RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-14 08:04:57 +00:00
Code Issues Activity Actions
serenity/Userland/Utilities/nc.cpp
brapru b04528c0de nc: Extend TCP listening port functionality 
Previously the nc implementation during listening mode would only accept
a single client and close the listening file description immediately.
Additionally, it did not have support for read/write handling of the
accepted client.

This patch extends the functionality of nc's listening capability by
allowing multiple client connections over TCP. Clients/server are able
to pass data back and forth between the connection.

Being able to listen on sockets and accept connections is helpful for
debugging the networking stack.
2022-02-14 11:47:14 +01:00

271 lines
9.2 KiB
C++
Raw Blame History

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteBuffer.h>
#include <AK/HashTable.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/EventLoop.h>
#include <LibCore/Stream.h>
#include <LibCore/System.h>
#include <LibMain/Main.h>
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
// NOTE: `warnln` is used instead of `outln` because we want to redirect all
// output to stderr to allow for commands like:
//
// nc -l someport > out.file
ErrorOr<int> serenity_main(Main::Arguments arguments)
{
bool should_listen = false;
bool verbose = false;
bool should_close = false;
bool udp_mode = false;
const char* target = nullptr;
int port = 0;
Core::ArgsParser args_parser;
args_parser.set_general_help("Network cat: Connect to network sockets as if it were a file.");
args_parser.add_option(should_listen, "Listen instead of connecting", "listen", 'l');
args_parser.add_option(verbose, "Log everything that's happening", "verbose", 'v');
args_parser.add_option(udp_mode, "UDP mode", "udp", 'u');
args_parser.add_option(should_close, "Close connection after reading stdin to the end", nullptr, 'N');
args_parser.add_positional_argument(target, "Address to listen on, or the address or hostname to connect to", "target");
args_parser.add_positional_argument(port, "Port to connect to or listen on", "port");
args_parser.parse(arguments);
if (udp_mode) {
if (should_listen) {
warnln("listening on UDP not yet supported");
return 1;
}
Core::EventLoop loop;
auto socket = TRY(Core::Stream::UDPSocket::connect(target, port));
if (verbose)
warnln("connected to {}:{}", target, port);
Array<u8, 1024> buffer;
for (;;) {
Bytes buffer_span = buffer.span();
auto nread = TRY(Core::System::read(STDIN_FILENO, buffer_span));
buffer_span = buffer_span.trim(nread);
TRY(socket->write({ buffer_span.data(), static_cast<size_t>(nread) }));
}
}
int fd = -1;
int listen_fd = -1;
if (should_listen) {
listen_fd = TRY(Core::System::socket(AF_INET, SOCK_STREAM, 0));
sockaddr_in sa {};
sa.sin_family = AF_INET;
sa.sin_port = htons(port);
sa.sin_addr.s_addr = htonl(INADDR_ANY);
if (target) {
if (inet_pton(AF_INET, target, &sa.sin_addr) <= 0) {
perror("inet_pton");
return 1;
}
}
TRY(Core::System::bind(listen_fd, (struct sockaddr*)&sa, sizeof(sa)));
TRY(Core::System::listen(listen_fd, 1));
char addr_str[INET_ADDRSTRLEN];
sockaddr_in sin;
socklen_t len;
len = sizeof(sin);
TRY(Core::System::getsockname(listen_fd, (struct sockaddr*)&sin, &len));
if (verbose)
warnln("waiting for a connection on {}:{}", inet_ntop(sin.sin_family, &sin.sin_addr, addr_str, sizeof(addr_str) - 1), ntohs(sin.sin_port));
} else {
fd = TRY(Core::System::socket(AF_INET, SOCK_STREAM, 0));
struct timeval timeout {
3, 0
};
TRY(Core::System::setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)));
TRY(Core::System::setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)));
auto* hostent = gethostbyname(target);
if (!hostent) {
warnln("Socket::connect: Unable to resolve '{}'", target);
return 1;
}
sockaddr_in dst_addr {};
dst_addr.sin_family = AF_INET;
