c - 服务器客户端程序未定义行为

Question

我正在用 Linux 编写服务器客户端聊天程序。由于某种原因，代码没有按预期工作。

问题出在客户端代码中，在 while 循环内，编译器不会在 scanf 处等待 获取输入，而是自己向服务器发送一些垃圾数据 ，作为返回，服务器也发送一些数据，客户端程序终止。

由于我的知识有限，我无法找出问题所在，非常感谢您的帮助。

Server.c

#define PORT 3690

#define MaxBufferLength 1024


int main()
{
    int sockFd, bytesRead, bytesSent;

    char buffer[MaxBufferLength];

    struct sockaddr_in server, client;


    server.sin_port= htons(PORT);
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = htonl(INADDR_ANY);
    sockFd = socket(AF_INET, SOCK_STREAM, 0);


    if(sockFd == -1)
        printf("Unable to open socket\n");


    int i = bind(sockFd, (struct sockaddr *) &server, sizeof(struct sockaddr));

    if(i == -1)
        perror("Unable to bind\n");



    i = listen(sockFd, 1);

    if(i == -1)
        printf("Unable to listen\n");




    int connectionSocket = accept(sockFd, (struct sockaddr *) &client, sizeof(struct sockaddr));

    if(connectionSocket == 1)
        printf("connection established\n");


    while(1)
    {           
        bytesRead = recv(connectionSocket, buffer, MaxBufferLength, 0);

        buffer[bytesRead] = '\0';

        printf("Client said: \n     %s\n", buffer);


        scanf("\n\n = %s", buffer);

        bytesSent = send(connectionSocket, buffer, strlen(buffer), 0);

        if(bytesSent == -1)
            perror("Failed to send a message");

        connectionSocket = accept(sockFd, (struct sockaddr *) &client, sizeof(struct sockaddr)); // wait for connection again
    }


    close(sockFd);

    return 0;



}

问候

Answer 1

这可能会导致问题。

sizeof(struct sockaddr) ==>sizeof(struct sockaddr_in) or sizeof(server)

int connection = connect(sockFd, (struct sockaddr *) &server, sizeof(server) )

和

scanf("Enter message: \n\n = %s", buffer); 
          |
          V 
printf("Enter message: ");
scanf("%s",buffer);   

参见 Networking and Socket programming tutorial in C