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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.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 are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <LibCore/ArgsParser.h>
28#include <arpa/inet.h>
29#include <netdb.h>
30#include <netinet/in.h>
31#include <stdio.h>
32#include <string.h>
33#include <unistd.h>
34
35int main(int argc, char** argv)
36{
37 if (pledge("stdio dns", nullptr) < 0) {
38 perror("pledge");
39 return 1;
40 }
41
42 const char* name_or_ip = nullptr;
43 Core::ArgsParser args_parser;
44 args_parser.add_positional_argument(name_or_ip, "Domain name or IPv4 address", "name");
45 args_parser.parse(argc, argv);
46
47 // If input looks like an IPv4 address, we should do a reverse lookup.
48 struct sockaddr_in addr;
49 memset(&addr, 0, sizeof(addr));
50 addr.sin_family = AF_INET;
51 addr.sin_port = htons(53);
52 int rc = inet_pton(AF_INET, name_or_ip, &addr.sin_addr);
53 if (rc == 1) {
54 // Okay, let's do a reverse lookup.
55 auto* hostent = gethostbyaddr(&addr.sin_addr, sizeof(in_addr), AF_INET);
56 if (!hostent) {
57 fprintf(stderr, "Reverse lookup failed for '%s'\n", name_or_ip);
58 return 1;
59 }
60 printf("%s is %s\n", name_or_ip, hostent->h_name);
61 return 0;
62 }
63
64 auto* hostent = gethostbyname(name_or_ip);
65 if (!hostent) {
66 fprintf(stderr, "Lookup failed for '%s'\n", name_or_ip);
67 return 1;
68 }
69
70 char buffer[32];
71 const char* ip_str = inet_ntop(AF_INET, hostent->h_addr_list[0], buffer, sizeof(buffer));
72
73 printf("%s is %s\n", name_or_ip, ip_str);
74 return 0;
75}