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Asterisk developer's documentation

---

pbx.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Core PBX routines.
 *
 * \author Mark Spencer <markster@digium.com>
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 144758 $")

#include <sys/types.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include <limits.h>

#include "asterisk/lock.h"
#include "asterisk/cli.h"
#include "asterisk/pbx.h"
#include "asterisk/channel.h"
#include "asterisk/options.h"
#include "asterisk/logger.h"
#include "asterisk/file.h"
#include "asterisk/callerid.h"
#include "asterisk/cdr.h"
#include "asterisk/config.h"
#include "asterisk/term.h"
#include "asterisk/manager.h"
#include "asterisk/ast_expr.h"
#include "asterisk/linkedlists.h"
#define  SAY_STUBS   /* generate declarations and stubs for say methods */
#include "asterisk/say.h"
#include "asterisk/utils.h"
#include "asterisk/causes.h"
#include "asterisk/musiconhold.h"
#include "asterisk/app.h"
#include "asterisk/devicestate.h"
#include "asterisk/stringfields.h"
#include "asterisk/threadstorage.h"

/*!
 * \note I M P O R T A N T :
 *
 *    The speed of extension handling will likely be among the most important
 * aspects of this PBX.  The switching scheme as it exists right now isn't
 * terribly bad (it's O(N+M), where N is the # of extensions and M is the avg #
 * of priorities, but a constant search time here would be great ;-)
 *
 */

#ifdef LOW_MEMORY
#define EXT_DATA_SIZE 256
#else
#define EXT_DATA_SIZE 8192
#endif

#define SWITCH_DATA_LENGTH 256

#define VAR_BUF_SIZE 4096

#define  VAR_NORMAL     1
#define  VAR_SOFTTRAN   2
#define  VAR_HARDTRAN   3

#define BACKGROUND_SKIP    (1 << 0)
#define BACKGROUND_NOANSWER   (1 << 1)
#define BACKGROUND_MATCHEXTEN (1 << 2)
#define BACKGROUND_PLAYBACK   (1 << 3)

AST_APP_OPTIONS(background_opts, {
   AST_APP_OPTION('s', BACKGROUND_SKIP),
   AST_APP_OPTION('n', BACKGROUND_NOANSWER),
   AST_APP_OPTION('m', BACKGROUND_MATCHEXTEN),
   AST_APP_OPTION('p', BACKGROUND_PLAYBACK),
});

#define WAITEXTEN_MOH      (1 << 0)

AST_APP_OPTIONS(waitexten_opts, {
   AST_APP_OPTION_ARG('m', WAITEXTEN_MOH, 0),
});

struct ast_context;

AST_THREADSTORAGE(switch_data, switch_data_init);

/*!
   \brief ast_exten: An extension
   The dialplan is saved as a linked list with each context
   having it's own linked list of extensions - one item per
   priority.
*/
struct ast_exten {
   char *exten;         /*!< Extension name */
   int matchcid;        /*!< Match caller id ? */
   const char *cidmatch;      /*!< Caller id to match for this extension */
   int priority;        /*!< Priority */
   const char *label;      /*!< Label */
   struct ast_context *parent;   /*!< The context this extension belongs to  */
   const char *app;     /*!< Application to execute */
   void *data;       /*!< Data to use (arguments) */
   void (*datad)(void *);     /*!< Data destructor */
   struct ast_exten *peer;    /*!< Next higher priority with our extension */
   const char *registrar;     /*!< Registrar */
   struct ast_exten *next;    /*!< Extension with a greater ID */
   char stuff[0];
};

/*! \brief ast_include: include= support in extensions.conf */
struct ast_include {
   const char *name;
   const char *rname;         /*!< Context to include */
   const char *registrar;        /*!< Registrar */
   int hastime;            /*!< If time construct exists */
   struct ast_timing timing;               /*!< time construct */
   struct ast_include *next;     /*!< Link them together */
   char stuff[0];
};

/*! \brief ast_sw: Switch statement in extensions.conf */
struct ast_sw {
   char *name;
   const char *registrar;        /*!< Registrar */
   char *data;          /*!< Data load */
   int eval;
   AST_LIST_ENTRY(ast_sw) list;
   char stuff[0];
};

/*! \brief ast_ignorepat: Ignore patterns in dial plan */
struct ast_ignorepat {
   const char *registrar;
   struct ast_ignorepat *next;
   const char pattern[0];
};

/*! \brief ast_context: An extension context */
struct ast_context {
   ast_mutex_t lock;          /*!< A lock to prevent multiple threads from clobbering the context */
   struct ast_exten *root;       /*!< The root of the list of extensions */
   struct ast_context *next;     /*!< Link them together */
   struct ast_include *includes;    /*!< Include other contexts */
   struct ast_ignorepat *ignorepats;   /*!< Patterns for which to continue playing dialtone */
   const char *registrar;        /*!< Registrar */
   AST_LIST_HEAD_NOLOCK(, ast_sw) alts;   /*!< Alternative switches */
   ast_mutex_t macrolock;        /*!< A lock to implement "exclusive" macros - held whilst a call is executing in the macro */
   char name[0];           /*!< Name of the context */
};


