diff options
Diffstat (limited to 'busybox/networking/nslookup.c')
| -rw-r--r-- | busybox/networking/nslookup.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/busybox/networking/nslookup.c b/busybox/networking/nslookup.c new file mode 100644 index 0000000..936fa33 --- /dev/null +++ b/busybox/networking/nslookup.c @@ -0,0 +1,206 @@ +/* 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 $ */ |