/* engine-assuan.c - Low-level Assuan protocol engine

 * Copyright (C) 2009 g10 Code GmbH

 *

 * This file is part of GPGME.

 *

 * GPGME is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * GPGME 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not, see <https://www.gnu.org/licenses/>.

 */

/*

   Note: This engine requires a modern Assuan server which uses

   gpg-error codes.  In particular there is no backward compatible

   mapping of old Assuan error codes implemented.

*/

#if HAVE_CONFIG_H

#include <config.h>

#endif

#include <stdlib.h>

#include <string.h>

#ifdef HAVE_SYS_TYPES_H

# include <sys/types.h>

#endif

#include <assert.h>

#ifdef HAVE_UNISTD_H

# include <unistd.h>

#endif

#ifdef HAVE_LOCALE_H

#include <locale.h>

#endif

#include <errno.h>

#include "gpgme.h"

#include "util.h"

#include "ops.h"

#include "wait.h"

#include "priv-io.h"

#include "sema.h"

#include "assuan.h"

#include "debug.h"

#include "engine-backend.h"

typedef struct

{

  int fd;	/* FD we talk about.  */

  int server_fd;/* Server FD for this connection.  */

  int dir;	/* Inbound/Outbound, maybe given implicit?  */

  void *data;	/* Handler-specific data.  */

  void *tag;	/* ID from the user for gpgme_remove_io_callback.  */

} iocb_data_t;

/* Engine instance data.  */

struct engine_llass

{

  assuan_context_t assuan_ctx;

  int lc_ctype_set;

  int lc_messages_set;

  iocb_data_t status_cb;

  struct gpgme_io_cbs io_cbs;

  /* Hack for old opassuan.c interface, see there the result struct.  */

  gpg_error_t last_op_err;

  /* User provided callbacks.  */

  struct {

    gpgme_assuan_data_cb_t data_cb;

    void *data_cb_value;

    gpgme_assuan_inquire_cb_t inq_cb;

    void *inq_cb_value;

    gpgme_assuan_status_cb_t status_cb;

    void *status_cb_value;

  } user;

  /* Option flags.  */

  struct {

    int gpg_agent:1;  /* Assume this is a gpg-agent connection.  */

  } opt;

};

typedef struct engine_llass *engine_llass_t;

gpg_error_t _gpgme_engine_assuan_last_op_err (void *engine)

{

  engine_llass_t llass = engine;

  return llass->last_op_err;

}

/* Prototypes.  */

static void llass_io_event (void *engine,

                            gpgme_event_io_t type, void *type_data);

/* return the default home directory.  */

static const char *

llass_get_home_dir (void)

{

  /* For this engine the home directory is not a filename but a string

     used to convey options.  The exclamation mark is a marker to show

     that this is not a directory name. Options are strings delimited

     by a space.  The only option defined for now is GPG_AGENT to

     enable GPG_AGENT specific commands to send to the server at

     connection startup.  */

  return "!GPG_AGENT";

}

static char *

llass_get_version (const char *file_name)

{

  (void)file_name;

  return NULL;

}

static const char *

llass_get_req_version (void)

{

  return NULL;

}

static void

close_notify_handler (int fd, void *opaque)

{

  engine_llass_t llass = opaque;

  assert (fd != -1);

  if (llass->status_cb.fd == fd)

    {

      if (llass->status_cb.tag)

	llass->io_cbs.remove (llass->status_cb.tag);

      llass->status_cb.fd = -1;

      llass->status_cb.tag = NULL;

    }

}

static gpgme_error_t

llass_cancel (void *engine)

{

  engine_llass_t llass = engine;

  if (!llass)

    return gpg_error (GPG_ERR_INV_VALUE);

  if (llass->status_cb.fd != -1)

    _gpgme_io_close (llass->status_cb.fd);

  if (llass->assuan_ctx)

    {

      assuan_release (llass->assuan_ctx);

      llass->assuan_ctx = NULL;

    }

  return 0;

}

static gpgme_error_t

llass_cancel_op (void *engine)

{

  engine_llass_t llass = engine;

  if (!llass)

    return gpg_error (GPG_ERR_INV_VALUE);

  if (llass->status_cb.fd != -1)

    _gpgme_io_close (llass->status_cb.fd);

  return 0;

}

static void

llass_release (void *engine)

{

  engine_llass_t llass = engine;

  if (!llass)

    return;

  llass_cancel (engine);

  free (llass);

}

/* Create a new instance. If HOME_DIR is NULL standard options for use

   with gpg-agent are issued.  */

static gpgme_error_t

llass_new (void **engine, const char *file_name, const char *home_dir,

           const char *version)

{

  gpgme_error_t err = 0;

  engine_llass_t llass;

  char *optstr;

  char *env_tty = NULL;

  (void)version; /* Not yet used.  */

  llass = calloc (1, sizeof *llass);

  if (!llass)

    return gpg_error_from_syserror ();

  llass->status_cb.fd = -1;

  llass->status_cb.dir = 1;

  llass->status_cb.tag = 0;

  llass->status_cb.data = llass;

  /* Parse_options.  */

  if (home_dir && *home_dir == '!')

