asshelp.c
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asshelp.c
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	/* asshelp.c - Helper functions for Assuan
	* Copyright (C) 2002, 2004, 2007, 2009, 2010 Free Software Foundation, Inc.
	*
	* This file is part of GnuPG.
	*
	* This file is free software; you can redistribute it and/or modify
	* it under the terms of either
	*
	* - the GNU Lesser General Public License as published by the Free
	* Software Foundation; either version 3 of the License, or (at
	* your option) any later version.
	*
	* or
	*
	* - the GNU General Public License as published by the Free
	* Software Foundation; either version 2 of the License, or (at
	* your option) any later version.
	*
	* or both in parallel, as here.
	*
	* This file 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, see <https://www.gnu.org/licenses/>.
	*/

	#include <config.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>
	#include <errno.h>
	#ifdef HAVE_LOCALE_H
	#include <locale.h>
	#endif

	#include "i18n.h"
	#include "util.h"
	#include "exechelp.h"
	#include "sysutils.h"
	#include "status.h"
	#include "membuf.h"
	#include "asshelp.h"

	/* The type we use for lock_agent_spawning. */
	#ifdef HAVE_W32_SYSTEM
	# define lock_spawn_t HANDLE
	#else
	# define lock_spawn_t dotlock_t
	#endif

	/* The time we wait until the agent or the dirmngr are ready for
	operation after we started them before giving up. */
	#ifdef HAVE_W32CE_SYSTEM
	# define SECS_TO_WAIT_FOR_AGENT 30
	# define SECS_TO_WAIT_FOR_DIRMNGR 30
	#else
	# define SECS_TO_WAIT_FOR_AGENT 5
	# define SECS_TO_WAIT_FOR_DIRMNGR 5
	#endif

	/* A bitfield that specifies the assuan categories to log. This is
	identical to the default log handler of libassuan. We need to do
	it ourselves because we use a custom log handler and want to use
	the same assuan variables to select the categories to log. */
	static int log_cats;
	#define TEST_LOG_CAT(x) (!! (log_cats & (1 << (x - 1))))

	/* The assuan log monitor used to temporary inhibit log messages from
	* assuan. */
	static int (*my_log_monitor) (assuan_context_t ctx,
	unsigned int cat,
	const char *msg);


	static int
	my_libassuan_log_handler (assuan_context_t ctx, void *hook,
	unsigned int cat, const char *msg)
	{
	unsigned int dbgval;

	if (! TEST_LOG_CAT (cat))
	return 0;

	dbgval = hook? (unsigned int)hook : 0;
	if (!(dbgval & 1024))
	return 0; /* Assuan debugging is not enabled. */

	if (ctx && my_log_monitor && !my_log_monitor (ctx, cat, msg))
	return 0; /* Temporary disabled. */

	if (msg)
	log_string (GPGRT_LOG_DEBUG, msg);

	return 1;
	}


	/* Setup libassuan to use our own logging functions. Should be used
	early at startup. */
	void
	setup_libassuan_logging (unsigned int *debug_var_address,
	int (*log_monitor)(assuan_context_t ctx,
	unsigned int cat,
	const char *msg))
	{
	char *flagstr;

	flagstr = getenv ("ASSUAN_DEBUG");
	if (flagstr)
	log_cats = atoi (flagstr);
	else /* Default to log the control channel. */
	log_cats = (1 << (ASSUAN_LOG_CONTROL - 1));
	my_log_monitor = log_monitor;
	assuan_set_log_cb (my_libassuan_log_handler, debug_var_address);
	}


	/* Change the Libassuan log categories to those given by NEWCATS.
	NEWCATS is 0 the default category of ASSUAN_LOG_CONTROL is
	selected. Note, that setup_libassuan_logging overrides the values
	given here. */
	void
	set_libassuan_log_cats (unsigned int newcats)
	{
	if (newcats)
	log_cats = newcats;
	else /* Default to log the control channel. */
	log_cats = (1 << (ASSUAN_LOG_CONTROL - 1));
	}



	static gpg_error_t
	send_one_option (assuan_context_t ctx, gpg_err_source_t errsource,
	const char name, const char value, int use_putenv)
	{
	gpg_error_t err;
	char *optstr;

