server.cpp

#include <iostream>
#include <string>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <fstream>

#define TMP_LENGTH 1024
using namespace std;

void receiveFromClient();
int newSd;
bool heloAccepted, fromAccepted, toAccepted, dataAccepted, quit;
char* fname;
int flag =0;


int serverSd;

void writeToFile(char content[],char* target);
void closeConnection();
char* extractName(const char* msg);

void sendStatusCode(string code) {
    char buf[TMP_LENGTH];

    bzero(buf,TMP_LENGTH);
    strcpy(buf, code.c_str());
    strcat(buf,"\n");
    send(newSd, (char*)&buf, strlen(buf), 0);
}

bool doesFileExist(const char* name) {
    //strcat(name, ".txt");
    if(freopen(name,"r",stdin))
        return true;
    else
        return false;
}

void checkClientMessage(char msg[]) {
    char buf[TMP_LENGTH];

    if(strstr(msg, "HELO")) {
        heloAccepted = true;
        sendStatusCode("220   Service ready");

    } else if(strstr(msg, "MAIL FROM")) {
        if(!heloAccepted) {
            sendStatusCode("503	 Bad sequence of commands");
            return;
        }
        fromAccepted = true;
        sendStatusCode("250    Requested mail action okay completed");
        string duplicate = buf;
        cout<<duplicate<<"\n";
        checkClientMessage(buf);
        fname = extractName(duplicate.c_str());


    } else if(strstr(msg, "RCPT TO")) {
        if(!fromAccepted) {
            sendStatusCode("503	 Bad sequence of commands");
            return;
        }
        strtok(msg, ":");
        char* targetUserName = strtok(NULL, "@");
        strcat(targetUserName, ".txt");
        if(doesFileExist(targetUserName)) {
            toAccepted = true;
            sendStatusCode("250    Requested mail action okay, completed");
        } else {
            //mailbox unavailable
            toAccepted = false;
            sendStatusCode("450    Requested mail action not taken: mailbox unavailable");
        }


    } else if(strstr(msg, "DATA")) {
        if(!toAccepted) {
            sendStatusCode("503	 Bad sequence of commands");
            return;
        }

        sendStatusCode("354  Start mail input; end with <CRLF>.<CRLF>");
        //header
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        writeToFile(buf, fname);
        cout<<buf <<"\n";

        //msg-body
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        writeToFile(buf, fname);
        sendStatusCode("250	    Requested mail action okay, completed");

        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        writeToFile(buf, fname);
        cout<<buf <<"\n";

    } else if(strstr(msg, "QUIT")) {

        sendStatusCode("221	  Service closing transmission channel");
        closeConnection();

    } else {
        sendStatusCode("500  Command not implemented");
    }

}

//Server side
int main(int argc, char *argv[]) {

    //for the server, we only need to specify a port number
    if(argc != 2) {
        cerr << "Usage: port" << endl;
        exit(0);
    }
    //grab the port number
    int port = atoi(argv[1]);

    //buffer to send and receive messages with
    char msg[1500];

    //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
    int serverSd = socket(AF_INET, SOCK_STREAM, 0);
    if(serverSd < 0) {
        cerr << "Error establishing the server socket" << endl;
        exit(0);
    }
    //bind the socket to its local address
    int bindStatus = bind(serverSd, (struct sockaddr*) &servAddr,
                          sizeof(servAddr));
    if(bindStatus < 0) {
        cerr << "Error binding socket to local address" << endl;
        exit(0);
    }
    cout << "Server ready..." << endl;
listening:
    listen(serverSd, 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
    newSd = accept(serverSd, (sockaddr *)&newSockAddr, &newSockAddrSize);
    if(newSd < 0) {
        cerr << "Error accepting request from client!" << endl;
        exit(1);
    }
    cout << "Connected with client" << endl;
    receiveFromClient();
    if(flag == 3370) {
        goto listening;
    } else
        close(serverSd);
    cout << "Connection closed..." << endl;
    return 0;
}

void receiveFromClient() {

    char buf[TMP_LENGTH];
    char msg[TMP_LENGTH];

    while(1) {

        memset(&msg, 0, sizeof(msg));//clear the buffer
        recv(newSd, (char*)&msg, sizeof(msg), 0);
        cout << "Client: " << msg << endl;
        cout << ">";
        checkClientMessage(msg);
    }
    /*
        //receiving MAIL FROM
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        checkClientMessage(buf);

        // RCPT TO
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        string duplicate = buf;
        cout<<duplicate<<"\n";
        checkClientMessage(buf);
        char* fname = extractName(duplicate.c_str());
        //char* fname = "nobody.txt";

        //DATA
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        checkClientMessage(buf);


        //header
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        writeToFile(buf, fname);
        cout<<buf <<"\n";

        //msg-body
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        writeToFile(buf, fname);
        sendStatusCode("250	    Requested mail action okay, completed");

        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        writeToFile(buf, fname);
        cout<<buf <<"\n";

        //QUIT
        bzero(buf,TMP_LENGTH);
        recv(newSd, (char*)&buf, sizeof(buf), 0);
        cout<<buf <<"\n";
        checkClientMessage(buf);

        */

}

void writeToFile(char content[], char* target) {
    ofstream outfile;
    outfile.open(target, std::ios_base::app);
    outfile << content<<endl<<endl;
}

char* extractName(const char* msg) {
    char* msg2 = (char*) msg;
    strtok(msg2, ":");
    char* targetUserName = strtok(NULL, "@");
    strcat(targetUserName, ".txt");
    cout<<targetUserName<<endl;
    return targetUserName;
}

void closeConnection() {
    close(newSd);
    flag = 1000;
    cout<<"Done processing this client, closed connection" <<"\n";
}