } 395 396 struct hostent * 397 _gethtent() 398 { 399 char *p; 400 register char *cp, **q; 401 402 if (hostf == NULL && (hostf = fopen(HOSTDB, "r" )) == NULL) 403 return (NULL); 404 again: 405 if ((p = fgets(line, BUFSIZ, hostf)) == NULL) 406 return (NULL); 407 if (*p == '#') 408 goto again; 409 cp = any(p, "#\n"); 410 if (cp == NULL) 411 goto again; 412 *cp = '\0'; 413 cp = any(p, " \t"); 414 if (cp == NULL) 415 goto again; 416 *cp++ = '\0'; 417 /* THIS STUFF IS INTERNET SPECIFIC */ 418 #if BSD >= 43 419 host.h_addr_list = host_addrs; 420 #endif 421 host.h_addr = hostaddr; 422 *((u_long *)host.h_addr) = inet_addr(p); 423 host.h_length = sizeof (u_long); 424 host.h_addrtype = AF_INET; 425 while (*cp == ' ' || *cp == '\t') 426 cp++; 427 host.h_name = cp; 428 q = host.h_aliases = host_aliases; 429 cp = any(cp, " \t"); 430 if (cp != NULL) 431 *cp++ = '\0'; 432 while (cp && *cp) { 433 if (*cp == ' ' || *cp == '\t') { 434 cp++; 435 continue; 436 } 437 if (q < &host_aliases[MAXALIASES - 1]) 438 *q++ = cp; 439 cp = any(cp, " \t"); 440 if (cp != NULL) 441 *cp++ = '\0'; 442 } 443 *q = NULL; 444 return (&host); 445 } 446 447 static char * 448 any(cp, match) 449 register char *cp; 450 char *match; 451 { 452 register char *mp, c; 453 454 while (c = *cp) { 455 for (mp = match; *mp; mp++) 456 if (*mp == c) 457 return (cp); 458 cp++; 459 } 460 return ((char *)0); 461 } 462 463 struct hostent * 464 _gethtbyname(name) 465 char *name; 466 { 467 register struct hostent *p; 468 register char **cp; 469 470 _sethtent(0); 471 while (p = _gethtent()) { 472 if (strcasecmp(p->h_name, name) == 0) 473 break; 474 for (cp = p->h_aliases; *cp != 0; cp++) 475 if (strcasecmp(*cp, name) == 0) 476 goto found; 477 } 478 found: 479 _endhtent(); 480 return (p); 481 } 482 483 struct hostent * 484 _gethtbyaddr(addr, len, type) 485 char *addr; 486 int len, type; 487 { 488 register struct hostent *p; 489 490 _sethtent(0); 491 while (p = _gethtent()) 492 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len)) 493 break; 494 _endhtent(); 495 return (p); 496 } 497