C++ 有没有办法，我可以使用套接字编程发送Telnet选项命令

我编写了以下客户机-服务器程序：

客户：

客户端：

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您已提前返回0；在客户端代码的main函数中，在开始发送这些序列之前关闭套接字并返回0将导致它们无法被发送，服务器也无法侦听它们。我将返回值更改为0。但客户端程序再次在读取1时停止，不再继续读取更多缓冲区。@molbdnilo请检查编辑的帖子。服务器在发送我收到你的消息后完成。您是否希望客户端从未运行的服务器接收某些内容？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cstring>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>

char buf1[] = {0xff, 0xfb, 0x18, 0xff, 0xfb, 0x1f};
char buf2[] = {0xff, 0xfc, 0x20, 0xff, 0xfc, 0x23, 0xff, 0xfb, 0x27};
char buf3[] = {0xff, 0xfa, 0x1f, 0x00, 0x78, 0x00, 0x32, 0xff, 0xf0};
char buf4[] = {0xff, 0xfa, 0x27, 0x00, 0xff, 0xf0, 0xff, 0xfa,
               0x18, 0x00, 0x41, 0x4e, 0x53, 0x49, 0xff, 0xf0};
char buf5[] = {0xff, 0xfd, 0x03};
char buf6[] = {0xff, 0xfb, 0x01, 0xff, 0xfe, 0x05, 0xff, 0xfc, 0x21};
char buf7[] = {0xff, 0xfc, 0x01};
char buf8[] = {0xff, 0xfd, 0x01};

void read(int sock)
{
    char buffer[256];

    /* Now read server response */
    memset(buffer, 0, sizeof(buffer));
    int n = recv(sock, buffer, 255, 0);

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

    printf("%d bytes received buffer is: %s\n", n, buffer);
    for (int i = 0; i < n; i++)
        printf("%2x ", buffer[i]);

    printf("\n");
}

void mwrite(int sock, char* buf, int size)
{
    int n = send(sock, buf, size, 0);
    if (n < 0)
    {
        perror("ERROR writing to socket");
        return;
    }
    printf("Bytes Sent: %d\n", n);
}

int main(int argc, char* argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent* server;

    char buffer[256];

    if (argc < 3)
    {
        fprintf(stderr, "usage %s hostname port\n", argv[0]);
        return (0);
    }

    portno = atoi(argv[2]);
    /* Create a socket point */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0)
    {
        perror("ERROR opening socket");
        return (1);
    }

    server = gethostbyname(argv[1]);
    if (server == NULL)
    {
        fprintf(stderr, "ERROR no such host \n");
        exit(0);
    }

    bzero((char*)&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;

    bcopy((char*)server->h_addr, (char*)&serv_addr.sin_addr.s_addr,
          server->h_length);

    serv_addr.sin_port = htons(portno);

    /* Now connect to the server */
    if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0)
    {
        perror("ERROR connecting");
        return (1);
    }

    printf("Please enter the message=");
    bzero(buffer, 256);
    fgets(buffer, 255, stdin);

    n = write(sockfd, buffer, strlen(buffer));
    if (n < 0)
        printf("ERROR writing in socket %d  len %d", n, strlen(buffer));

    bzero(buffer, 256);

    n = read(sockfd, buffer, 255);
    if (n < 0)
        perror("ERROR reading from socket");

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

    buffer[0] = 0x0d;
    buffer[1] = 0x0a;
    mwrite(sockfd, buffer, 2);
    printf("read 1 ");
    read(sockfd);

    mwrite(sockfd, buf1, sizeof(buf1));
    sleep(2);
    mwrite(sockfd, buf2, sizeof(buf2));
    printf("read 2 ");
    read(sockfd);

    mwrite(sockfd, buf3, sizeof(buf3));
    printf("read 3a ");
    read(sockfd);
    sleep(2);
    mwrite(sockfd, buf4, sizeof(buf4));
    printf("read 3b ");
    read(sockfd);

    mwrite(sockfd, buf5, sizeof(buf5));
    sleep(2);
    mwrite(sockfd, buf6, sizeof(buf6));
    printf("read 4 ");
    read(sockfd);

    mwrite(sockfd, buf7, sizeof(buf7));
    sleep(2);
    mwrite(sockfd, buf8, sizeof(buf8));
    read(sockfd);

    mwrite(sockfd, buffer, 2);
    read(sockfd);
    close(sockfd);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

void error(char* msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char* argv[])
{    
    int sockfd, newsockfd, portno;
    // unsigned clilen;
    socklen_t clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int n;

    if (argc < 2)
    {
        fprintf(stderr, "ERROR, no port provided\n");
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0)
    {
        error("ERROR opening socket");
    }

    bzero((char*)&serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR on binding");

    while(1)
    {
        listen(sockfd, 5);
        clilen = sizeof(cli_addr);

        newsockfd = accept(sockfd, (struct sockaddr*)&cli_addr, &clilen);

        if (newsockfd < 0)
        {
            error("ERROR on accept");
        }

        bzero(buffer, 256);

        n = read(newsockfd, buffer, 255);

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

        printf("Here is the message: %s\n", buffer);

        n = write(newsockfd, "I got your message", 18);

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

    return 0;
}

/server 6999

Here is the message : Hi

/client 127.0.0.1 6999

Please Enter the message = Hi

I got your message 

Sending buffer..

Bytes sent : 2

read 1 0 bytes received buffer is :