c - TCP 连接的错误和意外行为

Question

我希望我的 TCP 服务器和客户端能够根据对方所说的内容相互“交谈”。但是当我运行时，它似乎经历了一次迭代，但随后服务器和客户端似乎都“挂”在那里。一旦我在客户端杀死它，我最终会得到一个损坏的管道错误。

任何人都可以解释我在这里做错了什么吗？

服务器代码片段:

while(feof(file_ptr) == 0)
{
    fscanf(file_ptr, "%s", supplies);
    printf("%s\n", supplies);

    //SEND supplies to all clients (currently just one client)

    n = write(newsockfd, supplies, strlen(supplies));

    if (n < 0)
    {
        error("ERROR writing to socket");
    }


    //Receive a request from client that they can use supply

    bzero(buffer,2);
    n = read(newsockfd,buffer,2);

    if (n < 0)
    {
        error("ERROR reading from socket");
    }

    printf("Who is using supply? %s\n", buffer);


    if(strcmp(buffer, "A"))
    {
        aRounds++;  
    }


    while(done != 1)
    {
        //WAIT loop until message CO is received from client
        bzero(buffer,2);
        n = read(newsockfd,buffer,2);

        if (n < 0)
        {
            error("ERROR reading from socket");
        }

        printf("Done? %s\n", buffer);



        if(strcmp(buffer, "CO"))
        {
            done = 1;
        }
    }

    done = 0;
}

fclose(file_ptr);
n = write(newsockfd, "DN", 2);

客户端代码片段:

while(noSupplies != 1)
{
    //RECEIVE MSG from server about supplies
    bzero(buffer,2); 
    n = read(sockfd,buffer,2);

    if (n < 0) 
    {
        error("ERROR reading from socket");
    }

    printf("%s\n",buffer);

    if(strcmp(buffer, "BC") == 0 || strcmp(buffer, "CB") == 0)
    {
        //SEND server msg that you are using supply

        n = write(sockfd,"A", 1);
        if (n < 0)
        {
            error("ERROR writing to socket"); 
        }


        printf("Client A has received components %s during round %d.\n", buffer, round);


        n = write(sockfd,"CO", 2);
        if (n < 0)
        {
            error("ERROR writing to socket"); 
        }

    }
    else if(strcmp(buffer, "DN"))
    {
        noSupplies = 1;
    }

    round++;
}

我从服务器得到以下信息(在杀死之前):

BC
Who is smoking? A
Done smoking? CO

以及来自客户端的以下内容(在终止之前):

BC
Client A has received components BC during round 1.

然后从客户端杀死后..我从服务器得到以下信息:

BC
Who is using supply? A
Done? CO
Done? 
CB
Who is using supply? 
Done? 
CB
Who is using supply? 
Done? 
BC
Broken pipe

有人明白我做错了什么吗？ (寻找代码修复!)

仅供引用..我最终将更改服务器代码以处理监听多个客户端(TCP)，但一次会遇到一个障碍，对吗？ :S

谢谢!

Answer 1

不确定这是否是您的全部问题，但是

bzero(buffer, 2);
n = read(socket, buffer, 2);

...

printf("%s", buffer);

是不正确的，因为如果读取实际上获得了 2 个字节并且它们都不是 0，那么缓冲区可能不是一个以 null 结尾的字符串(除非之前有一些东西导致了这一点)。

对 strcmp 的多次调用也总是会因为同样的原因而失败 - 读取的字符串不是 0 终止的，因此 strcmp 认为它会继续进行，因此与比较的结果不同字符串，即使第一个字母相同。

编辑

 n = read(socket, buffer, 2);
 if (n<0) {
     die_horrible_death();
 }
 buffer[n] = 0; // since arrays are 0 indexed this should be after last read character
 printf("I just read: \"%s\"\n", buffer);