/*! \brief ast_app: A registered application */
struct ast_app {
   int (*execute)(struct ast_channel *chan, void *data);
   const char *synopsis;         /*!< Synopsis text for 'show applications' */
   const char *description;      /*!< Description (help text) for 'show application &lt;name&gt;' */
   AST_LIST_ENTRY(ast_app) list;    /*!< Next app in list */
   struct module *module;        /*!< Module this app belongs to */
   char name[0];           /*!< Name of the application */
};

/*! \brief ast_state_cb: An extension state notify register item */
struct ast_state_cb {
   int id;
   void *data;
   ast_state_cb_type callback;
   struct ast_state_cb *next;
};

/*! \brief Structure for dial plan hints

  \note Hints are pointers from an extension in the dialplan to one or
  more devices (tech/name) */
struct ast_hint {
   struct ast_exten *exten;   /*!< Extension */
   int laststate;          /*!< Last known state */
   struct ast_state_cb *callbacks;  /*!< Callback list for this extension */
   AST_LIST_ENTRY(ast_hint) list;   /*!< Pointer to next hint in list */
};

static const struct cfextension_states {
   int extension_state;
   const char * const text;
} extension_states[] = {
   { AST_EXTENSION_NOT_INUSE,                     "Idle" },
   { AST_EXTENSION_INUSE,                         "InUse" },
   { AST_EXTENSION_BUSY,                          "Busy" },
   { AST_EXTENSION_UNAVAILABLE,                   "Unavailable" },
   { AST_EXTENSION_RINGING,                       "Ringing" },
   { AST_EXTENSION_INUSE | AST_EXTENSION_RINGING, "InUse&Ringing" },
   { AST_EXTENSION_ONHOLD,                        "Hold" },
   { AST_EXTENSION_INUSE | AST_EXTENSION_ONHOLD,  "InUse&Hold" }
};

static int pbx_builtin_answer(struct ast_channel *, void *);
static int pbx_builtin_goto(struct ast_channel *, void *);
static int pbx_builtin_hangup(struct ast_channel *, void *);
static int pbx_builtin_background(struct ast_channel *, void *);
static int pbx_builtin_wait(struct ast_channel *, void *);
static int pbx_builtin_waitexten(struct ast_channel *, void *);
static int pbx_builtin_resetcdr(struct ast_channel *, void *);
static int pbx_builtin_setamaflags(struct ast_channel *, void *);
static int pbx_builtin_ringing(struct ast_channel *, void *);
static int pbx_builtin_progress(struct ast_channel *, void *);
static int pbx_builtin_congestion(struct ast_channel *, void *);
static int pbx_builtin_busy(struct ast_channel *, void *);
static int pbx_builtin_setglobalvar(struct ast_channel *, void *);
static int pbx_builtin_noop(struct ast_channel *, void *);
static int pbx_builtin_gotoif(struct ast_channel *, void *);
static int pbx_builtin_gotoiftime(struct ast_channel *, void *);
static int pbx_builtin_execiftime(struct ast_channel *, void *);
static int pbx_builtin_saynumber(struct ast_channel *, void *);
static int pbx_builtin_saydigits(struct ast_channel *, void *);
static int pbx_builtin_saycharacters(struct ast_channel *, void *);
static int pbx_builtin_sayphonetic(struct ast_channel *, void *);
int pbx_builtin_setvar(struct ast_channel *, void *);
static int pbx_builtin_importvar(struct ast_channel *, void *);

AST_MUTEX_DEFINE_STATIC(globalslock);
static struct varshead globals = AST_LIST_HEAD_NOLOCK_INIT_VALUE;

static int autofallthrough = 1;

AST_MUTEX_DEFINE_STATIC(maxcalllock);
static int countcalls;

static AST_LIST_HEAD_STATIC(acf_root, ast_custom_function);

/*! \brief Declaration of builtin applications */
static struct pbx_builtin {
   char name[AST_MAX_APP];
   int (*execute)(struct ast_channel *chan, void *data);
   char *synopsis;
   char *description;
} builtins[] =
{
   /* These applications are built into the PBX core and do not
      need separate modules */

   { "Answer", pbx_builtin_answer,
   "Answer a channel if ringing",
   "  Answer([delay]): If the call has not been answered, this application will\n"
   "answer it. Otherwise, it has no effect on the call. If a delay is specified,\n"
   "Asterisk will wait this number of milliseconds before returning to\n"
   "the dialplan after answering the call.\n"
   },

