gistfile1.c

#include <libwebsockets.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>

struct _data
{
    int id;
    char *nick;
    char *msg;
};
typedef struct _data chat_data;

// Connection id
static int id = 0;

static int chat_cb(struct libwebsocket_context *ctx,
                   struct libwebsocket *ws,
                   enum libwebsocket_callback_reasons reason,
                   void *user, void *in, size_t len)
{
    chat_data *data = (chat_data *)user;

    char *msg = (char *) in;
    switch (reason)
    {
        case LWS_CALLBACK_ESTABLISHED:
            printf("Connection Established\n");
            data->id = id++;
            data->nick = (char *) malloc (sizeof(char) * 8);
            sprintf(data->nick, "NO_NAME");
            data->msg = (char *)malloc(sizeof(char) * 16 + 4);
            sprintf(data->msg, "Connection id = %d", data->id);
            libwebsocket_callback_on_writable(ctx, ws);
            break;

        case LWS_CALLBACK_SERVER_WRITEABLE:
        {
            // The 2 is for the ": " in the message
            size_t size = strlen(data->msg) + strlen(data->nick) + 2;
            size_t buffsize = LWS_SEND_BUFFER_PRE_PADDING
                              + size
                              + LWS_SEND_BUFFER_POST_PADDING;

            unsigned char *buff = (unsigned char *)malloc(buffsize);
            unsigned char *p = &buff[LWS_SEND_BUFFER_PRE_PADDING];

            sprintf((char *)p , "%s: %s", data->nick, data->msg);
            libwebsocket_write(ws, p, size, LWS_WRITE_TEXT);
            free(buff);
        }
        break;

        case LWS_CALLBACK_RECEIVE:
            if (!strcmp(&msg[len - 5], "@nick"))
            {
                data->nick = (char *) realloc(data->nick, sizeof(char) * (len - 4));
                msg[len - 5] = 0;
                memcpy(data->nick, msg, len - 4);
                char *txt = (char *) malloc (sizeof(char) * 25 + strlen(data->nick));
                sprintf(txt, "Id %d now is know as %s\n\n", data->id, data->nick);
                data->msg = txt;
                libwebsocket_callback_on_writable(ctx, ws);
            }
            else
            {
                data->msg = (char *)realloc(data->msg, (sizeof(char) * len) + 1);
                memcpy(data->msg, msg, len + 1);
                libwebsocket_callback_on_writable(ctx, ws);
            }
            break;

        default:
            break;
    }
    return 0;
}

static struct libwebsocket_protocols protocols[] = {
    {
        "chat-protocol",
        chat_cb,
        sizeof(chat_data),
        128

    },
    {
        NULL, NULL, 0
    }
};

static volatile int end = 0;

void sig_cb(int sig)
{
    end = 1;
    printf("\nStopping server...\n");
}

int main()
{
    signal(SIGINT, sig_cb);

    struct lws_context_creation_info info = {
        9000,
        NULL,
        protocols,
        libwebsocket_get_internal_extensions(),
        0,0,0,0,0,0,0,0,0,0
    };

    struct libwebsocket_context *ctx;
    ctx = libwebsocket_create_context(&info);
    if (!ctx)
    {
        fprintf(stderr, "Error, can not allocate context\n");
        return -1;
    }

    printf("Starting server...\n");

    while(!end)
        libwebsocket_service(ctx, 50);

    libwebsocket_context_destroy(ctx);

    return 0;
}