| /* vi: set sw=4 ts=4: */ |
| /* |
| * Mini nslookup implementation for busybox |
| * |
| * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu |
| * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org> |
| * |
| * Correct default name server display and explicit name server option |
| * added by Ben Zeckel <bzeckel@hmc.edu> June 2001 |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| * |
| */ |
| |
| #include <ctype.h> |
| #include <errno.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <stdlib.h> |
| |
| #include <stdint.h> |
| #include <netdb.h> |
| #include <sys/socket.h> |
| #include <sys/types.h> |
| #include <netinet/in.h> |
| #include <resolv.h> |
| #include <arpa/inet.h> |
| #include "busybox.h" |
| |
| /* |
| | I'm only implementing non-interactive mode; |
| | I totally forgot nslookup even had an interactive mode. |
| */ |
| |
| /* only works for IPv4 */ |
| static int addr_fprint(char *addr) |
| { |
| uint8_t split[4]; |
| uint32_t ip; |
| uint32_t *x = (uint32_t *) addr; |
| |
| ip = ntohl(*x); |
| split[0] = (ip & 0xff000000) >> 24; |
| split[1] = (ip & 0x00ff0000) >> 16; |
| split[2] = (ip & 0x0000ff00) >> 8; |
| split[3] = (ip & 0x000000ff); |
| printf("%d.%d.%d.%d", split[0], split[1], split[2], split[3]); |
| return 0; |
| } |
| |
| /* takes the NULL-terminated array h_addr_list, and |
| * prints its contents appropriately |
| */ |
| static int addr_list_fprint(char **h_addr_list) |
| { |
| int i, j; |
| char *addr_string = (h_addr_list[1]) |
| ? "Addresses: " : "Address: "; |
| |
| printf("%s ", addr_string); |
| for (i = 0, j = 0; h_addr_list[i]; i++, j++) { |
| addr_fprint(h_addr_list[i]); |
| |
| /* real nslookup does this */ |
| if (j == 4) { |
| if (h_addr_list[i + 1]) { |
| printf("\n "); |
| } |
| j = 0; |
| } else { |
| if (h_addr_list[i + 1]) { |
| printf(", "); |
| } |
| } |
| |
| } |
| printf("\n"); |
| return 0; |
| } |
| |
| /* print the results as nslookup would */ |
| static struct hostent *hostent_fprint(struct hostent *host, const char *server_host) |
| { |
| if (host) { |
| printf("%s %s\n", server_host, host->h_name); |
| addr_list_fprint(host->h_addr_list); |
| } else { |
| printf("*** Unknown host\n"); |
| } |
| return host; |
| } |
| |
| /* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+ |
| * into a uint32_t |
| */ |
| static uint32_t str_to_addr(const char *addr) |
| { |
| uint32_t split[4]; |
| uint32_t ip; |
| |
| sscanf(addr, "%d.%d.%d.%d", |
| &split[0], &split[1], &split[2], &split[3]); |
| |
| /* assuming sscanf worked */ |
| ip = (split[0] << 24) | |
| (split[1] << 16) | (split[2] << 8) | (split[3]); |
| |
| return htonl(ip); |
| } |
| |
| /* gethostbyaddr wrapper */ |
| static struct hostent *gethostbyaddr_wrapper(const char *address) |
| { |
| struct in_addr addr; |
| |
| addr.s_addr = str_to_addr(address); |
| return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */ |
| } |
| |
| /* lookup the default nameserver and display it */ |
| static inline void server_print(void) |
| { |
| struct sockaddr_in def = _res.nsaddr_list[0]; |
| char *ip = inet_ntoa(def.sin_addr); |
| |
| hostent_fprint(gethostbyaddr_wrapper(ip), "Server:"); |
| printf("\n"); |
| } |
| |
| /* alter the global _res nameserver structure to use |
| an explicit dns server instead of what is in /etc/resolv.h */ |
| static inline void set_default_dns(char *server) |
| { |
| struct in_addr server_in_addr; |
| |
| if(inet_aton(server,&server_in_addr)) |
| { |
| _res.nscount = 1; |
| _res.nsaddr_list[0].sin_addr = server_in_addr; |
| } |
| } |
| |
| /* naive function to check whether char *s is an ip address */ |
| static int is_ip_address(const char *s) |
| { |
| while (*s) { |
| if ((isdigit(*s)) || (*s == '.')) { |
| s++; |
| continue; |
| } |
| return 0; |
| } |
| return 1; |
| } |
| |
| /* ________________________________________________________________________ */ |
| int nslookup_main(int argc, char **argv) |
| { |
| struct hostent *host; |
| |
| /* |
| * initialize DNS structure _res used in printing the default |
| * name server and in the explicit name server option feature. |
| */ |
| |
| res_init(); |
| |
| /* |
| * We allow 1 or 2 arguments. |
| * The first is the name to be looked up and the second is an |
| * optional DNS server with which to do the lookup. |
| * More than 3 arguments is an error to follow the pattern of the |
| * standard nslookup |
| */ |
| |
| if (argc < 2 || *argv[1]=='-' || argc > 3) |
| bb_show_usage(); |
| else if(argc == 3) |
| set_default_dns(argv[2]); |
| |
| server_print(); |
| if (is_ip_address(argv[1])) { |
| host = gethostbyaddr_wrapper(argv[1]); |
| } else { |
| host = xgethostbyname(argv[1]); |
| } |
| hostent_fprint(host, "Name: "); |
| if (host) { |
| return EXIT_SUCCESS; |
| } |
| return EXIT_FAILURE; |
| } |
| |
| /* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */ |