telnet_phases.cpp

// telnet_phases.cpp - handle telnet phases in incoming text stream

#include "stdafx.h"
#include "MUSHclient.h"

#include "doc.h"

/* Phases for processing input stream ...


  To allow for these to be broken between packets we only do one
  character at a time, and maintain a "state" (Phase) which indicates
  how far through the sequence we are.

  The two "triggering" codes we might get in normal text (ie. phase NONE) are
  ESC or IAC.

  Tested (5 Feb 2010):

  * MCCP v1
  * MCCP v2
  * IAC GA              \ff\f9
  * IAC EOR             \ff\ef
  * IAC IAC inside subnegotiation   \FF\FD\66 \ff\fa\66hello\ff\ffboys\ff\f0
  * IAC IAC in normal text      what\ff\ffever
  * MXP
  * Charset: \FF\FD\2A \ff\fa\2A\01,UTF-8,US-ASCII\ff\f0
  * terminal type: \FF\FD\18 \ff\fa\18\01\ff\f0
  * NAWS: \FF\FD\1f \ff\fa\1f\ff\f0
  * Chat system


*/

// ESC x

void CMUSHclientDoc::Phase_ESC (const unsigned char c)
  {
  if (c == '[')
    {
    m_phase = DOING_CODE;
    m_code = 0;
    }
  else
    m_phase = NONE;

  } // end of Phase_ESC

// ANSI - We have ESC [ x

void CMUSHclientDoc::Phase_ANSI (const unsigned char c)
  {
  if (isdigit (c))
    {
    m_code *= 10;
    m_code += c - '0';
    }
  else if (c == 'm')
    {
    if (m_phase != DOING_CODE)
      Interpret256ANSIcode (m_code);
    else
      InterpretANSIcode (m_code);
    m_phase = NONE;
    }
  else if (c == ';')
    {
    if (m_phase != DOING_CODE)
      Interpret256ANSIcode (m_code);
    else
      InterpretANSIcode (m_code);
    m_code = 0;
    }
  else if (c == 'z')    // MXP line security mode
    {
    if (m_code == eMXP_reset)
      MXP_Off ();
    else
      {
//      TRACE1 ("\nMXP security mode now %i\n", m_code);
      MXP_mode_change (m_code);
      }
    m_phase = NONE;
    }
  else
    m_phase = NONE;
  } // end of Phase_ANSI

// IAC - we have IAC x

void CMUSHclientDoc::Handle_IAC_GA ()
  {
  CPlugin * pSavedPlugin = m_CurrentPlugin;

  // tell each plugin what we have received
  for (POSITION pluginpos = m_PluginList.GetHeadPosition(); pluginpos; )
    {
    CPlugin * pPlugin = m_PluginList.GetNext (pluginpos);


    if (!(pPlugin->m_bEnabled))   // ignore disabled plugins
      continue;

    // see what the plugin makes of this,
    pPlugin->ExecutePluginScript (ON_PLUGIN_IAC_GA,
                                  pPlugin->m_dispid_plugin_IAC_GA);

    }   // end of doing each plugin

  m_CurrentPlugin = pSavedPlugin;

  }   // end of  CMUSHclientDoc::Handle_IAC_GA

void CMUSHclientDoc::Phase_IAC (unsigned char & c)
  {
  char * p;
  unsigned char new_c = 0;    // returning zero stops further processing of c

  switch (c)
    {
    case EOR                 : 
          m_phase = NONE; 
          p = "EOR"; 
          if (m_bConvertGAtoNewline)
            new_c = '\n';
          Handle_IAC_GA ();
          break;
    case GO_AHEAD            : 
          m_phase = NONE; 
          p = "GA"; 
          if (m_bConvertGAtoNewline)
            new_c = '\n';
          Handle_IAC_GA ();
          break;

