connection.cc

// ------------------------------------------------------------------
//
//				   Client/Server communication package
//
//					   Connection implementation file
//
// Change log
//	950323	RH	Initial version
//	951212	RH	Modified to allow subclassing of class Connection
//	970127	RH	Added extra include to make the file compile under Linux
//	990125	PH	Changed function names: Read -> read, ...
//	000114	PH	int -> bool, virtual destructors, other minor changes
//	010129	PH	added void type to initConnection
//	011212	PH	changed char* arguments to const char*
//				changed connection closed handling to exception
//				unsigned char instead of char/int in write/read
//	020102	PH	split into separate file for each class
//	040421	PH	added namespace, new casts, cleaned up a lot
//	050113	PH	added deregisterConnection, new registration (vector),
//				added check for server shutdown, many more changes
//	090127	PH	added include of cstdlib, for exit()
//  130515  PH  removed namespace
//
// ------------------------------------------------------------------

#include "connection.h"
#include "connectionclosedexception.h"

#include <iostream>
#include <cstdlib>      /* exit() */
#include <cstring>      /* memcpy() */
#include <csignal>      /* signal() */
#include <sys/types.h>  /* socket(), connect(), read(), write() */
#include <sys/socket.h> /* socket(), connect() */
#include <netdb.h>      /* gethostbyname() */
#include <arpa/inet.h>  /* htons() */
#include <unistd.h>     /* close(), read(), write() */
#include <sys/uio.h>    /* read(), write() */
#include <netinet/in.h> /* sockaddr_in */

bool Connection::ignoresPipeSignals = false;

Connection::Connection(const char* host, int port) {
	/*
	 * Ignore SIGPIPE signals (broken pipe). A broken pipe (only?)
	 * occurs in a client, when it tries to write to a dead server.
	 * When the signal is ignored, ::write() returns -1 as the count
	 * of written bytes. Connection::write() tests for this and
	 * throws ConnectionClosedException when it happens.
	 */
	if (!ignoresPipeSignals) {
		signal(SIGPIPE, SIG_IGN);
		ignoresPipeSignals = true;
	}
	
	my_socket = socket(AF_INET,SOCK_STREAM, 0);
	if (my_socket < 0) {
		my_socket = -1;
		return;
	}
	
	sockaddr_in server;
	server.sin_family = AF_INET;
	hostent* hp = gethostbyname(host);
	if (hp == 0) {
		my_socket = -1;
		return;
	}
	
	memcpy(reinterpret_cast<char*>(&server.sin_addr),
		   reinterpret_cast<char*>(hp->h_addr),
		   hp->h_length);
	server.sin_port = htons(port);
	if (connect(my_socket,
				reinterpret_cast<sockaddr*>(&server),
				sizeof(server)) < 0) {
		my_socket = -1;
	}
}

Connection::Connection() {
	/*
	 * See previous constructor for comments.
	 */
	if (!ignoresPipeSignals) {
		signal(SIGPIPE, SIG_IGN);
		ignoresPipeSignals = true;
	}
	my_socket = -1;
}

Connection::~Connection() {
	if (my_socket != -1) {
		close(my_socket);
	}
}

bool Connection::isConnected() const {
	return my_socket != -1;
}

void Connection::write(unsigned char ch) const {
	if (my_socket == -1) {
		error("Write attempted on a not properly opened connection");
	}
	int count = ::write(my_socket, &ch, 1);
	if (count != 1) {
		throw ConnectionClosedException();
	}
}

unsigned char Connection::read() const {
	if (my_socket == -1) {
		error("Read attempted on a not properly opened connection");
	}
	char data;
	int count = ::read(my_socket, &data, 1);
	if (count != 1) {
		throw ConnectionClosedException();
	}
	return data;
}

void Connection::initConnection(int s) {
	my_socket = s;
}

int Connection::getSocket() const {
	return my_socket;
}

void Connection::error(const char* msg) const {
	std::cerr << "Class Connection: " << msg << std::endl;
	exit(1);
}