threaded_network_chat/modified-example.cc

/*an attempt at pthread and network and ncurses all in the same function
 */
#include <arpa/inet.h>
#include <curses.h>
#include <fstream>
#include <iostream>
#include <netdb.h>
#include <netinet/in.h>
#include <ostream>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <unistd.h>

#include <vector> //try to make the program work without this without doing anything awful but do it later

using namespace std;

const int PORT_NUM = 8888;
const string IP_ADDRESS = "127.0.0.1";
const int DEFAULT_CUR_X = 2; // the x position of the preferred default cursor
			     // position for message entry
const int DEFAULT_CUR_Y = 12; // the x position of the preferred default cursor
			      // position for message entry

int mode = 0;		    // what mode is this program in. 0 = nothing. 1 = server. 2 = client
int serverSocketDescriptor; // a global variable for storing the server socket
			    // descriptor.
int clientSocketDescriptor;
vector<int> clientSocketDescriptors; // a global vector for storing client
				     // socket descriptors

// keep track of the session time using global variables
struct timeval start1, end1;

// also keep track of the amount of data sent as well
int bytesRead, bytesWritten = 0;

const int LOG_LENGTH = 10; // number of text log file lines to display
int linePos = 0;	   // counter for what current position to use in the file

string logFileName; // the name of the log file

pthread_t client_wait_thread;

int writeToFile(string path, string line, bool incLineNum = true);
void *waitForClient(void *argss);
void *pollForClient();
void *pollForSever(void *args);

// clears ncurses rows in a specific region only
void
clearRows(int startingRow, int endingRow)
{
	// preserve the cursor location
	int yBefore, xBefore;
	getyx(stdscr, yBefore, xBefore);

	for (int i = startingRow; i < endingRow; i++) {
		move(i, 0);
		clrtoeol(); // clear to end of line
	}

	// restore original cursor location
	move(yBefore, xBefore);
}

// display a file using ncurses
int
displayFile(string path, int startLineNum = 0, int numLines = 10)
{
	ifstream file(path);
	if (!file) {
		return 1;
	} else {
		clearRows(0, numLines + 1); // clear the chat area
		int lineNum = 0;
		string line;

		// print each line directly to the screen
		int num = 0;
		while (getline(file, line) && num <= numLines + startLineNum + 1) // while there is file content and the
										  // line number isn't too high
		{
			if (num >= startLineNum) {
				move(lineNum, 0);
				printw("%s", line.c_str());
				lineNum++; // increment the row number after
					   // printing each line
			}
			num++;
		}
		move(DEFAULT_CUR_Y, DEFAULT_CUR_X);
		refresh();
		return 0;
	}
}

// gets the number of lines in a file. returns -1 if there was an error.
int
linesInFile(string path)
{
	ifstream file(path);
	if (!file) {
		return 1;
	} else {
		int lineNum = 0;
		string line;

		int num = 0;
		while (getline(file, line))
			num++;
		return num;
	}
}

struct waitClientArgs {
	sockaddr_in newSockAddr;
	socklen_t newSockAddrSize;
	int auxInt; // used in client mode because I didn't want to make another
		    // struct to keep track of
};

void *
waitForClient(void *argss)
{
	waitClientArgs *args = static_cast<waitClientArgs *>(argss);
	clientSocketDescriptor = accept(serverSocketDescriptor, (sockaddr *)&args->newSockAddr, &args->newSockAddrSize);
	if (clientSocketDescriptor >= 0) {
		writeToFile(logFileName, "client connected");
		if (linesInFile(logFileName) > LOG_LENGTH)
			linePos++;
		displayFile(logFileName, linePos, LOG_LENGTH);
	}
	delete args; // delete to avoid memory leaks

	return pollForClient();
}

void *
pollForClient()
{
	char msg[1024];
	while (1) {
		// receive a message from the client (listen)
		memset(&msg, 0, sizeof(msg)); // clear the buffer
		bytesRead += recv(clientSocketDescriptor, (char *)&msg, sizeof(msg), 0);
		writeToFile(logFileName,
			    msg); // write the client's message to file
		if (linesInFile(logFileName) > LOG_LENGTH)
			linePos++;
		displayFile(logFileName, linePos, LOG_LENGTH);
	}

	return nullptr;
}

// set up a suitable server for this
int
setupServer(int port)
{
	// setup a socket and connection tools
	sockaddr_in servAddr;
	bzero((char *)&servAddr, sizeof(servAddr));
	servAddr.sin_family = AF_INET;
	servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servAddr.sin_port = htons(port);

	// open stream oriented socket with internet address
	// also keep track of the socket descriptor
	serverSocketDescriptor = socket(AF_INET, SOCK_STREAM, 0);
	if (serverSocketDescriptor < 0) {
		// keeps from bricking the terminal if this happens
		endwin();

		fprintf(stderr, "Error establishing the server socket!\n");
		exit(0);
	}
	// bind the socket to its local address
	int bindStatus = bind(serverSocketDescriptor, (struct sockaddr *)&servAddr, sizeof(servAddr));
	if (bindStatus < 0) {
		// keeps from bricking the terminal if this happens
		endwin();

		fprintf(stderr, "Error binding socket to local address!\n");
		exit(0);
	}
	writeToFile(logFileName, "Waiting for a client to connect...");
	// listen for up to 5 requests at a time
	listen(serverSocketDescriptor, 5);
	// receive a request from client using accept
	// we need a new address to connect with the client
	sockaddr_in newSockAddr;
	socklen_t newSockAddrSize = sizeof(newSockAddr);
	// accept, create a new socket descriptor to
	// handle the new connection with client
	auto *aaa = new waitClientArgs{}; // it looks stupid but it works
	aaa->newSockAddr = newSockAddr;
	aaa->newSockAddrSize = newSockAddrSize;
	int rc = pthread_create(&client_wait_thread, nullptr, waitForClient, aaa);
	pthread_detach(client_wait_thread);
	writeToFile(logFileName, "Server started sucessfully");
	gettimeofday(&start1, NULL);

	return 0;
}

void
closeServer()
{
	long e = end1.tv_sec - start1.tv_sec; /* the linter freaks out if you
						 don't save it as a variable */

