/* Tera Term extension mechanism
   Robert O'Callahan (roc+tt@cs.cmu.edu)
   
   Tera Term by Takashi Teranishi (teranishi@rikaxp.riken.go.jp)
*/

/* HOW TO WRITE A TERATERM EXTENSION

   First of all, you will need the source code to Tera Term. For that, you
   should visit the Tera Term Web page:
   http://www.vector.co.jp/authors/VA002416/teraterm.html
   You will frequently need to refer to the source code to find out how things
   work and when your functions are called. However, please try to write your
   extension without assuming too much about the behaviour of Tera Term, in
   case it changes in the future!

   You will also need a compiler that can build Tera Term. So far, the
   extension system has only been tested with Visual C++ 4.2. Please report
   any problems to me (roc).

   Then you can compile this sample extension.

   Make sure you set the structure alignment option in the project to
   8 bytes (for Win32) or 2 bytes (for Win16), to be compatible with the
   standard Tera Term binary.
   
   You must add the Tera Term "common" directory to your include path
   to find the following 3 include files:
*/

#include "teraterm.h"
#include "tttypes.h"
#include "ttplugin.h"

/* These are the standard libraries used below. The main Tera Term program and
   all its DLLs are each statically linked to the C runtime library --- i.e.
   they do not require any runtime library DLL, and they each have private
   copies of the runtime library functions that they use. Therefore, it's
   probably best if TTXs use the same strategy.
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "compat_w95.h"

/* When you build this extension, it should be called TTXTEST.DLL. To try it
   out, copy it into the directory containing Tera Term. Currently, in order
   to use extensions with Tera Term, you have to set the environment variable
   TERATERM_EXTENSIONS to something. So in a command shell, use
   "set TERATERM_EXTENSIONS=1". Then use "ttermpro > dump" to run Tera Term
   and save the debugging output below to the file "dump".

   When TERATERM_EXTENSIONS is set, Tera Term automatically scans the
   directory containing it, looking for files of the form TTX*.DLL.
   It loads any that it finds. For each one that it finds, it calls TTXBind;
   see below for details.
*/


/* This variable is used for the load order of the extension (see below for
   details). We also print it out in all the diagnostics, to make sure the
   functions are being called according to the correct order. */
#define ORDER 4000

/* This code demonstrates how to maintain separate instance variables for
   each instance of Tera Term that's using the DLL. It's easy in Win32,
   because it happens automatically, but in Win16 there is only one set of
   global data for all Tera Terms using the DLL, so we have to jump through
   some hoops.
*/
static HANDLE hInst; /* Instance handle of TTX*.DLL */

typedef struct {
  PTTSet ts;
  PComVar cv;
  HMENU SetupMenu;
} TInstVar;

static TInstVar *pvar;

/* WIN32 allows multiple instances of a DLL */
static TInstVar InstVar;

/* When this function is called, you should save copies of the ts and cv
   pointers if you need to access them later. All sorts of global session data
   is stored in these variables, and you can do all sorts of tricks by reading
   and modifying their fields in some of the functions below. You'll have to
   look at the Tera Term source code to see what the fields do and how and
   when they're used.
   
   This is called when Tera Term starts up, so don't do too much work in here
   or you will slow down the startup process even if your extension is not
   going to be used.
*/
static void PASCAL TTXInit(PTTSet ts, PComVar cv) {
  pvar->ts = ts;
  pvar->cv = cv;
}

/* This function is called when Tera Term is opening a TCP connection, before
   any Winsock functions have actually been called.

   You receive a 'hooks' structure containing pointers to pointers to all the
   Winsock functions that Tera Term will use. You can replace any of these
   function pointers to point to your own routines. However, if you replace a
   function pointer, you should save the old pointer somewhere and use that
   instead of calling Winsock directly. Some other extension might have put
   something there for you to use!

   For example:
   
   [in TTXOpenTCP]
   ... saved_connect = hooks->Pconnect; hooks->Pconnect = my_connect; ...
   
   [in my_connect]
   ... saved_connect(...); ...
   [don't call the real connect!]

