1 /*- 2 * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 31 #include <sys/socket.h> 32 #include <netdb.h> 33 #include <netinet/in.h> 34 #include <arpa/inet.h> 35 36 #include <stdio.h> 37 #include <string.h> 38 39 #include "libutil.h" 40 41 int 42 realhostname(char *host, size_t hsize, const struct in_addr *ip) 43 { 44 int result; 45 struct hostent *hp; 46 47 result = HOSTNAME_INVALIDADDR; 48 hp = gethostbyaddr((char *)ip, sizeof(*ip), AF_INET); 49 50 if (hp != NULL && strlen(hp->h_name) <= hsize) { 51 char lookup[MAXHOSTNAMELEN]; 52 53 strncpy(lookup, hp->h_name, sizeof(lookup) - 1); 54 lookup[sizeof(lookup) - 1] = '\0'; 55 hp = gethostbyname(lookup); 56 if (hp == NULL) 57 result = HOSTNAME_INVALIDNAME; 58 else for (; ; hp->h_addr_list++) { 59 if (hp->h_addr_list[0] == NULL) { 60 result = HOSTNAME_INCORRECTNAME; 61 break; 62 } 63 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) { 64 strncpy(host, lookup, hsize); 65 return HOSTNAME_FOUND; 66 } 67 } 68 } 69 70 strncpy(host, inet_ntoa(*ip), hsize); 71 72 return result; 73 } 74