popsession.cc

/*
    PowerMail versatile mail receiver
    Copyright (C) 2002 - 2009  PowerDNS.COM BV

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <stdlib.h>
#include "popsession.hh"
#include "userbase.hh"
#include "delivery.hh"
#include "logger.hh"
#include "misc.hh"
#include <sys/types.h>
#include <dirent.h>
#include <time.h>
#include <syslog.h>
#include <sys/stat.h>
#include <fcntl.h> 
#include <unistd.h>
#include <sstream>
#include <ctype.h>
#include "argsettings.hh"
#include "pool.hh"
#include "common.hh"

extern PoolClass<UserBase>* UBP;
extern Logger L;

// UIDL, TOP 

void PopSession::strip(string &line)
{
  string::size_type pos=line.find_first_of("\r\n");
  if(pos!=string::npos) {
    line.resize(pos);
  }

}

PopSession::~PopSession()
{
  if(d_megatalker)
    delete d_megatalker;
}

void PopSession::firstWordUC(string &line)
{
  for(string::iterator i=line.begin();i!=line.end();++i) {
    if(*i==' ')
      return;
    *i=toupper(*i);
  }
}

int PopSession::delDeleted(string &response)
{
  try {
    for(msgData_t::const_iterator i=d_msgData.begin();i!=d_msgData.end();++i) {
      if(i->d_deleted) {
	d_megatalker->delMsg(i->d_fname);
	d_deleted++;
      }
    }
  }
  catch(MegaTalkerException &e) {
    response="-ERR "+e.getReason();
    return -1;
  }

  return 0;
}

bool PopSession::topCommands(const string &line, string &response, quit_t &quit)
{
  if(line=="NOOP") {
    response="+OK Done";
    return true;
  }
  if(line=="QUIT") {
    if(delDeleted(response))
      return true; 

    response="+OK ";
    if(d_login)
      L<<Logger::Error<<"Mailbox '"<<d_user<<"' logging out, retrieved: "<<d_retrieved<<", deleted: "<<d_deleted<<endl;
    quit=pleaseQuit;
    return 1;
  }
  
  if(line=="RSET") {
    for(msgData_t::iterator i=d_msgData.begin();i!=d_msgData.end();++i) {
      i->d_deleted=false;
    }
    response="+OK ";
    return true;
  }

  return false;
}

bool PopSession::loginCommands(const string &line, string &response, quit_t &quit)
{
  if(!line.find("APOP ")) {
    if(d_login) {
      response="-ERR Already logged in";
      return true;
    }

    d_user=line.substr(5,(line.find(" ",5)-5));
    string digit = line.substr(line.find(" ",5)+1); 
    if (d_user.empty()) {
      response="-ERR Too few parameters (no username and digit)";
      return true;
    }
    if (digit.empty()) {
      response="-ERR Too few parameters (no digit)";
      return true;
    }
    
    string::size_type pos=d_user.find("%");
    if (pos!=string::npos)
      d_user[pos]='@';
   
    bool exists=false, pwcorrect=false;
    MboxData md;
    int res;

    string tries[2];
    tries[0]=d_user;
    tries[1]="*";
    string::size_type offset=d_user.find('@');
    if(offset!=string::npos) {
      tries[1]+=d_user.substr(offset);
    }
    else
      tries[1]="*@"+d_user;

    string *dest;
    for(dest=tries;dest!=&tries[2];++dest) {
      PoolClass<UserBase>::handle ubh=UBP->get();
      res=ubh.d_thing->mboxData(*dest,md,digit,response, exists, pwcorrect,d_challenge); // sets response!
      if(res<0) {
	response="-ERR 1"+response;
	sleep(1); // thwart dictionary attacks
	return 1;
      }
      if(exists) {
	d_user=md.canonicalMbox; // we may have been renamed by the userbase!
	break;
      }
    }

    if(exists && *dest!=d_user) {
      L<<Logger::Warning<<"Fallback match of '"<<d_user<<"' as '"<<*dest<<"'"<<endl;
    }

    response="-ERR Invalid credentials (wrong username or password?)";
    if(exists && pwcorrect) {
      L<<Logger::Warning<<"Mailbox '"<<d_user<<"' logged in"<<endl;
      d_login=true;

      
      try {
	d_megatalker=0;
	d_megatalker=new MegaTalker;
      }
      catch(MegaTalkerException &e) {
	L<<"Fatal error connecting to MegaTalker: "<<e.getReason()<<endl;
	response="-ERR Temporary error connecting to backends";
	return 1;
      }
      if(scanDir(response))
	return false;

      response=makeStatResponse();
    }
    else if(exists && !pwcorrect) {
      L<<Logger::Warning<<"Mailbox '"<<d_user<<"' exists but tried wrong password"<<endl;
    }
    else
      L<<Logger::Warning<<"No such mailbox '"<<d_user<<"'"<<endl;
    return 1;
  }

