Wrapper library for the BSD sockets API with a nicer C99 interface

Last update: Dec 10, 2022

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Overview

A wrapper library for the BSD sockets API.

Why?

This library trades the series of getaddrinfo, socket, connect, bind, listen, etc. functions and their convoluted, casted arguments for just one function that takes two structs (configuration and output). By creatively using C99's "designated initializers", the configuration struct works rather like a configuration key/value hash; the output struct contains either the socket file descriptor or error information.

The sheer generality of the BSD sockets API also makes it rather unwieldy. While the sockets API can be used for a lot of esoteric things, there's no reason common use cases such as opening a TCP socket to a given host and port should take dozens of lines of code.

License

socket99 is released under the ISC license.

Requirements

This depends on C99 and a POSIX environment. You've got one of those lying around somewhere, right?

Basic Usage

Look at the fields in struct socket99_config listen in socket99.h, call socket99_open with a pointer to a configuration struct using the C99 designated initializer syntax. Only a few of the fields will be used, such as:

socket99_config cfg = {
    .host = "127.0.0.1",
    .port = 8080,
    .server = true,
    .nonblocking = true,
};

for a non-blocking TCP server that listens to 127.0.0.1. This function will return a bool for whether the socket was successfully created, and the result struct argument will be modified to contain a status code and either a file descriptor (on success) or error information on failure:

socket99_result res;   // result output in this struct
bool ok = socket99_open(&cfg, &res);

The configuration and result structs are no longer needed after the result struct's file descriptor has been saved / errors are handled, so both structs can be stack-allocated.

For more usage examples, look at test_socket99.c.

Running the tests

To run the tests:

$ make test

Note that the tests create a couple short-lived sockets on port 8080, and if that port is already in use, the tests will fail. To run the tests on a different port, set the PORT environment variable:

$ env PORT=12345 make test

Supported Use Cases

Client and server
TCP, UDP, and Unix domain sockets (either stream and datagram)
Blocking and nonblocking
IPV4, IPv6, and "don't care"
setsockopt(2) options

Future Development

Capturing other common use cases for sockets would be good.

Comments

Found memleak if make_tcp_udp returns unsuccessfully...

Hello, I found a memory leak if make_tcp_udp returns unsuccessfully after getaddrinfo is called on line 197 of socket99.c. I've added freeaddrinfo calls before the relevant return statements within make_tcp_udp to fix this memory leak.

opened by robert-warmka 3
Added -D_DARWIN_C_SOURCE=1 to compiler flags to ensure non-default exten...

I found this solution which eliminates the build warning when built on OSX Clang stating that snprintf is not defined.

By default, when POSIX compliance is enabled, snprintf, and some other extensions are not available in the default stdio inclusion. Adding this flag re-enables these extensions, in addition to the POSIX requirements.

I stumbled on this patch in this thread

opened by barneywilliams 2
implicit snprintf declaration warning

The -D_POSIX_C_SOURCE=1 define appears to exclude snprintf's prototype from stdio.h in some environments. Figure out if there's a different POSIX version that should be used, or another define that is also needed.

opened by silentbicycle 2
Shouldn't you zero initialize the socket99_cfg struct before using it to avoid garbage data?

So just from a quick look at this code, I'm wondering how exactly you avoid situations where the socket99_cfg struct is polluted with garbage data. In the socket99_open function, it's assumed that cfg->path will be NULL if the user doesn't want to make a UNIX domain socket, but if there's garbage data in the cfg->path member, would that not cause it to accidentally try creating a UNIX domain socket instead?

opened by zeeman 1
Add function to construct error messages

Rather than making the user call strerror(3), etc., it should have a function that takes a socket99_result * and fprintf's e.g. "connect: Connection refused".
enhancement

opened by silentbicycle 1

Owner

Scott Vokes

GitHub

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