    {

      home_dir++;

      /* Very simple parser only working for the one option we support.  */

      /* Note that wk promised to write a regression test if this

         parser will be extended.  */

      if (!strncmp (home_dir, "GPG_AGENT", 9)

          && (!home_dir[9] || home_dir[9] == ' '))

        llass->opt.gpg_agent = 1;

    }

  err = assuan_new_ext (&llass->assuan_ctx, GPG_ERR_SOURCE_GPGME,

			&_gpgme_assuan_malloc_hooks, _gpgme_assuan_log_cb,

			NULL);

  if (err)

    goto leave;

  assuan_ctx_set_system_hooks (llass->assuan_ctx, &_gpgme_assuan_system_hooks);

  assuan_set_flag (llass->assuan_ctx, ASSUAN_CONVEY_COMMENTS, 1);

  err = assuan_socket_connect (llass->assuan_ctx, file_name, 0, 0);

  if (err)

    goto leave;

  if (llass->opt.gpg_agent)

    {

      char *dft_display = NULL;

      err = _gpgme_getenv ("DISPLAY", &dft_display);

      if (err)

        goto leave;

      if (dft_display)

        {

          if (gpgrt_asprintf (&optstr, "OPTION display=%s", dft_display) < 0)

            {

              err = gpg_error_from_syserror ();

              free (dft_display);

              goto leave;

            }

          free (dft_display);

          err = assuan_transact (llass->assuan_ctx, optstr, NULL, NULL, NULL,

                                 NULL, NULL, NULL);

          gpgrt_free (optstr);

          if (err)

            goto leave;

        }

    }

  if (llass->opt.gpg_agent)

    err = _gpgme_getenv ("GPG_TTY", &env_tty);

  if (llass->opt.gpg_agent && (isatty (1) || env_tty || err))

    {

      int rc = 0;

      char dft_ttyname[64];

      char *dft_ttytype = NULL;

      if (err)

        goto leave;

      else if (env_tty)

        {

          snprintf (dft_ttyname, sizeof (dft_ttyname), "%s", env_tty);

          free (env_tty);

        }

      else

        rc = ttyname_r (1, dft_ttyname, sizeof (dft_ttyname));

      /* Even though isatty() returns 1, ttyname_r() may fail in many

	 ways, e.g., when /dev/pts is not accessible under chroot.  */

      if (!rc)

	{

	  if (gpgrt_asprintf (&optstr, "OPTION ttyname=%s", dft_ttyname) < 0)

	    {

	      err = gpg_error_from_syserror ();

	      goto leave;

	    }

	  err = assuan_transact (llass->assuan_ctx, optstr, NULL, NULL, NULL,

				 NULL, NULL, NULL);

	  gpgrt_free (optstr);

	  if (err)

            goto leave;

	  err = _gpgme_getenv ("TERM", &dft_ttytype);

	  if (err)

	    goto leave;

	  if (dft_ttytype)

	    {

	      if (gpgrt_asprintf (&optstr, "OPTION ttytype=%s", dft_ttytype)< 0)

		{

		  err = gpg_error_from_syserror ();

		  free (dft_ttytype);

		  goto leave;

		}

	      free (dft_ttytype);

	      err = assuan_transact (llass->assuan_ctx, optstr, NULL, NULL,

				     NULL, NULL, NULL, NULL);

	      gpgrt_free (optstr);

	      if (err)

                goto leave;

	    }

	}

    }

#ifdef HAVE_W32_SYSTEM

  /* Under Windows we need to use AllowSetForegroundWindow.  Tell

     llass to tell us when it needs it.  */

  if (!err && llass->opt.gpg_agent)

    {

      err = assuan_transact (llass->assuan_ctx, "OPTION allow-pinentry-notify",

                             NULL, NULL, NULL, NULL, NULL, NULL);

      if (gpg_err_code (err) == GPG_ERR_UNKNOWN_OPTION)

        err = 0; /* This work only with recent gpg-agents.  */

    }

#endif /*HAVE_W32_SYSTEM*/

 leave:

  /* Close the server ends of the pipes (because of this, we must use

     the stored server_fd_str in the function start).  Our ends are

     closed in llass_release().  */

  if (err)

    llass_release (llass);

  else

    *engine = llass;

  return err;

}

static gpgme_error_t

llass_set_locale (void *engine, int category, const char *value)

{

  gpgme_error_t err;

  engine_llass_t llass = engine;

  char *optstr;

  const char *catstr;

  if (!llass->opt.gpg_agent)

    return 0;

  /* FIXME: If value is NULL, we need to reset the option to default.

