1 /* 2 * Copyright (c) 1985, 1988 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)gethostnamadr.c 6.45 (Berkeley) 02/24/91"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <sys/param.h> 13 #include <sys/socket.h> 14 #include <netinet/in.h> 15 #include <arpa/inet.h> 16 #include <arpa/nameser.h> 17 #include <netdb.h> 18 #include <resolv.h> 19 #include <stdio.h> 20 #include <ctype.h> 21 #include <errno.h> 22 #include <string.h> 23 24 #define MAXALIASES 35 25 #define MAXADDRS 35 26 27 static char *h_addr_ptrs[MAXADDRS + 1]; 28 29 static struct hostent host; 30 static char *host_aliases[MAXALIASES]; 31 static char hostbuf[BUFSIZ+1]; 32 static struct in_addr host_addr; 33 static FILE *hostf = NULL; 34 static char hostaddr[MAXADDRS]; 35 static char *host_addrs[2]; 36 static int stayopen = 0; 37 char *strpbrk(); 38 39 #if PACKETSZ > 1024 40 #define MAXPACKET PACKETSZ 41 #else 42 #define MAXPACKET 1024 43 #endif 44 45 typedef union { 46 HEADER hdr; 47 u_char buf[MAXPACKET]; 48 } querybuf; 49 50 typedef union { 51 long al; 52 char ac; 53 } align; 54 55 int h_errno; 56 57 static struct hostent * 58 getanswer(answer, anslen, iquery) 59 querybuf *answer; 60 int anslen; 61 int iquery; 62 { 63 register HEADER *hp; 64 register u_char *cp; 65 register int n; 66 u_char *eom; 67 char *bp, **ap; 68 int type, class, buflen, ancount, qdcount; 69 int haveanswer, getclass = C_ANY; 70 char **hap; 71 72 eom = answer->buf + anslen; 73 /* 74 * find first satisfactory answer 75 */ 76 hp = &answer->hdr; 77 ancount = ntohs(hp->ancount); 78 qdcount = ntohs(hp->qdcount); 79 bp = hostbuf; 80 buflen = sizeof(hostbuf); 81 cp = answer->buf + sizeof(HEADER); 82 if (qdcount) { 83 if (iquery) { 84 if ((n = dn_expand((u_char *)answer->buf, 85 (u_char *)eom, (u_char *)cp, (u_char *)bp, 86 buflen)) < 0) { 87 h_errno = NO_RECOVERY; 88 return ((struct hostent *) NULL); 89 } 90 cp += n + QFIXEDSZ; 91 host.h_name = bp; 92 n = strlen(bp) + 1; 93 bp += n; 94 buflen -= n; 95 } else 96 cp += __dn_skipname(cp, eom) + QFIXEDSZ; 97 while (--qdcount > 0) 98 cp += __dn_skipname(cp, eom) + QFIXEDSZ; 99 } else if (iquery) { 100 if (hp->aa) 101 h_errno = HOST_NOT_FOUND; 102 else 103 h_errno = TRY_AGAIN; 104 return ((struct hostent *) NULL); 105 } 106 ap = host_aliases; 107 *ap = NULL; 108 host.h_aliases = host_aliases; 109 hap = h_addr_ptrs; 110 *hap = NULL; 111 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */ 112 host.h_addr_list = h_addr_ptrs; 113 #endif 114 haveanswer = 0; 115 while (--ancount >= 0 && cp < eom) { 116 if ((n = dn_expand((u_char *)answer->buf, (u_char *)eom, 117 (u_char *)cp, (u_char *)bp, buflen)) < 0) 118 break; 119 cp += n; 120 type = _getshort(cp); 121 cp += sizeof(u_short); 122 class = _getshort(cp); 123 cp += sizeof(u_short) + sizeof(u_long); 124 n = _getshort(cp); 125 cp += sizeof(u_short); 126 if (type == T_CNAME) { 127 cp += n; 128 if (ap >= &host_aliases[MAXALIASES-1]) 129 continue; 130 *ap++ = bp; 131 n = strlen(bp) + 1; 132 bp += n; 133 buflen -= n; 134 continue; 135 } 136 if (iquery && type == T_PTR) { 137 if ((n = dn_expand((u_char *)answer->buf, 138 (u_char *)eom, (u_char *)cp, (u_char *)bp, 139 buflen)) < 0) { 140 cp += n; 141 continue; 142 } 143 cp += n; 144 host.h_name = bp; 145 return(&host); 146 } 147 if (iquery || type != T_A) { 148 #ifdef DEBUG 149 if (_res.options & RES_DEBUG) 150 printf("unexpected answer type %d, size %d\n", 151 type, n); 152 #endif 153 cp += n; 154 continue; 155 } 156 if (haveanswer) { 157 if (n != host.h_length) { 158 cp += n; 159 continue; 160 } 161 if (class != getclass) { 162 cp += n; 163 continue; 164 } 165 } else { 166 host.h_length = n; 167 getclass = class; 168 host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC; 169 if (!iquery) { 170 host.h_name = bp; 171 bp += strlen(bp) + 1; 172 } 173 } 174 175 bp += sizeof(align) - ((u_long)bp % sizeof(align)); 176 177 if (bp + n >= &hostbuf[sizeof(hostbuf)]) { 178 #ifdef DEBUG 179 if (_res.options & RES_DEBUG) 180 printf("size (%d) too big\n", n); 181 #endif 182 break; 183 } 184 bcopy(cp, *hap++ = bp, n); 185 bp +=n; 186 cp += n; 187 haveanswer++; 188 } 189 if (haveanswer) { 190 *ap = NULL; 191 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */ 192 *hap = NULL; 193 #else 194 host.h_addr = h_addr_ptrs[0]; 195 #endif 196 return (&host); 197 } else { 198 h_errno = TRY_AGAIN; 199 return ((struct hostent *) NULL); 200 } 201 } 202 203 struct hostent * 204 gethostbyname(name) 205 char *name; 206 { 207 querybuf buf; 208 register char *cp; 209 int n; 210 extern struct hostent *_gethtbyname(); 211 212 /* 213 * disallow names consisting only of digits/dots, unless 214 * they end in a dot. 215 */ 216 if (isdigit(name[0])) 217 for (cp = name;; ++cp) { 218 if (!*cp) { 219 if (*--cp == '.') 220 break; 221 /* 222 * All-numeric, no dot at the end. 223 * Fake up a hostent as if we'd actually 224 * done a lookup. What if someone types 225 * 255.255.255.255? The test below will 226 * succeed spuriously... ??? 227 */ 228 if ((host_addr.s_addr = inet_addr(name)) == -1) { 229 h_errno = HOST_NOT_FOUND; 230 return((struct hostent *) NULL); 231 } 232 host.h_name = name; 233 host.h_aliases = host_aliases; 234 host_aliases[0] = NULL; 235 host.h_addrtype = AF_INET; 236 host.h_length = sizeof(u_long); 237 h_addr_ptrs[0] = (char *)&host_addr; 238 h_addr_ptrs[1] = (char *)0; 239 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */ 240 host.h_addr_list = h_addr_ptrs; 241 #else 242 host.h_addr = h_addr_ptrs[0]; 243 #endif 244 return (&host); 245 } 246 if (!isdigit(*cp) && *cp != '.') 247 break; 248 } 249 250 if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) { 251 #ifdef DEBUG 252 if (_res.options & RES_DEBUG) 253 printf("res_search failed\n"); 254 #endif 255 if (errno == ECONNREFUSED) 256 return (_gethtbyname(name)); 257 else 258 return ((struct hostent *) NULL); 259 } 260 return (getanswer(&buf, n, 0)); 261 } 262 263 struct hostent * 264 gethostbyaddr(addr, len, type) 265 const char *addr; 266 int len, type; 267 { 268 int n; 269 querybuf buf; 270 register struct hostent *hp; 271 char qbuf[MAXDNAME]; 272 extern struct hostent *_gethtbyaddr(); 273 274 if (type != AF_INET) 275 return ((struct hostent *) NULL); 276 (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", 277 ((unsigned)addr[3] & 0xff), 278 ((unsigned)addr[2] & 0xff), 279 ((unsigned)addr[1] & 0xff), 280 ((unsigned)addr[0] & 0xff)); 281 n = res_query(qbuf, C_IN, T_PTR, (char *)&buf, sizeof(buf)); 282 if (n < 0) { 283 #ifdef DEBUG 284 if (_res.options & RES_DEBUG) 285 printf("res_query failed\n"); 286 #endif 287 if (errno == ECONNREFUSED) 288 return (_gethtbyaddr(addr, len, type)); 289 return ((struct hostent *) NULL); 290 } 291 hp = getanswer(&buf, n, 1); 292 if (hp == NULL) 293 return ((struct hostent *) NULL); 294 hp->h_addrtype = type; 295 hp->h_length = len; 296 h_addr_ptrs[0] = (char *)&host_addr; 297 h_addr_ptrs[1] = (char *)0; 298 host_addr = *(struct in_addr *)addr; 299 #if BSD < 43 && !defined(h_addr) /* new-style hostent structure */ 300 hp->h_addr = h_addr_ptrs[0]; 301 #endif 302 return(hp); 303 } 304 305 _sethtent(f) 306 int f; 307 { 308 if (hostf == NULL) 309 hostf = fopen(_PATH_HOSTS, "r" ); 310 else 311 rewind(hostf); 312 stayopen |= f; 313 } 314 315 _endhtent() 316 { 317 if (hostf && !stayopen) { 318 (void) fclose(hostf); 319 hostf = NULL; 320 } 321 } 322 323 struct hostent * 324 _gethtent() 325 { 326 char *p; 327 register char *cp, **q; 328 329 if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL) 330 return (NULL); 331 again: 332 if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL) 333 return (NULL); 334 if (*p == '#') 335 goto again; 336 cp = strpbrk(p, "#\n"); 337 if (cp == NULL) 338 goto again; 339 *cp = '\0'; 340 cp = strpbrk(p, " \t"); 341 if (cp == NULL) 342 goto again; 343 *cp++ = '\0'; 344 /* THIS STUFF IS INTERNET SPECIFIC */ 345 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */ 346 host.h_addr_list = host_addrs; 347 #endif 348 host.h_addr = hostaddr; 349 *((u_long *)host.h_addr) = inet_addr(p); 350 host.h_length = sizeof (u_long); 351 host.h_addrtype = AF_INET; 352 while (*cp == ' ' || *cp == '\t') 353 cp++; 354 host.h_name = cp; 355 q = host.h_aliases = host_aliases; 356 cp = strpbrk(cp, " \t"); 357 if (cp != NULL) 358 *cp++ = '\0'; 359 while (cp && *cp) { 360 if (*cp == ' ' || *cp == '\t') { 361 cp++; 362 continue; 363 } 364 if (q < &host_aliases[MAXALIASES - 1]) 365 *q++ = cp; 366 cp = strpbrk(cp, " \t"); 367 if (cp != NULL) 368 *cp++ = '\0'; 369 } 370 *q = NULL; 371 return (&host); 372 } 373 374 struct hostent * 375 _gethtbyname(name) 376 char *name; 377 { 378 register struct hostent *p; 379 register char **cp; 380 381 _sethtent(0); 382 while (p = _gethtent()) { 383 if (strcasecmp(p->h_name, name) == 0) 384 break; 385 for (cp = p->h_aliases; *cp != 0; cp++) 386 if (strcasecmp(*cp, name) == 0) 387 goto found; 388 } 389 found: 390 _endhtent(); 391 return (p); 392 } 393 394 struct hostent * 395 _gethtbyaddr(addr, len, type) 396 const char *addr; 397 int len, type; 398 { 399 register struct hostent *p; 400 401 _sethtent(0); 402 while (p = _gethtent()) 403 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len)) 404 break; 405 _endhtent(); 406 return (p); 407 } 408