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Utilities/nc: Add support to -I/--length option like SO_RCVBUF

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dayarthvader 2022-02-18 06:34:31 +02:00 • committed by Andreas Kling
parent b689e8b7f4
commit 5a94402b60
Notes: sideshowbarker 2024-07-19 17:08:34 +09:00
2 changed files with 26 additions and 3 deletions
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3
Base/usr/share/man/man1/nc.md
View file

@ -5,7 +5,7 @@ nc
## Synopsis
```sh
$ nc [--listen] [--verbose] [--udp] [-N] <target> <port>
$ nc [--listen] [--verbose] [--udp] [-N] [--length ] <target> <port>
```
## Description
@ -20,6 +20,7 @@ Network cat: Connect to network sockets as if it were a file.
* `-v`, `--verbose`: Log everything that's happening
* `-u`, `--udp`: UDP mode
* `-N`: Close connection after reading stdin to the end
* `-I`, `--length`: Set maximum tcp receive buffer size
## Arguments:

26
Userland/Utilities/nc.cpp
View file

@ -28,6 +28,21 @@
// output to stderr to allow for commands like:
//
// nc -l someport > out.file
//
// Below man page was considered to come up default bounds
// for SO_RCVBUF
// https://man7.org/linux/man-pages/man7/socket.7.html
static constexpr size_t maximum_tcp_receive_buffer_size_upper_bound = 212992;
static constexpr size_t maximum_tcp_receive_buffer_size_lower_bound = 256;
static size_t get_maximum_tcp_buffer_size(size_t input_buf_size)
{
if (input_buf_size < maximum_tcp_receive_buffer_size_lower_bound)
return maximum_tcp_receive_buffer_size_lower_bound;
if (input_buf_size > maximum_tcp_receive_buffer_size_upper_bound)
return maximum_tcp_receive_buffer_size_upper_bound;
return input_buf_size;
};
ErrorOr<int> serenity_main(Main::Arguments arguments)
{
@ -37,6 +52,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
bool udp_mode = false;
const char* target = nullptr;
int port = 0;
int maximum_tcp_receive_buffer_size_input = -1;
Core::ArgsParser args_parser;
args_parser.set_general_help("Network cat: Connect to network sockets as if it were a file.");
@ -44,6 +60,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
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_option(maximum_tcp_receive_buffer_size_input, "Set maximum tcp receive buffer size", "length", 'I', nullptr);
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);
@ -138,6 +155,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
fd_set readfds, writefds, exceptfds;
size_t receive_buffer_size = get_maximum_tcp_buffer_size(maximum_tcp_receive_buffer_size_input);
if (verbose && (maximum_tcp_receive_buffer_size_input != -1)) {
warnln("receive_buffer_size set to {}", receive_buffer_size);
}
while (!stdin_closed || !fd_closed || !listen_fd_closed) {
FD_ZERO(&readfds);
FD_ZERO(&writefds);
@ -211,8 +233,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
}
if (!fd_closed && FD_ISSET(fd, &readfds)) {
Array<u8, 1024> buffer;
Bytes buffer_span = buffer.span();
auto buffer = TRY(ByteBuffer::create_uninitialized(receive_buffer_size));
Bytes buffer_span = buffer.bytes();
auto nread = TRY(Core::System::read(fd, buffer_span));
buffer_span = buffer_span.trim(nread);