	(void)errsource;

	if (!value \|\| !*value)
	err = 0; /* Avoid sending empty strings. */
	else if (asprintf (&optstr, "OPTION %s%s=%s",
	use_putenv? "putenv=":"", name, value) < 0)
	err = gpg_error_from_syserror ();
	else
	{
	err = assuan_transact (ctx, optstr, NULL, NULL, NULL, NULL, NULL, NULL);
	xfree (optstr);
	}

	return err;
	}


	/* Send the assuan commands pertaining to the pinentry environment. The
	OPT_* arguments are optional and may be used to override the
	defaults taken from the current locale. */
	gpg_error_t
	send_pinentry_environment (assuan_context_t ctx,
	gpg_err_source_t errsource,
	const char *opt_lc_ctype,
	const char *opt_lc_messages,
	session_env_t session_env)

	{
	gpg_error_t err = 0;
	#if defined(HAVE_SETLOCALE)
	char *old_lc = NULL;
	#endif
	char *dft_lc = NULL;
	const char *dft_ttyname;
	int iterator;
	const char name, assname, *value;
	int is_default;

	iterator = 0;
	while ((name = session_env_list_stdenvnames (&iterator, &assname)))
	{
	value = session_env_getenv_or_default (session_env, name, NULL);
	if (!value)
	continue;

	if (assname)
	err = send_one_option (ctx, errsource, assname, value, 0);
	else
	{
	err = send_one_option (ctx, errsource, name, value, 1);
	if (gpg_err_code (err) == GPG_ERR_UNKNOWN_OPTION)
	err = 0; /* Server too old; can't pass the new envvars. */
	}
	if (err)
	return err;
	}


	dft_ttyname = session_env_getenv_or_default (session_env, "GPG_TTY",
	&is_default);
	if (dft_ttyname && !is_default)
	dft_ttyname = NULL; /* We need the default value. */

	/* Send the value for LC_CTYPE. */
	#if defined(HAVE_SETLOCALE) && defined(LC_CTYPE)
	old_lc = setlocale (LC_CTYPE, NULL);
	if (old_lc)
	{
	old_lc = xtrystrdup (old_lc);
	if (!old_lc)
	return gpg_error_from_syserror ();
	}
	dft_lc = setlocale (LC_CTYPE, "");
	#endif
	if (opt_lc_ctype \|\| (dft_ttyname && dft_lc))
	{
	err = send_one_option (ctx, errsource, "lc-ctype",
	opt_lc_ctype ? opt_lc_ctype : dft_lc, 0);
	}
	#if defined(HAVE_SETLOCALE) && defined(LC_CTYPE)
	if (old_lc)
	{
	setlocale (LC_CTYPE, old_lc);
	xfree (old_lc);
	}
	#endif
	if (err)
	return err;

	/* Send the value for LC_MESSAGES. */
	#if defined(HAVE_SETLOCALE) && defined(LC_MESSAGES)
	old_lc = setlocale (LC_MESSAGES, NULL);
	if (old_lc)
	{
	old_lc = xtrystrdup (old_lc);
	if (!old_lc)
	return gpg_error_from_syserror ();
	}
	dft_lc = setlocale (LC_MESSAGES, "");
	#endif
	if (opt_lc_messages \|\| (dft_ttyname && dft_lc))
	{
	err = send_one_option (ctx, errsource, "lc-messages",
	opt_lc_messages ? opt_lc_messages : dft_lc, 0);
	}
	#if defined(HAVE_SETLOCALE) && defined(LC_MESSAGES)
	if (old_lc)
	{
	setlocale (LC_MESSAGES, old_lc);
	xfree (old_lc);
	}
	#endif
	if (err)
	return err;

	return 0;
	}


	/* Lock a spawning process. The caller needs to provide the address
	of a variable to store the lock information and the name or the
	process. */
	static gpg_error_t
	lock_spawning (lock_spawn_t lock, const char homedir, const char *name,
	int verbose)
	{
	char *fname;
	(void)verbose;

	*lock = NULL;

	fname = make_absfilename_try
	(homedir,
	!strcmp (name, "agent")? "gnupg_spawn_agent_sentinel":
	!strcmp (name, "dirmngr")? "gnupg_spawn_dirmngr_sentinel":
	/* */ "gnupg_spawn_unknown_sentinel",
	NULL);
	if (!fname)
	return gpg_error_from_syserror ();

