#include <common.h>
Inheritance diagram for ReceivingPort:
Public Member Functions | |
ReceivingPort () | |
void | init () |
Packet * | receivePacket () |
The main receive function of receiving port to receive a single packet. | |
Protected Attributes | |
Packet * | pkt_ |
char * | tmpBuffer_ |
temporary buffer for packets |
ReceivingPort is an abstract class for the interface to receive a packet. The main function for the receiving port:
Definition at line 369 of file common.h.
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Constructor Definition at line 429 of file common.cpp. References pkt_.
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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 448 of file common.cpp. References Address::getPort(), Address::isSet(), Port::myaddr_, Port::mySockAddress_, Port::setHostname(), Port::setPort(), Port::setSockAddress(), Port::sockfd_, and tmpBuffer_. 00449 { 00450 if (sockfd_ != 0) { 00451 return; 00452 } 00453 if ( myaddr_.isSet() == false) { 00454 setHostname("localhost"); 00455 setPort(DEFAULT_RECV_PORT); 00456 } 00457 00458 if ((sockfd_ = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 00459 throw "Error while opening UDP socket of a receiver"; 00460 } 00461 Address *emptyAddr = new Address("", myaddr_.getPort()); 00462 struct sockaddr* addr = setSockAddress(emptyAddr, &mySockAddress_); 00463 if ( bind(sockfd_, addr, sizeof(struct sockaddr_in)) < 0 ){ 00464 throw "Scoket Bind Error occured in an UDP receiver"; 00465 } 00466 //cout << "binding to port: " << myaddr_.getPort() << "......" << endl; 00467 // needs a dummy buffer for storing packets 00468 tmpBuffer_ = new char[MAXBUFLENGTH]; 00469 }
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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 484 of file common.cpp. References Port::decodeSockAddress(), Packet::extractHeader(), Packet::fillPayload(), Packet::getHeaderSize(), Port::itsaddr_, pkt_, Port::sockfd_, and tmpBuffer_. Referenced by LossyReceivingPort::receivePacket(). 00485 { 00486 struct sockaddr_in tmpSockAddr; 00487 int length = sizeof(struct sockaddr); 00488 int len = (int)recvfrom(sockfd_, tmpBuffer_, MAXBUFLENGTH, 0, (struct sockaddr*)&tmpSockAddr,(socklen_t *)&length); 00489 if (len == -1) 00490 { 00491 perror("recvfrom"); 00492 return false; 00493 } 00494 decodeSockAddress( &itsaddr_, &tmpSockAddr); 00495 pkt_->extractHeader(tmpBuffer_); 00496 //tmpBuffer_ pointer shall not be moved/shifted,it will reused by the receiving port. 00497 pkt_->fillPayload(len-1-pkt_->getHeaderSize(), tmpBuffer_+pkt_->getHeaderSize()+1 ); 00498 return pkt_; 00499 }
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This pointer points to the packet. This packet is just received. Definition at line 382 of file common.h. Referenced by receivePacket(), and ReceivingPort(). |