在C中使用UDP进行服务器 - 客户端文件传输 [英] Server-client file transfer using UDP in C

问题描述

我必须使用UDP进行服务器 - 客户端文件传输。我创建了一个基本服务器，它接收客户端发送的消息。就这样。现在主要是： -



1.客户端发送的消息是文件名。

2.现在服务器检查是否存在此文件。

3.如果存在，则将文件发送到客户端，并且还保留客户端发出的文件请求数。



这是服务器代码

 #include< sys / socket.h> 
 #include< arpa / inet.h> 
 #include< stdio.h> 
 #include< unistd.h> 
 #include< fcntl.h> 
 #include< sys / types.h> 
 #include< string.h> 
 
 
 
 
 int main（）
 {
 
 char buff [2000]; 
 char file_buffer [2000]; 
 int sd，connfd，len; 
 
 struct sockaddr_in servaddr，cliaddr; 
 
 sd = socket（AF_INET，SOCK_DGRAM，0）; 
 
 if（sd ==  -  1）
 {
 printf（socket not not in server\\\
）; 
退出（0）; 
} 
 else 
 {
 printf（在server \\\
中创建的套接字）; 
} 
 
 bzero（& servaddr，sizeof（servaddr））; 
 
 servaddr.sin_family = AF_INET; 
 servaddr.sin_addr.s_addr = INADDR_ANY; 
 servaddr.sin_port = htons（7802）; 
 
 if（bind（sd，（struct sockaddr *）& servaddr，sizeof（servaddr））！= 0）
 printf（Not binded\\\
）; 
 else 
 printf（Binded\\\
）; 
 
 
 
 len = sizeof（cliaddr）; 
 
 recvfrom（sd，buff，1024,0，
（struct sockaddr *）& cliaddr，& len）; 
 
 printf（％s \ n，buff）; 
 / * * / 
 FILE * fp; 
 fp = fopen（buff，r）; 
 if（fp == NULL）
 {
 printf（file not exists\\\
）; 
} 
 
 fseek（fp，0，SEEK_END）; 
 size_t file_size = ftell（fp）; 
 fseek（fp，0，SEEK_SET）; 
 if（fread（file_buffer，file_size，1，fp）< = 0）
 {
 printf（无法将文件复制到buffer \ n）; 
退出（1）; 
} 
 if（sendto（sd，file_buffer，strlen（file_buffer），0，（struct sockaddr *）& cliaddr，& len）< 0）{
 printf（error在发送文件\\\
）; 
退出（1）; 
} 
 bzero（file_buffer，sizeof（file_buffer））; 
 
 
 / * * / 
 close（sd）; 
 
 return（0）; 
} 

这是客户代码

 #include< ; stdio.h中> 
 #include< errno.h> 
 #include< sys / socket.h> 
 #include< resolv.h> 
 #include< netinet / in.h> 
 #include< sys / types.h> 
 
 
 
 int main（）
 {
 char buff [2000]; 
 int sockfd，connfd，len; 
 
 struct sockaddr_in servaddr，cliaddr; 
 
 //在客户端创建套接字
 sockfd = socket（AF_INET，SOCK_DGRAM，0）; 
 
 if（sockfd ==  -  1）
 {
 printf（socket不在client \\\
中创建）; 
退出（0）; 
} 
 else 
 {
 printf（在client \ n中创建的套接字）; 
} 
 
 
 bzero（& servaddr，sizeof（servaddr））; 
 
 servaddr.sin_family = AF_INET; 
 servaddr.sin_addr.s_addr = INADDR_ANY; //任何地址或使用特定地址
 servaddr.sin_port = htons（7802）; //端口地址
 
 
 printf（输入你的UDP客户端消息\ n）; 
 scanf（％s，buff）; 
 
 //将msg发送到服务器
 
 sendto（sockfd，buff，strlen（buff），0，
（struct sockaddr *）& servaddr，sizeof（ struct sockaddr））; 
 char file_buffer [2000]; 
 
 if（recvfrom（sockfd，file_buffer，2000,0，（struct sockaddr *）& servaddr，sizeof（struct sockaddr））< 0）
 {
 printf（ 收到文件中的错误\ n）; 
退出（1）; 
} 
 
 char new_file [] =复制; 
 strcat（new_file，buff）; 
 FILE * fp; 
 fp = fopen（new_file，w +）; 
 if（fwrite（file_buffer，1，sizeof（file_buffer），fp）< 0）
 {
 printf（error writinging file \\\
）; 
退出（1）; 
} 
 
 
 //关闭客户端连接
 close（sockfd）; 
 
 return（0）; 
} 

服务器从中读取数据文件并写入并发送到客户端，另一端客户端接收数据并复制此文件并写入其中。但在编译时，它会在写入文件时出错：（

解决方案

完成！



有文件句柄有问题

而不是使用fopen，使用open（），write（）和read（）来完成工作Smile |：）

can有谁告诉我如何编译这段代码，我们在那里指定文件目录??????????????????????

