Skip to content

Commit 0c39b00

Browse files
lpcvoidlpcvoid
committed
* added udp based time protocol demo
1 parent 37e80d3 commit 0c39b00

4 files changed

Lines changed: 71 additions & 2 deletions

File tree

‎examples/CMakeLists.txt‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
set(EXAMPLE_SOURCES echo_server.cpp daytime_client.cpp threadpool.cpp)
1+
set(EXAMPLE_SOURCES echo_server.cpp daytime_client.cpp threadpool.cpp time_client.cpp)
22

33
foreach (examplesource ${EXAMPLE_SOURCES})
44
string(REPLACE ".cpp" "" examplename ${examplesource})

‎examples/daytime_client.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@ int main(int argc, char** argv) {
1414
signal(SIGINT, exit_handler);
1515

1616
uint16_t port = 13;
17-
std::string time_host = "time-b-b.nist.gov";
17+
std::string time_host = "time.nist.gov"; //https://tf.nist.gov/tf-cgi/servers.cgi#
1818
if (argc == 3) {
1919
time_host = argv[1];
2020
port = std::atol(argv[2]);

‎examples/time_client.cpp‎

Lines changed: 68 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,68 @@
1+
#include "../src/netlib.hpp"
2+
#include <csignal>
3+
#include <iomanip>
4+
#include <iostream>
5+
6+
using namespace std::chrono_literals;
7+
8+
void exit_handler(int s){
9+
std::cout << "Goodbye!" << std::endl;
10+
exit(EXIT_SUCCESS);
11+
}
12+
13+
int main(int argc, char** argv) {
14+
15+
signal(SIGINT, exit_handler);
16+
uint16_t port = 37;
17+
std::string time_host = "time.nist.gov"; //https://tf.nist.gov/tf-cgi/servers.cgi#
18+
if (argc == 3) {
19+
time_host = argv[1];
20+
port = std::atol(argv[2]);
21+
}
22+
23+
std::cout << "Connecting to " << time_host << " on port " << port << std::endl;
24+
netlib::client client;
25+
26+
std::error_condition client_create_res =
27+
client.connect(time_host, port, netlib::AddressFamily::IPv4,
28+
netlib::AddressProtocol::UDP, 1000ms);
29+
30+
if (client_create_res) {
31+
std::cerr << "Error connecting to host, error : " << client_create_res.message() << std::endl;
32+
exit(EXIT_FAILURE);
33+
}
34+
35+
//since time uses udp, we need to send some random udp datagram to server,
36+
//since it has no way of knowing that we want the datetime
37+
//(udp is connectionless)
38+
//Interesting that the send payload can be lower than the 4 expected bytes -
39+
//this could potentially be used in an udp reflection attack
40+
std::vector<uint8_t> dummy_payload(4, 0);
41+
auto send_res = client.send(dummy_payload, 1000ms);
42+
if (send_res.second) {
43+
std::cout << "Error sending byte in udp mode for triggering response: " <<
44+
send_res.second.message() << std::endl;
45+
exit(EXIT_FAILURE);
46+
}
47+
48+
auto time_res = client.recv(1024, 1000ms);
49+
if (time_res.second) {
50+
std::cerr << "Failed to get UDP datagram. Error: " << time_res.second.message() << std::endl;
51+
exit(EXIT_FAILURE);
52+
}
53+
54+
if (time_res.first.size() != 4) {
55+
std::cerr << "Did not recieve 32 bits - instead got " << time_res.first.size() << std::endl;
56+
exit(EXIT_FAILURE);
57+
}
58+
59+
uint32_t time_result = (time_res.first[0] << 24) |
60+
(time_res.first[1] << 16) |
61+
(time_res.first[2] << 8) |
62+
(time_res.first[3]);
63+
64+
std::cout << "Value from server: " << time_result << std::endl;
65+
//print out actual time
66+
std::time_t temp = time_result - 2208988800;
67+
std::cout << std::put_time(std::gmtime(&temp), "Formatted: %Y-%m-%d %I:%M:%S %p") << std::endl;
68+
}

‎src/client.hpp‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -96,6 +96,7 @@ namespace netlib {
9696
global_connect_error = connect_error.first;
9797
continue;
9898
}
99+
99100
_endpoint_addr = res_addrinfo;
100101
_socket = sock;
101102
break;

0 commit comments

Comments
 (0)