#include <winsock2.h>
#include <io.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//#include <time.h>
#pragma comment(lib,"ws2_32")
#define BUFSIZE			8192
#define DEFAULT_PORT	5320

enum {CMD_NAME,DST_IP,DST_PORT};
void InitWinSocket();
void ParseCmdLine(int*port ,unsigned long *ip,int argc,char*argv[]);
void CreateUdpSocket(SOCKET* sock);
void CommunicateWithServer(SOCKET sock,int port,unsigned long IP);
void BindToIPAndPort(SOCKET listen_sock,int port,unsigned long IP);
void SetIpAndPort(struct sockaddr_in *addr,int port,unsigned long IP);

int main(int argc, char *argv[]){
	int port;
	SOCKET sock;
	unsigned long dst_ip;
	InitWinSocket();
	ParseCmdLine(&port,&dst_ip,argc,argv);
	CreateUdpSocket(&sock);
	BindToIPAndPort(sock, 5325,INADDR_ANY);
	CommunicateWithServer(sock,port,dst_ip);
	closesocket(sock);
	WSACleanup(); 

	return 0;
}

void InitWinSocket(){
	WSADATA wsaData;

	if (WSAStartup(MAKEWORD(2,1),&wsaData) != 0){
	fprintf(stderr,"WSAStartup failed: %d\n",GetLastError());
	exit(EXIT_FAILURE);
  }
}

void ParseCmdLine(int*port ,unsigned long *ip,int argc,char*argv[]){
	if(argc != 2 && argc!=3){
		fprintf(stderr," Usag: %s hostname [port]\n",argv[0]);
		exit(EXIT_FAILURE);
	}

	if((*ip=inet_addr(argv[DST_IP]))==INADDR_NONE){
		struct hostent* he;
		if((he=gethostbyname(argv[DST_IP]))==NULL){
			fprintf(stderr,"gethostbyname error\n");
			exit(EXIT_FAILURE);
		}
		memcpy((char*)ip,(char*)he->h_addr,he->h_length);
	}
	*ip=ntohl(*ip);
	if(argc==3){
		if((*port=(atoi(argv[DST_PORT])))==0){
			struct servent *se;
			if((se=getservbyname(argv[DST_PORT],"UDP"))!=NULL)
				*port=(int)ntohs((u_short)se->s_port);
			else{
				fprintf(stderr,"getservbynmame error\n");
				exit(EXIT_FAILURE);
			}
		}
	}else *port=DEFAULT_PORT;
}

void CreateUdpSocket(SOCKET* sock){
	if((*sock=socket(AF_INET,SOCK_DGRAM,0))<0){
		perror("socket");
		exit(EXIT_FAILURE);
	}
}
void SetIpAndPort(struct sockaddr_in *addr,int port,unsigned long IP){
	memset((char*)addr,0,sizeof(addr));
	addr->sin_family=AF_INET;
	addr->sin_addr.s_addr=htonl(IP);
	addr->sin_port=htons(port);
}
	
void BindToIPAndPort(SOCKET listen_sock,int port,unsigned long IP){
	struct sockaddr_in localAddr;
	SetIpAndPort(&localAddr,port,IP);
	if(bind(listen_sock,
		(struct sockaddr*)&localAddr,
		sizeof(localAddr))<0){

		perror("bind");
		exit(EXIT_FAILURE);
	}
}

void CommunicateWithServer(SOCKET sock,int port,unsigned long IP){
	char buf[BUFSIZE],cmd[BUFSIZE],recv_buf[BUFSIZE];
	int n,len=0;
	struct sockaddr_in server;
	struct sockaddr_in rnode;
	SetIpAndPort(&server,port,IP);
	printf("UDP>");
	fflush(stdout);
	len=sizeof(rnode);
	while(gets(buf)!=NULL){
		sscanf(buf,"%s",cmd);
		if(strcmp(cmd,"quit")==0) break;
		if(sendto(sock,buf,strlen(buf),0,(struct sockaddr*)&server,
			sizeof(server))<0)		break;
		if((n=recvfrom(sock,recv_buf,BUFSIZE-1,0,
			(struct sockaddr*)&rnode,&len))<0){
			fprintf(stderr,"recvfrom failed: %d\n",GetLastError());
			break;
		}
		recv_buf[n]='\0';
		printf("%s",recv_buf);
		printf("UDP>");
		fflush(stdout);
	}

}