	
  if(!line.find("USER ")) {
    if(d_login) {
      response="-ERR Already logged in";
      return true;
    }

    d_user=line.substr(5);
    response="+OK ";
    return 1;
  }

  if(!line.find("PASS ")) {
    if(d_login) {
      response="-ERR Already logged in";
      return true;
    }
    if(d_user.empty()) {
      response="-ERR USER first";
      return true;
    }
    string::size_type pos=d_user.find("%");
    if(pos!=string::npos)
      d_user[pos]='@';

    bool exists=false, pwcorrect=false;
    MboxData md;
    int res;

    string tries[2];
    tries[0]=d_user;
    tries[1]="*";
    string::size_type offset=d_user.find('@');
    if(offset!=string::npos) {
      tries[1]+=d_user.substr(offset);
    }
    else
      tries[1]="*@"+d_user;

    string *dest;
    for(dest=tries;dest!=&tries[2];++dest) {
      PoolClass<UserBase>::handle ubh=UBP->get();
      res=ubh.d_thing->mboxData(*dest,md,line.substr(5), response, exists, pwcorrect, ""); // sets response!
      if(res<0) {
	response="-ERR "+response;
	sleep(1); // thwart dictionary attacks
	return 1;
      }
      if(exists) {
	d_user=md.canonicalMbox; // we may have been renamed by the userbase!
	break;
      }
    }

    if(exists && *dest!=d_user) {
      L<<Logger::Warning<<"Fallback match of '"<<d_user<<"' as '"<<*dest<<"'"<<endl;
    }

    response="-ERR Invalid credentials (wrong username or password?)";
    if(exists && pwcorrect) {
      L<<Logger::Warning<<"Mailbox '"<<d_user<<"' logged in"<<endl;
      d_login=true;

      
      try {
	d_megatalker=0;
	d_megatalker=new MegaTalker;
      }
      catch(MegaTalkerException &e) {
	L<<"Fatal error connecting to MegaTalker: "<<e.getReason()<<endl;
	response="-ERR Temporary error connecting to backends";
	return 1;
      }
      if(scanDir(response))
	return false;

      response=makeStatResponse();
    }
    else if(exists && !pwcorrect) {
      L<<Logger::Warning<<"Mailbox '"<<d_user<<"' exists but tried wrong password"<<endl;
    }
    else
      L<<Logger::Warning<<"No such mailbox '"<<d_user<<"'"<<endl;
    return 1;
  }
  return 0;
}

const string PopSession::makeStatResponse()
{
  size_t tot=0;
  int num=0;
  for(msgData_t::const_iterator i=d_msgData.begin();i!=d_msgData.end();++i) {
    if(!i->d_deleted) {
      tot+=i->d_size;
      num++;
    }
  }
  ostringstream o;
  o<<"+OK "<<num<<" "<<tot;
  return o.str();
}

bool PopSession::restCommands(const string &line, string &response, quit_t &quit, int &fd)
{
  fd=0;
  if(!d_login) {
      return 0;
  }

  if(!d_scanned) {
    if(scanDir(response))
      return true;
  }

  vector<string>arguments;
  stringtok(arguments,line);
  if(!arguments.size())
    return 0;

  int numArgs=arguments.size();

  string &command=arguments[0];

  if(command=="UIDL") {
    if(numArgs==1) {
      response="+OK\r\n";
      
      for(msgData_t::const_iterator i=d_msgData.begin();i!=d_msgData.end();++i) {
	if(i->d_deleted)
	  continue;
	
	ostringstream o;
	o<<1+i-d_msgData.begin()<<" "<<i->d_fname<<"\r\n";
	response+=o.str();
      }
      response+=".";
      return 1;
    }
    
    unsigned int num=atoi(arguments[1].c_str())-1;
    if(num>=d_msgData.size()) {
      response="-ERR Number out of range";
      return 1;
    }
    
    ostringstream o;
    o<<"+OK "<<num+1<<" "<<d_msgData[num].d_fname;
    response=o.str();
    return 1;
  }



  if(command=="RETR" && numArgs==2) {
    response="+OK";
    unsigned int num=atoi(arguments[1].c_str())-1;
    if(num>=d_msgData.size()) {
      response="-ERR Number out of range";
      return 1;
    }
    try {
      if (! d_msgData[num].d_deleted) {
      d_megatalker->blastMessageFD(d_msgData[num].d_fname,d_msgData[num].d_size,d_clisock);
      d_retrieved++;
      response="";
      } else 
        response="-ERR Message was deleted";
    }
    catch(MegaTalkerException &e) {
      response="-ERR Retrieving message, "+e.getReason();
    }

