c - 如何计算tcp服务器中的数字

Question

我有一个关于 c 语言和套接字编程的作业，我不知道如何开始我要求做的是用 SELECT() 函数（不是 FORK()）编写一个 TCP 服务器，服务器需要计算 N 个数字的总和由连接到此服务器的客户端提供。服务器需要打印N个最大的数字和发送这个数字的客户端的IP地址客户端使用终端中的telnet服务连接到服务器

我已经有了 TCP 服务器，但我不知道如何获取客户端发送的数字。谢谢您的帮助

Answer 1

要使用 telnet 服务器，您需要将套接字绑定到端口号。标准的 telnet 端口是 23。由于您已经拥有服务器部分，因此客户端连接到服务器；我会把读取数字的部分发给你。将其复制并粘贴到您的程序中。要使用它，只需使用从接受中获得的套接字调用 ProcessConnection() 函数。

// Some "special" characters definitions
#define RETURN 13
#define NEWLINE 10
#define ESCAPE 27
#define BACKSPACE 8

// this is the max numbers that can be accepted per session
// you may change to do it dynamically, pointers and malloc, case you want to.
#define MAX_NUMS 250
int theNumbers[MAX_NUMS];

// To do the echo of remote typed chars
int doEcho = 0;

// return the sum of the Int theNumbers
int sumThemUp(int count)
{
    int sum=0, i=0;
    for (i=0; i < count; i++) sum+=theNumbers[i];
    return sum;
}

// return the biggest number
int getBiggest(int count)
{
    int ret=0, i=0;
    for (i=0; i < count; i++)
        if (ret < theNumbers[i]) ret = theNumbers[i];
    return ret;
}

// return the smallest number
int getSmallest(int count)
{
    int ret=0, i=0;
    for (i=0; i < count; i++)
        if (ret == 0 || ret > theNumbers[i]) ret = theNumbers[i];
    return ret;
}

void ProcessConnection(SOCKET wConSock)
{
    fd_set sfds;
    struct timeval timeout={0, 0};
    char actNum[12];
    int numNums=0;
    char ch;

    char  * WelcomeMessage1 = "Welcome to my telnet emulator\r\n";
    char  * WelcomeMessage2 = "Please type in a number and press enter\r\n";
    char  * WelcomeMessage3 = "To end the session press the Esc key\r\n";
    char  * WakeUpMessage = "Are you sleeping?, common wake up!!\r\n";
    int sentSleep=0;

    send(wConSock, WelcomeMessage1, strlen(WelcomeMessage1), 0);
    send(wConSock, WelcomeMessage2, strlen(WelcomeMessage2), 0);
    send(wConSock, WelcomeMessage3, strlen(WelcomeMessage3), 0);
    memset(actNum, 0, sizeof(actNum));
    memset(theNumbers, 0, sizeof(int) * MAX_NUMS);

    int KeepOnReading = 1;
    while (KeepOnReading)
    {
         FD_ZERO(&sfds);
         FD_SET(wConSock, &sfds);
         timeout.tv_sec=60; // 1 minute
         timeout.tv_usec=0;

         switch (select(1, &sfds, NULL, NULL, &timeout))
         {
            default:
                // there are errors in the socket, close it and quit
                close(wConSock);
                return;

            case 0: // time out has elapsed
                if (!sentSleep) send(wConSock, WakeUpMessage, strlen(WakeUpMessage), 0);
                sentSleep=1;
                break;

            case 1: // socket has data, let's read it
                if (recv(wConSock, &ch, sizeof(ch), 0) == sizeof(ch))
                { // got a char, let's see it
                    switch (ch)
                    {
                        case '0':
                        case '1':
                        case '2':
                        case '3':
                        case '4':
                        case '5':
                        case '6':
                        case '7':
                        case '8':
                        case '9':
                            if (strlen(actNum) < 10) strncat(actNum, &ch, 1);
                            if (doEcho) send(wConSock, &ch, sizeof(ch), 0);
                            sentSleep=0;
                            break;

                        case BACKSPACE:
                            if (strlen(actNum)) actNum[strlen(actNum)-1] = '\0';
                            if (doEcho) send(wConSock, "\b", 1, 0);
                            break;

                        case ESCAPE: // Esc
                            KeepOnReading=0;
                            break;

                        case RETURN:
                            if (doEcho) send(wConSock, "\r\n", 2, 0);
                            if (strlen(actNum))
                            {
                                theNumbers[numNums] = atoi(actNum);
                                if (theNumbers[numNums] > 0 && numNums < MAX_NUMS) numNums++;
                                memset(actNum, 0, sizeof(actNum));
                            }
                            break;
                    }
                }
                break;
       }
    }
    char text[64];
    sprintf(text, "\n\n\r  Numbers entered:%10d\r\n", numNums);
    send(wConSock, text, strlen(text), 0);
    sprintf(text, "   Sum of numbers:%10d\r\n", sumThemUp(numNums));
    send(wConSock, text, strlen(text), 0);
    sprintf(text, "  Smallest number:%10d\r\n", getSmallest(numNums));
    send(wConSock, text, strlen(text), 0);
    sprintf(text, "   Biggest number:%10d\r\n", getBiggest(numNums));
    send(wConSock, text, strlen(text), 0);
    strcpy(text, "\r\n\nPress any key to quit...");
    send(wConSock, text, strlen(text), 0);
    recv(wConSock, &ch, sizeof(ch), 0);
    close(wConSock);
}