基于Linux和C++的socket编程示例(TCP)

原文地址：https://www.geeksforgeeks.org/socket-programming-cc/

服务端：

// Server side C program to demonstrate Socket
// programming
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

#define PORT 8080

int main(int argc, char const* argv[])
{
    int server_fd, new_socket;
    ssize_t valread;
    struct sockaddr_in address;
    int opt = 1;
    socklen_t addrlen = sizeof(address);
    char buffer[1024] = { 0 };
    const char* hello = "Hello from server";

    // AF_INET表示IPV4网络通信领域。SOCKET_STREAM表示TCP，即流式。0表示默认(也可以填6表示TCP)
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }
    // SOL_SOCKET表示套接字级别的选项。SO_REUSEADDR表示服务关闭后，地址和端口可重入。这段可删
    if (setsockopt(server_fd, SOL_SOCKET,
                SO_REUSEADDR, &opt,
                sizeof(opt))) {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    } //这段可删

    address.sin_family = AF_INET; //设置协议簇为IPV4
    address.sin_addr.s_addr = INADDR_ANY; //设置服务端接收的套接字的IP地址，INADDR_ANY表示任何本地地址
    address.sin_port = htons(PORT);//设置端口号为8080

    // Forcefully attaching socket to the port 8080
    if (bind(server_fd, (struct sockaddr*)&address,
            sizeof(address))
        < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    //3表示消息等待队列的最大长度
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }
    if ((new_socket = accept(server_fd, (struct sockaddr*)&address, &addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    valread = read(new_socket, buffer,
                1024 - 1); // subtract 1 for the null
                            // terminator at the end
    printf("%s\n", buffer);
    send(new_socket, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    // closing the connected socket
    close(new_socket);
    // closing the listening socket
    close(server_fd);
    return 0;
}

客户端：

// Client side C program to demonstrate Socket
// programming
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#define PORT 8080

int main(int argc, char const* argv[])
{
    int status, valread, client_fd;
    struct sockaddr_in serv_addr;
    const char* hello = "Hello from client";
    char buffer[1024] = { 0 };
    if ((client_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("\n Socket creation error \n");
        return -1;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);

    // Convert IPv4 and IPv6 addresses from text to binary
    // form
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)
        <= 0) {
        printf(
            "\nInvalid address/ Address not supported \n");
        return -1;
    }

    if ((status
        = connect(client_fd, (struct sockaddr*)&serv_addr,
                sizeof(serv_addr)))
        < 0) {
        printf("\nConnection Failed \n");
        return -1;
    }
    send(client_fd, hello, strlen(hello), 0);
    printf("Hello message sent\n");
    valread = read(client_fd, buffer,
                1024 - 1); // subtract 1 for the null
                            // terminator at the end
    printf("%s\n", buffer);

    // closing the connected socket
    close(client_fd);
    return 0;
}

结果如下图：