MobiusHorizons / net_module

simple socket library for cbuild

net

The network module provides an interface for setting up and tearing down secure and unsecure sockets.

Installation

To install, add this repository as a submodule of your project under a deps directory. Then the module can be imported into your project as seen below.

import net from "deps/net/net.module.c"

This library depends on the stream, which can be installed in the same way.

LibreSSL

This library uses libtls provided by LibreSSL. The default settings of the library look for this library in the usual places as well as under HOMEBREW for OSX. If you have installed the library in a non-standard place, or if it can't be found, you can set the following variables with the correct locations

LIBRESSL_INCLUDE_DIR  # sets the include directory for finding LibreSSL
LIBRESSL_LIB_DIR      # sets the lib directory for finding LibreSSL

root.pem

At the current time, this library expects the file root.pem to be available in the working directory to run the program. This is clearly not ideal, and will be updated in the future. The version of the file included with the library was downloaded from firefox's certificates.

API

The API is super simple, it consists of two functions:

connect

stream.t connect(const char * host, int port, bool use_tls)

This function allows you to open a new connection by just providing a host and port. You can easily choose to use tls or raw native sockets just based on the use_tls boolean flag.

The function returns a stream that can be used to both read and write on the connection. Any errors that occur in the network stack are exposed through the error handling on the stream so for example you can check for a failed connection like so:

// error-test.module.c
package "main";

#include <stdio.h>
#include <stdbool.h>

import stream from "deps/stream/stream.module.c";
import net    from "deps/net/net.module.c";

int main(){
  stream.t conn = net.connect("invalid.example.com", 1234, false);
  if (conn.error.code != 0){
    fprintf(stderr, "Error Connecting: %s\n", conn.error.message);
    return -1;
  }

  // ... if it hasn't failed we could use our connection
}

which would return the error: Error Connecting: Unknown host

hangup

int net_hangup(stream.t conn)

This function will shutdown the connection and close out the underlying file pointers. Any errors which occur will cause a non-zero return code, and set the message and code fields of the the stream's error struct.