    case SE                  : m_phase = NONE;      p = "SE"; break;
    case NOP                 : m_phase = NONE;      p = "NOP"; break;
    case DATA_MARK           : m_phase = NONE;      p = "DM"; break;
    case BREAK               : m_phase = NONE;      p = "BRK"; break;
    case INTERRUPT_PROCESS   : m_phase = NONE;      p = "IP"; break;
    case ABORT_OUTPUT        : m_phase = NONE;      p = "AO"; break;
    case ARE_YOU_THERE       : m_phase = NONE;      p = "AYT"; break;
    case ERASE_CHARACTER     : m_phase = NONE;      p = "EC"; break;
    case ERASE_LINE          : m_phase = NONE;      p = "EL"; break;
    case SB                  : m_phase = HAVE_SB;   p = "SB"; break;
    case WILL                : m_phase = HAVE_WILL; p = "WILL"; break;
    case WONT                : m_phase = HAVE_WONT; p = "WONT"; break;
    case DO                  : m_phase = HAVE_DO;   p = "DO"; break;
    case DONT                : m_phase = HAVE_DONT; p = "DONT"; break;
    default                  : m_phase = NONE;      p = "none"; break;
    } // end of switch
  TRACE1 ("<%s>", p);
  m_subnegotiation_type = 0;    // no subnegotiation type yet
  c = new_c;

  } // end of Phase_IAC

// send to all plugins: function OnPluginTelnetRequest (num, type)
//    eg. num = 200, type = DO
// They reply true or false to handle or not handle that telnet type
 
bool CMUSHclientDoc::Handle_Telnet_Request (const int iNumber, const string sType)

  {
  bool bOK = false;

  CPlugin * pSavedPlugin = m_CurrentPlugin;

  // tell each plugin what we have received
  for (POSITION pluginpos = m_PluginList.GetHeadPosition(); pluginpos; )
    {
    CPlugin * pPlugin = m_PluginList.GetNext (pluginpos);


    if (!(pPlugin->m_bEnabled))   // ignore disabled plugins
      continue;

    // don't default to true if routine does not exist
    if (!(pPlugin->m_ScriptEngine) || 
        pPlugin->m_dispid_plugin_telnet_request == DISPID_UNKNOWN)
      continue;

    // see what the plugin makes of this,
    if (pPlugin->ExecutePluginScript (ON_PLUGIN_TELNET_REQUEST,
                                  pPlugin->m_dispid_plugin_telnet_request,
                                  iNumber,
                                  sType))  // what we got
      {
      bOK = true;
      break;   // only get the first positive reply
      }

    }   // end of doing each plugin

    m_CurrentPlugin = pSavedPlugin;
    return bOK;

  } // end of CMUSHclientDoc::Handle_Telnet_Request 

void CMUSHclientDoc::Send_IAC_DO (const unsigned char c)
  {
  // if we are already in a mode do not agree again - see RFC 854 
  // and forum subject 3061                           

  if (m_bClient_IAC_DO [c])
      return;

  unsigned char do_do_it [3]   = { IAC, DO, c };

  TRACE1 ("\nSending IAC DO <%d>\n", c);
  SendPacket (do_do_it, sizeof do_do_it);
  m_bClient_IAC_DO [c]   = true;
  m_bClient_IAC_DONT [c] = false;

  } // end of CMUSHclientDoc::Send_IAC_DO

void CMUSHclientDoc::Send_IAC_DONT (const unsigned char c)
  {
  // if we are already in a mode do not agree again - see RFC 854 
  // and forum subject 3061                           
  if (m_bClient_IAC_DONT [c])
      return;

  unsigned char dont_do_it [3] = { IAC, DONT, c };

  TRACE1 ("\nSending IAC DONT <%d>\n", c);
  SendPacket (dont_do_it, sizeof dont_do_it);
  m_bClient_IAC_DONT [c] = true;
  m_bClient_IAC_DO [c]   = false;

  } // end of CMUSHclientDoc::Send_IAC_DONT

void CMUSHclientDoc::Send_IAC_WILL (const unsigned char c)
  {
  // if we are already in a mode do not agree again - see RFC 854 
  // and forum subject 3061                           
  if (m_bClient_IAC_WILL [c])
      return;

  unsigned char will_do_it [3]   = { IAC, WILL, c };

