ReceivingPort Class Reference

A Receiving Port Class. More...

#include <common.h>

Inheritance diagram for ReceivingPort:

Port LossyReceivingPort List of all members.

Public Member Functions

 ReceivingPort ()
virtual ~ReceivingPort ()
void init ()
PacketreceivePacket ()
 The main receive function of receiving port to receive a single packet.

Protected Attributes

Packetpkt_
char * tmpBuffer_
 temporary buffer for packets

Detailed Description

A Receiving Port Class.

ReceivingPort is an abstract class for the interface to receive a packet. The main function for the receiving port:

Definition at line 301 of file common.h.


Constructor & Destructor Documentation

ReceivingPort::ReceivingPort  ) 
 

Constructor

Definition at line 428 of file common.cpp.

References pkt_.

00428                             : Port()
00429 {
00430   pkt_= new Packet(MAXBUFLENGTH);
00431 }


Member Function Documentation

void ReceivingPort::init  )  [virtual]
 

Init Funciton to initialize a socket port.

The port binds to its own address, generate a UDP socket.

Bind to local address is one important task in init() Here source address of node itself (myaddr_) does not really be used by bind function of port. The program use INADDR_ANY as the address filled in address parameters of bind(). So, we need an empty hostname with the port number.

When the UDP port is recieving, we need to create a default buffer to store received packet. The data in buffer will be copy to the corresponding flow once the packet's sender address is checked.

Implements Port.

Definition at line 447 of file common.cpp.

References Address::isSet(), Port::myaddr_, Port::setHostname(), Port::setPort(), and Port::sockfd_.

00448 { 
00449   if (sockfd_ != 0) {
00450     return;
00451   }
00452   if ( myaddr_.isSet() == false) {
00453     setHostname("localhost");
00454     setPort(DEFAULT_RECV_PORT);
00455   }
00456   
00457   if ((sockfd_ = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
00458     throw "Error while opening UDP socket of a receiver";
00459   }
00460   Address *emptyAddr = new Address("", myaddr_.getPort());
00461   struct sockaddr* addr = setSockAddress(emptyAddr, &mySockAddress_);
00462   if (  bind(sockfd_, addr, sizeof(struct sockaddr_in))  < 0 ){
00463     throw "Scoket Bind Error occured in an UDP receiver";
00464   }
00465   //cout << "binding to port: " << myaddr_.getPort() << "......" << endl;
00466   // needs a dummy buffer for storing packets
00467   tmpBuffer_ =  new char[MAXBUFLENGTH];
00468 }

Packet * ReceivingPort::receivePacket  ) 
 

The main receive function of receiving port to receive a single packet.

The main receive function of a receiving port. First,check addresses. Then call recvfrom() to get a packet. after this, pkt_ variable stores information of the packet and tmpSockAddr stores the sender information. then, recast tmpSockAddr to itsaddr_. As the socket is not set as non-blocking, the recvfrom() call blocks usually, but if the main program use select() to do synchronized I/O Multiplexing, this call will not block.

The design structure allows a future implementation improvement.

packet size is the maximum allowed packet above UDP or buffer size

Reimplemented in LossyReceivingPort.

Definition at line 483 of file common.cpp.

References Port::decodeSockAddress(), Packet::extractHeader(), Packet::fillPayload(), Packet::getHeaderSize(), Port::itsaddr_, pkt_, Port::sockfd_, and tmpBuffer_.

Referenced by LossyReceivingPort::receivePacket().

00484 {
00485   struct sockaddr_in tmpSockAddr;
00486   int length = sizeof(struct sockaddr);
00487   int len = (int)recvfrom(sockfd_, tmpBuffer_, MAXBUFLENGTH, 0, (struct sockaddr*)&tmpSockAddr,(socklen_t *)&length); 
00488   if (len == -1) 
00489   {
00490            perror("recvfrom");
00491            return false;
00492   }         
00493   decodeSockAddress( &itsaddr_, &tmpSockAddr);
00494   pkt_->extractHeader(tmpBuffer_);
00495   //tmpBuffer_ point shall not be moved,it will reused by the receiving port.
00496   pkt_->fillPayload(len-1-pkt_->getHeaderSize(), tmpBuffer_+pkt_->getHeaderSize()+1 );
00497   return pkt_;
00498 }


Member Data Documentation

Packet* ReceivingPort::pkt_ [protected]
 

This pointer points to the packet. This packet is just received.

Definition at line 314 of file common.h.

Referenced by receivePacket(), and ReceivingPort().


The documentation for this class was generated from the following files:
Generated on Fri Feb 9 12:49:37 2007 for Common_Classes_Projects_ECE544 by  doxygen 1.4.6