Extend the basic TW-Mailer project with some pro features. • Refactor the first version so that the server works concurrent (not iterative) o Use fork() or threads o Identify possible synchronization problems and guard the critical sections. • Extend the project with a LOGIN command and allow the other commands only to authenticated users (except QUIT). o The login checks the credentials using the internal LDAP server. o For security reasons only 3 login attempts are allowed per user and IP. o In case the user fails to login within 3 attempts her/his IP is blacklisted for 1 minute. o Persist the blacklist. o Remove the possibility in SEND to set a sender manually. ▪ Sender in SEND should automatically be set (session information after login) o Remove the possibility in LIST/READ/DEL to set the username manually. ▪ The username should automatically be set (session information after login) • Custom features are welcome (please talk to your supervisor in advance) Hints corresponding to LDAP: • Use OpenLDAP C-API Ubuntu Packet libldap2-dev include file <ldap.h> gcc Option -lldap -llber e.g.: g++ -std=c++11 -Wall -o myldap myldap.c -lldap -llber • Internal LDAP-Server address Host: ldap.technikum.wien.at Port: 389 Search Base: dc=technikum-wien,dc=at • Further docs: http://www.yolinux.com/TUTORIALS/LinuxTutorialLDAP-SoftwareDevelopment.html www.technikum-wien.at 2 Protocol specification (update) LOGIN LOGIN\n <LDAP username> <password in plain text> • The server responds with OK\n (and enables all commands for the session) or ERR\n SEND SEND\n <Receiver>\n <Subject (max. 80 chars)>\n <message (multi-line; no length restrictions)\n> .\n • The final dot ends the command. • The server always responds with either “OK\n” or “ERR\n”. LIST LIST\n • The server responds with <count of messages of the current user (0 if no message or user unknown)>\n <subject 1>\n <subject 2>\n … <subject N>\n www.technikum-wien.at 3 READ READ\n <Message-Number>\n • The server responds with OK\n <complete message content (as defined in SEND)>\n • or ERR\n DEL DEL\n <Message-Number>\n • The server responds with OK\n • or ERR\n www.technikum-wien.at 4 Deliverables • Hand-in o The commented code for the client and the server code o Makefile for the targets “all” and “clean” o Executables o Description of (1 page; pdf) ▪ the client and server architecture, ▪ used technologies ▪ development strategy and needed adaptions The second part of the project will be presented in a code review. If there is no presentation at the end of the semester, the submission is automatically rated with 0 points. Marking System (40 Points) • 3: submission contains Makefile and protocol • 5: server is concurrent and synchronized • 3: persistent and efficient storage of the mail spool directory • 12: connections and commands o 3 SEND (+ Sender from session data) o 3 LIST o 3 READ o 3 DEL • 5: LOGIN and LDAP connection • 3: locking clients after 3 attempts • 4: structure, error-handling, code quality, indentation, comments • 5: Code understanding during the presentation

#include <iostream>
using namespace std;

int main()
{
  cout << "Hello World!" << endl;
  return 0;
}