  TRACE1 ("\nSending IAC WILL <%d>\n", c);
  SendPacket (will_do_it, sizeof will_do_it);
  m_bClient_IAC_WILL [c] = true;
  m_bClient_IAC_WONT [c] = false;

  } // end of CMUSHclientDoc::Send_IAC_WILL

void CMUSHclientDoc::Send_IAC_WONT (const unsigned char c)
  {
  // if we are already in a mode do not agree again - see RFC 854 
  // and forum subject 3061                           
  if (m_bClient_IAC_WONT [c])
      return;

  unsigned char wont_do_it [3] = { IAC, WONT, c };

  TRACE1 ("\nSending IAC WONT <%d>\n", c);
  SendPacket (wont_do_it, sizeof wont_do_it);
  m_bClient_IAC_WONT [c] = true;
  m_bClient_IAC_WILL [c] = false;

  } // end of CMUSHclientDoc::Send_IAC_WONT


// WILL - we have IAC WILL x   - reply DO or DONT (generally based on client option settings)
// for unknown types we query plugins: function OnPluginTelnetRequest (num, type) 
//    eg. num = 200, type = WILL
// They reply true or false to handle or not handle that telnet type

void CMUSHclientDoc::Phase_WILL (const unsigned char c)
  {

// telnet negotiation : in response to WILL, we say DONT
// (except for compression, MXP, TERMINAL_TYPE and SGA), we *will* handle that)

  TRACE1 ("<%d>", c);
  m_phase = NONE;  // back to normal text after this character
  switch (c)
    {
    case TELOPT_COMPRESS2:
    case TELOPT_COMPRESS:
      // initialise compression library if not already decompressing
      if (!m_bCompressInitOK && !m_bCompress)
        m_bCompressInitOK = InitZlib (m_zCompress);
      if (m_bCompressInitOK && !m_bDisableCompression)
        {
        if (!m_CompressOutput)
          m_CompressOutput = (Bytef *) malloc (COMPRESS_BUFFER_LENGTH);
        if (!m_CompressInput)
          m_CompressInput = (Bytef *) malloc (COMPRESS_BUFFER_LENGTH);

        if (m_CompressOutput && !m_CompressInput)
          {
          free (m_CompressOutput);    // only got one? may as well free it
          m_CompressOutput = NULL;
          }

        if (m_CompressOutput && m_CompressInput &&     // we got memory - we can do it
            !(c == TELOPT_COMPRESS && m_bSupports_MCCP_2)) // don't agree to MCCP1 and MCCP2
          {
          Send_IAC_DO (c);
          if (c == TELOPT_COMPRESS2)
            m_bSupports_MCCP_2 = true;
          }
        else
          {   // not enough memory or already agreed to MCCP 2 - no compression
          Send_IAC_DONT (c);
          }
        }   // end of compression wanted and zlib engine initialised
      else
        {
        Send_IAC_DONT (c);
        }
      break;    // end of TELOPT_COMPRESS

    // here for SGA (Suppress GoAhead) 
    case SGA:
          Send_IAC_DO (c);
          break;  // end of SGA 

    // here for TELOPT_MUD_SPECIFIC 
    case TELOPT_MUD_SPECIFIC:
          Send_IAC_DO (c);
          break;  // end of TELOPT_MUD_SPECIFIC 

    case TELOPT_ECHO:
          if (!m_bNoEchoOff)
              {
              m_bNoEcho = true;
              TRACE ("Echo turned off\n");
              }
          break; // end of TELOPT_ECHO

    case TELOPT_MXP:
          if (m_iUseMXP == eNoMXP)
            {
            Send_IAC_DONT (c);
            }     // end of no MXP wanted
          else
            {
            Send_IAC_DO (c);
            if (m_iUseMXP == eQueryMXP)     // turn MXP on now
              MXP_On ();
            } // end of MXP wanted
          break;  // end of MXP
          