    return 1;
  }

  if(command=="TOP" && numArgs>=1 && numArgs<=3) {
    if(numArgs<2) {
      response="-ERR Missing parameter";
      return true;
    }
      
    response="+OK";
    unsigned int num=atoi(arguments[1].c_str())-1;

    if(num>=d_msgData.size()) {
      response="-ERR Number out of range";
      return 1;
    }
    if (d_msgData[num].d_deleted) {
      response="-ERR Message was deleted";
      return 1;
    }

    int limit=-1;
    if(arguments.size()>2)
      limit=atoi(arguments[2].c_str());

    d_megatalker->blastMessageFD(d_msgData[num].d_fname,0,d_clisock,limit);
    response="";
    return 1;
  }


  if(command=="DELE" && numArgs==2) {
    if(!d_scanned) {
      if(scanDir(response))
	return true;
    }

    unsigned int num=atoi(arguments[1].c_str())-1;
    if(num>=d_msgData.size()) {
      response="-ERR Number out of range";
      return 1;
    }
    if(!d_msgData[num].d_deleted) {
      d_msgData[num].d_deleted=true;
      response="+OK";
    }
    else {
      response="-ERR Already deleted";
    }

    return 1;
  }

  if(command=="STAT" && numArgs==1) {
    response=makeStatResponse();

    return 1;
  }
  
  if(command=="LIST" && numArgs==2) {
    if(!d_scanned) {
      if(scanDir(response))
	return true;
    }

    unsigned int num=atoi(arguments[1].c_str())-1;
    if(num>=d_msgData.size()) {
      response="-ERR Number out of range";
      return 1;
    }

    if(d_msgData[num].d_deleted) {
      response="-ERR was deleted";
      return 1;
    }

    ostringstream o;
    o<<"+OK "<<num+1<<" "<<d_msgData[num].d_size;
    response=o.str();
    return 1;
  }


  if(command=="LIST" && numArgs==1) {
    response="+OK\r\n";
    ostringstream o;
    for(msgData_t::const_iterator i=d_msgData.begin();i!=d_msgData.end();++i) {
      if(i->d_deleted)
	continue;


      o<<1+i-d_msgData.begin()<<" "<<i->d_size<<"\r\n";

    }
    response+=o.str();
    response+=".";
    return 1;
  }

  return 0;
}

int PopSession::scanDir(string &response)
{
  MegaTalker::mboxInfo_t data;
  try {
    d_megatalker->getMsgs(d_user, data);
  }
  catch(MegaTalkerException &e) {
    response="-ERR "+e.getReason();
    return true;
  }
  
  MsgDatum md;

  for(MegaTalker::mboxInfo_t::const_iterator i=data.begin();
      i!=data.end();
      ++i) {
    md.d_size=i->size;
    md.d_fname=i->index;
    md.d_deleted=false;
    d_msgData.push_back(md);
  }
  d_scanned=1;
  return false;
}    

bool PopSession::controlCommands(const string &line, string &response, quit_t &quit)
{
  response="-ERR Unknown error processing control command";
  vector<string> words;
  stringtok(words,line);
  if(words.empty())
    return false;

  if(words[0]!="CONTROL")
    return false;

  if(d_remote.find("127.0.0.1:") && d_remote.find(args().paramString("listen-address")+":")) {
    L<<Logger::Error<<"Remote "<<d_remote<<" tried a control command: "<<line<<endl;
    return false;
  }
    

  if(words.size()<2) {
    response="-ERR Missing control command";
    return true;
  }

  else if(words[1]=="stop") {
    response="+OK BYE!";
    quit=pleaseDie;
  }
  else if(words[1]=="status") {
    response="+OK OK!";
  }
  else {
    response="-ERR Unknown control command '"+words[1]+"'";
  }
  return true;
}


bool PopSession::giveLine(string &line, string &response, quit_t &quit, int &fd)
{
  quit=noQuit;
  fd=0;
  strip(line);

  firstWordUC(line);

  if(controlCommands(line,response,quit))
    return true;

  if(topCommands(line, response, quit)) // RSET, HELP, QUIT, NOOP
    return true;

  if(loginCommands(line,response,quit)) // USER, PASS, and later APOP
    return true;

  if(restCommands(line,response,quit,fd))
    return true;
  
  response="-ERR Not Implemented or Not Authorized Yet";
  L<<Logger::Error<<"Unable to parse or process line '"<<line<<"'"<<endl;
  return true;
}

string PopSession::getBanner()
{
  d_challenge="<"+itoa(getpid())+"."+itoa(time(0))+"@"+getHostname()+">";
  return "+OK POP3 server ready "+d_challenge+"\r\n"; 
}