socket基础知识

windows环境下的基础代码：

// server.cpp
#include <stdio.h>
#include <winsock.h>
#pragma comment(lib, "ws2_32.lib")

int main()
{
    // 初始化DLL
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    printf("wVersion: %d.%d\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion));
    printf("wHighVersion: %d.%d\n", LOBYTE(wsaData.wHighVersion), HIBYTE(wsaData.wHighVersion));
    printf("szDescription: %s\n", wsaData.szDescription);
    printf("szSystemStatus: %s\n", wsaData.szSystemStatus);

    // 创建套接字
    SOCKET servSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

    // 绑定套接字
    struct sockaddr_in sockAddr;
    memset(&sockAddr, 0, sizeof(sockAddr));
    sockAddr.sin_family = PF_INET;
    sockAddr.sin_addr.s_addr = inet_addr("192.168.182.1");
    sockAddr.sin_port = htons(1234);
    bind(servSock, (SOCKADDR*)(&sockAddr), sizeof(SOCKADDR));

    // 进入监听状态
    listen(servSock, 20);

    // 接收客户端请求
    SOCKADDR clntAddr;
    int nSize = sizeof(SOCKADDR);
    SOCKET clntSock = accept(servSock, (SOCKADDR*)(&clntAddr), &nSize);

    // 向客户端发送数据
    const char* str = "Hello world!";
    send(clntSock, str, strlen(str) + sizeof(char), NULL);

    // 关闭套接字
    closesocket(clntSock);
    closesocket(servSock);

    // 终止DLL
    WSACleanup();

    return 0;
}





// clent.cpp
#include <stdio.h>
#include <stdlib.h>
#include <WinSock2.h>

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

int main()
{
    // 初始化DLL
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    printf("wVersion: %d.%d\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion));
    printf("wHighVersion: %d.%d\n", LOBYTE(wsaData.wHighVersion), HIBYTE(wsaData.wHighVersion));
    printf("szDescription: %s\n", wsaData.szDescription);
    printf("szSystemStatus: %s\n", wsaData.szSystemStatus);

    // 通过域名获取ip
    struct hostent* host = gethostbyname("www.yanzhihui.com");
    if (!host) {
        printf("Failed to get ip address!");
        // 终止DLL
        WSACleanup();
        return -1;
    }

    //别名
    for (int i = 0; host->h_aliases[i]; i++) {
        printf("Aliases %d: %s\n", i + 1, host->h_aliases[i]);
    }

    //地址类型
    printf("Address type: %s\n", (host->h_addrtype == AF_INET) ? "AF_INET" : "AF_INET6");

    //IP地址
    for (int i = 0; host->h_addr_list[i]; i++) {
        printf("IP addr %d: %s\n", i + 1, inet_ntoa(*(struct in_addr*)host->h_addr_list[i]));
    }

    // 创建套接字
    SOCKET sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

    // 绑定套接字
    struct sockaddr_in sockAddr;
    memset(&sockAddr, 0, sizeof(sockAddr));
    sockAddr.sin_family = PF_INET;
    sockAddr.sin_addr.s_addr = inet_addr("192.168.182.128");
    //sockAddr.sin_addr.s_addr = inet_addr(inet_ntoa(*(struct in_addr*)host->h_addr_list[0]));
    sockAddr.sin_port = htons(1234);
    connect(sock, (SOCKADDR*)(&sockAddr), sizeof(SOCKADDR));

    // 接收服务器传回的数据
    char szBuffer[MAXBYTE] = { 0 };
    recv(sock, szBuffer, MAXBYTE, NULL);

    printf("Message from server: %s\n", szBuffer);

    // 关闭套接字
    closesocket(sock);

    // 终止DLL
    WSACleanup();

    system("pause");

    return 0;
}

 

linux环境下的基础代码：

// server.cpp
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

int main()
{
    // 创建套接字
    int serv_sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    // 通过域名获取ip
    struct hostent *host = gethostbyname("www.yanzhihui.com");
    if(!host){
        printf("Failed to get ip address!");
        return -1;
    }

    // 别名
    for(int i = 0; host->h_aliases[i]; i++){
        printf("Aliases %d: %s\n", i+1, host->h_aliases[i]);
    }
    
    // 地址类型
    printf("Address type: %s\n", (host->h_addrtype == AF_INET) ? "AF_INET" : "AF_INET6");

    // IP地址
    for(int i = 0; host->h_addr_list[i]; ++i)
    {
        printf("ip addr %d: %s\n", i+1, inet_ntoa(*(struct in_addr*)host->h_addr_list[i]));
    }

    // 将套接字绑定到指定IP、端口 
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr("192.168.182.128");
    //serv_addr.sin_addr.s_addr = inet_addr(inet_ntoa(*(struct in_addr*)host->h_addr_list[0]));
    serv_addr.sin_port = htons(1234);
    bind(serv_sock, (struct sockaddr*)(&serv_addr), sizeof(serv_addr));

    // 进入监听状态，等待用户发起请求
    listen(serv_sock, 20);

    // 接受客户端请求
    struct sockaddr_in clnt_addr;
    socklen_t clnt_addr_size = sizeof(clnt_addr);
    int clnt_sock = accept(serv_sock, (struct sockaddr*)(&clnt_addr), &clnt_addr_size);

    // 向客户端发送数据
    char str[] = "Hello World";
    write(clnt_sock, str, sizeof(str));

    // 关闭套接字
    close(clnt_sock);
    close(serv_sock);

    return 0;
}






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

int main()
{
    // 创建套接字
    int sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    // 将套接字绑定到指定IP、端口 
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr("192.168.182.1");
    serv_addr.sin_port = htons(1234);
    connect(sock, (struct sockaddr*)(&serv_addr), sizeof(serv_addr));

    // 读取服务器传回的消息
    char buffer[40];
    read(sock, buffer, sizeof(buffer) - 1);

    printf("Message from server: %s\n", buffer);
    // 关闭套接字
    close(sock);

    return 0;
}