编写一个基于windows socket的c语言程序。该程序允许多个用户同时在互联网上进行沟通。该程序应该包括以下模块：1.数据库：用于存储和组织用户信息，群组类别和聊天历史。2.用户管理：允许管理员/用户添加、更新或删除账户。3.连接：支持至少三个并发连接。4.聊天历史记录：记录每个会话的IP地址和连接时间。

以下是一个基于Windows socket的C语言程序，实现了多个用户在互联网上进行沟通，包括数据库模块、用户管理模块、连接模块和聊天历史记录模块。

注意：这只是一个基本框架，需要根据实际需求进行修改和完善。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#include <mysql.h>

#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "libmysql.lib")

#define MAX_CLIENTS 3
#define BUFFER_SIZE 1024
#define SERVER_PORT 8888

// 数据库连接信息
#define DB_HOST "localhost"
#define DB_USER "root"
#define DB_PASSWORD "123456"
#define DB_NAME "chatroom"

// 客户端信息结构
typedef struct {
    char username[32];
    char password[32];
    char ip[16];
    int port;
} client_info;

// TCP连接信息结构
typedef struct {
    SOCKET socket;
    char ip[16];
    int port;
} tcp_info;

// 聊天记录结构
typedef struct {
    int id;
    char sender[32];
    char receiver[32];
    char content[256];
    char datetime[32];
} chat_record;

// 数据库连接
MYSQL* connect_db() {
    MYSQL* conn = mysql_init(NULL);
    if (conn == NULL) {
        printf("Failed to init MySQL.\n");
        return NULL;
    }
    if (mysql_real_connect(conn, DB_HOST, DB_USER, DB_PASSWORD, DB_NAME, 0, NULL, 0) == NULL) {
        printf("Failed to connect to MySQL: %s\n", mysql_error(conn));
        mysql_close(conn);
        return NULL;
    }
    return conn;
}

// 关闭数据库连接
void close_db(MYSQL* conn) {
    mysql_close(conn);
}

// 用户登录
int login(MYSQL* conn, client_info* client) {
    char sql[BUFFER_SIZE];
    sprintf(sql, "SELECT * FROM users WHERE username='%s' AND password='%s'", client->username, client->password);
    if (mysql_query(conn, sql) != 0) {
        printf("Failed to query from MySQL: %s\n", mysql_error(conn));
        return 0;
    }
    MYSQL_RES* res = mysql_store_result(conn);
    if (mysql_num_rows(res) == 0) {
        printf("Invalid username or password.\n");
        mysql_free_result(res);
        return 0;
    }
    mysql_free_result(res);
    return 1;
}

// 用户注册
int register_user(MYSQL* conn, client_info* client) {
    char sql[BUFFER_SIZE];
    sprintf(sql, "INSERT INTO users(username,password,ip,port) VALUES('%s','%s','%s',%d)", client->username, client->password, client->ip, client->port);
    if (mysql_query(conn, sql) != 0) {
        printf("Failed to insert into MySQL: %s\n", mysql_error(conn));
        return 0;
    }
    return 1;
}

// 获取在线用户列表
int get_online_users(MYSQL* conn, char* list) {
    char sql[BUFFER_SIZE];
    sprintf(sql, "SELECT * FROM users WHERE status=1");
    if (mysql_query(conn, sql) != 0) {
        printf("Failed to query from MySQL: %s\n", mysql_error(conn));
        return 0;
    }
    MYSQL_RES* res = mysql_store_result(conn);
    int num_rows = mysql_num_rows(res);
    MYSQL_ROW row;
    for (int i = 0; i < num_rows; i++) {
        row = mysql_fetch_row(res);
        strcat(list, row[1]);
        strcat(list, "\n");
    }
    mysql_free_result(res);
    return num_rows;
}

// 保存聊天记录
int save_chat_record(MYSQL* conn, chat_record record) {
    char sql[BUFFER_SIZE];
    sprintf(sql, "INSERT INTO chat_history(sender,receiver,content,datetime) VALUES('%s','%s','%s','%s')", record.sender, record.receiver, record.content, record.datetime);
    if (mysql_query(conn, sql) != 0) {
        printf("Failed to insert into MySQL: %s\n", mysql_error(conn));
        return 0;
    }
    return 1;
}

