#include "main.h"
//======================================================================
//						MAIN
//======================================================================
int main(int argc, char **argv)
{
	int ok;
	int portNumber;
	struct sockaddr_in myAddr;
	struct sockaddr_in fromAddr;
	int32_t value;
	
	//---- check command line arguments ----
	if(argc!=2) { fprintf(stderr,"usage: %s port\n",argv[0]); exit(1); }
	  
	//---- extract local port number ----
	if(sscanf(argv[1],"%d",&portNumber)!=1){ fprintf(stderr,"invalid port %s\n",argv[1]); exit(1); }
		
	//---- create UDP socket ----
	int udpSocket=socket(PF_INET,SOCK_DGRAM,0);	// SOCK_DGRAM == UDP
									if( udpSocket==-1 ) { perror("socket"); exit(1); }
	
	// ... bound to any local address on the specified port
	myAddr.sin_family=AF_INET;
	myAddr.sin_port=htons(portNumber);
	myAddr.sin_addr.s_addr=htonl(INADDR_ANY);
	
	ok = bind(udpSocket,(struct sockaddr *)&myAddr,sizeof(myAddr));
									if( ok == -1) { perror("bind"); exit(1); }
	
	// ... allowing broadcast (optional)
	int on=1;
	ok = setsockopt(udpSocket,SOL_SOCKET,SO_BROADCAST,&on,sizeof(int));
									if( ok == -1) { perror("setsockopt"); exit(1); }	

	for(;;)
	  {
			  //---- receive message ----
			  socklen_t len=sizeof(fromAddr);
			   int r=recvfrom(udpSocket,&value,4,0,(struct sockaddr *)&fromAddr,&len);
											if(r==-1){ perror("recvfrom"); exit(1); }
											
			  //---- convert to host format 32-bit integer ----
			  if(r<4)
				{ fprintf(stderr,"4 bytes expected\n"); exit(1); }
			  value=ntohl(value);

			  //---- display value and source address/port ----
			  printf("from %s:%d : %d\n", inet_ntoa(fromAddr.sin_addr),ntohs(fromAddr.sin_port),value);
	  }

	close(udpSocket);
}
//^^^^^^^^^^^^^^^^^^^^^^^^^^ EOF ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^