     But we can't do this.  So we error out here.  gpg-agent needs

     support for this.  */

  if (0)

    ;

#ifdef LC_CTYPE

  else if (category == LC_CTYPE)

    {

      catstr = "lc-ctype";

      if (!value && llass->lc_ctype_set)

	return gpg_error (GPG_ERR_INV_VALUE);

      if (value)

	llass->lc_ctype_set = 1;

    }

#endif

#ifdef LC_MESSAGES

  else if (category == LC_MESSAGES)

    {

      catstr = "lc-messages";

      if (!value && llass->lc_messages_set)

	return gpg_error (GPG_ERR_INV_VALUE);

      if (value)

	llass->lc_messages_set = 1;

    }

#endif /* LC_MESSAGES */

  else

    return gpg_error (GPG_ERR_INV_VALUE);

  /* FIXME: Reset value to default.  */

  if (!value)

    return 0;

  if (gpgrt_asprintf (&optstr, "OPTION %s=%s", catstr, value) < 0)

    err = gpg_error_from_syserror ();

  else

    {

      err = assuan_transact (llass->assuan_ctx, optstr, NULL, NULL,

			     NULL, NULL, NULL, NULL);

      gpgrt_free (optstr);

    }

  return err;

}

/* This is the inquiry callback.  It handles stuff which ee need to

   handle here and passes everything on to the user callback.  */

static gpgme_error_t

inquire_cb (engine_llass_t llass, const char *keyword, const char *args)

{

  gpg_error_t err;

  if (llass->opt.gpg_agent && !strcmp (keyword, "PINENTRY_LAUNCHED"))

    {

      _gpgme_allow_set_foreground_window ((pid_t)strtoul (args, NULL, 10));

    }

  if (llass->user.inq_cb)

    {

      gpgme_data_t data = NULL;

      err = llass->user.inq_cb (llass->user.inq_cb_value,

                                keyword, args, &data);

      if (!err && data)

        {

          /* FIXME: Returning data is not yet implemented.  However we

             need to allow the caller to cleanup his data object.

             Thus we run the callback in finish mode immediately.  */

          err = llass->user.inq_cb (llass->user.inq_cb_value,

                                    NULL, NULL, &data);

        }

    }

  else

    err = 0;

  return err;

}

static gpgme_error_t

llass_status_handler (void *opaque, int fd)

{

  struct io_cb_data *data = (struct io_cb_data *) opaque;

  engine_llass_t llass = (engine_llass_t) data->handler_value;

  gpgme_error_t err = 0;

  char *line;

  size_t linelen;

  do

    {

      err = assuan_read_line (llass->assuan_ctx, &line, &linelen);

      if (err)

	{

	  /* Reading a full line may not be possible when

	     communicating over a socket in nonblocking mode.  In this

	     case, we are done for now.  */

	  if (gpg_err_code (err) == GPG_ERR_EAGAIN)

	    {

	      TRACE1 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		      "fd 0x%x: EAGAIN reading assuan line (ignored)", fd);

	      err = 0;

	      continue;

	    }

	  TRACE2 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: error reading assuan line: %s",

                  fd, gpg_strerror (err));

	}

      else if (linelen >= 2 && line[0] == 'D' && line[1] == ' ')

        {

          char *src = line + 2;

	  char *end = line + linelen;

	  char *dst = src;

          linelen = 0;

          while (src < end)

            {

              if (*src == '%' && src + 2 < end)

                {

                  /* Handle escaped characters.  */

                  ++src;

                  *dst++ = _gpgme_hextobyte (src);

                  src += 2;

                }

              else

                *dst++ = *src++;

              linelen++;

            }

          src = line + 2;

          if (linelen && llass->user.data_cb)

            err = llass->user.data_cb (llass->user.data_cb_value,

                                       src, linelen);

          TRACE2 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: D inlinedata; status from cb: %s",

                  fd, (llass->user.data_cb ?

