So I’ve been working on this project that heavily uses Sockets in C++, for the base of this project I’ve created a TCP Socket class so I concentrate on the protocol I’m using rather than worrying about the socket itself and I thought I would share this class with your.
so here it is:

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Header

//tcpCase.h
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <time.h>

#ifndef TCPCASE_H_
#define TCPCASE_H_

class tcpCase
{
public:
	tcpCase(char * _port, char * _addr);
	virtual ~tcpCase();

	void startConnection();
	bool charSearch(char *toSearch, char *searchFor);

private:
	addrinfo hints, *servinfo;
	char *addr;
	char *port;
	int s; //the socket descriptor

	bool sendData(char *msg);

	void manageRecv(int numbytes, char * buf);
};

#endif /* TCPCASE_H_ */

Class

 

//tcpCase.cpp
#include "tcpCase.h"

using namespace std;

#define MAXDATASIZE 100

tcpCase::tcpCase(char * _port, char * _addr)
{
	port = _port;
	addr = _addr;

	//Ensure that servinfo is clear
	memset(&hints, 0, sizeof hints); // make sure the struct is empty

	//setup hints
	hints.ai_family = AF_UNSPEC; // don't care IPv4 or IPv6
	hints.ai_socktype = SOCK_STREAM; // TCP stream sockets

	//Setup the structs if error print why
	int res;
	if ((res = getaddrinfo(addr,port,&hints,&servinfo)) != 0)
	{
		fprintf(stderr,"getaddrinfo: %s\n", gai_strerror(res));
	}

	//setup the socket
	if ((s = socket(servinfo->ai_family,servinfo->ai_socktype,servinfo->ai_protocol)) == -1)
	{
		perror("client: socket");
	}

}

tcpCase::~tcpCase()
{
	// TODO Auto-generated destructor stub
}

void tcpCase::startConnection()
{//This goes into the send/rcv loop
	//Connect
	if (connect(s,servinfo->ai_addr, servinfo->ai_addrlen) == -1)
	{
		close (s);
		perror("Client Connect");
	}

	//We dont need this anymore
	freeaddrinfo(servinfo);

	int numbytes;
	char buf[MAXDATASIZE];
	while (1)
	{
		//Recv & print Data
		numbytes = recv(s,buf,MAXDATASIZE-1,0);
		buf[numbytes]='\0';
		cout << buf;

		//What do I do with the recived data
		manageRecv(numbytes,buf);

		//break if connection closed
		if (numbytes==0)
		{
			cout << "----------------------CONNECTION CLOSED---------------------------"<< endl;

			break;
		}
	}

}

bool tcpCase::charSearch(char *toSearch, char *searchFor)
{
	int len = strlen(toSearch);
	int forLen = strlen(searchFor); // The length of the searchfor field

	//Search through each char in toSearch
	for (int i = 0; i < len;i++)
	{
		//If the active char is equil to the first search item then search toSearch
		if (searchFor[0] == toSearch[i])
		{
			bool found = true;
			//search the char array for search field
			for (int x = 1; x < forLen; x++)
			{
				if (toSearch[i+x]!=searchFor[x])
				{
					found = false;
				}
			}

			//if found return true;
			if (found == true)
				return true;
		}
	}

	return 0;
}

bool tcpCase::sendData(char *msg)
{//Send some data
	//Send some data
	int len = strlen(msg);
	int bytes_sent = send(s,msg,len,0);

	if (bytes_sent == 0)
		return false;
	else
		return true;
}

void tcpCase::manageRecv(int numbytes, char * buf)
{
	/*
	*	TODO: Add your code here!
	*	int numbytes: this is the number of bytes in the recived msg
	*	char * buf: this is the message recieved
	*/
}

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To use this class edit the manageRecv() to fit to the protocol you wish to use, this function is called every time a new message is received. You get the variables:

• int numbytes : the number of bytes in the recived message
• char * buf : the message recived

from this you should be able to program your protocol.

Calling this class is also pretty simple, all you need to do is give the parameters:

• port: the port you want to connect to
• addr: the server you want to connect to

then call the startConnection() function to get the client to connect, here is a quick example:

  tcpCase test = tcpCase("6667","irc.ubuntu.com");
  test.startConnection();

If you want more information on c++ socket programming I recommend you read Beej’s Guide to Network Programming. As socket programming is a complicated thing i recommend you read the whole of this great guide, rather then just skipping to the the examples (learn from my mistake there)