	*lock = dotlock_create (fname, 0);
	xfree (fname);
	if (!*lock)
	return gpg_error_from_syserror ();

	/* FIXME: We should use a timeout of 5000 here - however
	make_dotlock does not yet support values other than -1 and 0. */
	if (dotlock_take (*lock, -1))
	return gpg_error_from_syserror ();

	return 0;
	}


	/* Unlock the spawning process. */
	static void
	unlock_spawning (lock_spawn_t lock, const char name)
	{
	if (*lock)
	{
	(void)name;
	dotlock_destroy (*lock);
	*lock = NULL;
	}
	}

	static gpg_error_t
	wait_for_sock (int secs, const char name, const char sockname, int verbose, assuan_context_t ctx, int *did_success_msg)
	{
	gpg_error_t err = 0;
	int target_us = secs * 1000000;
	int elapsed_us = 0;
	/*
	* 977us * 1024 = just a little more than 1s.
	* so we will double this timeout 10 times in the first
	* second, and then switch over to 1s checkins.
	*/
	int next_sleep_us = 977;
	int lastalert = secs+1;
	int secsleft;

	while (elapsed_us < target_us)
	{
	if (verbose)
	{
	secsleft = (target_us - elapsed_us + 999999)/1000000;
	/* log_clock ("left=%d last=%d targ=%d elap=%d next=%d\n", */
	/* secsleft, lastalert, target_us, elapsed_us, */
	/* next_sleep_us); */
	if (secsleft < lastalert)
	{
	log_info (_("waiting for the %s to come up ... (%ds)\n"),
	name, secsleft);
	lastalert = secsleft;
	}
	}
	gnupg_usleep (next_sleep_us);
	elapsed_us += next_sleep_us;
	err = assuan_socket_connect (ctx, sockname, 0, 0);
	if (!err)
	{
	if (verbose)
	{
	log_info (_("connection to %s established\n"),
	name);
	*did_success_msg = 1;
	}
	break;
	}
	next_sleep_us *= 2;
	if (next_sleep_us > 1000000)
	next_sleep_us = 1000000;
	}
	return err;
	}

	/* Try to connect to the agent via socket or start it if it is not
	running and AUTOSTART is set. Handle the server's initial
	greeting. Returns a new assuan context at R_CTX or an error
	code. */
	gpg_error_t
	start_new_gpg_agent (assuan_context_t *r_ctx,
	gpg_err_source_t errsource,
	const char *agent_program,
	const char *opt_lc_ctype,
	const char *opt_lc_messages,
	session_env_t session_env,
	int autostart, int verbose, int debug,
	gpg_error_t (*status_cb)(ctrl_t, int, ...),
	ctrl_t status_cb_arg)
	{
	gpg_error_t err;
	assuan_context_t ctx;
	int did_success_msg = 0;
	char *sockname;
	const char *argv[6];

	*r_ctx = NULL;

	err = assuan_new (&ctx);
	if (err)
	{
	log_error ("error allocating assuan context: %s\n", gpg_strerror (err));
	return err;
	}

	sockname = make_filename_try (gnupg_socketdir (), GPG_AGENT_SOCK_NAME, NULL);
	if (!sockname)
	{
	err = gpg_err_make (errsource, gpg_err_code_from_syserror ());
	assuan_release (ctx);
	return err;
	}

	err = assuan_socket_connect (ctx, sockname, 0, 0);
	if (err && autostart)
	{
	char *abs_homedir;
	lock_spawn_t lock;
	char *program = NULL;
	const char *program_arg = NULL;
	char *p;
	const char *s;
	int i;

	/* With no success start a new server. */
	if (!agent_program \|\| !*agent_program)
	agent_program = gnupg_module_name (GNUPG_MODULE_NAME_AGENT);
	else if ((s=strchr (agent_program, '\|')) && s[1] == '-' && s[2]=='-')
	{
	/* Hack to insert an additional option on the command line. */
	program = xtrystrdup (agent_program);
	if (!program)
	{
	gpg_error_t tmperr = gpg_err_make (errsource,
	gpg_err_code_from_syserror ());
	xfree (sockname);
	assuan_release (ctx);
	return tmperr;
	}
	p = strchr (program, '\|');
	*p++ = 0;
	program_arg = p;
	}

	if (verbose)
	log_info (_("no running gpg-agent - starting '%s'\n"),
	agent_program);

	if (status_cb)
	status_cb (status_cb_arg, STATUS_PROGRESS,
	"starting_agent ? 0 0", NULL);