                       (err? gpg_strerror (err):"ok"):"no callback"));

        }

      else if (linelen >= 3

               && line[0] == 'E' && line[1] == 'N' && line[2] == 'D'

               && (line[3] == '\0' || line[3] == ' '))

        {

          /* END received.  Tell the data callback.  */

          if (llass->user.data_cb)

            err = llass->user.data_cb (llass->user.data_cb_value, NULL, 0);

          TRACE2 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: END line; status from cb: %s",

                  fd, (llass->user.data_cb ?

                       (err? gpg_strerror (err):"ok"):"no callback"));

        }

      else if (linelen > 2 && line[0] == 'S' && line[1] == ' ')

	{

	  char *args;

          char *src;

          for (src=line+2; *src == ' '; src++)

            ;

	  args = strchr (src, ' ');

	  if (!args)

	    args = line + linelen; /* Let it point to an empty string.  */

	  else

	    *(args++) = 0;

          while (*args == ' ')

            args++;

          if (llass->user.status_cb)

            err = llass->user.status_cb (llass->user.status_cb_value,

                                         src, args);

          TRACE3 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: S line (%s) - status from cb: %s",

                  fd, line+2, (llass->user.status_cb ?

                               (err? gpg_strerror (err):"ok"):"no callback"));

	}

      else if (linelen >= 7

               && line[0] == 'I' && line[1] == 'N' && line[2] == 'Q'

               && line[3] == 'U' && line[4] == 'I' && line[5] == 'R'

               && line[6] == 'E'

               && (line[7] == '\0' || line[7] == ' '))

        {

          char *src;

	  char *args;

          for (src=line+7; *src == ' '; src++)

            ;

	  args = strchr (src, ' ');

	  if (!args)

	    args = line + linelen; /* Let it point to an empty string.  */

	  else

	    *(args++) = 0;

          while (*args == ' ')

            args++;

          err = inquire_cb (llass, src, args);

          if (!err)

            {

              /* Flush and send END.  */

              err = assuan_send_data (llass->assuan_ctx, NULL, 0);

            }

          else if (gpg_err_code (err) == GPG_ERR_ASS_CANCELED)

            {

              /* Flush and send CANcel.  */

              err = assuan_send_data (llass->assuan_ctx, NULL, 1);

            }

        }

      else if (linelen >= 3

	       && line[0] == 'E' && line[1] == 'R' && line[2] == 'R'

	       && (line[3] == '\0' || line[3] == ' '))

	{

	  if (line[3] == ' ')

	    err = atoi (line+4);

	  else

	    err = gpg_error (GPG_ERR_GENERAL);

          TRACE2 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: ERR line: %s",

                  fd, err ? gpg_strerror (err) : "ok");

	  /* Command execution errors are not fatal, as we use

	     a session based protocol.  */

	  data->op_err = err;

	  llass->last_op_err = err;

	  /* The caller will do the rest (namely, call cancel_op,

	     which closes status_fd).  */

	  return 0;

	}

      else if (linelen >= 2

	       && line[0] == 'O' && line[1] == 'K'

	       && (line[2] == '\0' || line[2] == ' '))

	{

          TRACE1 (DEBUG_CTX, "gpgme:llass_status_handler", llass,

		  "fd 0x%x: OK line", fd);

	  llass->last_op_err = 0;

	  _gpgme_io_close (llass->status_cb.fd);

	  return 0;

	}

      else

        {

          /* Comment line or invalid line.  */

        }

    }

  while (!err && assuan_pending_line (llass->assuan_ctx));

  return err;

}

static gpgme_error_t

add_io_cb (engine_llass_t llass, iocb_data_t *iocbd, gpgme_io_cb_t handler)

{

  gpgme_error_t err;

  TRACE_BEG2 (DEBUG_ENGINE, "engine-assuan:add_io_cb", llass,

              "fd %d, dir %d", iocbd->fd, iocbd->dir);

  err = (*llass->io_cbs.add) (llass->io_cbs.add_priv,

			      iocbd->fd, iocbd->dir,

			      handler, iocbd->data, &iocbd->tag);

  if (err)

    return TRACE_ERR (err);

  if (!iocbd->dir)

    /* FIXME Kludge around poll() problem.  */

    err = _gpgme_io_set_nonblocking (iocbd->fd);

  return TRACE_ERR (err);

}

static gpgme_error_t

start (engine_llass_t llass, const char *command)

{

  gpgme_error_t err;

  assuan_fd_t afdlist[5];

  int fdlist[5];

  int nfds;

  int i;

