xuchuan.c

断点续传的小程序

//断点续传的小程序，实现文件传输中断后从断点开始传送
#include <stdio.h> 
#include <stdlib.h> 
#include <errno.h> 
#include <string.h> 
#include <netdb.h> 
#include <sys/types.h> 
#include <netinet/in.h> 
#include <sys/socket.h>
#include <fcntl.h>

#define PORT 2048 /* Server的端口 */ 

int main(int argc, char *argv[]) 

{ 

	int sockfd, numbytes, sin_size; 
	struct hostent *he; /* 主机信息 */ 
	struct sockaddr_in their_addr; /* 对方地址信息 */
	if (argc != 2) { 
		fprintf(stderr,"usage: client hostname\n"); 
		exit(1); 

	} 


	/* get the host info */ 

	if ((he=gethostbyname(argv[1])) == NULL) { 
	herror("gethostbyname"); 
	exit(1); 
	}

	if ((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1) { 
	perror("socket"); 
	exit(1); 
	}

	their_addr.sin_family = AF_INET; 
	their_addr.sin_port = htons(PORT); /* short, NBO */ 
	their_addr.sin_addr = *((struct in_addr *)he->h_addr); 
	bzero(&(their_addr.sin_zero), 8); /* 其余部分设成0 */
	int i;
	for(i=0;i<2;i++)
	{
		numbytes = sendto(sockfd, "aaaaaaaaaaa", 11, 0, (struct sockaddr *)&their_addr,sizeof(their_addr));
		printf("datagram from %s\n",inet_ntoa(their_addr.sin_addr));
	}


	char buf[2048];
	long offset;
	int fd;
	fd=open("test.mp3",O_RDWR|00666);
	if(fd==-1)
	{
		  perror("open:");
		  exit(1);
	}

	while(1)
	{
		 int readbytes,sendbytes;
		 readbytes=read(fd,buf,2048);
       		 if(readbytes==-1)
  		{
    		perror("read:");
   		exit(1);
  		}
  		printf("readbytes==%d\n",readbytes);
   		sendbytes=sendto(sockfd, buf, readbytes, 0, (struct sockaddr *)&their_addr,sizeof(their_addr));
   		printf("sendbytes==%d\n",sendbytes);
    		printf("zhengzai fa song...\n");
   		if(getchar()=='a')
   		{
      		offset=lseek(fd,0,SEEK_CUR);
      		printf("offset===%d\n",offset);
      		close(fd);
      		sleep(1);
      		printf("close file\n");
      		break;
   		}
	}
	printf("跳出第一个while\n");

	int ff;
	ff=open("test.mp3",O_RDWR|00666);
	if(ff==-1)
	{
	  perror("open:");
	  exit(1);
	}

	printf("offset===%d\n",offset);

	int a = lseek(ff,offset,SEEK_SET);
	if(a==-1)
	{
	  perror("lseek:");
	  exit(1);
	}
	while(1)
	{
	   int readbytes,sendbytes;
	    //readbytes=fread(buf,1,2048,fb);
	    readbytes=read(ff,buf,2048);
	    printf("readbytes===%d\n",readbytes);
	    sendbytes=sendto(sockfd, buf, readbytes, 0, (struct sockaddr *)&their_addr,sizeof(their_addr));
	   if(readbytes==0)
	   {
	   //if(feof(ff))
	   //{
	      //fclose(ff);
	      close(ff);
	      printf("file end ,close file\n");
	      break;
	   //}
	   }
	}
	close(sockfd); 

	return 0; 

}