   Extensions that don't apply to all sessions (e.g. any extension that can be
   disabled by the user) will check to see if they apply to the current
   session, and if they don't, then no functions are be changed.

   This function is called for each extension, in load order (see below).
   Thus, the extension with highest load order puts its hooks in last.
*/
static void PASCAL TTXOpenTCP(TTXSockHooks *hooks) {
  printf("TTXOpenTCP %d\n", ORDER);
}

/* This function is called when Tera Term is closing a TCP connection, after
   all Winsock functions have been called.

   Here you should restore any hooked pointers that you saved away. For
   example:
   ... hooks->Pconnect = saved_connect; ...

   This function is called for each extension, in reverse load order (see
   below).
*/
static void PASCAL TTXCloseTCP(TTXSockHooks *hooks) {
  printf("TTXCloseTCP %d\n", ORDER);
}

/* This function is called when Tera Term has loaded the TTDLG library. It
   gives the extension an opportunity to modify the function pointers that are
   used to create dialog boxes.

   Unlike the TCP functions, there's no reason to call the previous version of
   a hooked function. When you replace a dialog box, the new dialog box should
   do everything that the original dialog box did, plus any extra controls
   that you want. You'll probably have to copy the code from TTDLG to do this.
   
   If multiple extensions want to replace the same dialog box, the one with
   the highest load order number (see below) wins. For this reason, when
   writing an extension, you should look at the extensions that already exist
   and try to figure out how to make your extension work nicely with the
   others that modify the same dialog box as you do. I suggest that anyone who
   modifies a dialog box should export functions from their extension DLL so
   that other code can change the extra settings without going through that
   dialog box. Then, if there is an extension with a lower load order number
   that changes a dialog box that you also want to change, you can create a
   new dialog box that has all their changes plus your own, and call the
   exported functions in the other DLL when the user sets options for that
   other DLL. If that didn't make sense, send me email :-).

   A typical use for this function is to hook the GetHostName function so that
   extra options can be added to the connection dialog box. Whenever possible
   (without making the user interface clumsy), an extension should introduce
   new dialog boxes reachable by adding menu items (see below), rather than
   overriding an existing dialog box. Any UI for setup options should probably
   be handled this way.

   This function is called for each extension, in load order (see below).
   Thus, the extension with highest load order puts its hooks in last.
*/
static void PASCAL TTXGetUIHooks(TTXUIHooks *hooks) {
  printf("TTXSetUIHooks %d\n", ORDER);
}

/* This function is called when Tera Term has loaded the TTSETUP library. It
   gives the extension an opportunity to modify the function pointers that are
   used to read and write the settings file (TERATERM.INI) and to read and
   write the command line.

   An extension will almost always hook these functions. When Tera Term reads
   or writes its setup file, the extension will read or write its own internal
   settings to an appropriate section of the INI file. When Tera Term parses
   its command line, or builds a new command line to spawn a new Tera Term
   session, the extension will check for its own options or write out its own
   options.

   Any hooked functions should pass through to the old functions, just as in
   TTXOpenTCP.

   This function is called for each extension, in load order (see below).
   Thus, the extension with highest load order puts its hooks in last.
*/
static void PASCAL TTXGetSetupHooks(TTXSetupHooks *hooks) {
  printf("TTXSetSetupHooks %d\n", ORDER);
}

/* This function is called whenever Tera Term changes the window size.

   This function is called for each extension, in load order (see below).
*/
static void PASCAL TTXSetWinSize(int rows, int cols) {
  printf("TTXSetWinSize %d\n", ORDER);
}

/* This function is called when Tera Term creates a new menu. This can happen
   quite often, especially when the menubar is hidden and Tera Term wants to
   create a popup menu because the user ctrl-clicked in the window.

   The 'menu' parameter is the HMENU for the menu bar. The extension can add
   items to the existing submenus or even add an entirely new submenu. This is
   great for adding menu items that control the extension's options.

