#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 228 of file common.h.
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Constructor Definition at line 351 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 370 of file common.cpp. References Address::getPort(), Address::isSet(), Port::myaddr_, Port::mySockAddress_, Port::setHostname(), Port::setPort(), Port::setSockAddress(), Port::sockfd_, and tmpBuffer_. 00371 { 00372 if (sockfd_ != 0) { 00373 return; 00374 } 00375 if ( myaddr_.isSet() == false) { 00376 setHostname("localhost"); 00377 setPort(DEFAULT_RECV_PORT); 00378 } 00379 00380 if ((sockfd_ = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 00381 throw "Error while opening UDP socket of a receiver"; 00382 } 00383 Address *emptyAddr = new Address("", myaddr_.getPort()); 00384 struct sockaddr* addr = setSockAddress(emptyAddr, &mySockAddress_); 00385 if ( bind(sockfd_, addr, sizeof(struct sockaddr_in)) < 0 ){ 00386 throw "Scoket Bind Error occured in an UDP receiver"; 00387 } 00388 //cout << "binding to port: " << myaddr_.getPort() << "......" << endl; 00389 // needs a dummy buffer for storing packets 00390 tmpBuffer_ = new char[MAXBUFLENGTH]; 00391 }
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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 Definition at line 406 of file common.cpp. References Port::decodeSockAddress(), Packet::fillPayload(), Port::itsaddr_, pkt_, Port::sockfd_, and tmpBuffer_. 00407 { 00408 struct sockaddr_in tmpSockAddr; 00409 int length = sizeof(struct sockaddr); 00410 int len = (int)recvfrom(sockfd_, tmpBuffer_, MAXBUFLENGTH, 0, (struct sockaddr*)&tmpSockAddr,(socklen_t *)&length); 00411 if (len == -1) 00412 { 00413 perror("recvfrom"); 00414 return false; 00415 } 00416 decodeSockAddress( &itsaddr_, &tmpSockAddr); 00417 pkt_->fillPayload(len, tmpBuffer_); 00418 return pkt_; 00419 }
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This pointer points to the packet. This packet is just received. Definition at line 241 of file common.h. Referenced by receivePacket(), and ReceivingPort(). |