	/* We better pass an absolute home directory to the agent just
	in case gpg-agent does not convert the passed name to an
	absolute one (which it should do). */
	abs_homedir = make_absfilename_try (gnupg_homedir (), NULL);
	if (!abs_homedir)
	{
	gpg_error_t tmperr = gpg_err_make (errsource,
	gpg_err_code_from_syserror ());
	log_error ("error building filename: %s\n",gpg_strerror (tmperr));
	xfree (sockname);
	assuan_release (ctx);
	xfree (program);
	return tmperr;
	}

	if (fflush (NULL))
	{
	gpg_error_t tmperr = gpg_err_make (errsource,
	gpg_err_code_from_syserror ());
	log_error ("error flushing pending output: %s\n",
	strerror (errno));
	xfree (sockname);
	assuan_release (ctx);
	xfree (abs_homedir);
	xfree (program);
	return tmperr;
	}

	/* If the agent has been configured for use with a standard
	socket, an environment variable is not required and thus
	we can safely start the agent here. */
	i = 0;
	argv[i++] = "--homedir";
	argv[i++] = abs_homedir;
	argv[i++] = "--use-standard-socket";
	if (program_arg)
	argv[i++] = program_arg;
	argv[i++] = "--daemon";
	argv[i++] = NULL;

	if (!(err = lock_spawning (&lock, gnupg_homedir (), "agent", verbose))
	&& assuan_socket_connect (ctx, sockname, 0, 0))
	{
	err = gnupg_spawn_process_detached (program? program : agent_program,
	argv, NULL);
	if (err)
	log_error ("failed to start agent '%s': %s\n",
	agent_program, gpg_strerror (err));
	else
	err = wait_for_sock (SECS_TO_WAIT_FOR_AGENT, "agent",
	sockname, verbose, ctx, &did_success_msg);
	}

	unlock_spawning (&lock, "agent");
	xfree (abs_homedir);
	xfree (program);
	}
	xfree (sockname);
	if (err)
	{
	if (autostart \|\| gpg_err_code (err) != GPG_ERR_ASS_CONNECT_FAILED)
	log_error ("can't connect to the agent: %s\n", gpg_strerror (err));
	assuan_release (ctx);
	return gpg_err_make (errsource, GPG_ERR_NO_AGENT);
	}

	if (debug && !did_success_msg)
	log_debug ("connection to agent established\n");

	err = assuan_transact (ctx, "RESET",
	NULL, NULL, NULL, NULL, NULL, NULL);
	if (!err)
	{
	err = send_pinentry_environment (ctx, errsource,
	opt_lc_ctype, opt_lc_messages,
	session_env);
	if (gpg_err_code (err) == GPG_ERR_FORBIDDEN
	&& gpg_err_source (err) == GPG_ERR_SOURCE_GPGAGENT)
	{
	/* Check whether we are in restricted mode. */
	if (!assuan_transact (ctx, "GETINFO restricted",
	NULL, NULL, NULL, NULL, NULL, NULL))
	{
	if (verbose)
	log_info (_("connection to agent is in restricted mode\n"));
	err = 0;
	}
	}
	}
	if (err)
	{
	assuan_release (ctx);
	return err;
	}

	*r_ctx = ctx;
	return 0;
	}


	/* Try to connect to the dirmngr via a socket. On platforms
	supporting it, start it up if needed and if AUTOSTART is true.
	Returns a new assuan context at R_CTX or an error code. */
	gpg_error_t
	start_new_dirmngr (assuan_context_t *r_ctx,
	gpg_err_source_t errsource,
	const char *dirmngr_program,
	int autostart,
	int verbose, int debug,
	gpg_error_t (*status_cb)(ctrl_t, int, ...),
	ctrl_t status_cb_arg)
	{
	gpg_error_t err;
	assuan_context_t ctx;
	const char *sockname;
	int did_success_msg = 0;