   This function is called for each extension, in load order (see below).
   Thus, the extension with highest load order number puts its items in last.
*/
#define ID_MENUITEM 6000
static void PASCAL TTXModifyMenu(HMENU menu) {
  UINT flag = MF_ENABLED;

  printf("TTXModifyMenu %d\n", ORDER);

  pvar->SetupMenu = GetSubMenu(menu,2);
  AppendMenu(pvar->SetupMenu,MF_SEPARATOR,0,NULL); 
  if (pvar->ts->Debug>0) flag |= MF_CHECKED;
  AppendMenu(pvar->SetupMenu,flag, ID_MENUITEM,"&Debug mode");
}

/* This function is called when Tera Term pops up a submenu menu.

   The 'menu' parameter is the HMENU for the submenu. The extension can change
   the status of any of the menu items, for example graying out some items.
   Extensions should make sure that this is actually the submenu that they
   care about!

   This function is called for each extension, in load order (see below).
*/
static void PASCAL TTXModifyPopupMenu(HMENU menu) {
  printf("TTXModifyPopupMenu %d\n", ORDER);

  if (menu==pvar->SetupMenu)
  {
    if (pvar->cv->Ready)
      EnableMenuItem(pvar->SetupMenu,ID_MENUITEM,MF_BYCOMMAND | MF_ENABLED);
    else
      EnableMenuItem(pvar->SetupMenu,ID_MENUITEM,MF_BYCOMMAND | MF_GRAYED);
  }
}

/* This function is called when Tera Term receives a command message.

   The extension returns 1 if it processed the message, 0 otherwise. If it
   says it processed the message, then the message will not be processed
   anywhere else. The extensions look at the messages before the main
   Tera Term code, so be careful of overriding existing commands.

   This function is called for each extension, in reverse load order (see
   below). Thus, the extension that has highest load order number gets to
   process the command first.
*/
static int PASCAL TTXProcessCommand(HWND hWin, WORD cmd) {
  printf("TTXProcessCommand %d\n", ORDER);

  if (cmd==ID_MENUITEM)
  {
    if (pvar->ts->Debug==0)
    {
      pvar->ts->Debug=1;
      CheckMenuItem(pvar->SetupMenu,ID_MENUITEM,MF_BYCOMMAND | MF_CHECKED);
    }
    else {
      pvar->ts->Debug=0;
      CheckMenuItem(pvar->SetupMenu,ID_MENUITEM,MF_BYCOMMAND | MF_UNCHECKED);
    } 
    return 1;
  }
  return 0;
}

/* This function is called when Tera Term is quitting. You can use it to clean
   up.

   This function is called for each extension, in reverse load order (see
   below).
*/
static void PASCAL TTXEnd(void) {
  printf("TTXEnd %d\n", ORDER);
}

/*
*/
static void PASCAL TTXSetCommandLine(PCHAR cmd, int cmdlen, PGetHNRec rec) {
  printf("TTXSetCommandLine %d\n", ORDER);
}

/* This function is called when Tera Term is opening a Serial port and Replay
   log file.

   You receive a 'hooks' structure containing pointers to pointers to all the
   file IO functions that Tera Term will use. You can replace any of these
   function pointers to point to your own routines. However, if you replace a
   function pointer, you should save the old pointer somewhere and use that
   instead of calling file IO functions directly. Some other extension might
   have put something there for you to use!

   For example:
   
   [in TTXOpenFile]
   ... saved_createfile = hooks->PCreateFile; hooks->PCreateFile = my_createfile; ...
   
   [in my_createfile]
   ... saved_createfile(...); ...
   [don't call the real CreateFile!]

   Extensions that don't apply to all sessions (e.g. any extension that can be
   disabled by the user) will check to see if they apply to the current
   session, and if they don't, then no functions are be changed.

   This function is called for each extension, in load order (see below).
   Thus, the extension with highest load order puts its hooks in last.
*/
static void PASCAL TTXOpenFile(TTXFileHooks *hooks) {
  printf("TTXOpenFile %d\n", ORDER);
}

/* This function is called when Tera Term is closing a serial connection,
   after all file IO functions have been called.

   Here you should restore any hooked pointers that you saved away. For
   example:
   ... hooks->PCreateFile = saved_createfile; ...