I have to make a server-client file transfer using UDP . I have created a basic server which receives message sent by client . That's all. Now comes the major part :-

1. The message sent by client is the name of file .
2. Now the server checks whether there exists this file or not .
3. If there exists it sends the file to the client and it also keeps the count of the number of requests of file made by the client .

Here is the Server Code

#include<sys/socket.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
#include<sys/types.h>
#include<string.h>




int main()
{

  char buff[2000];
  char file_buffer[2000];
  int sd,connfd,len;

  struct sockaddr_in servaddr,cliaddr;

  sd = socket(AF_INET, SOCK_DGRAM, 0);

  if(sd==-1)
    {
      printf(" socket not created in server\n");
      exit(0);
    }
  else
    {
      printf("socket created in  server\n");
    }

  bzero(&servaddr, sizeof(servaddr));

  servaddr.sin_family = AF_INET;
  servaddr.sin_addr.s_addr = INADDR_ANY;
  servaddr.sin_port = htons(7802);

  if ( bind(sd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0 )
    printf("Not binded\n");
  else
    printf("Binded\n");



  len=sizeof(cliaddr);

  recvfrom(sd,buff,1024,0,
   (struct sockaddr *)&cliaddr, &len);

  printf("%s\n",buff);
  /* */
  FILE *fp;
  fp=fopen(buff,"r");
  if(fp==NULL)
    {
      printf("file does not exist\n");
    }

  fseek(fp,0,SEEK_END);
  size_t file_size=ftell(fp);
  fseek(fp,0,SEEK_SET);
  if(fread(file_buffer,file_size,1,fp)<=0)
    {
      printf("unable to copy file into buffer\n");
      exit(1);
    }
  if(sendto(sd,file_buffer,strlen(file_buffer),0,  (struct sockaddr *)&cliaddr, &len)<0)    {
    printf("error in sending the file\n");
    exit(1);
  }
  bzero(file_buffer,sizeof(file_buffer));


  /* */
  close(sd);

  return(0);
}

Here is the client code

#include <stdio.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include<netinet/in.h>
#include<sys/types.h>



int main()
{
    char buff[2000];
    int sockfd,connfd,len;

struct sockaddr_in servaddr,cliaddr;

// create socket in client side
sockfd = socket(AF_INET, SOCK_DGRAM, 0);

if(sockfd==-1)
{
    printf(" socket not created in client\n");
    exit(0);
}
else
{
    printf("socket created in  client\n");
}


bzero(&servaddr, sizeof(servaddr));

servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = INADDR_ANY; // ANY address or use specific address
servaddr.sin_port = htons(7802);  // Port address


    printf("Type ur  UDP client message\n");
    scanf("%s",buff);

// send  msg to server

sendto(sockfd, buff, strlen(buff), 0,
          (struct sockaddr *)&servaddr, sizeof(struct sockaddr));
      char file_buffer[2000];

    if (recvfrom(sockfd,file_buffer,2000,0,  (struct sockaddr *)&servaddr, sizeof(struct sockaddr))<0)
    {
      printf("error in recieving the file\n");
      exit(1);
    }

  char new_file[]="copied";
  strcat(new_file,buff);
  FILE *fp;
  fp=fopen(new_file,"w+");
  if(fwrite(file_buffer,1,sizeof(file_buffer),fp)<0)
    {
      printf("error writting file\n");
      exit(1);
    }


  //close client side connection
    close(sockfd);

return(0);
}

The server reads the data from file and writes into it and send to the client , On the other end client receive the data and make duplicate of this file and write into it. But on compiling it gives error in writting the file :(

解决方案

Done that !

there was something wrong with file handle
Instead of using fopen ,use of open() ,write() and read() do the work Smile | :)

can anyone tell me how to compile this code ,where we are specifying the file directory???????????

这篇关于在C中使用UDP进行服务器 - 客户端文件传输的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！