dst_addr.sin_port = htons(port);
dst_addr.sin_addr.s_addr = *(const in_addr_t*)hostent->h_addr_list[0];
if (verbose) {
char addr_str[INET_ADDRSTRLEN];
warnln("connecting to {}:{}", inet_ntop(dst_addr.sin_family, &dst_addr.sin_addr, addr_str, sizeof(addr_str) - 1), ntohs(dst_addr.sin_port));
}
TRY(Core::System::connect(fd, (struct sockaddr*)&dst_addr, sizeof(dst_addr)));
if (verbose)
warnln("connected!");
}
HashTable<int> connected_clients;
bool stdin_closed = false;
bool fd_closed = false;
bool listen_fd_closed = false;
fd_set readfds, writefds, exceptfds;
while (!stdin_closed || !fd_closed || !listen_fd_closed) {
FD_ZERO(&readfds);
FD_ZERO(&writefds);
FD_ZERO(&exceptfds);
int highest_fd = 0;
if (!stdin_closed) {
FD_SET(STDIN_FILENO, &readfds);
FD_SET(STDIN_FILENO, &exceptfds);
highest_fd = max(highest_fd, STDIN_FILENO);
}
if (!fd_closed && fd) {
FD_SET(fd, &readfds);
FD_SET(fd, &exceptfds);
highest_fd = max(highest_fd, fd);
}
if (!listen_fd_closed && listen_fd) {
FD_SET(listen_fd, &readfds);
FD_SET(listen_fd, &exceptfds);
highest_fd = max(highest_fd, listen_fd);
}
bool has_clients = (should_listen && !connected_clients.is_empty());
if (has_clients) {
for (auto const& client_fd : connected_clients) {
FD_SET(client_fd, &readfds);
FD_SET(client_fd, &exceptfds);
highest_fd = max(highest_fd, client_fd);
}
}
int ready = select(highest_fd + 1, &readfds, &writefds, &exceptfds, nullptr);
if (ready == -1) {
if (errno == EINTR)
continue;
perror("select");
return 1;
}
if (!stdin_closed && FD_ISSET(STDIN_FILENO, &readfds)) {
Array<u8, 1024> buffer;
Bytes buffer_span = buffer.span();
auto nread = TRY(Core::System::read(STDIN_FILENO, buffer_span));
buffer_span = buffer_span.trim(nread);
// stdin closed
if (nread == 0) {
stdin_closed = true;
if (verbose)
warnln("stdin closed");
if (should_close) {
if (should_listen) {
TRY(Core::System::close(listen_fd));
listen_fd_closed = true;
} else {
TRY(Core::System::close(fd));
fd_closed = true;
}
}
} else {
if (should_listen && has_clients) {
for (auto const& client_fd : connected_clients)
TRY(Core::System::write(client_fd, buffer_span));
} else {
TRY(Core::System::write(fd, buffer_span));
}
}
}
if (!fd_closed && FD_ISSET(fd, &readfds)) {
Array<u8, 1024> buffer;
Bytes buffer_span = buffer.span();
auto nread = TRY(Core::System::read(fd, buffer_span));
buffer_span = buffer_span.trim(nread);
// remote end closed
if (nread == 0) {
close(STDIN_FILENO);
stdin_closed = true;
fd_closed = true;
if (verbose)
warnln("remote closed");
} else {
TRY(Core::System::write(STDOUT_FILENO, buffer_span));
}
}
if (!listen_fd_closed && FD_ISSET(listen_fd, &readfds)) {
char client_str[INET_ADDRSTRLEN];
sockaddr_in client;
socklen_t clientlen = sizeof(client);
int new_client = TRY(Core::System::accept(listen_fd, (struct sockaddr*)&client, &clientlen));
connected_clients.set(new_client);
if (verbose)
warnln("got connection from {}:{}", inet_ntop(client.sin_family, &client.sin_addr, client_str, sizeof(client_str) - 1), ntohs(client.sin_port));
}
if (has_clients) {
for (auto const client_fd : connected_clients) {
if (FD_ISSET(client_fd, &readfds)) {
Array<u8, 1024> buffer;
Bytes buffer_span = buffer.span();
auto nread = TRY(Core::System::read(client_fd, buffer_span));
buffer_span = buffer_span.trim(nread);
if (nread == 0) {
if (verbose) {
struct sockaddr_in client;
socklen_t clientlen = sizeof(client);
TRY(Core::System::getpeername(client_fd, (struct sockaddr*)&client, &clientlen));
warnln("remote connection closed {}:{}", inet_ntoa(client.sin_addr), ntohs(client.sin_port));
}
connected_clients.remove(client_fd);
close(client_fd);
FD_CLR(client_fd, &readfds);
FD_CLR(client_fd, &exceptfds);
} else {
TRY(Core::System::write(STDOUT_FILENO, buffer_span));
}
}
}
}
}
return 0;
}
Reference in a new issue View git blame Copy permalink