c++ - 客户端/服务器 C++ 之间的通信问题

Question

我有一个 client(c++)/server(c) 程序，目前我很难在它们之间进行通信(我看不到客户端在服务器上说了什么，反之亦然)。我也在尝试让这个项目多线程化，或者至少接受来自客户端的多个连接。非常感谢所有帮助这里是与聊天有关的代码，您可以完整查看它 here

客户:

    recv(sockfd , server_reply , 2000 , 0);

    puts("Enter message :"); // asking for password
    scanf("%s" , message);
    send(sockfd , message , strlen(message) , 0);

    recv(sockfd, server_reply, 2000, 0);
    //Receive a reply from the server
    if( recv(sockfd , server_reply , 2000 , 0) < 0)
    {
        puts("recv failed");
    }

while( (read_size = recv(nsockfd , server_reply , 4000 , 0)) != 0)
  {

    puts("Enter message :"); // asking for password
    scanf("%s" , message);
    send(sockfd , message , strlen(message) , 0);

    recv(sockfd, server_reply, 2000, 0);


  }

服务器

      char client_address[90];
    sprintf(client_address, "Welcome %s", inet_ntoa(addr_remote.sin_addr));

    char welc_msg[90] = "Welcome %s";
    char friend_msg[50] = "Hello little friend \n";
    char username[30] = "Enter user:";
    char pass[30] = "Enter pass: ";

    write(nsockfd , client_address , strlen(client_address)); // attempting to send client "Hello, (their ip address)"
    read_size = recv(nsockfd , client_message , 4000 , 0);

    read_size = recv(nsockfd , client_message , 4000 , 0);
printf( "%s", client_message);
printf( "\n");



//Receive a message from client
while( 1 )  //    while( (read_size = recv(nsockfd , client_message , 4000 , 0)) != 0)
{
    //clearing buffer
    memset(client_message, 0, sizeof(client_message));

    //taking received message and printing it
    read_size = recv(nsockfd , client_message , 4000 , 0);
        printf( "%s", client_message);
        printf( "\n");

    //Send the message back to client
   // write(nsockfd , server_message , strlen(server_message));


    if (strcmp(client_message , "Hello")) // condition for project
    {
        write(nsockfd, friend_msg, strlen(friend_msg));
    }

}

Answer 1

调用系统函数时，一定要检查错误!在相关的地方，还要检查部分写入/接收。例如，当您有此行时:

send(sockfd , message , strlen(message) , 0);

你应该有这样的东西(未经测试，所以自己想一想):

(编辑:删除了不必要的重新发送循环以简化代码。如果您想查看编辑历史记录...)

int msglen = strlen(message);
fprintf(stderr, "debug: about to send %d bytes", msglen);

int sent = send(sockfd , message , msglen , 0);

if (sent == -1) { // for each function, read docs for error result
    perror("send message");
    // do some error handling
} else if (sent < msglen) {
    fprintf(stderr, "debug: partial send %d/%d\n", sent, msglen);
    // do some disconnect handling
}

一旦你有正确的错误报告，如果你不能解决你的问题，然后用这个调试/错误信息更新问题。