SimpleEmailClientPhase1.cpp

#include<iostream>
#include<fstream>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<regex>
#include<unistd.h>
#include<dirent.h>
#include<list>
#include<string>
#include<string.h>
#include<stdlib.h>
using namespace std;

const int chunk_size = 1024;

/////////////////////////
//FUNCTION DECLARATIONS//
/////////////////////////

int send_message(int sockfd, string message);
//If not sent, prints error message and returns -10
//Else returns number of bytes sent
string rec_message(int sockfd);
//Receives upto chunk_size bytes and returns string
//If error receiving, prints appropriate error and returns "error"

int send_login(string username, string password, int sockfd);
//Sends login message
//Returns -10 and prints "Login failed" if failed

///////////////
//MAIN STARTS//
///////////////

int main(int argc, char*argv[]){
//Validate and extract arguments
//	string IP
//	int port
//	string username
//	string password
	if (argc != 4){
		cerr<<"Invalid number of arguments\nUsage: SimpleEmailClientPhase3 <IP:PortNum> <Username> <Password>\n";
		exit(1);
	}
	string arg1(argv[1]),username(argv[2]),password(argv[3]);
	int col = arg1.find(":");
	string IP = arg1.substr(0,col);
	string port_s = arg1.substr(col+1);
	int port;
	try{
		port = stoi(port_s);
	}
	catch(...){
		port = 0;
	}

//Initialize sockaddr
	sockaddr_in server_address;
    memset(&server_address, '0', sizeof(server_address));
	server_address.sin_family = AF_INET;
	server_address.sin_addr.s_addr = inet_addr(IP.c_str());
	server_address.sin_port = htons(port);
	int size_addr = sizeof(struct sockaddr);

//Set up socket
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == 0){
		cerr<<"Couldn't form socket\n";
		exit(2);
	}

//Connect to server
	if(connect(sockfd,  (struct sockaddr *)&server_address, sizeof(struct sockaddr)) < 0){
		cerr<<"Connection to server failed\n";
		exit(2);
	}
	else{
		cout<<"ConnectDone: "<<argv[1]<<endl;
	}

//Login
	if(send_login(username,password,sockfd)<0){
		return 0;
	}
	cout<<rec_message(sockfd);

//Quit
	send_message(sockfd,"quit");
	close(sockfd);

}

////////////////////////
//FUNCTION DEFINITIONS//
////////////////////////

int send_message(int sockfd, string message){
//Prints error message if not sent and returns -10
//Else returns number of bytes sent
	//Convert to char array
	char mess[message.length()+1];
	for (int i=0; i< message.length();i++){
		mess[i] = message[i];
	}
	mess[message.length()] = '\0';
	//Send char array
	int x = send(sockfd,&mess,strlen(mess),0);
	if(x<0){
		cerr<<"Message not sent: "<<message<<endl;
		return -10;
	}
	return x;
}

string rec_message(int sockfd){
//Receives upto chunk_size bytes and returns string
//If error receiving, prints appropriate error and returns string "error"
	char buff[chunk_size] = {0};
	int read_bytes = recv(sockfd,(void*)&buff, chunk_size, 0);
	if(read_bytes == 0){
		cerr<<"Connection closed before reading\n";
		exit(3);
	}
	else if(read_bytes == -1){
		cerr<<"Error on receive\n";
		return "error";
	}
	string buf(buff);
	return buf;
}

int send_login(string username, string password, int sockfd){
//Sends login message
//Returns -10 and prints "Login failed" if failed
	if(send_message(sockfd,"User: "+username+" Pass: "+password) < 0){
		cout<<"Login failed"<<endl;
		return -10;
	}
	return 0;
}