udpclient.c

Linux网络编程之UDP的客户端程序简单代码

/*
************************ File Info ******************************
** File name:           client.c
** Descriptions:        client of UDP.
**********************************************************************************************************
*/

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

#define PORT 4567                 
#define LENGTH 1024                
   
int main(int argc, char *argv[]){
   
   int    fd,sockfd,numbytes;   
//	int	 addrlen;                                    
	char   buf[LENGTH];
	char   msg[]={"hello"};  
	socklen_t addrlen;           						
	struct sockaddr_in addr_sev;  
	struct sockaddr_in addr_cli;             
   //struct hostent     *he;

         /*  检查参数 */
   if (argc != 2){                          
      printf("Please input server IP!\n");
      exit(1);
          }
 	/*打开文件*/
   fd=open("/home/rev",O_CREAT|O_WRONLY); 
   if(fd<0){           
      printf("open file error!\n");
      exit(1);
           } 

    /*if((he=gethostbyaddr((char *)&addr_sev.sin_addr,4,AF_INET)) == NULL){
      printf("get error\n");
      exit(1);
          }  */

          /*  获取Socket文件描述符  */
   if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1){
       printf("creat socket error!\n");
       exit(1);
         }

          /*  填充Socket地址结构*/
   bzero(&(addr_cli), sizeof(addr_cli));                       
   addr_cli.sin_family = AF_INET;                        
   addr_cli.sin_port = htons(PORT);
	
	addrlen = sizeof(struct sockaddr);                      
   //addr_sev.sin_addr=*((struct in_addr *)he->h_addr);  

	if(inet_aton(argv[1],&addr_cli.sin_addr)<0){
		printf("IP convert error!\n");
		exit(1);
	}    
  	printf("Receiving data please wait......\n");
   //bzero(buf,LENGTH);
   
	 /*  接收数据 */         
	while(1){
		if(sendto(sockfd, msg, strlen(msg), 0, (struct sockaddr *)&addr_cli, sizeof(addr_cli))==-1){
      	printf ("sendto fail!\n");
      	exit(1);
		}

      numbytes=recvfrom(sockfd,buf,LENGTH,0,(struct sockaddr *)&addr_sev,&addrlen);
		if(numbytes<0){
			printf("download from server error\n"); 			
			exit(1);
		}
	
	   if((write(fd,buf,numbytes))<0){
			printf("write fail!\n");
			exit(1);	      
               }    
		if(numbytes != LENGTH){
			printf("Receive data complete!\n");
			break;
		}

//		close(sockfd); 
//		close(fd);  
	}
	exit(0);
}