wsServer - a very tiny WebSocket server library written in C

wsServer is a tiny, lightweight WebSocket server library written in C that intends to be easy to use, fast, hackable, and compliant to the RFC 6455.

The main features are:

• Send/Receive Text and Binary messages
• PING/PONG frames
• Opening/Closing handshakes
• Event based (onmessage, onopen, onclose)
• Portability: Works fine on Windows, Linux (Android included), macOS and FreeBSD

See Autobahn report and the docs for an 'in-depth' analysis.

wsServer only requires a C99-compatible compiler (such as GCC, Clang, TCC and others) and no external libraries.

The preferred way to build wsServer on Linux environments:

git clone https://github.com/Theldus/wsServer
cd wsServer/
make

# Optionally, a user can also install wsServer into the system,
# either on default paths or by providing PREFIX or DESTDIR env
# vars to the Makefile.

make install # Or make install DESTDIR=/my/folder/

CMake enables the user to easily build wsServer in others environments other than Linux and also allows the use of an IDE to build the project automatically. If that's your case:

git clone https://github.com/Theldus/wsServer
cd wsServer/
mkdir build && cd build/
cmake ..
make
./examples/echo/echo # Waiting for incoming connections...

Windows has native support via MinGW, toolchain setup and build steps are detailed here.

wsServer abstracts the idea of sockets and you only need to deal with three types of events defined:

/* New client. */
void onopen(ws_cli_conn_t *client);

/* Client disconnected. */
void onclose(ws_cli_conn_t *client);

/* Client sent a text message. */
void onmessage(ws_cli_conn_t *client, const unsigned char *msg,
    uint64_t size, int type);

this is all you need to worry about, nothing to think about return values in socket, accepting connections, and so on.

As a gift, each client is handled in a separate thread, so you will not have to worry about it.

More examples, including the respective html files, can be found in examples/ folder, ;-).

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ws.h>

/**
 * @brief This function is called whenever a new connection is opened.
 * @param client Client connection.
 */
void onopen(ws_cli_conn_t *client)
{
    char *cli;
    cli = ws_getaddress(client);
    printf("Connection opened, addr: %s\n", cli);
}

/**
 * @brief This function is called whenever a connection is closed.
 * @param client Client connection.
 */
void onclose(ws_cli_conn_t *client)
{
    char *cli;
    cli = ws_getaddress(client);
    printf("Connection closed, addr: %s\n", cli);
}

/**
 * @brief Message events goes here.
 * @param client Client connection.
 * @param msg    Message content.
 * @param size   Message size.
 * @param type   Message type.
 */
void onmessage(ws_cli_conn_t *client,
    const unsigned char *msg, uint64_t size, int type)
{
    char *cli;
    cli = ws_getaddress(client);
    printf("I receive a message: %s (%zu), from: %s\n", msg,
        size, cli);

    sleep(2);
    ws_sendframe_txt(client, "hello");
    sleep(2);
    ws_sendframe_txt(client, "world");
}

int main(void)
{
    /* Register events. */
    struct ws_events evs;
    evs.onopen    = &onopen;
    evs.onclose   = &onclose;
    evs.onmessage = &onmessage;

    /*
     * Main loop, this function never* returns.
     *
     * *If the third argument is != 0, a new thread is created
     * to handle new connections.
     */
    ws_socket(&evs, 8080, 0, 1000);

    return (0);
}

the example above can be built with: make examples.

Inside extra/toyws there is a companion project called ToyWS. ToyWS is a very simple & dumb WebSocket client made exclusively to work with wsServer. Extremely limited, its usage is highly discouraged with other servers other than wsServer and is only meant to be used in conjunction with wsServer.

This mini-project only serves as an aid to wsServer and frees the user from using additional projects to use wsServer in its entirety.

More info at: extra/toyws/README.md

wsServer does not currently support encryption. However, it is possible to use it in conjunction with Stunnel, a proxy that adds TLS support to existing projects. Just follow these four easy steps to get TLS support on wsServer.

wsServer is always open to the community and willing to accept contributions, whether with issues, documentation, testing, new features, bugfixes, typos... welcome aboard. Make sure to read the coding-style guidelines before sending a PR.

Was the project helpful to you? Have something to say about it? Leave your comments here.

wsServer is licensed under GPLv3 License. Written by Davidson Francis and others contributors.