socket.c

#include <libwebsockets.h>

static int callback_example(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len)
{
    switch (reason) {

        case LWS_CALLBACK_ESTABLISHED: // just log message that someone is connecting
            printf("connection established\n");
            break;

        case LWS_CALLBACK_SERVER_WRITEABLE:
            {
                char buffer[LWS_PRE + 100];
                char *p = &buffer[LWS_PRE];
                sprintf(p, "Hello from server");
                lws_write(wsi, (unsigned char *)p, strlen(p), LWS_WRITE_TEXT);
                break;
            }

        default:
            break;
    }

    return 0;
}

int main(void)
{
    struct lws_protocols protocols[] = {
        {
            "example-protocol",
            callback_example,
            0,
            100,
        },
        { NULL, NULL, 0, 0 } /* terminator */
    };

    struct lws_context_creation_info info;
    memset(&info, 0, sizeof info);
    info.port = 9000;
    info.protocols = protocols;

    struct lws_context *context = lws_create_context(&info);

    while (1) {
        lws_service(context, 50);
    }

    lws_context_destroy(context);
    return 0;
}

/*
- Initialize the libwebsockets library by calling the lws_context_creation_info function and passing in the necessary parameters such as the server port and protocol.

- Create a callback function that will handle incoming connections and requests from clients. This function will be invoked whenever a new connection is established or data is received from a client.

- Start the server by calling the lws_initloop function and passing in the lws_context and the callback function.

- In the callback function, one can use the lws_write function to send data back to the client, and the lws_callback_on_writable function to enable writing to the socket.

- Once the server is running, clients can connect to it using a websocket library or by manually sending websocket handshake headers.
*/