  /* We need to know the fd used by assuan for reads.  We do this by

     using the assumption that the first returned fd from

     assuan_get_active_fds() is always this one.  */

  nfds = assuan_get_active_fds (llass->assuan_ctx, 0 /* read fds */,

                                afdlist, DIM (afdlist));

  if (nfds < 1)

    return gpg_error (GPG_ERR_GENERAL);	/* FIXME */

  /* For now... */

  for (i = 0; i < nfds; i++)

    fdlist[i] = (int) afdlist[i];

  /* We "duplicate" the file descriptor, so we can close it here (we

     can't close fdlist[0], as that is closed by libassuan, and

     closing it here might cause libassuan to close some unrelated FD

     later).  Alternatively, we could special case status_fd and

     register/unregister it manually as needed, but this increases

     code duplication and is more complicated as we can not use the

     close notifications etc.  A third alternative would be to let

     Assuan know that we closed the FD, but that complicates the

     Assuan interface.  */

  llass->status_cb.fd = _gpgme_io_dup (fdlist[0]);

  if (llass->status_cb.fd < 0)

    return gpg_error_from_syserror ();

  if (_gpgme_io_set_close_notify (llass->status_cb.fd,

				  close_notify_handler, llass))

    {

      _gpgme_io_close (llass->status_cb.fd);

      llass->status_cb.fd = -1;

      return gpg_error (GPG_ERR_GENERAL);

    }

  err = add_io_cb (llass, &llass->status_cb, llass_status_handler);

  if (!err)

    err = assuan_write_line (llass->assuan_ctx, command);

  /* FIXME: If *command == '#' no answer is expected.  */

  if (!err)

    llass_io_event (llass, GPGME_EVENT_START, NULL);

  return err;

}

static gpgme_error_t

llass_transact (void *engine,

                const char *command,

                gpgme_assuan_data_cb_t data_cb,

                void *data_cb_value,

                gpgme_assuan_inquire_cb_t inq_cb,

                void *inq_cb_value,

                gpgme_assuan_status_cb_t status_cb,

                void *status_cb_value)

{

  engine_llass_t llass = engine;

  gpgme_error_t err;

  if (!llass || !command || !*command)

    return gpg_error (GPG_ERR_INV_VALUE);

  llass->user.data_cb = data_cb;

  llass->user.data_cb_value = data_cb_value;

  llass->user.inq_cb = inq_cb;

  llass->user.inq_cb_value = inq_cb_value;

  llass->user.status_cb = status_cb;

  llass->user.status_cb_value = status_cb_value;

  err = start (llass, command);

  return err;

}

static void

llass_set_io_cbs (void *engine, gpgme_io_cbs_t io_cbs)

{

  engine_llass_t llass = engine;

  llass->io_cbs = *io_cbs;

}

static void

llass_io_event (void *engine, gpgme_event_io_t type, void *type_data)

{

  engine_llass_t llass = engine;

  TRACE3 (DEBUG_ENGINE, "gpgme:llass_io_event", llass,

          "event %p, type %d, type_data %p",

          llass->io_cbs.event, type, type_data);

  if (llass->io_cbs.event)

    (*llass->io_cbs.event) (llass->io_cbs.event_priv, type, type_data);

}

struct engine_ops _gpgme_engine_ops_assuan =

  {

    /* Static functions.  */

    _gpgme_get_default_agent_socket,

    llass_get_home_dir,

    llass_get_version,

    llass_get_req_version,

    llass_new,

    /* Member functions.  */

    llass_release,

    NULL,		/* reset */

    NULL,               /* set_status_cb */

    NULL,               /* set_status_handler */

    NULL,		/* set_command_handler */

    NULL,               /* set_colon_line_handler */

    llass_set_locale,

    NULL,		/* set_protocol */

    NULL,               /* decrypt */

    NULL,               /* delete */

    NULL,		/* edit */

    NULL,               /* encrypt */

    NULL,		/* encrypt_sign */

    NULL,               /* export */

    NULL,               /* export_ext */

    NULL,               /* genkey */

    NULL,               /* import */

    NULL,               /* keylist */

    NULL,               /* keylist_ext */

    NULL,               /* keylist_data */

    NULL,               /* keysign */

    NULL,               /* tofu_policy */

    NULL,               /* sign */

    NULL,		/* trustlist */

    NULL,               /* verify */

    NULL,               /* getauditlog */

    llass_transact,     /* opassuan_transact */

    NULL,		/* conf_load */

    NULL,		/* conf_save */

    NULL,		/* conf_dir */

    NULL,               /* query_swdb */

    llass_set_io_cbs,

    llass_io_event,

    llass_cancel,

    llass_cancel_op,

    NULL,               /* passwd */

    NULL,               /* set_pinentry_mode */

    NULL                /* opspawn */

  };