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 6.13 (Berkeley) 07/16/86"; 9 #endif LIBC_SCCS and not lint 10 11 #include <sys/types.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 host.h_addr_list = h_addr_ptrs; 142 haveanswer = 0; 143 while (--ancount >= 0 && cp < eom) { 144 if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0) 145 break; 146 cp += n; 147 type = getshort(cp); 148 cp += sizeof(u_short); 149 class = getshort(cp); 150 cp += sizeof(u_short) + sizeof(u_long); 151 n = getshort(cp); 152 cp += sizeof(u_short); 153 if (type == T_CNAME) { 154 cp += n; 155 if (ap >= &host_aliases[MAXALIASES-1]) 156 continue; 157 *ap++ = bp; 158 n = strlen(bp) + 1; 159 bp += n; 160 buflen -= n; 161 continue; 162 } 163 if (type == T_PTR) { 164 if ((n = dn_expand((char *)&answer, eom, 165 cp, bp, buflen)) < 0) { 166 cp += n; 167 continue; 168 } 169 cp += n; 170 host.h_name = bp; 171 return(&host); 172 } 173 if (type != T_A) { 174 #ifdef DEBUG 175 if (_res.options & RES_DEBUG) 176 printf("unexpected answer type %d, size %d\n", 177 type, n); 178 #endif 179 cp += n; 180 continue; 181 } 182 if (haveanswer) { 183 if (n != host.h_length) { 184 cp += n; 185 continue; 186 } 187 if (class != getclass) { 188 cp += n; 189 continue; 190 } 191 } else { 192 host.h_length = n; 193 getclass = class; 194 host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC; 195 if (!iquery) { 196 host.h_name = bp; 197 bp += strlen(bp) + 1; 198 } 199 } 200 201 bp += (sizeof(align) - ((u_long)bp % sizeof(align))) &~ 202 sizeof(align); 203 204 if (bp + n >= &hostbuf[sizeof(hostbuf)]) { 205 #ifdef DEBUG 206 if (_res.options & RES_DEBUG) 207 printf("size (%d) too big\n", n); 208 #endif 209 break; 210 } 211 bcopy(cp, *hap++ = bp, n); 212 bp +=n; 213 cp += n; 214 haveanswer++; 215 } 216 if (haveanswer) { 217 *ap = NULL; 218 *hap = NULL; 219 return (&host); 220 } else { 221 h_errno = TRY_AGAIN; 222 return (NULL); 223 } 224 } 225 226 struct hostent * 227 gethostbyname(name) 228 char *name; 229 { 230 int n; 231 querybuf buf; 232 register struct hostent *hp; 233 extern struct hostent *_gethtbyname(); 234 235 n = res_mkquery(QUERY, name, C_IN, T_A, (char *)NULL, 0, NULL, 236 (char *)&buf, sizeof(buf)); 237 if (n < 0) { 238 #ifdef DEBUG 239 if (_res.options & RES_DEBUG) 240 printf("res_mkquery failed\n"); 241 #endif 242 return (NULL); 243 } 244 hp = getanswer((char *)&buf, n, 0); 245 if (hp == NULL && errno == ECONNREFUSED) 246 hp = _gethtbyname(name); 247 return(hp); 248 } 249 250 struct hostent * 251 gethostbyaddr(addr, len, type) 252 char *addr; 253 int len, type; 254 { 255 int n; 256 querybuf buf; 257 register struct hostent *hp; 258 char qbuf[MAXDNAME]; 259 extern struct hostent *_gethtbyaddr(); 260 261 if (type != AF_INET) 262 return (NULL); 263 (void)sprintf(qbuf, "%d.%d.%d.