   This function is called for each extension, in reverse load order (see
   below).
*/
static void PASCAL TTXCloseFile(TTXFileHooks *hooks) {
  printf("TTXCloseFile %d\n", ORDER);
}

/* This record contains all the information that the extension forwards to the
   main Tera Term code. It mostly consists of pointers to the above functions.
   Any of the function pointers can be replaced with NULL, in which case
   Tera Term will just ignore that function and assume default behaviour,
   which means "do nothing".
*/
static TTXExports Exports = {
/* This must contain the size of the structure. See below for its usage. */
  sizeof(TTXExports),

/* This is the load order number of this DLL. It affects which order the above
   functions are called in, as noted for each function. Choose this number
   carefully! Typically the DLLs with higher numbers are layered on top of the
   DLLs with lower numbers. Thus, a DLL that does SOCKS redirection will have
   a lower load order than a DLL that does the SSH protocol, because SOCKS
   redirection must happen "before" SSH processing. Likewise, a DLL that does
   Kerberos authentication must have a higher order number than a DLL that
   does SSL, because the Kerberos protocol uses telnet options that would go
   "on top of" SSL.

   Currently, no order numbers are used because no real extensions have been
   written.
   I suggest the following numbers:
   0-999:     Basic network naming and communication (e.g. SOCKS)
   1000-1999: Transport emulation (e.g. SSL)
   2000-2999: Protocols (e.g. SSH, telnet)
   3000-3999: Protocol extensions (e.g. Kerberos telnet options)
   4000-4999: Application features (e.g. file transfers, UI for hidden setup
              options)

   Try to use numbers in the middle of any available range so that other
   extensions can load before or after you as they wish.
*/
  ORDER,

/* Now we just list the functions that we've implemented. */
  TTXInit,
  TTXGetUIHooks,
  TTXGetSetupHooks,
  TTXOpenTCP,
  TTXCloseTCP,
  TTXSetWinSize,
  TTXModifyMenu,
  TTXModifyPopupMenu,
  TTXProcessCommand,
  TTXEnd,
  TTXSetCommandLine,
  TTXOpenFile,
  TTXCloseFile
};

/* This is the function that Tera Term calls to retrieve the export
   information. This code is for Visual C++. The name that gets exported is
   "_TTXBind@8" and that is what the Tera Term program looks for. So,
   whichever compiler you use, you must make sure that that name is exported.

   The job of this function is to copy the export data from the structure
   above into the record that Tera Term passed us a pointer to. That record
   contains its size; we make sure we don't copy more than that amount of
   data. In the future, if we add TTX functions to the TTXExports record,
   then we could have new extensions that have a bigger TTXExports record than
   old Tera Term binaries. In this case, the extra functions will simply not
   be called. This means we can write extensions that will work with both old
   and new versions of Tera Term.

   (In a similar way, we can run old extensions with new versions of Tera Term.
   The main program initialises its exports record to zeroes before it calls
   TTXBind. This means that any data we don't copy in there is NULL, so any 
   extra functions that have been added since this extension was compiled
   will automatically be NULL and thus get default behaviour.)
*/
BOOL __declspec(dllexport) PASCAL TTXBind(WORD Version, TTXExports *exports) {
  int size = sizeof(Exports) - sizeof(exports->size);
  /* do version checking if necessary */
  /* if (Version!=TTVERSION) return FALSE; */

  if (size > exports->size) {
    size = exports->size;
  }
  memcpy((char *)exports + sizeof(exports->size),
    (char *)&Exports + sizeof(exports->size),
    size);
  return TRUE;
}

BOOL WINAPI DllMain(HANDLE hInstance, 
		    ULONG ul_reason_for_call,
		    LPVOID lpReserved)
{
  switch( ul_reason_for_call ) {
    case DLL_THREAD_ATTACH:
      /* do thread initialization */
      break;
    case DLL_THREAD_DETACH:
      /* do thread cleanup */
      break;
    case DLL_PROCESS_ATTACH:
      /* do process initialization */
      DoCover_IsDebuggerPresent();
      hInst = hInstance;
      pvar = &InstVar;
      break;
    case DLL_PROCESS_DETACH:
      /* do process cleanup */
      break;
  }
  return TRUE;
}