	// we need to close the socket descriptors after we're all done
	gettimeofday(&end1, NULL);
	close(clientSocketDescriptor);
	close(serverSocketDescriptor);

	/* Don't just die silently */
	printf("********Session********\n");
	printf("Bytes written: %i\nBytes Read: %i\n", bytesWritten, bytesRead);
	printf("Elapsed time: %ld\n secs\n", e);
	printf("Connection closed...\n");
}

void
closeClient()
{
	long e = end1.tv_sec - start1.tv_sec;

	gettimeofday(&end1, NULL);
	close(clientSocketDescriptor);
	printf("********Session********");
	printf("Bytes written: %i\nBytes read: %i\n", bytesWritten, bytesRead);
	printf("Elapsed time: %ld\n secs\n", e);
	printf("Connection closed...\n");
}

void *
pollForSever(void *args)
{
	waitClientArgs *aaa = static_cast<waitClientArgs *>(args);
	int socketDescriptor = (int)aaa->auxInt;
	char msg[1024];
	while (1) {
		memset(&msg, 0, sizeof(msg)); // clear the buffer
		bytesRead += recv(socketDescriptor, (char *)&msg, sizeof(msg), 0);

		// not needed for proofs of concept testing
		/*if(!strcmp(msg, "exit"))
		{
		    writeToFile(logFileName, msg);
		    displayFile(logFileName, linePos, LOG_LENGTH);
		    break;
		}*/
		// cout << "Server: " << msg << endl;
		// printf("Server: %s\n");
		writeToFile(logFileName, msg);
		if (linesInFile(logFileName) > LOG_LENGTH)
			linePos++;
		displayFile(logFileName, linePos, LOG_LENGTH);
	}
}

void
setupClient()
{
	// we need 2 things: ip address and port number, in that order
	// if(argc != 3)
	//{
	//     cerr << "Usage: ip_address port" << endl; exit(0);
	// } //grab the IP address and port number
	// create a message buffer
	char msg[1024];
	// setup a socket and connection tools
	struct hostent *host = gethostbyname(IP_ADDRESS.c_str());
	sockaddr_in sendSockAddr;
	bzero((char *)&sendSockAddr, sizeof(sendSockAddr));
	sendSockAddr.sin_family = AF_INET;
	sendSockAddr.sin_addr.s_addr = inet_addr(inet_ntoa(*(struct in_addr *)*host->h_addr_list));
	sendSockAddr.sin_port = htons(PORT_NUM);
	clientSocketDescriptor = socket(AF_INET, SOCK_STREAM, 0);
	// try to connect...
	int status = connect(clientSocketDescriptor, (sockaddr *)&sendSockAddr, sizeof(sendSockAddr));
	if (status < 0)
		writeToFile(logFileName, "Error connecting to socket!");
	writeToFile(logFileName, "Connected to the server!");
	int bytesRead, bytesWritten = 0;
	struct timeval start1, end1;
	gettimeofday(&start1, NULL);
	auto *aaa = new waitClientArgs{}; // it looks stupid but it works
	aaa->auxInt = clientSocketDescriptor;
	int rc = pthread_create(&client_wait_thread, nullptr, pollForSever, aaa);
	pthread_detach(client_wait_thread);
}

// appends a line of text to the end of a given file. returns 0 if the file
// existed, 1 if it didn't work
int
writeToFile(string path, string line, bool incLineNum)
{
	ofstream file;
	file.open(path, ios_base::app); // open the file in append mode

	if (file.is_open()) {
		file << line << endl;
		// this probably would help but theres too much broken stuff
		// right now to be sure if (incLineNum)
		//{
		//     linePos++;
		// }
		return 0;
	} else {
		// do something if it didn't work
		return 1; // i guess that's good enough for now
	}
}

int
main(int argc, char *argv[])
{
	if (argc > 1 && argv[1][0] == 'c') {
		// client mode
		logFileName = "client.txt";
		mode = 2;
	} else {
		// server mode
		logFileName = "server.txt";
		mode = 1;
	}

	// putting this lower down to circumvent the terminal brick when the
	// socket was already in use results in all network functonality no
	// longer working.
	initscr();	      // creates stdscr. important step
	use_default_colors(); // this apparently tells it to use default
			      // terminal colors whenever there is no color
			      // attribute applied

	// printw("Starting server...");

	// you have to do this to make the scrolling still work correctly if
	// there was already content in the log file
	linePos = linesInFile(logFileName) - LOG_LENGTH + 1;

	char *userInput = new char[1024];
	bool exit = false;

	if (mode == 2) {
		writeToFile(logFileName, "CLIENT MODE");
		setupClient();
	} else if (mode == 1) {
		writeToFile(logFileName, "SERVER MODE");
		setupServer(PORT_NUM);
	}

	while (!exit) {
		displayFile(logFileName, linePos, LOG_LENGTH);

		// scroll along the screen if and when required so that it stays
		// in sync
		if (linesInFile(logFileName) > LOG_LENGTH)
			linePos++;

		move(12, 0);
		printw("> ");
		getstr(userInput);
		writeToFile(logFileName, userInput);
		if (mode == 1)
			send(clientSocketDescriptor, (char *)userInput, strlen(userInput), 0);
		else
			send(clientSocketDescriptor, (char *)userInput, strlen(userInput), 0);
	}

	endwin();
	closeServer();

	return 0;
}