linux tcp 编程

Linux TCP 编程指的是在 Linux 操作系统下利用 TCP 协议进行网络编程。下面是一个简单的 TCP 客户端和服务器端的实现代码，可以作为学习的起点。

TCP 服务器端：

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

#define PORT 8080

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

    // 创建 socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        return -1;
    }

    // 设置 socket 选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt failed");
        return -1;
    }
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    // 绑定 socket
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        return -1;
    }

    // 监听连接
    if (listen(server_fd, 3) < 0) {
        perror("listen failed");
        return -1;
    }

    // 接受连接
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept failed");
        return -1;
    }

    // 读取客户端发送的消息
    valread = read(new_socket, buffer, 1024);
    printf("%s\n", buffer);

    // 发送消息给客户端
    send(new_socket, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    return 0;
}

TCP 客户端：

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

#define PORT 8080

int main(int argc, char const *argv[]) {
    int sock = 0, valread;
    struct sockaddr_in serv_addr;
    char *hello = "Hello from client";
    char buffer[1024] = {0};

    // 创建 socket
    if ((sock = 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);

    // 将 IPv4 地址从点数格式转换成二进制格式
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }

    // 连接服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        printf("\nConnection Failed \n");
        return -1;
    }

    // 发送消息给服务器
    send(sock, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    // 读取服务器的回复
    valread = read(sock, buffer, 1024);
    printf("%s\n", buffer);

    return 0;
}

以上代码只是一个简单的示例，TCP 编程还涉及到套接字编程、网络字节序和主机字节序转换、多线程、非阻塞 I/O 等内容，需要深入学习。