// 获取聊天记录
int get_chat_history(MYSQL* conn, char* sender, char* receiver, char* history) {
    char sql[BUFFER_SIZE];
    sprintf(sql, "SELECT * FROM chat_history WHERE (sender='%s' AND receiver='%s') OR (sender='%s' AND receiver='%s') ORDER BY id ASC", sender, receiver, receiver, sender);
    if (mysql_query(conn, sql) != 0) {
        printf("Failed to query from MySQL: %s\n", mysql_error(conn));
        return 0;
    }
    MYSQL_RES* res = mysql_store_result(conn);
    int num_rows = mysql_num_rows(res);
    MYSQL_ROW row;
    for (int i = 0; i < num_rows; i++) {
        row = mysql_fetch_row(res);
        sprintf(history, "%s[%s] %s: %s\n", history, row[4], row[1], row[3]);
    }
    mysql_free_result(res);
    return num_rows;
}

// 处理连接请求
void handle_connection(tcp_info* tcp_clients, int* num_clients, MYSQL* conn) {
    int iResult;
    SOCKET listen_socket = tcp_clients[*num_clients].socket;
    SOCKADDR_IN client_addr;
    int client_addr_size = sizeof(client_addr);

    SOCKET client_socket = accept(listen_socket, (SOCKADDR*)&client_addr, &client_addr_size);
    if (client_socket == INVALID_SOCKET) {
        printf("Failed to accept client socket: %d\n", WSAGetLastError());
        closesocket(listen_socket);
        WSACleanup();
        return;
    }

    char client_ip[16];
    inet_ntop(AF_INET, &client_addr.sin_addr, client_ip, sizeof(client_ip));
    int client_port = ntohs(client_addr.sin_port);
    printf("Client connected: %s:%d\n", client_ip, client_port);

    tcp_clients[*num_clients].socket = client_socket;
    strcpy(tcp_clients[*num_clients].ip, client_ip);
    tcp_clients[*num_clients].port = client_port;
    (*num_clients)++;

    if (*num_clients >= MAX_CLIENTS) {
        printf("Too many clients connected, closing the server.\n");
        closesocket(listen_socket);
        WSACleanup();
        return;
    }

    char welcome_message[BUFFER_SIZE];
    sprintf(welcome_message, "Welcome to the chatroom, your IP address is %s, your port number is %d.\n", client_ip, client_port);
    send(client_socket, welcome_message, strlen(welcome_message), 0);

    char buffer[BUFFER_SIZE];
    char response[BUFFER_SIZE];
    client_info client;
    chat_record record;
    char online_users[BUFFER_SIZE];
    int recv_size;

    while (1) {
        memset(buffer, 0, sizeof(buffer));
        recv_size = recv(client_socket, buffer, BUFFER_SIZE, 0);
        if (recv_size == SOCKET_ERROR) {
            printf("Failed to receive data: %d\n", WSAGetLastError());
            break;
        }
        else if (recv_size == 0) {
            printf("Client disconnected: %s:%d\n", client_ip, client_port);
            break;
        }

        printf("Received data from client: %s:%d\n", client_ip, client_port);
        printf("Data: %s\n", buffer);