%d.in-addr.arpa", 264 ((unsigned)addr[3] & 0xff), 265 ((unsigned)addr[2] & 0xff), 266 ((unsigned)addr[1] & 0xff), 267 ((unsigned)addr[0] & 0xff)); 268 n = res_mkquery(QUERY, qbuf, C_IN, T_PTR, (char *)NULL, 0, NULL, 269 (char *)&buf, sizeof(buf)); 270 if (n < 0) { 271 #ifdef DEBUG 272 if (_res.options & RES_DEBUG) 273 printf("res_mkquery failed\n"); 274 #endif 275 return (NULL); 276 } 277 hp = getanswer((char *)&buf, n, 1); 278 if (hp == NULL && errno == ECONNREFUSED) 279 hp = _gethtbyaddr(addr, len, type); 280 if (hp == NULL) 281 return(NULL); 282 hp->h_addrtype = type; 283 hp->h_length = len; 284 h_addr_ptrs[0] = (char *)&host_addr; 285 h_addr_ptrs[1] = (char *)0; 286 host_addr = *(struct in_addr *)addr; 287 return(hp); 288 } 289 290 291 _sethtent(f) 292 int f; 293 { 294 if (hostf == NULL) 295 hostf = fopen(HOSTDB, "r" ); 296 else 297 rewind(hostf); 298 stayopen |= f; 299 } 300 301 _endhtent() 302 { 303 if (hostf && !stayopen) { 304 (void) fclose(hostf); 305 hostf = NULL; 306 } 307 } 308 309 struct hostent * 310 _gethtent() 311 { 312 char *p; 313 register char *cp, **q; 314 315 if (hostf == NULL && (hostf = fopen(HOSTDB, "r" )) == NULL) 316 return (NULL); 317 again: 318 if ((p = fgets(line, BUFSIZ, hostf)) == NULL) 319 return (NULL); 320 if (*p == '#') 321 goto again; 322 cp = any(p, "#\n"); 323 if (cp == NULL) 324 goto again; 325 *cp = '\0'; 326 cp = any(p, " \t"); 327 if (cp == NULL) 328 goto again; 329 *cp++ = '\0'; 330 /* THIS STUFF IS INTERNET SPECIFIC */ 331 host.h_addr_list = host_addrs; 332 host.h_addr = hostaddr; 333 *((u_long *)host.h_addr) = inet_addr(p); 334 host.h_length = sizeof (u_long); 335 host.h_addrtype = AF_INET; 336 while (*cp == ' ' || *cp == '\t') 337 cp++; 338 host.h_name = cp; 339 q = host.h_aliases = host_aliases; 340 cp = any(cp, " \t"); 341 if (cp != NULL) 342 *cp++ = '\0'; 343 while (cp && *cp) { 344 if (*cp == ' ' || *cp == '\t') { 345 cp++; 346 continue; 347 } 348 if (q < &host_aliases[MAXALIASES - 1]) 349 *q++ = cp; 350 cp = any(cp, " \t"); 351 if (cp != NULL) 352 *cp++ = '\0'; 353 } 354 *q = NULL; 355 return (&host); 356 } 357 358 static char * 359 any(cp, match) 360 register char *cp; 361 char *match; 362 { 363 register char *mp, c; 364 365 while (c = *cp) { 366 for (mp = match; *mp; mp++) 367 if (*mp == c) 368 return (cp); 369 cp++; 370 } 371 return ((char *)0); 372 } 373 374 struct hostent * 375 _gethtbyname(name) 376 char *name; 377 { 378 register struct hostent *p; 379 register char **cp; 380 char lowname[128]; 381 register char *lp = lowname; 382 383 while (*name) 384 if (isupper(*name)) 385 *lp++ = tolower(*name++); 386 else 387 *lp++ = *name++; 388 *lp = '\0'; 389 390 _sethtent(0); 391 while (p = _gethtent()) { 392 if (strcmp(p->h_name, lowname) == 0) 393 break; 394 for (cp = p->h_aliases; *cp != 0; cp++) 395 if (strcmp(*cp, lowname) == 0) 396 goto found; 397 } 398 found: 399 _endhtent(); 400 return (p); 401 } 402 403 struct hostent * 404 _gethtbyaddr(addr, len, type) 405 char *addr; 406 int len, type; 407 { 408 register struct hostent *p; 409 410 _sethtent(0); 411 while (p = _gethtent()) 412 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len)) 413 break; 414 _endhtent(); 415 return (p); 416 } 417