udpserver.c

Linux下网络编程中UDP服务器端的简单代码

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

#include <unistd.h> 
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h> 
#include <sys/types.h>
#include <sys/stat.h> 
#include <netinet/in.h>
#include <sys/wait.h>
#include <arpa/inet.h>           
#include <sys/socket.h>
                                  
#define PORT 4567            
#define LENGTH  1024
                                                                            
int main(int argc, char *argv[]){

	int    sockfd,numbytes,read_bytes;                                
   socklen_t    addrlen;  
	int    fd;                    
   char   buf[LENGTH];  
	char   msg[LENGTH+1];            
   struct sockaddr_in addr_sev;   
	struct sockaddr_in addr_cli;
	/*  检查参数 */
   if (argc != 2){                          
     printf("please input file dirctory!\n");
     exit(1);
         }     

  	if((fd=open(argv[1],O_RDONLY)) < 0){           //加入命令行后，没法读普通文件?！
      printf("open file 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);
	}
    
    	/*  填充本地Socket地址结构*/
	bzero(&addr_sev, sizeof(addr_sev));  
   addr_sev.sin_family = AF_INET;          
   addr_sev.sin_port = htons(PORT);         
   addr_sev.sin_addr.s_addr  = htonl(INADDR_ANY); 
    
    	/* 绑定端口*/
	if(bind(sockfd, (struct sockaddr*)&addr_sev, sizeof(struct sockaddr)) == -1 ){
		printf ("Failed to bind Port %d.\n",PORT);
      exit(1);
	}

	addrlen = sizeof(struct sockaddr_in);
	printf("Please wait......\n");
	
	while(1){	  		
		read_bytes=read(fd,buf,LENGTH);
		//printf("read %d bytes\n",read_bytes);

		if(read_bytes < 1){
			printf("read file error\n");        //若读取失败，程序结束。
			exit(1);
		}	

		if((numbytes = recvfrom(sockfd, msg, LENGTH, 0, (struct sockaddr *)&addr_cli, &addrlen)) == -1){
			printf("receive error!\n");
			exit(1);   
		} 
		//printf("get message:%s\n",msg);
		
		if((numbytes=sendto(sockfd, buf, read_bytes, 0, (struct sockaddr *)&addr_cli, sizeof(addr_cli)))==-1){
			printf("send data error!\n");
			exit(1);
		}
	//	printf("Send success:total data is %d bytes!\n",numbytes);
	
		if(numbytes != LENGTH){
			printf("Data sent complete!\n");
			break;
		}

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