    // here for EOR (End of record)
    case WILL_END_OF_RECORD:
          if (m_bConvertGAtoNewline)
            Send_IAC_DO (c);
          else
            Send_IAC_DONT (c);
          break;  // end of WILL_END_OF_RECORD


    default:
        if (Handle_Telnet_Request (c, "WILL"))
          {
          Send_IAC_DO (c);
          Handle_Telnet_Request (c, "SENT_DO");
          }
        else
          Send_IAC_DONT (c);
        break;  // end of others

    } // end of switch


  } // end of Phase_WILL

// Received: IAC WONT x

void CMUSHclientDoc::Phase_WONT (const unsigned char c)
  {

// telnet negotiation : in response to WONT, we say DONT

  TRACE1 ("<%d>", c);
  m_phase = NONE;

  switch (c)
    {
    case TELOPT_ECHO:
        if (!m_bNoEchoOff)
          {
          m_bNoEcho = false;
          TRACE ("Echo turned on\n");
          }
          break; // end of TELOPT_ECHO

    default:
      Send_IAC_DONT (c);
      break;
    } // end of switch
  } // end of Phase_WONT

// Received: IAC DO x

// for unknown types we query plugins: function OnPluginTelnetRequest (num, type) 
//    eg. num = 200, type = DO
// They reply true or false to handle or not handle that telnet type

void CMUSHclientDoc::Phase_DO (const unsigned char c)
  {
// telnet negotiation : in response to DO, we say WILL for:  
//  <102> (Aardwolf), SGA, echo, NAWS, CHARSET, MXP and Terminal type
// for others we query plugins to see if they want to handle it or not

  TRACE1 ("<%d>", c);
  m_phase = NONE;

  switch (c)
    {
    case SGA:
    case TELOPT_MUD_SPECIFIC:
    case TELOPT_TERMINAL_TYPE:   
    case TELOPT_ECHO:
    case TELOPT_CHARSET:
        Send_IAC_WILL (c);
        break; // end of things we will do 
                
    case TELOPT_NAWS:
      // option off - must be server initiated
      if (!m_bNAWS)
        Send_IAC_WILL (c);
      m_bNAWS_wanted = true;
      SendWindowSizes (m_nWrapColumn);
      break;

    case TELOPT_MXP:
          if (m_iUseMXP == eNoMXP)
            Send_IAC_WONT (c);
          else
            {
            Send_IAC_WILL (c);
            if (m_iUseMXP == eQueryMXP)     // turn MXP on now
              MXP_On ();
            } // end of MXP wanted
          break;  // end of MXP

    default:
          if (Handle_Telnet_Request (c, "DO"))
            {
            Send_IAC_WILL (c);
            Handle_Telnet_Request (c, "SENT_WILL");
            }
          else
            Send_IAC_WONT (c);
          break;    // end of others
    }   // end of switch

  } // end of Phase_DO

// Received: IAC DONT x

void CMUSHclientDoc::Phase_DONT (const unsigned char c)
  {
// telnet negotiation : in response to DONT, we say WONT

  TRACE1 ("<%d>", c);
  m_phase = NONE;
  unsigned char p [3] = { IAC, WONT, c };
  SendPacket (p, sizeof p);

  switch (c)
    {

    case TELOPT_MXP:
          if (m_bMXP)
            MXP_Off (true);
          break;  // end of MXP

    }   // end of switch

  } // end of Phase_DONT

// SUBNEGOTIATION - we have IAC SB c 
// remember c (the type) and start collecting the data, as in:
// IAC SB c <data> IAC SE

void CMUSHclientDoc::Phase_SB (const unsigned char c)
  {
  TRACE1 ("<%d>", c);

  // note IAC SB COMPRESS is a special case because they forgot to specify
  // the IAC SE, and thus we can't use normal negotiation
  if (c == TELOPT_COMPRESS)
    m_phase = HAVE_COMPRESS;
  else
    {
    m_subnegotiation_type = c;
    m_IAC_subnegotiation_data.erase ();
    m_phase = HAVE_SUBNEGOTIATION;
    }
  } // end of CMUSHclientDoc::Phase_SB 

