写一段websocket的示例程序

好的，以下是一个简单的 WebSocket 示例程序：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define PORT 808

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int addrlen = sizeof(address);
    char buffer[1024] = {};
    char *hello = "Hello from server";

    // 创建 socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, )) == ) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置地址和端口
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    // 绑定 socket
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < ) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听 socket
    if (listen(server_fd, 3) < ) {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    // 接受连接
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < ) {
        perror("accept failed");
        exit(EXIT_FAILURE);
    }

    // 发送欢迎消息
    send(new_socket, hello, strlen(hello), );
    printf("Hello message sent\n");

    // 接收消息
    int valread;
    while ((valread = read(new_socket, buffer, 1024)) > ) {
        printf("%s\n", buffer);
        send(new_socket, buffer, strlen(buffer), );
        memset(buffer, , sizeof(buffer));
    }

    return ;
}

这个程序创建了一个 WebSocket 服务器，监听 808 端口。当客户端连接上来后，服务器会发送一条欢迎消息，然后不断接收客户端发送的消息，并将其原样返回给客户端。