socket-Windows

通信流程

服务器

  1. 初始化Winsock
  2. 创建套接字
  3. 绑定套接字
  4. 侦听客户端的套接字
  5. 接收来自客户端的连接
  6. 接收和发送数据
  7. 断开连接

客户端

  1. 初始化Winsock
  2. 创建套接字
  3. 连接到该服务器
  4. 发送和接收数据
  5. 断开连接

Windows下使用CMake

  1. CMake

    • CMake官网下载并安装
    • 无需重启，更新环境变量指令：refreshenv

  2. make

    • 安装MinGW
    • 添加环境变量：bin目录添加到PATH
    • bin目录中mingw-make.exe重命名为make.exe

  3. 编译指令

    • cmake -G “Unix Makefiles” -DCMAKE_BUILD_TYPE=Release ..
    • make

Winsock入门

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#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>

#pragma comment(lib, "Ws2_32.lib")

int main() {
  return 0;
}
  1. winsock2.h头文件包含大多数Winsock函数，结构和定义
  2. ws2tcpip.h头文件包含了用于处理TCP/IP网络协议的特定功能
  3. 对于winsock2.h需要连接到ws2_32.lib

初始化Winsock

调用Winsock函数（应用程序或DLL）的所有进程，都必须在调用Winsock函数之前初始化Windows套接字DLL，从而确保Winsock在系统上受支持。

  1. 创建名为wsaDate的WSADATA对象

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    WSADATA wsaData;

  2. 调用WSAStartup并将其值作为整数返回，并检查错误。

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    int iResult;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }
  • WSAStartup函数用于初始化Winsock DLL，在调用任何Winsock函数之前，必须成功调用该函数。
  • MAKEWORD(2,2)指定所需的Winsock的版本号，这里表示版本2.2

为客户端创建套接字

初始化之后，必须实例化socket对象，以供客户端使用。

  1. 声明包含sockaddr结构的addrinfo对象并初始化这些值。

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    struct addrinfo *result = NULL;
    struct addrinfo *ptr = NULL;
    struct addrinfo hints;
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family   = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

  2. 调用getaddrinfo函数，请求传递的服务器名称的IP地址。

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    char *node = "baidu.com";
    char *service = "http";

    // Resolve the server address and port
    iResult = getaddrinfo(node, service, &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }

示例代码：

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#include <WinSock2.h>
#include <WS2tcpip.h>
#include <stdio.h>
#pragma comment(lib, "Ws2_32.lib")
#define DEFAULT_PORT "27015"

int main(){
    WSADATA WSAData;
    struct addrinfo* result = NULL;
    struct addrinfo* ptr = NULL;
    struct addrinfo  hints;
    char *node = "baidu.com";
    char *service = "http";

    // 初始化Winsock
    int iResult = WSAStartup(MAKEWORD(2,2), &WSAData);
    if(iResult != 0){
        printf("WSAStartup is failed:%d...\n", iResult);
        return 1;
    }

    // 设置hints结构
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    //解析地址
    iResult = getaddrinfo(node, service, &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // 遍历结果链表
    for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {
        struct sockaddr_in *ipv4 = (struct sockaddr_in *)ptr->ai_addr;
        printf("IP Address: %s\n", inet_ntoa(ipv4->sin_addr));
    }

    // 清理
    freeaddrinfo(result);
    WSACleanup();
    return 0;
}

连接到套接字

调用connect函数，将创建的套接字和sockaddr结构作为参数传递。 检查常规错误。

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iResult = connect( ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
if (iResult == SOCKET_ERROR) {
    closesocket(ConnectSocket);
    ConnectSocket = INVALID_SOCKET;
}

freeaddrinfo(result);

if (ConnectSocket == INVALID_SOCKET) {
    printf("Unable to connect to server!\n");
    WSACleanup();
    return 1;
}

在客户端上发送和接收数据

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#define DEFAULT_BUFLEN 512
int recvbuflen = DEFAULT_BUFLEN;
const char *sendbuf = "this is a test";
char recvbuf[DEFAULT_BUFLEN];
int iResult;