// SUBNEGOTIATION - we have IAC SB c (data)
// if we get an IAC remember it, because it may or may not be followed by IAC or SE
void CMUSHclientDoc::Phase_SUBNEGOTIATION (const unsigned char c)
  {

  if (c == IAC)
    {
    // have IAC SB x <data> IAC
    // we may or may not have another IAC or possibly an SE
    m_phase = HAVE_SUBNEGOTIATION_IAC;
    }
  else
    // just collect the data until IAC SE
    m_IAC_subnegotiation_data += c;


  } // end of Phase_SUBNEGOTIATION

// SUBNEGOTIATION - we have IAC SB x (data) IAC c
// if the c after IAC is IAC then that becomes a single IAC (which we store now)
// otherwise it should be SE, and we assume it is, otherwise we have an invalid sequence
void CMUSHclientDoc::Phase_SUBNEGOTIATION_IAC (const unsigned char c)
  {

  if (c == IAC)
    {
    // have IAC SB x <data> IAC IAC
    // store the single IAC
    m_IAC_subnegotiation_data += c;
    // press on with subnegotiation
    m_phase = HAVE_SUBNEGOTIATION;
    return;
    }

  // see: http://www.gammon.com.au/forum/?id=10043
  // we have to assume that anything other than IAC is a SE, because 
  // the spec is silent on what to do otherwise
  if (c == SE)        // end of subnegotiation
    TRACE ("<SE>");
  else
    TRACE1 ("<%d> (invalid)", c);

  m_phase = NONE;      // negotiation is over, next byte is plain text

  // subnegotiation is complete ...
  // we have IAC SB <m_subnegotiation_type> <m_IAC_subnegotiation_data> IAC SE

  switch (m_subnegotiation_type)
    {
    case TELOPT_COMPRESS2:      
      Handle_TELOPT_COMPRESS2 ();     
      break;

    case TELOPT_MXP:            
      Handle_TELOPT_MXP ();           
      break;

    case TELOPT_TERMINAL_TYPE:  
      Handle_TELOPT_TERMINAL_TYPE (); 
      break;

    case TELOPT_CHARSET:        
      Handle_TELOPT_CHARSET ();       
      break;


    case TELOPT_MUD_SPECIFIC:   
        Handle_TELOPT_MUD_SPECIFIC ();  
    // NOTE: no break, fall through and also do the default

    default:
      {
      CPlugin * pSavedPlugin = m_CurrentPlugin;

      // tell each plugin what we have received
      for (POSITION pluginpos = m_PluginList.GetHeadPosition(); pluginpos; )
        {
        CPlugin * pPlugin = m_PluginList.GetNext (pluginpos);


        if (!(pPlugin->m_bEnabled))   // ignore disabled plugins
          continue;

        // see what the plugin makes of this,
        pPlugin->ExecutePluginScript (ON_PLUGIN_TELNET_SUBNEGOTIATION,
                                      pPlugin->m_dispid_plugin_telnet_subnegotiation,
                                      m_subnegotiation_type,
                                      m_IAC_subnegotiation_data);  // what we got

        }   // end of doing each plugin

      m_CurrentPlugin = pSavedPlugin;

      }
      break;  // end of default

    } // end of switch

  } // end of  CMUSHclientDoc::Phase_SUBNEGOTIATION_IAC 


// turn MCCP v2 on
void CMUSHclientDoc::Handle_TELOPT_COMPRESS2 ()
  {
  CString strMessage;

  m_iMCCP_type = 2;

  // initialise compression library if not already done
  if (!m_bCompressInitOK && !m_bCompress)
    m_bCompressInitOK = InitZlib (m_zCompress);

  if (!(m_bCompressInitOK && m_CompressOutput && m_CompressInput))
    strMessage = Translate ("Cannot process compressed output. World closed.");
  else
    {

    int izError = inflateReset (&m_zCompress);

    if (izError == Z_OK)
      {
      m_bCompress  = true;
      TRACE ("Compression on\n");
      return;
      }

    if (m_zCompress.msg)
      strMessage = TFormat ("Could not reset zlib decompression engine: %s",
                               m_zCompress.msg);
    else
      strMessage = TFormat ("Could not reset zlib decompression engine: %i",
                               izError);
    } 

