I’m looking for advice on writing a very safe C/C++ app that will listen to a tcp port. I d like to peek at what others are trying to do to my machine, but I’d rather not install an elaborate honeypot app if I can do what I need with a very short program. With my goal being simple and safe, I want to make sure I handle at least the following:
1) The client should not be able to send an unlimited amount of data,
2) The client(s) should not be able to overload the server with too many connections and
3) The client should not be able to keep a connection open indefinitely.
Because my current app is small and functional, a third party library doesn t seem warranted for this project. However, a small library that would simplify the app further would be interesting. Also, I expect the C++ standard library may help in simplifying my code.

以下是我最初尝试的一些关键职能。 该守则汇编了Windows、OSX和Lino。

我怎么能够使这种说法更加安全或简单?

void SafeClose(SOCKET s)
{
    if (s == INVALID_SOCKET)
        return;
    shutdown(s, SHUT_RDWR);
    closesocket(s);
}

void ProcessConnection(SOCKET sock, sockaddr_in *sockAddr)
{
    time_t time1;
    char szTime[TIME_BUF_SIZE];
    char readBuf[READ_BUF_SIZE];

    time(&time1);
    strftime(szTime, TIME_BUF_SIZE-1, "%Y/%m/%d %H:%M:%S", localtime(&time1)); 
    printf("%s - %s
", szTime, inet_ntoa(sockAddr->sin_addr));
    usleep(1000000);       // Wait 1 second for client to send something
    int actualReadCount = recv(sock, readBuf, READ_BUF_SIZE-1, 0); 

    if (actualReadCount < 0 || actualReadCount >= READ_BUF_SIZE){
        actualReadCount = 0;
        strcpy(readBuf, "(Nothing)");
    } else {
        CleanString(readBuf, actualReadCount); // Replace non-printable characters
        readBuf[actualReadCount] = 0;
    }

    printf("%s

", readBuf);
    SafeClose(sock);
}


int main(int argc, char* argv[])
{
    int             port            = 80;
    char            cmd[CMD_BUF_SIZE]   = {0};
    sockaddr_in     newSockAddr;
    sockaddr_in     localSockAddr;

    if(argc < 2){
        printf("Usage: safelisten PORT

");
        return error_code;
    }

    error_code++;
    port = atoi(argv[1]); 
    BuildCleanAsciiMap(); // Used to replace non-printable characters

    localSockAddr.sin_family        = AF_INET;              
    localSockAddr.sin_addr.s_addr   = INADDR_ANY;           
    localSockAddr.sin_port          = htons(port);          
    sizeNewSockAddr                 = sizeof newSockAddr;

    CHK( listenSocket = socket(AF_INET, SOCK_STREAM, 0));
    CHK( setsockopt(listenSocket, SOL_SOCKET,  SO_REUSEADDR, (char *)&on, sizeof(on)));
    CHK( bind(listenSocket, (sockaddr*)&localSockAddr, sizeof localSockAddr));
    CHK( listen(listenSocket, BACKLOG));
    CHK( SetNonBlocking(listenSocket));
    CHK( SetNonBlocking(0));        // Set STDIN to nonblocking for linux    
    printf ("Listening on port: %d
Enter q to quit.

", port);

    while(strcmp(cmd, "q")) // While the user has not entered q ...
    {
        newSocket = accept(listenSocket, (sockaddr*)&newSockAddr, &sizeNewSockAddr);
        ReadCmd(cmd, CMD_BUF_SIZE);

        if(newSocket == INVALID_SOCKET) { 
            // accept() would have blocked, thus we wait and try again
            usleep(10000);
            continue;   
        }

        // Set to nonblocking because we don t want the client to dictate how 
        // long we are connected.
        CHK( SetNonBlocking(newSocket)); 
        ProcessConnection(newSocket, &newSockAddr);
    }

    SafeClose(listenSocket);
    return 0;
}