多客户端套接字服务器客户端在首次请求到服务器后断开连接。 （C编程）

Question

我正在尝试编写一个多客户端套接字服务器和一个客户端来使用该服务器，这将发送服务器简单请求，如当前时间，日期等。我的问题似乎是，我可以＆＃39;让客户端保持连接，因为在第一次请求后它似乎断开连接并且请求没有到达服务器。

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <time.h>

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

void doprocessing (int sock)
{
   int n;
   char buffer[5];
   bzero(buffer,5);
   n = read(sock,buffer,4);
   time_t rawtime;
   char tim[22];
   char dat[20];
   char day[16];
   char yer[18];

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

   printf("Got %.3s command.\n",buffer);

   if (strcasecmp(buffer, "tim\n") == 0)
   {
      rawtime = time(NULL);
      strncpy(tim, "Current time: ", 14);
      strncpy(tim+14, (ctime(&rawtime))+11, 8);
      n = write(sock, tim, 22);
   }
   else if (strcasecmp(buffer, "dat\n") == 0)
   {
      rawtime = time(NULL);
      strncpy(dat, "Current date: ", 14);
      strncpy(dat+14, (ctime(&rawtime))+4, 6);
      n = write(sock, dat, 20);
   }
   else if (strcasecmp(buffer, "day\n") == 0)
   {
      rawtime = time(NULL);
      strncpy(day, "Current day: ", 13);
      strncpy(day+13, (ctime(&rawtime)), 3);
      n = write(sock, day, 16);
   }
   else if (strcasecmp(buffer, "yer\n") == 0)
   {
      rawtime = time(NULL);
      strncpy(yer, "Current year: ", 14);
      strncpy(yer+14, (ctime(&rawtime))+20, 4);
      n = write(sock, yer, 18);
   }
   else if (strcasecmp(buffer, "com\n") == 0)
   {
      n = write(sock, "TIM - current time\nDAT - Month and day\nDAY - current weekday\nYER - Year", 71);
   }
   else  n = write(sock, "Wrong command enter COM to see commands.",40);

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

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

    if (argc < 2)
    {
        fprintf(stderr, "ERROR, no port provided");
        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_port = htons(portno);
    serv_addr.sin_addr.s_addr = INADDR_ANY;

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

    listen(sockfd, 5);
    clilen = sizeof(cli_addr);

    while(1)
    {
         newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
         if (newsockfd < 0) error("ERROR on accept");

         pid = fork();

         if (pid < 0) error("ERROR on fork");

         if (pid == 0)
         {
             close(sockfd);
             doprocessing(newsockfd);
             exit(0);
         }
         else close(newsockfd);
    }
}

这就是服务器和客户端：

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

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

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

    char rbuffer[256];
    char sbuffer[256];

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

    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

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

    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);

    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) error("ERROR connecting");

    for(;;)
    {
       printf("Enter a command: ");
       bzero(sbuffer,sizeof(sbuffer));
       fgets(sbuffer,255,stdin);
       n = write(sockfd,sbuffer,strlen(sbuffer));
       if (n < 0) error("ERROR writing to socket");

       bzero(rbuffer,sizeof(rbuffer));
       n = read(sockfd,rbuffer,255);
       if (n < 0) error("ERROR reading from socket");

       printf("%s\n",rbuffer);
    }
    close(sockfd);
    return 0;
}