annotate core/UdpServer.cpp @ 54:d3f869b98147 ultra-staging

Udp transmission working (enough) for demo in Nottingham

/*
 * udpServer.cpp
 *
 *  Created on: 19 May 2015
 *      Author: giulio moro
 */
#include "../include/UdpServer.h"

UdpServer::UdpServer(int aPort){
	init(aPort);
};
UdpServer::UdpServer(){
	init(0);
}
UdpServer::~UdpServer(){
	//TODO: unbind from port. AFAIK, this involves closing the socket, therefore creating the socket should become part of bindToPort
};
bool UdpServer::init(int aPort){
	enabled=true;
	stTimeOut.tv_sec = 0; //set timeout to 0
	stTimeOut.tv_usec = 0;
	inSocket=socket(AF_INET, SOCK_DGRAM, 0);
	if (inSocket < 0){
		enabled=false;
	}
	length = sizeof(server);
	server.sin_family=AF_INET;
	server.sin_addr.s_addr=INADDR_ANY;
	enabled=bindToPort(aPort);
	wasteBufferSize=2048;
	wasteBuffer=malloc(wasteBufferSize);
	return enabled;
}

bool UdpServer::bindToPort(int aPort){
	port=aPort;
	if(port<1){
		enabled=false;
		return false;
	}
	server.sin_port=htons(port);
	if (bind(inSocket,(struct sockaddr *)&server,length)<0){
		enabled=false;
		return false;
	}
	enabled=true;
	return true;
};
int UdpServer::read(//Returns the number of bytes read, or -1 if there was an error.
					void *destBuffer,
					int maxBytesToRead){
	if(enabled==false)
		return -1;
	FD_ZERO(&stReadFDS);
	FD_SET(inSocket, &stReadFDS);
	int descriptorReady= select(inSocket+1, &stReadFDS, NULL, NULL, &stTimeOut);
	if(descriptorReady<0){ //an error occurred
		return -1;
	}
	int numberOfBytes=0;
	if (FD_ISSET(inSocket, &stReadFDS)) {
		numberOfBytes=recvfrom(inSocket,destBuffer,maxBytesToRead,0,(struct sockaddr *)&from,&fromLength);
		if(numberOfBytes<0)
			return -1;
	}
	return numberOfBytes;
};
int UdpServer::emptySocket(){
	return emptySocket(0);
}
int UdpServer::emptySocket(int maxBytes){//discards up to maxBytes from the socket. Returns the number of bytes discarded.
	if(wasteBuffer==NULL)
		return -1;
	int numberOfBytes=0;
	while(int n=read(wasteBuffer, wasteBufferSize)){// calls the read function until it does not return any more bytes (i.e.: socket is empty)
		if(n>0)
			numberOfBytes+=n;
		if(n<0)
			return -1;
		if(maxBytes>0 && numberOfBytes>=maxBytes)
			break;
	};
	return numberOfBytes;
}
void* UdpServer::getWaste(){ //returns the last datagram retrieved by emptySocket()
	return wasteBuffer;
}