使用UDP和套接字进行客户端-服务器文本文件传输 在C++中，服务器创建一个空白文件

首先，我想指出我不是一个好的程序员，所以请耐心等待。程序中的逻辑如下:客户端向服务器发送一个文本文件，服务器将其以不同的名称保存。简而言之，非常类似于这个话题:"文件传输服务器/客户端使用套接字"，除了我使用不同的协议。我想我已经成功地发送了文件，但似乎服务器，创建一个空白文件后，卡在一个循环/不写任何东西在它。

下面是客户端的代码:

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h> /* memset() */
#include <sys/time.h> /* select() */ 
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>  

#define REMOTE_SERVER_PORT 1500
#define MAX_MSG 100
#define PLIK    "/home/aatami/Documents/programowanie/serwer/plik.txt"
#define LENGTH 512
int main(int argc, char *argv[]) {
  int sd, rc, i,fd;
  unsigned int cliLen;
  struct sockaddr_in cliAddr, remoteServAddr;
  struct hostent *h;
  char  buf[LENGTH];
  /* check command line args */
  if(argc<3) {
    printf("usage : %s <server> <data1> ... <dataN> n", argv[0]);
    exit(1);
  }
  /* get server IP address (no check if input is IP address or DNS name */
  h = gethostbyname(argv[1]);
  if(h==NULL) {
    printf("%s: unknown host '%s' n", argv[0], argv[1]);
    exit(1);
  }
  printf("%s: sending data to '%s' (IP : %s) n", argv[0], h->h_name,
     inet_ntoa(*(struct in_addr *)h->h_addr_list[0]));
  remoteServAddr.sin_family = h->h_addrtype;
  memcpy((char *) &remoteServAddr.sin_addr.s_addr, 
     h->h_addr_list[0], h->h_length);
  remoteServAddr.sin_port = htons(REMOTE_SERVER_PORT);
  /* socket creation */
  sd = socket(AF_INET,SOCK_DGRAM,0);  /* port 0 - system gets the first free one */ 
  if(sd<0) {
    printf("%s: cannot open socket n",argv[0]);
    exit(1);
  }
  /* bind any port */
  cliAddr.sin_family = AF_INET;
  cliAddr.sin_addr.s_addr = htonl(INADDR_ANY);
  cliAddr.sin_port = htons(0);
  rc = bind(sd, (struct sockaddr *) &cliAddr, sizeof(cliAddr));
  if(rc<0) {
    printf("%s: cannot bind portn", argv[0]);
    exit(1);
  }

  /* send data */
  for(i=2;i<argc;i++) {
    rc = sendto(sd, argv[i], strlen(argv[i])+1, 0, 
        (struct sockaddr *) &remoteServAddr, 
        sizeof(remoteServAddr));
    if(rc<0) {
      printf("%s: cannot send data %d n",argv[0],i-1);
      close(sd);
      exit(1);
    }
    /* send text file */

        char sdbuf[LENGTH]; 
        printf("[Client] Sending %s to the Server... ", PLIK);
        FILE *fs = fopen(PLIK, "r");
        if(fs == NULL)
        {
            printf("ERROR: File %s not found.n", PLIK);
            exit(1);
        }
        bzero(sdbuf, LENGTH); 
        int fs_block_sz; 
        while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs)) > 0)
        {
            if(send(sd, sdbuf, fs_block_sz, 0) < 0)
            {
                fprintf(stderr, "ERROR: Failed to send file %s. (errno = %d)n", PLIK,           errno);
                break;
            }
            bzero(sdbuf, LENGTH);
        }
        printf("Ok File %s from Client was Sent!n", PLIK);

  }
  return 1;
}

服务器的代码:

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h> /* close() */
#include <string.h> /* memset() */
#include <errno.h>
#define LENGTH 512
#define LOCAL_SERVER_PORT 1500
#define MAX_MSG 100
#define PLIKSERV    "/home/aatami/Documents/programowanie/serwer/plikserv.txt"
int main(int argc, char *argv[]) { /* licznik argumentow, tablica argumentow */
  int sd, rc,nsockfd;
  unsigned int n,cliLen;
  struct sockaddr_in cliAddr, servAddr;
  char msg[MAX_MSG];
   char  buf[512],sbuf[LENGTH];
  /* socket creation */
  sd=socket(AF_INET, SOCK_DGRAM, 0);
  if(sd<0) {
    printf("%s: cannot open socket n",argv[0]);
    exit(1);
  }
  /* bind local server port */
  servAddr.sin_family = AF_INET;
  servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
  servAddr.sin_port = htons(LOCAL_SERVER_PORT);
  rc = bind (sd, (struct sockaddr *) &servAddr,sizeof(servAddr));
  if(rc<0) {
    printf("%s: cannot bind port number %d n", 
       argv[0], LOCAL_SERVER_PORT);
    exit(1);
  }
  printf("%s: waiting for data on port UDP %un", 
       argv[0],LOCAL_SERVER_PORT);

  /* server infinite loop */
  while(1) {
    /* init buffer */
    memset(msg,0x0,MAX_MSG);

    /* receive message */
    cliLen = sizeof(cliAddr);
    n = recvfrom(sd, msg, MAX_MSG, 0, 
         (struct sockaddr *) &cliAddr, &cliLen);
    if(n<0) {
      printf("%s: cannot receive data n",argv[0]);
      continue;
    }
    /* print received message */
    printf("%s: from %s:UDP%u : %s n", 
       argv[0],inet_ntoa(cliAddr.sin_addr),
       ntohs(cliAddr.sin_port),msg);
         unsigned int sin_size = sizeof(struct sockaddr_in);


        FILE *fr = fopen(PLIKSERV, "a");
        if(fr == NULL)
            printf("File %s Cannot be opened file on server.n", PLIKSERV);
        else
        {
            bzero(sbuf, LENGTH); 
            int fr_block_sz = 0;
            while((fr_block_sz = recvfrom(sd, buf, LENGTH, 0,(struct sockaddr *) &cliAddr, &cliLen)) > 0) 
            {
                int write_sz = fwrite(buf, sizeof(char), fr_block_sz, fr);
                if(write_sz < fr_block_sz)
                {
                    perror("File write failed on server.n");
                }
                bzero(buf, LENGTH);
                if (fr_block_sz == 0 || fr_block_sz != 512) 
                {
                    break;
                }
            }
            if(fr_block_sz < 0)
            {
                if (errno == EAGAIN)
                {
                    printf("recv() timed out.n");
                }
                else
                {
                    fprintf(stderr, "recv() failed due to errno = %dn", errno);
                    exit(1);
                    }
                }
            printf("Ok received from client!n");
            fclose(fr); 
        }
  }/* end of server infinite loop */
return 0;
}

任何帮助都非常感谢!