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我已经使用该网站一段时间了，（本学期之后）期待回馈！但是，我最后一次希望您的帮助，并且似乎没有其他答案可以提供任何帮助。

背景：使用 C++、套接字和客户端/服务器架构设计一个基本的聊天室，最多有十个客户端与服务器交谈。一个客户端所说的任何内容都会在所有客户端和服务器之间回显（发送客户端除外）。

问题：错误发生在 recv 调用中，作为 clientTalk 函数中的 while 循环条件。我得到一个“接收失败：错误的文件描述符”，但服务器和客户端都没有完全“崩溃”，并且没有发生明显的行为变化，尽管接收完全被炸毁了。

尝试解决：

  • 谷歌和 SOf。持续2个小时...

  • 移动变量，玩弄套接字设置和打开/关闭

-瓦尔格林：

==773== Warning: invalid file descriptor 96600128 in syscall read()

Recieve failed: Bad file descriptor
==773== Thread 2:
==773== Conditional jump or move depends on uninitialised value(s)
==773==    at 0x4015A0: ??? (in /nethome/users/ghm455/CS284/ChatServer/server)
==773==    by 0x4E39E99: start_thread (pthread_create.c:308)
==773==    by 0x5442CBC: clone (clone.S:112)
==773==
==773== Conditional jump or move depends on uninitialised value(s)
==773==    at 0x401614: ??? (in /nethome/users/ghm455/CS284/ChatServer/server)
==773==    by 0x4E39E99: start_thread (pthread_create.c:308)
==773==    by 0x5442CBC: clone (clone.S:112)
==773==
==773== Warning: invalid file descriptor 96600128 in syscall close()

第一个警告出现在我的接受声明中。接收失败发生在 recv 并且最后一个警告发生在尝试关闭时。这是由散布在整个代码中的 cout 语句决定的。

代码：下面。如果您认为错误存在，我会发布客户端，但一切都表明这是服务器端问题。

`#define SERVER_PORT 9999        /* define a server port number */

using std::cout;
using std::endl;
using std::string;

//Globals - descriptorArray holds client FDs.  arraySize is its size.
//soc holds the information on the server's socket.
//m is the global mutex shared among the server and all clients
const int MAX_CLIENT = 10;
int descriptorArray[MAX_CLIENT];
int arraySize = 0;
int soc;
pthread_mutex_t m;

struct thread_info
{
pthread_t threadID; //Stores the ID number returned by pthread_create
int threadNumber;   //We have to number incoming threads correctly
char *messageSent;  //Message taken in from command line
};

int main()
{
void exitHandler(int sig); // Function that handles the control-C
void* clientTalk(void *arg); // Reads and writes with clients
struct sockaddr_in server_addr, client_addr;
int option = 1;
unsigned int clientCount;
uint8_t *new_socket;

//Initialize the socket
soc = socket(AF_INET, SOCK_STREAM, 0);
if (soc < 0)
{
    cout << "ERROR : problem opening socket" <<endl;
    return 1;
}

//Create socket structure
bzero((char *) &server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = INADDR_ANY;
server_addr.sin_port = htons(SERVER_PORT);

//Binding host address
if (bind(soc, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0)
{
    cout << "ERROR : problem occured while binding" <<endl;
    close(soc);
    exit(1);
}
if(setsockopt(soc, SOL_SOCKET, SO_REUSEADDR, (char*) &option, sizeof(option)) < 0)
{
    printf("setsockopt failed\n");
    close(soc);
    exit(1);
} 

signal(SIGINT, exitHandler);
listen(soc, MAX_CLIENT);

clientCount = sizeof(struct sockaddr_in);
int clientID;
//cout << "Z " <<endl;
while(clientID = accept(soc, (struct sockaddr *) &client_addr, (socklen_t*)&clientCount))
{
    //printf( "A");
    if (clientID < 0 )  
    {   
        perror("ERROR ON ACCEPT");
        exit(1);
    }
    else
    {
        pthread_t newClient;
        new_socket = (uint8_t*)malloc(1);
        *new_socket = clientID;
        pthread_mutex_lock(&m);
        if (arraySize < 10)
        {
            descriptorArray[arraySize++] = newClient;
        }
        else
        {
            cout << "There are already 10 clients connected!" << endl;
        }
        pthread_mutex_unlock(&m);
        if( pthread_create(&newClient, NULL, clientTalk, &new_socket) < 0)
        {
            perror("ERROR Creating thread");
            return 1;
        }
        cout << "Assigned!" <<endl;
        pthread_join(newClient, NULL);
    }
}
close(soc);
return 0;
}

