jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Assertions.h>
8#include <AK/DeprecatedString.h>
9#include <LibCore/ArgsParser.h>
10#include <LibCore/ElapsedTimer.h>
11#include <LibCore/System.h>
12#include <LibMain/Main.h>
13#include <arpa/inet.h>
14#include <errno.h>
15#include <netdb.h>
16#include <netinet/in.h>
17#include <netinet/ip_icmp.h>
18#include <serenity.h>
19#include <stdio.h>
20#include <string.h>
21#include <sys/socket.h>
22#include <unistd.h>
23
24ErrorOr<int> serenity_main(Main::Arguments arguments)
25{
26 TRY(Core::System::pledge("stdio id inet unix"));
27
28 DeprecatedString host_name;
29 int max_hops = 30;
30 int max_retries = 3;
31 int echo_timeout = 5;
32
33 Core::ArgsParser args_parser;
34 args_parser.add_positional_argument(host_name, "destination", "destination", Core::ArgsParser::Required::Yes);
35 args_parser.add_option(max_hops, "use at most <hops> to the destination", "max-hops", 'h', "hops");
36 args_parser.add_option(max_retries, "retry TTL at most <tries> times", "max-retries", 'r', "tries");
37 args_parser.add_option(echo_timeout, "wait at most <seconds> for a response", "timeout", 't', "seconds");
38 args_parser.parse(arguments);
39
40 if (max_hops < 1 || max_hops > 255) {
41 return Error::from_string_literal("Invalid maximum hops amount");
42 }
43
44 if (max_retries < 1) {
45 return Error::from_string_literal("Invalid maximum retries amount");
46 }
47
48 auto* hostent = gethostbyname(host_name.characters());
49 if (!hostent) {
50 warnln("Lookup failed for '{}'", host_name);
51 return 1;
52 }
53 sockaddr_in host_address {};
54 host_address.sin_family = AF_INET;
55 host_address.sin_port = 44444;
56 host_address.sin_addr.s_addr = *(in_addr_t const*)hostent->h_addr_list[0];
57
58 int fd = TRY(Core::System::socket(AF_INET, SOCK_RAW, IPPROTO_ICMP));
59
60 TRY(Core::System::drop_privileges());
61 TRY(Core::System::pledge("stdio inet unix"));
62
63 timeval timeout { echo_timeout, 0 };
64 TRY(Core::System::setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)));
65
66 struct icmp_request {
67 struct icmphdr header;
68 char msg[64 - sizeof(struct icmphdr)];
69 };
70
71 struct icmp_response {
72 u8 ip_header[20];
73 struct icmphdr header;
74 char msg[64 - sizeof(struct icmphdr)];
75 };
76
77 // 1: reached target
78 // 0: got ttl exhausted response
79 // -1: error or no response
80 auto try_reach_host = [&](int ttl) -> ErrorOr<int> {
81 Core::ElapsedTimer m_timer { true };
82 auto ttl_number = DeprecatedString::number(ttl);
83 for (auto i = 0; i < max_retries; i++) {
84 icmp_request request {};
85 request.header = { ICMP_ECHO, 0, 0, { { 0, 0 } } };
86 bool fits = ttl_number.copy_characters_to_buffer(request.msg, sizeof(request.msg));
87 VERIFY(fits);
88 request.header.checksum = internet_checksum(&request, sizeof(request));
89
90 m_timer.start();
91 TRY(Core::System::sendto(fd, &request, sizeof(request), 0, (sockaddr*)&host_address, sizeof(host_address)));
92
93 icmp_response response {};
94 sockaddr_in peer_address {};
95 socklen_t peer_address_size = sizeof(peer_address);
96
97 auto result = Core::System::recvfrom(fd, &response, sizeof(response), 0, (sockaddr*)&peer_address, &peer_address_size);
98 if (result.is_error()) {
99 if (result.error().code() == EAGAIN)
100 return result.release_error();
101 continue;
102 }
103
104 if (response.header.type != ICMP_ECHOREPLY && response.header.type != ICMP_TIME_EXCEEDED)
105 continue;
106
107 auto response_time = m_timer.elapsed();
108 auto* peer = gethostbyaddr(&peer_address.sin_addr, sizeof(peer_address.sin_addr), AF_INET);
109
110 DeprecatedString peer_name;
111 if (peer) {
112 peer_name = peer->h_name;
113 } else {
114 char addr_buf[INET_ADDRSTRLEN];
115 peer_name = inet_ntop(AF_INET, &peer_address.sin_addr, addr_buf, sizeof(addr_buf));
116 }
117 outln("{:2}: {:50} {:4}ms", ttl, peer_name, response_time);
118
119 if (response.header.type == ICMP_TIME_EXCEEDED)
120 return 0;
121 if (response.header.type == ICMP_ECHOREPLY)
122 return 1;
123 }
124 return -1;
125 };
126
127 for (auto ttl = 1; ttl <= max_hops; ttl++) {
128 TRY(Core::System::setsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)));
129
130 int result = TRY(try_reach_host(ttl));
131 if (result < 0) {
132 outln("{:2}: no reply", ttl);
133 } else if (result == 1) {
134 outln(" Hops: {}", ttl);
135 return 0;
136 }
137 }
138 outln(" Too many hops: {}", max_hops);
139 return 0;
140}