+/* 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>
*
- * Copyright (C) 2000 by Lineo, inc.
- * Written by John Beppu <beppu@lineo.com>
+ * 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
*
*/
-#include "internal.h"
#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.
- |
- | [ TODO ]
- | + find out how to use non-default name servers
- | + find out how the real nslookup gets the default name server
*/
-static const char nslookup_usage[] =
- "nslookup [HOST]\n\n"
-;
-
+/* 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;
+}
-/* I have to see how the real nslookup does this.
- * I could dig through /etc/resolv.conf, but is there a
- * better (programatic) way?
+/* takes the NULL-terminated array h_addr_list, and
+ * prints its contents appropriately
*/
-static void
-server_fprint(FILE *dst)
+static int addr_list_fprint(char **h_addr_list)
{
- fprintf(dst, "Server: %s\n", "something");
- fprintf(dst, "Address: %s\n\n", "something");
+ 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;
}
-/* only works for IPv4 */
-static int
-addr_fprint(char *addr, FILE *dst)
+/* print the results as nslookup would */
+static struct hostent *hostent_fprint(struct hostent *host, const char *server_host)
{
- 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);
- fprintf (
- dst, "%d.%d.%d.%d",
- split[0], split[1], split[2], split[3]
- );
- return 0;
+ 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)
+static uint32_t str_to_addr(const char *addr)
{
- uint32_t split[4];
- uint32_t ip;
+ uint32_t split[4];
+ uint32_t ip;
- sscanf(addr, "%d.%d.%d.%d",
- &split[0], &split[1], &split[2], &split[3]);
+ 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]);
+ /* assuming sscanf worked */
+ ip = (split[0] << 24) |
+ (split[1] << 16) | (split[2] << 8) | (split[3]);
- return htonl(ip);
+ return htonl(ip);
}
-/* takes the NULL-terminated array h_addr_list, and
- * prints its contents appropriately
- */
-static int
-addr_list_fprint(char **h_addr_list, FILE *dst)
+/* gethostbyaddr wrapper */
+static struct hostent *gethostbyaddr_wrapper(const char *address)
{
- int i, j;
- char *addr_string = (h_addr_list[1])
- ? "Addresses"
- : "Address";
-
- fprintf(dst, "%s: ", addr_string);
- for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
- addr_fprint(h_addr_list[i], dst);
-
- /* real nslookup does this */
- if (j == 4) {
- if (h_addr_list[i+1]) {
- fprintf(dst, "\n ");
- }
- j = 0;
- } else {
- if (h_addr_list[i+1]) {
- fprintf(dst, ", ");
- }
- }
+ struct in_addr addr;
- }
- fprintf(dst,"\n");
- return 0;
+ addr.s_addr = str_to_addr(address);
+ return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
}
-/* gethostbyaddr wrapper */
-static struct hostent *
-gethostbyaddr_wrapper(const char *address)
+/* lookup the default nameserver and display it */
+static inline void server_print(void)
{
- struct in_addr addr;
+ struct sockaddr_in def = _res.nsaddr_list[0];
+ char *ip = inet_ntoa(def.sin_addr);
- addr.s_addr = str_to_addr(address);
- return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
+ hostent_fprint(gethostbyaddr_wrapper(ip), "Server:");
+ printf("\n");
}
-/* print the results as nslookup would */
-static struct hostent *
-hostent_fprint(struct hostent *host, FILE *dst)
+/* 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)
{
- if (host) {
- fprintf(dst, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, dst);
- } else {
- fprintf(dst, "*** %s\n", hstrerror(h_errno));
- }
- return host;
-}
+ 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)
+static int is_ip_address(const char *s)
{
- while (*s) {
- if ((isdigit(*s)) || (*s == '.')) { s++; continue; }
- return 0;
- }
- return 1;
+ while (*s) {
+ if ((isdigit(*s)) || (*s == '.')) {
+ s++;
+ continue;
+ }
+ return 0;
+ }
+ return 1;
}
/* ________________________________________________________________________ */
-int
-nslookup_main(int argc, char **argv)
+int nslookup_main(int argc, char **argv)
{
- struct hostent *host;
-
- if (argc < 2) {
- usage(nslookup_usage);
- }
-
- server_fprint(stdout);
- if (is_ip_address(argv[1])) {
- host = gethostbyaddr_wrapper(argv[1]);
- } else {
- host = gethostbyname(argv[1]);
- }
- hostent_fprint(host, stdout);
- return 0;
+ 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 1.3 2000/02/07 05:29:42 erik Exp $ */
+/* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */
projects / oweals / busybox.git / blobdiff