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.
	*
	* GnuPG 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; either version 3 of the License, or
	* (at your option) any later version.
	*
	* GnuPG 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 <http://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

	#define JNLIB_NEED_LOG_LOGV
	#include "i18n.h"
	#include "util.h"
	#include "exechelp.h"
	#include "sysutils.h"
	#include "status.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))))


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

	(void)ctx;

	if (! TEST_LOG_CAT (cat))
	return 0;

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

	if (msg)
	log_string (JNLIB_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)
	{
	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));
	assuan_set_log_cb (my_libassuan_log_handler, debug_var_address);
	}



	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)
	{
	#ifdef HAVE_W32_SYSTEM
	int waitrc;
	int timeout = (!strcmp (name, "agent")
	? SECS_TO_WAIT_FOR_AGENT
	: SECS_TO_WAIT_FOR_DIRMNGR);

	(void)homedir; /* Not required. */

	*lock = CreateMutexW
	(NULL, FALSE,
	!strcmp (name, "agent")? L"GnuPG_spawn_agent_sentinel":
	!strcmp (name, "dirmngr")? L"GnuPG_spawn_dirmngr_sentinel":
	/* */ L"GnuPG_spawn_unknown_sentinel");
	if (!*lock)
	{
	log_error ("failed to create the spawn_%s mutex: %s\n",
	name, w32_strerror (-1));
	return gpg_error (GPG_ERR_GENERAL);
	}

	retry:
	waitrc = WaitForSingleObject (*lock, 1000);
	if (waitrc == WAIT_OBJECT_0)
	return 0;

	if (waitrc == WAIT_TIMEOUT && timeout)
	{
	timeout--;
	if (verbose)
	log_info ("another process is trying to start the %s ... (%ds)\n",
	name, timeout);
	goto retry;
	}
	if (waitrc == WAIT_TIMEOUT)
	log_info ("error waiting for the spawn_%s mutex: timeout\n", name);
	else
	log_info ("error waiting for the spawn_%s mutex: (code=%d) %s\n",
	name, waitrc, w32_strerror (-1));
	return gpg_error (GPG_ERR_GENERAL);
	#else /!HAVE_W32_SYSTEM/
	char *fname;

	(void)verbose;

	*lock = NULL;

	fname = make_filename
	(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);
	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;
	#endif /!HAVE_W32_SYSTEM/
	}


	/* Unlock the spawning process. */
	static void
	unlock_spawning (lock_spawn_t lock, const char name)
	{
	if (*lock)
	{
	#ifdef HAVE_W32_SYSTEM
	if (!ReleaseMutex (*lock))
	log_error ("failed to release the spawn_%s mutex: %s\n",
	name, w32_strerror (-1));
	CloseHandle (*lock);
	#else /!HAVE_W32_SYSTEM/
	(void)name;
	dotlock_destroy (*lock);
	#endif /!HAVE_W32_SYSTEM/
	*lock = NULL;
	}
	}

	/* Try to connect to the agent via socket or fork it off and work by
	pipes. 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 *homedir,
	const char *agent_program,
	const char *opt_lc_ctype,
	const char *opt_lc_messages,
	session_env_t session_env,
	int verbose, int debug,
	gpg_error_t (*status_cb)(ctrl_t, int, ...),
	ctrl_t status_cb_arg)
	{
	/* If we ever failed to connect via a socket we will force the use
	of the pipe based server for the lifetime of the process. */
	static int force_pipe_server = 0;

	gpg_error_t err = 0;
	char infostr, p;
	assuan_context_t ctx;
	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;
	}

	restart:
	infostr = force_pipe_server? NULL : getenv ("GPG_AGENT_INFO");
	if (!infostr \|\| !*infostr)
	{
	char *sockname;
	const char *argv[3];
	pid_t pid;
	int excode;

	/* First check whether we can connect at the standard
	socket. */
	sockname = make_filename (homedir, "S.gpg-agent", NULL);
	err = assuan_socket_connect (ctx, sockname, 0, 0);

	if (err)
	{
	/* With no success start a new server. */
	if (!agent_program \|\| !*agent_program)
	agent_program = gnupg_module_name (GNUPG_MODULE_NAME_AGENT);

	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);

	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);
	return tmperr;
	}

	argv[0] = "--use-standard-socket-p";
	argv[1] = NULL;
	err = gnupg_spawn_process_fd (agent_program, argv, -1, -1, -1, &pid);
	if (err)
	log_debug ("starting `%s' for testing failed: %s\n",
	agent_program, gpg_strerror (err));
	else if ((err = gnupg_wait_process (agent_program, pid, 1, &excode)))
	{
	if (excode == -1)
	log_debug ("running `%s' for testing failed (wait): %s\n",
	agent_program, gpg_strerror (err));
	}
	gnupg_release_process (pid);

	if (!err && !excode)
	{
	/* If the agent has been configured for use with a
	standard socket, an environment variable is not
	required and thus we we can savely start the agent
	here. */
	lock_spawn_t lock;

	argv[0] = "--daemon";
	argv[1] = "--use-standard-socket";
	argv[2] = NULL;

	if (!(err = lock_spawning (&lock, homedir, "agent", verbose))
	&& assuan_socket_connect (ctx, sockname, 0, 0))
	{
	err = gnupg_spawn_process_detached (agent_program, argv,NULL);
	if (err)
	log_error ("failed to start agent `%s': %s\n",
	agent_program, gpg_strerror (err));
	else
	{
	int i;

	for (i=0; i < SECS_TO_WAIT_FOR_AGENT; i++)
	{
	if (verbose)
	log_info (_("waiting for the agent "
	"to come up ... (%ds)\n"),
	SECS_TO_WAIT_FOR_AGENT - i);
	gnupg_sleep (1);
	err = assuan_socket_connect (ctx, sockname, 0, 0);
	if (!err)
	{
	if (verbose)
	{
	log_info (_("connection to agent "
	"established\n"));
	did_success_msg = 1;
	}
	break;
	}
	}
	}
	}

	unlock_spawning (&lock, "agent");
	}
	else
	{
	/* If using the standard socket is not the default we
	start the agent as a pipe server which gives us most
	of the required features except for passphrase
	caching etc. */
	const char *pgmname;
	int no_close_list[3];
	int i;

	if ( !(pgmname = strrchr (agent_program, '/')))
	pgmname = agent_program;
	else
	pgmname++;

	argv[0] = pgmname;
	argv[1] = "--server";
	argv[2] = NULL;

	i=0;
	if (log_get_fd () != -1)
	no_close_list[i++] = assuan_fd_from_posix_fd (log_get_fd ());
	no_close_list[i++] = assuan_fd_from_posix_fd (fileno (stderr));
	no_close_list[i] = -1;

	/* Connect to the agent and perform initial handshaking. */
	err = assuan_pipe_connect (ctx, agent_program, argv,
	no_close_list, NULL, NULL, 0);
	}
	}
	xfree (sockname);
	}
	else
	{
	int prot;
	int pid;

	infostr = xstrdup (infostr);
	if ( !(p = strchr (infostr, PATHSEP_C)) \|\| p == infostr)
	{
	log_error (_("malformed GPG_AGENT_INFO environment variable\n"));
	xfree (infostr);
	force_pipe_server = 1;
	goto restart;
	}
	*p++ = 0;
	pid = atoi (p);
	while (p && p != PATHSEP_C)
	p++;
	prot = *p? atoi (p+1) : 0;
	if (prot != 1)
	{
	log_error (_("gpg-agent protocol version %d is not supported\n"),
	prot);
	xfree (infostr);
	force_pipe_server = 1;
	goto restart;
	}

	err = assuan_socket_connect (ctx, infostr, pid, 0);
	xfree (infostr);
	if (gpg_err_code (err) == GPG_ERR_ASS_CONNECT_FAILED)
	{
	log_info (_("can't connect to the agent - trying fall back\n"));
	force_pipe_server = 1;
	goto restart;
	}
	}

	if (err)
	{
	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 (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. 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 *homedir,
	const char *dirmngr_program,
	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)
	{
	lock_spawn_t lock;
	const char *argv[2];

	/* With no success try start a new Dirmngr. On most systems
	this will fail because the Dirmngr is expected to be a system
	service. However on Wince we don't distinguish users and
	thus we can start it. A future extension might be to use the
	userv system to start the Dirmngr as a system service. */
	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);

	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";
	argv[1] = NULL;

	if (!(err = lock_spawning (&lock, 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
	{
	int i;

	for (i=0; i < SECS_TO_WAIT_FOR_DIRMNGR; i++)
	{
	if (verbose)
	log_info (_("waiting for the dirmngr "
	"to come up ... (%ds)\n"),
	SECS_TO_WAIT_FOR_DIRMNGR - i);
	gnupg_sleep (1);
	err = assuan_socket_connect (ctx, sockname, 0, 0);
	if (!err)
	{
	if (verbose)
	{
	log_info (_("connection to the dirmngr"
	" established\n"));
	did_success_msg = 1;
	}
	break;
	}
	}
	}
	}

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

	if (err)
	{
	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;
	}

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