// Send an initial buffer
iResult = send(ConnectSocket, sendbuf, (int) strlen(sendbuf), 0);
if (iResult == SOCKET_ERROR) {
    printf("send failed: %d\n", WSAGetLastError());
    closesocket(ConnectSocket);
    WSACleanup();
    return 1;
}

printf("Bytes Sent: %ld\n", iResult);

// shutdown the connection for sending since no more data will be sent
// the client can still use the ConnectSocket for receiving data
iResult = shutdown(ConnectSocket, SD_SEND);
if (iResult == SOCKET_ERROR) {
    printf("shutdown failed: %d\n", WSAGetLastError());
    closesocket(ConnectSocket);
    WSACleanup();
    return 1;
}

// Receive data until the server closes the connection
do {
    iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
    if (iResult > 0)
        printf("Bytes received: %d\n", iResult);
    else if (iResult == 0)
        printf("Connection closed\n");
    else
        printf("recv failed: %d\n", WSAGetLastError());
} while (iResult > 0);

示例代码：

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#include <WinSock2.h>
#include <WS2tcpip.h>
#include <stdio.h>
#pragma comment(lib, "Ws2_32.lib")
#define DEFAULT_PORT "27015"
#define DEFAULT_BUFLEN 512

int main(){
    WSADATA WSAData;
    struct addrinfo* result = NULL;
    struct addrinfo* ptr = NULL;
    struct addrinfo  hints;
    char *node = "baidu.com";
    char *service = "http";
    SOCKET ConnectSocket = INVALID_SOCKET;

    // 初始化Winsock
    int iResult = WSAStartup(MAKEWORD(2,2), &WSAData);
    if(iResult != 0){
        printf("WSAStartup is failed:%d...\n", iResult);
        return 1;
    }

    // 设置hints结构
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    //解析地址
    iResult = getaddrinfo(node, service, &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // 遍历结果链表
    for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {
        struct sockaddr_in *ipv4 = (struct sockaddr_in *)ptr->ai_addr;
        printf("IP Address: %s\n", inet_ntoa(ipv4->sin_addr));
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            continue; // Create socket failed, try next address
        }

        iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);
    if (ConnectSocket == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }

    int recvbuflen = DEFAULT_BUFLEN;
    const char *sendbuf = "this is a test";
    char recvbuf[DEFAULT_BUFLEN];

    // Send an initial buffer
    iResult = send(ConnectSocket, sendbuf, (int)strlen(sendbuf), 0);
    if (iResult == SOCKET_ERROR) {
        printf("send failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    printf("Bytes Sent: %ld\n", iResult);

    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    do {
        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if (iResult > 0) {
            printf("Bytes received: %d\n", iResult);
            recvbuf[iResult] = '\0'; // Null-terminate the received data
            printf("Received data: %s\n", recvbuf);
        } else if (iResult == 0) {
            printf("Connection closed\n");
        } else {
            printf("recv failed: %d\n", WSAGetLastError());
        }
    } while (iResult > 0);

    closesocket(ConnectSocket);
    iResult = WSACleanup();
    if (iResult != 0) {
        printf("WSACleanup failed: %d\n", iResult);
        return 1;
    }
    return 0;
}

断开客户端的连接

  1. 当客户端将数据发送到服务器后，可以调用shutdown函数，指定SD_SEND关闭套接字的发送端。 这允许服务器释放此套接字的某些资源。 客户端应用程序仍可接收套接字上的数据。

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    // shutdown the send half of the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

  2. 客户端应用程序完成接收数据后，调用closesocket函数关闭套接字，使用Windows套接字DLL完成客户端应用程序时，调用WSACleanup函数释放资源。

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    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();
    return 0;

参考文档

Windows套接字

Windows Socket API-us

Windows Socket API-zh

socket-Windows
http://example.com/2025/02/22/NetworkCommunications/socket_Win/
作者
ZhangHangming
发布于
2025年2月22日
许可协议