	*r_ctx = NULL;

	err = assuan_new (&ctx);
	if (err)
	{
	log_error ("error allocating assuan context: %s\n", gpg_strerror (err));
	return err;
	}

	sockname = dirmngr_socket_name ();
	err = assuan_socket_connect (ctx, sockname, 0, 0);

	#ifdef USE_DIRMNGR_AUTO_START
	if (err && autostart)
	{
	lock_spawn_t lock;
	const char *argv[4];
	char *abs_homedir;

	/* No connection: Try start a new Dirmngr. */
	if (!dirmngr_program \|\| !*dirmngr_program)
	dirmngr_program = gnupg_module_name (GNUPG_MODULE_NAME_DIRMNGR);

	if (verbose)
	log_info (_("no running Dirmngr - starting '%s'\n"),
	dirmngr_program);

	if (status_cb)
	status_cb (status_cb_arg, STATUS_PROGRESS,
	"starting_dirmngr ? 0 0", NULL);

	abs_homedir = make_absfilename (gnupg_homedir (), NULL);
	if (!abs_homedir)
	{
	gpg_error_t tmperr = gpg_err_make (errsource,
	gpg_err_code_from_syserror ());
	log_error ("error building filename: %s\n",gpg_strerror (tmperr));
	assuan_release (ctx);
	return tmperr;
	}

	if (fflush (NULL))
	{
	gpg_error_t tmperr = gpg_err_make (errsource,
	gpg_err_code_from_syserror ());
	log_error ("error flushing pending output: %s\n",
	strerror (errno));
	assuan_release (ctx);
	return tmperr;
	}

	argv[0] = "--daemon";
	/* Try starting the daemon. Versions of dirmngr < 2.1.15 do
	* this only if the home directory is given on the command line. */
	argv[1] = "--homedir";
	argv[2] = abs_homedir;
	argv[3] = NULL;

	if (!(err = lock_spawning (&lock, gnupg_homedir (), "dirmngr", verbose))
	&& assuan_socket_connect (ctx, sockname, 0, 0))
	{
	err = gnupg_spawn_process_detached (dirmngr_program, argv, NULL);
	if (err)
	log_error ("failed to start the dirmngr '%s': %s\n",
	dirmngr_program, gpg_strerror (err));
	else
	err = wait_for_sock (SECS_TO_WAIT_FOR_DIRMNGR, "dirmngr",
	sockname, verbose, ctx, &did_success_msg);
	}

	unlock_spawning (&lock, "dirmngr");
	xfree (abs_homedir);
	}
	#else
	(void)dirmngr_program;
	(void)verbose;
	(void)status_cb;
	(void)status_cb_arg;
	#endif /USE_DIRMNGR_AUTO_START/

	if (err)
	{
	if (autostart \|\| gpg_err_code (err) != GPG_ERR_ASS_CONNECT_FAILED)
	log_error ("connecting dirmngr at '%s' failed: %s\n",
	sockname, gpg_strerror (err));
	assuan_release (ctx);
	return gpg_err_make (errsource, GPG_ERR_NO_DIRMNGR);
	}

	if (debug && !did_success_msg)
	log_debug ("connection to the dirmngr established\n");

	*r_ctx = ctx;
	return 0;
	}


	/* Return the version of a server using "GETINFO version". On success
	0 is returned and R_VERSION receives a malloced string with the
	version which must be freed by the caller. On error NULL is stored
	at R_VERSION and an error code returned. Mode is in general 0 but
	certain values may be used to modify the used version command:

	MODE == 0 = Use "GETINFO version"
	MODE == 2 - Use "SCD GETINFO version"
	*/
	gpg_error_t
	get_assuan_server_version (assuan_context_t ctx, int mode, char **r_version)
	{
	gpg_error_t err;
	membuf_t data;

	init_membuf (&data, 64);
	err = assuan_transact (ctx,
	mode == 2? "SCD GETINFO version"
	/**/ : "GETINFO version",
	put_membuf_cb, &data,
	NULL, NULL, NULL, NULL);
	if (err)
	{
	xfree (get_membuf (&data, NULL));
	*r_version = NULL;
	}
	else
	{
	put_membuf (&data, "", 1);
	*r_version = get_membuf (&data, NULL);
	if (!*r_version)
	err = gpg_error_from_syserror ();
	}
	return err;
	}

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