1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* vi: set sw=4 ts=4: */
/*
* Mini nslookup implementation for busybox
*
* Copyright (C) 2000 by Lineo, inc.
* Written by John Beppu <beppu@lineo.com>
*
* 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 "busybox.h"
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.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
*/
/* I have to see how the real nslookup does this.
* I could dig through /etc/resolv.conf, but is there a
* better (programatic) way?
*/
static inline void server_print(void)
{
printf("Server: %s\n", "default");
printf("Address: %s\n\n", "default");
}
/* only works for IPv4 */
static int addr_fprint(char *addr)
{
u_int8_t split[4];
u_int32_t ip;
u_int32_t *x = (u_int32_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;
}
/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
* into a u_int32_t
*/
static u_int32_t str_to_addr(const char *addr)
{
u_int32_t split[4];
u_int32_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);
}
/* 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;
}
/* 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 */
}
/* print the results as nslookup would */
static struct hostent *hostent_fprint(struct hostent *host)
{
if (host) {
printf("Name: %s\n", host->h_name);
addr_list_fprint(host->h_addr_list);
} else {
printf("*** Unknown host\n");
}
return host;
}
/* 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;
if (argc < 2 || *argv[1]=='-') {
usage(nslookup_usage);
}
server_print();
if (is_ip_address(argv[1])) {
host = gethostbyaddr_wrapper(argv[1]);
} else {
host = gethostbyname(argv[1]);
}
hostent_fprint(host);
return EXIT_SUCCESS;
}
/* $Id: nslookup.c,v 1.18 2001/01/24 18:44:54 andersen Exp $ */
|