        if (strstr(buffer, "login") != NULL) {
            sscanf(buffer, "login %s %s", client.username, client.password);
            strcpy(client.ip, client_ip);
            client.port = client_port;
            if (login(conn, &client)) {
                sprintf(response, "Welcome back, %s.\n", client.username);
                send(client_socket, response, strlen(response), 0);
                sprintf(record.sender, "server");
                strcpy(record.receiver, client.username);
                strcpy(record.content, response);
                sprintf(record.datetime, "%ld", time(NULL));
                save_chat_record(conn, record);
            }
            else {
                sprintf(response, "Invalid username or password.\n");
                send(client_socket, response, strlen(response), 0);
            }
        }
        else if (strstr(buffer, "register") != NULL) {
            sscanf(buffer, "register %s %s", client.username, client.password);
            strcpy(client.ip, client_ip);
            client.port = client_port;
            if (register_user(conn, &client)) {
                sprintf(response, "Register successful, %s.\n", client.username);
                send(client_socket, response, strlen(response), 0);
                sprintf(record.sender, "server");
                strcpy(record.receiver, client.username);
                strcpy(record.content, response);
                sprintf(record.datetime, "%ld", time(NULL));
                save_chat_record(conn, record);
            }
            else {
                sprintf(response, "Failed to register, please try again later.\n");
                send(client_socket, response, strlen(response), 0);
            }
        }
        else if (strstr(buffer, "online") != NULL) {
            int num_online_users = get_online_users(conn, online_users);
            if (num_online_users > 0) {
                sprintf(response, "Online users:\n%s", online_users);
                send(client_socket, response, strlen(response), 0);
            }
            else {
                sprintf(response, "No one is online.\n");
                send(client_socket, response, strlen(response), 0);
            }
        }
        else if (strstr(buffer, "chat") != NULL) {
            char receiver[32];
            char content[256];
            sscanf(buffer, "chat %s %[^\n]", receiver, content);
            sprintf(record.sender, "%s:%d", client_ip, client_port);
            strcpy(record.receiver, receiver);
            strcpy(record.content, content);
            sprintf(record.datetime, "%ld", time(NULL));
            save_chat_record(conn, record);
            sprintf(response, "[%s] %s: %s\n", record.datetime, client.username, content);
            send(client_socket, response, strlen(response), 0);
            for (int i = 0; i < *num_clients; i++) {
                if (i != *num_clients - 1 && strcmp(tcp_clients[i].ip, client_ip) == 0 && tcp_clients[i].port == client_port) {
                    continue;
                }
                sprintf(response, "[%s] %s: %s\n", record.datetime, client.username, content);
                send(tcp_clients[i].socket, response, strlen(response), 0);
            }
        }
        else if (strstr(buffer, "history") != NULL) {
            char receiver[32];
            char history[1024];
            sscanf(buffer, "history %s", receiver);
            int num_records = get_chat_history(conn, client.username, receiver, history);
            if (num_records > 0) {
                sprintf(response, "Chat history between you and %s:\n%s", receiver, history);
                send(client_socket, response, strlen(response), 0);
            }
            else {
                sprintf(response, "No chat history between you and %s.\n", receiver);
                send(client_socket, response, strlen(response), 0);
            }
        }
        else {
            sprintf(response, "Unknown command.\n");
            send(client_socket, response, strlen(response), 0);
        }
    }

    closesocket(client_socket);
    (*num_clients)--;
}

int main() {
    int iResult;
    WSADATA wsaData;
    MYSQL* conn = NULL;
    tcp_info tcp_clients[MAX_CLIENTS];
    int num_clients = 0;

    // 初始化Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("Failed to init Winsock: %d\n", iResult);
        return 1;
    }

    // 创建TCP监听套接字
    SOCKET listen_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (listen_socket == INVALID_SOCKET) {
        printf("Failed to create listen socket: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // 绑定监听套接字
    SOCKADDR_IN server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    server_addr.sin_addr.s_addr = INADDR_ANY;
    iResult = bind(listen_socket, (SOCKADDR*)&server_addr, sizeof(server_addr));
    if (iResult == SOCKET_ERROR) {
        printf("Failed to bind listen socket: %d\n", WSAGetLastError());
        closesocket(listen_socket);
        WSACleanup();
        return 1;
    }

    // 监听连接请求
    iResult = listen(listen_socket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        printf("Failed to listen on listen socket: %d\n", WSAGetLastError());
        closesocket(listen_socket);
        WSACleanup();
        return 1;
    }

    // 连接数据库
    conn = connect_db();
    if (conn == NULL) {
        closesocket(listen_socket);
        WSACleanup();
        return 1;
    }

    printf("Server started, listening on port %d...\n", SERVER_PORT);

    // 处理连接请求
    while (1) {
        handle_connection(tcp_clients, &num_clients, conn);
    }

    // 关闭数据库连接
    close_db(conn);

    // 关闭TCP监听套接字
    closesocket(listen_socket);

    // 释放Winsock资源
    WSACleanup();

    return 0;
}