  OnConnectionDisconnect ();    // close the world
  UMessageBox (strMessage, MB_ICONEXCLAMATION);
  } // end of CMUSHclientDoc::Handle_TELOPT_COMPRESS2


// turn MXP on, if required on subnegotiation
void CMUSHclientDoc::Handle_TELOPT_MXP ()
  {
  if (m_iUseMXP == eOnCommandMXP)   // if wanted now
    MXP_On ();
  } // end of CMUSHclientDoc::Handle_TELOPT_MXP ()

// IAC SB CHARSET REQUEST DELIMITER <name> DELIMITER
/*
Server sends:  IAC DO CHARSET
Client sends:  IAC WILL CHARSET
Server sends:  IAC SB CHARSET REQUEST DELIM NAME IAC SE
Client sends:  IAC SB CHARSET ACCEPTED NAME IAC SE
or
Client sends:  IAC SB CHARSET REJECTED IAC SE

where:

  CHARSET: 0x2A
  REQUEST: 0x01
  ACCEPTED:0x02
  REJECTED:0x03
  DELIM:   some character that does not appear in the charset name, other than IAC, eg. comma, space
  NAME:    the character string "UTF-8" (or some other name like "S-JIS")

*/

void CMUSHclientDoc::Handle_TELOPT_CHARSET ()
  {
  // must have at least REQUEST DELIM NAME [ DELIM NAME2 ...]
  if (m_IAC_subnegotiation_data.size () < 3)
    return;  

  int tt = m_IAC_subnegotiation_data [0];

  if (tt != 1) 
    return;  // not a REQUEST

  string delim = m_IAC_subnegotiation_data.substr (1, 1);

  vector <string> v;
  StringToVector (m_IAC_subnegotiation_data.substr (2), v, delim, false);

  bool found = false;
  CString strCharset = "US-ASCII"; // default

  if (m_font)
    {

    // hack! ugh.
    if (m_bUTF_8)
       strCharset = "UTF-8";

    for (vector<string>::const_iterator i = v.begin (); i != v.end (); i++)
      if (i->c_str () == strCharset)
        {
        found = true;

        unsigned char p1 [] = { IAC, SB, TELOPT_CHARSET, 2 };  // 2 = accepted
        unsigned char p2 [] = { IAC, SE }; 
        unsigned char sResponse [40];
        int iLength = 0;

        // build up response, eg. IAC, SB, TELOPT_CHARSET, 2, "UTF-8", IAC, SE 

        // preamble
        memcpy (sResponse, p1, sizeof p1);
        iLength += sizeof p1;

        // ensure max of 20 so we don't overflow the field
        CString strTemp = strCharset.Left (20);

        memcpy (&sResponse [iLength], strTemp, strTemp.GetLength ());
        iLength += strTemp.GetLength ();

        // postamble
        memcpy (&sResponse [iLength], p2, sizeof p2);
        iLength += sizeof p2;

        SendPacket (sResponse, iLength);

        }
    } // end of having an output font

  if (!found)
    {
    unsigned char p [] = { IAC, SB, TELOPT_CHARSET, 3, IAC, SE };    // 3 = rejected
    SendPacket (p, sizeof p);
    }  // end of charset not in use


  } // end of CMUSHclientDoc::Handle_TELOPT_CHARSET ()


// stuff for Aardwolf (telopt 102) - call specific plugin handler: OnPluginTelnetOption
void CMUSHclientDoc::Handle_TELOPT_MUD_SPECIFIC ()
  {
  CPlugin * pSavedPlugin = m_CurrentPlugin;

  // tell each plugin what we have received
  for (POSITION pluginpos = m_PluginList.GetHeadPosition(); pluginpos; )
    {
    CPlugin * pPlugin = m_PluginList.GetNext (pluginpos);


    if (!(pPlugin->m_bEnabled))   // ignore disabled plugins
      continue;