void exitHandler(int sig)
{
sig = sig + 0; //Removing the warning. A clean compile looks a lot nicer.
for (int i = 0; i < arraySize; i++)
{
    write(descriptorArray[i], "WARNING: Server exiting in ten seconds. End your conversation!", 1000);
}
cout << "WARNING: Server exiting in ten seconds.  ";
cout << "End your conversation!" << endl;
sleep(10f); 
for (int i = 0; i < arraySize; i++)
{
    close(descriptorArray[i]);
}
close(soc);
exit(1);
}


void* clientTalk(void* arg)
{
int* myFD = (int*) arg;
char buffer[2000];
read(*myFD, buffer, 20);
char username[20];
//strcpy(username, buffer); // Takes in the username and stores it
char movableString[2000];
int amount_read;

// for (int i = 0; i < arraySize; i++)
// {
    //strcpy(movableString, username);
//  strcat(movableString, " has joined the room!");
    //if (descriptorArray[0] != *myFD)
    //{
    //  write(descriptorArray[0], movableString, 2000);
    //}
//}
cout << "x" << endl;
int arrayLocation;  
while ( (amount_read = recv(*myFD, buffer, 2000, MSG_WAITALL)) > 0)
{
    cout << " Um" << endl;
    pthread_mutex_lock(&m);
    for (int i = 0; i < arraySize; i++)
    {
        if (descriptorArray[i] == *myFD)
        {
            arrayLocation = i;
            break;
        }
    }
    strcpy(movableString, username);
    strcat(movableString, ": ");
    strcat(movableString, buffer);
    for (int i = 0; i < arraySize; i++)
    {
        //if (i != arrayLocation)
        //{
            write(*myFD, movableString, 2000); 
        //}
    }
    pthread_mutex_unlock(&m);
}
if (amount_read == 0)
{
    cout << username << "disconnected unexpectedly" <<endl;
    fflush(stdout);
}
if (amount_read == -1)
{
    perror("Recieve failed");
}


pthread_mutex_lock(&m);
for (int i = 0; i < arraySize; i++)
{
    if (descriptorArray[i] == *myFD)
    {
        arrayLocation = i;
        break;
    }
}

for (int i = arrayLocation; i < arraySize - 1; i++)
{
    descriptorArray[i] = descriptorArray[i + 1];
}
arraySize--;

pthread_mutex_unlock(&m);
close(*myFD);
pthread_exit(NULL);
free(arg);
}

`

我将监视该站点以回答您可能遇到的任何问题。对于在提问时犯了任何新手错误，我提前道歉。

谢谢您的帮助！

4

2 回答 2

1

该错误表示传递给 read 函数的文件描述符不是有效的文件描述符，因此调试时首先要确保 ClientTalk 函数中的文件描述符的值与 main 中的相同。

@JN 就在评论中。它们不会相同，因为 FD 是一个 int 并且您只是将第一个字节传递给函数（并将其转换为 int* 指针。）

您可能想用 C 编写这个程序，因为它看起来不像 C++ 代码。

  1. 将 ClientID 和 new_socket 更改为 int / int*。使用一致的类型，并使用函数定义中的类型 accept 返回一个 int ，因此对所有内容都使用 int / int* 。
  2. 调用 malloc 时，尽可能使用 sizeof 而不是字节数。

可能还有其他问题。

于 2012-11-29T00:05:40.710 回答
1

这里至少有两个问题。首先，您永远不会调用pthread_mutex_init，因此您的互斥锁从未被创建为正常状态（尽管如果它在全局范围内它将被归零）。

其次，您将&new_socket作为传递void*给您的线程。这是类型uint8_t**，而在您的clientTalk函数内部，您 C 样式强制转换int*为完全不同的指针类型，并且肯定不会提供您想要的结果。

于 2012-11-29T00:24:33.113 回答