Cpp网络通信01-基本的Socket通信

服务端代码

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>

using namespace std;

int main(int argc, char *argv[]) {

    if (argc != 2) {
            printf("usage:\n\t./Server <服务端端口>\n");
        return -1;
    }

    printf("Hello Server!\n");
  
    // 1.创建服务端的socket
    // AF_INET: ipv4    SOCK_STREAM: 流模式(TCP)
    int listenFd = socket(AF_INET, SOCK_STREAM, 0);
    if (listenFd == -1) {
        perror("socket");
        exit(-1);
    }

    // 2.把服务端用于通信的IP和端口绑定到socket上
    struct sockaddr_in serverAddr;
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET; // ipv4
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY); // 表示接收所有地址的请求
    serverAddr.sin_port = htons(atoi(argv[1])); // 服务器端口
    // 绑定
    if (bind(listenFd, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) != 0) {
        perror("bind");
        close(listenFd);
        return -1;
    }
    
    // 3.把socket设置为监听状态
    if (listen(listenFd, 5) != 0) {
        perror("listen");
        close(listenFd);
        return -1;
    }

    cout << "监听端口: " << argv[1] << endl;

    // 4.手里客户端的连接请求, accept是阻塞的
    int clientFd = accept(listenFd, 0, 0);
    if (clientFd == -1) {
        perror("accept");
        close(listenFd);
        return -1;
    }

    cout << "客户端已连接\n";

    // 5.与客户端通信，接收客户端发过来的报文后，回复ok.
    char buffer[1024];
    while (true) {
        int iret;
        memset(buffer, 0, sizeof(buffer));
        // 接收客户端的请求报文，recv同样是阻塞的
        // 如果客户端断开连接，recv()返回0
        if ((iret = recv(clientFd, buffer, sizeof(buffer), 0)) <= 0) {
            cout << "iret=" << iret << endl;
            break;
        }
        cout << "接收: " << buffer << endl;

        strcpy(buffer, "ok"); // 生成回应报文
        // 向客户端发送回应报文
        if ((iret = send(clientFd, buffer, strlen(buffer), 0)) <= 0) {
            perror("send");
            break;
        }
        cout << "发送: " << buffer << endl;
    }
    // 6.关闭socket
    close(listenFd);
    close(clientFd);
    return 0;
}

客户端代码

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <iterator>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>

using namespace std;

int main(int argc, char *argv[]) {
    
    if (argc != 3) {
        cout << "Usage:\n\t./Client <服务端IP> <服务端端口>\n";
        return -1;
    }

    cout << "连接到 " << argv[1] << ":" << argv[2] << endl;

    // 1.创建客户端的socket
    int socketFd = socket(AF_INET, SOCK_STREAM, 0);
    if (socketFd == -1) {
        perror("socket");
        return -1;
    }


    // 2.向服务器发起连接请求
    struct hostent* h; // 用于存放服务端ip
    if ((h = gethostbyname(argv[1])) == 0) {
        perror("gethostbyname");
        close(socketFd);
        return -1;
    }
    struct sockaddr_in serverAddr;
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    memcpy(&serverAddr.sin_addr, h->h_addr, h->h_length);
    serverAddr.sin_port = htons(atoi(argv[2]));
    if (connect(socketFd, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) != 0) {
        perror("connect");
        close(socketFd);
        return -1;
    }

    // 3.与服务器通信，发送一个请求报文后等待回复，然后再发下一个报文
    char buffer[1024];
    for (int i = 0; i < 3; i++) {
        int iret;
        memset(buffer, 0, sizeof(buffer));
        sprintf(buffer, "这是第%d条报文", i + 1);

        if ((iret = send(socketFd, buffer, strlen(buffer), 0)) <= 0) {
            perror("send");
            break;
        }
        cout << "发送: " << buffer << endl;

        memset(buffer, 0, sizeof(buffer));
        // 接收服务端的回应，recv会阻塞
        if ((iret = recv(socketFd, buffer, sizeof(buffer), 0)) <= 0) {
            cout << "iret=" << iret << endl;
            break;
        }
        cout << "接收: " << buffer << endl;
    }
    // 4.关闭socket
    close(socketFd);
    return 0;
}