    CString strReceived (m_IAC_subnegotiation_data.c_str ());

    // see what the plugin makes of this,
    pPlugin->ExecutePluginScript (ON_PLUGIN_TELNET_OPTION,
                                  strReceived,  // what we got
                                  pPlugin->m_dispid_plugin_telnet_option); 

    }   // end of doing each plugin

  m_CurrentPlugin = pSavedPlugin;

  } // end of CMUSHclientDoc::Handle_TELOPT_MUD_SPECIFIC ()


// terminal type request
void CMUSHclientDoc::Handle_TELOPT_TERMINAL_TYPE ()
  {

  int tt = m_IAC_subnegotiation_data [0];

  if (tt != 1) 
    return;  // not a SEND

  TRACE ("<SEND>");
  // we reply: IAC SB TERMINAL-TYPE IS ... IAC SE
  // see: RFC 930 and RFC 1060
  unsigned char p1 [] = { IAC, SB, TELOPT_TERMINAL_TYPE, 0 }; 
  unsigned char p2 [] = { IAC, SE }; 
  unsigned char sResponse [40];
  int iLength = 0;

  // build up response, eg. IAC, SB, TELOPT_TERMINAL_TYPE, 0, "MUSHCLIENT", IAC, SE 

  // preamble
  memcpy (sResponse, p1, sizeof p1);
  iLength += sizeof p1;

  // ensure max of 20 so we don't overflow the field
  CString strTemp = m_strTerminalIdentification.Left (20);

  memcpy (&sResponse [iLength], strTemp, strTemp.GetLength ());
  iLength += strTemp.GetLength ();

  // postamble
  memcpy (&sResponse [iLength], p2, sizeof p2);
  iLength += sizeof p2;

  SendPacket (sResponse, iLength);

  } // end of CMUSHclientDoc::Handle_TELOPT_TERMINAL_TYPE ()


// COMPRESSION - we have IAC SB COMPRESS x
void CMUSHclientDoc::Phase_COMPRESS (const unsigned char c)
  {
  if (c == WILL)      // should get COMPRESS WILL
    {
    TRACE ("<WILL>");
    m_phase = HAVE_COMPRESS_WILL;
    }
  else
    {
    m_phase = NONE;   // error
    TRACE1 ("<%d>", c);
    }
  }

// COMPRESSION - we have IAC SB COMPRESS IAC/WILL x   (MCCP v1)

// we will return one of:
//  0 - error in starting compression - close world and display strMessage
//  1 - got IAC or unexpected input, do nothing
//  2 - compression OK - prepare for it

void CMUSHclientDoc::Phase_COMPRESS_WILL (const unsigned char c)
  {
  if (c == SE)        // end of subnegotiation
    {        
    TRACE ("<SE>");

    CString strMessage;

    m_iMCCP_type = 1;

    // initialise compression library if not already done
    if (!m_bCompressInitOK && !m_bCompress)
      m_bCompressInitOK = InitZlib (m_zCompress);

    if (!(m_bCompressInitOK && m_CompressOutput && m_CompressInput))
      strMessage = Translate ("Cannot process compressed output. World closed.");
    else
      {

      int izError = inflateReset (&m_zCompress);

      if (izError == Z_OK)
        {
        m_bCompress  = true;
        TRACE ("Compression on\n");
        return;
        }

      if (m_zCompress.msg)
        strMessage = TFormat ("Could not reset zlib decompression engine: %s",
                                 m_zCompress.msg);
      else
        strMessage = TFormat ("Could not reset zlib decompression engine: %i",
                                 izError);
      } 

    OnConnectionDisconnect ();    // close the world
    UMessageBox (strMessage, MB_ICONEXCLAMATION);
    }   // end of IAC SB COMPRESS WILL/IAC SE

  
  // not SE? error
  TRACE1 ("<%d>", c);
  m_phase = NONE;
  } // end of Phase_COMPRESS_WILL