C语言中的TCP Server-Client实现

先决条件–使用select的C / C++，TCP和UDP服务器进行套接字编程，C中的UDP服务器-客户端实现
如果我们使用TCP在客户端和服务器之间建立连接，则它的功能很少，例如TCP适用于要求高可靠性的应用程序，并且传输时间的重要性相对较低。其他协议(例如HTTP，HTTP，FTP，SMTP，Telnet)使用它。 TCP按照指定的顺序重新排列数据包。绝对保证所传输的数据保持完整并以与发送时相同的顺序到达。 TCP执行流控制，并需要三个数据包来建立套接字连接，然后才能发送任何用户数据。 TCP处理可靠性和拥塞控制。它还执行错误检查和错误恢复。错误的数据包将从源重新传输到目的地。

整个过程可以分为以下步骤：

整个过程可以分为以下步骤：

TCP服务器–

1. 使用create()创建TCP套接字。
2. 使用bind()，将套接字绑定到服务器地址。
3. 使用listen()，将服务器套接字置于被动模式，在该模式下，它等待客户端接近服务器以建立连接
4. 使用accept()，此时，客户端和服务器之间已建立连接，并且它们已准备好传输数据。
5. 返回步骤3。

TCP客户端–

1. 创建TCP套接字。
2. 将新创建的客户端套接字连接到服务器。

TCP Server:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define MAX 80
#define PORT 8080
#define SA struct sockaddr
  
// Function designed for chat between client and server.
void func(int sockfd)
{
    char buff[MAX];
    int n;
    // infinite loop for chat
    for (;;) {
        bzero(buff, MAX);
  
        // read the message from client and copy it in buffer
        read(sockfd, buff, sizeof(buff));
        // print buffer which contains the client contents
        printf("From client: %s\t To client : ", buff);
        bzero(buff, MAX);
        n = 0;
        // copy server message in the buffer
        while ((buff[n++] = getchar()) != '\n')
            ;
  
        // and send that buffer to client
        write(sockfd, buff, sizeof(buff));
  
        // if msg contains "Exit" then server exit and chat ended.
        if (strncmp("exit", buff, 4) == 0) {
            printf("Server Exit...\n");
            break;
        }
    }
}
  
// Driver function
int main()
{
    int sockfd, connfd, len;
    struct sockaddr_in servaddr, cli;
  
    // socket create and verification
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        printf("socket creation failed...\n");
        exit(0);
    }
    else
        printf("Socket successfully created..\n");
    bzero(&servaddr, sizeof(servaddr));
  
    // assign IP, PORT
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(PORT);
  
    // Binding newly created socket to given IP and verification
    if ((bind(sockfd, (SA*)&servaddr, sizeof(servaddr))) != 0) {
        printf("socket bind failed...\n");
        exit(0);
    }
    else
        printf("Socket successfully binded..\n");
  
    // Now server is ready to listen and verification
    if ((listen(sockfd, 5)) != 0) {
        printf("Listen failed...\n");
        exit(0);
    }
    else
        printf("Server listening..\n");
    len = sizeof(cli);
  
    // Accept the data packet from client and verification
    connfd = accept(sockfd, (SA*)&cli, &len);
    if (connfd < 0) {
        printf("server acccept failed...\n");
        exit(0);
    }
    else
        printf("server acccept the client...\n");
  
    // Function for chatting between client and server
    func(connfd);
  
    // After chatting close the socket
    close(sockfd);
}

TCP Client:

#include 
#include 
#include 
#include 
#include 
#define MAX 80
#define PORT 8080
#define SA struct sockaddr
void func(int sockfd)
{
    char buff[MAX];
    int n;
    for (;;) {
        bzero(buff, sizeof(buff));
        printf("Enter the string : ");
        n = 0;
        while ((buff[n++] = getchar()) != '\n')
            ;
        write(sockfd, buff, sizeof(buff));
        bzero(buff, sizeof(buff));
        read(sockfd, buff, sizeof(buff));
        printf("From Server : %s", buff);
        if ((strncmp(buff, "exit", 4)) == 0) {
            printf("Client Exit...\n");
            break;
        }
    }
}
  
int main()
{
    int sockfd, connfd;
    struct sockaddr_in servaddr, cli;
  
    // socket create and varification
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        printf("socket creation failed...\n");
        exit(0);
    }
    else
        printf("Socket successfully created..\n");
    bzero(&servaddr, sizeof(servaddr));
  
    // assign IP, PORT
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    servaddr.sin_port = htons(PORT);
  
    // connect the client socket to server socket
    if (connect(sockfd, (SA*)&servaddr, sizeof(servaddr)) != 0) {
        printf("connection with the server failed...\n");
        exit(0);
    }
    else
        printf("connected to the server..\n");
  
    // function for chat
    func(sockfd);
  
    // close the socket
    close(sockfd);
}

编译–
服务器端：
gcc server.c -o服务器
。/服务器

客户端：
gcc client.c -o客户端
。/客户

输出 –
服务器端：

Socket successfully created..
Socket successfully binded..
Server listening..
server acccept the client...
From client: hi
     To client : hello
From client: exit
     To client : exit
Server Exit... 

客户端：

Socket successfully created..
connected to the server..
Enter the string : hi
From Server : hello
Enter the string : exit
From Server : exit
Client Exit... 

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