   { "BackGround", pbx_builtin_background,
   "Play an audio file while waiting for digits of an extension to go to.",
   "  Background(filename1[&filename2...][|options[|langoverride][|context]]):\n"
   "This application will play the given list of files (do not put extension)\n"
   "while waiting for an extension to be dialed by the calling channel. To\n"
   "continue waiting for digits after this application has finished playing\n"
   "files, the WaitExten application should be used. The 'langoverride' option\n"
   "explicitly specifies which language to attempt to use for the requested sound\n"
   "files. If a 'context' is specified, this is the dialplan context that this\n"
   "application will use when exiting to a dialed extension."
   "  If one of the requested sound files does not exist, call processing will be\n"
   "terminated.\n"
   "  Options:\n"
   "    s - Causes the playback of the message to be skipped\n"
   "          if the channel is not in the 'up' state (i.e. it\n"
   "          hasn't been answered yet). If this happens, the\n"
   "          application will return immediately.\n"
   "    n - Don't answer the channel before playing the files.\n"
   "    m - Only break if a digit hit matches a one digit\n"
   "          extension in the destination context.\n"
   "See Also: Playback (application) -- Play sound file(s) to the channel,\n"
    "                                    that cannot be interrupted\n"
   },

   { "Busy", pbx_builtin_busy,
   "Indicate the Busy condition",
   "  Busy([timeout]): This application will indicate the busy condition to\n"
   "the calling channel. If the optional timeout is specified, the calling channel\n"
   "will be hung up after the specified number of seconds. Otherwise, this\n"
   "application will wait until the calling channel hangs up.\n"
   },

   { "Congestion", pbx_builtin_congestion,
   "Indicate the Congestion condition",
   "  Congestion([timeout]): This application will indicate the congestion\n"
   "condition to the calling channel. If the optional timeout is specified, the\n"
   "calling channel will be hung up after the specified number of seconds.\n"
   "Otherwise, this application will wait until the calling channel hangs up.\n"
   },

   { "Goto", pbx_builtin_goto,
   "Jump to a particular priority, extension, or context",
   "  Goto([[context|]extension|]priority): This application will set the current\n"
   "context, extension, and priority in the channel structure. After it completes, the\n"
   "pbx engine will continue dialplan execution at the specified location.\n"
   "If no specific extension, or extension and context, are specified, then this\n"
   "application will just set the specified priority of the current extension.\n"
   "  At least a priority is required as an argument, or the goto will return a -1,\n"
   "and the channel and call will be terminated.\n"
   "  If the location that is put into the channel information is bogus, and asterisk cannot\n"
        "find that location in the dialplan,\n"
   "then the execution engine will try to find and execute the code in the 'i' (invalid)\n"
   "extension in the current context. If that does not exist, it will try to execute the\n"
   "'h' extension. If either or neither the 'h' or 'i' extensions have been defined, the\n"
   "channel is hung up, and the execution of instructions on the channel is terminated.\n"
   "What this means is that, for example, you specify a context that does not exist, then\n"
   "it will not be possible to find the 'h' or 'i' extensions, and the call will terminate!\n"
   },

   { "GotoIf", pbx_builtin_gotoif,
   "Conditional goto",
   "  GotoIf(condition?[labeliftrue]:[labeliffalse]): This application will set the current\n"
   "context, extension, and priority in the channel structure based on the evaluation of\n"
   "the given condition. After this application completes, the\n"
   "pbx engine will continue dialplan execution at the specified location in the dialplan.\n"
   "The channel will continue at\n"
   "'labeliftrue' if the condition is true, or 'labeliffalse' if the condition is\n"
   "false. The labels are specified with the same syntax as used within the Goto\n"
   "application.  If the label chosen by the condition is omitted, no jump is\n"
   "performed, and the execution passes to the next instruction.\n"
   "If the target location is bogus, and does not exist, the execution engine will try \n"
   "to find and execute the code in the 'i' (invalid)\n"
   "extension in the current context. If that does not exist, it will try to execute the\n"
   "'h' extension. If either or neither the 'h' or 'i' extensions have been defined, the\n"
   "channel is hung up, and the execution of instructions on the channel is terminated.\n"
   "Remember that this command can set the current context, and if the context specified\n"
   "does not exist, then it will not be able to find any 'h' or 'i' extensions there, and\n"
   "the channel and call will both be terminated!\n"
   },

   { "GotoIfTime", pbx_builtin_gotoiftime,
   "Conditional Goto based on the current time",
   "  GotoIfTime(<times>|<weekdays>|<mdays>|<months>?[[context|]exten|]priority):\n"
   "This application will set the context, extension, and priority in the channel structure\n"
   "if the current time matches the given time specification. Otherwise, nothing is done.\n"
        "Further information on the time specification can be found in examples\n"
        "illustrating how to do time-based context includes in the dialplan.\n" 
   "If the target jump location is bogus, the same actions would be taken as for Goto.\n"
   },

   { "ExecIfTime", pbx_builtin_execiftime,
   "Conditional application execution based on the current time",
   "  ExecIfTime(<times>|<weekdays>|<mdays>|<months>?appname[|appargs]):\n"
   "This application will execute the specified dialplan application, with optional\n"
   "arguments, if the current time matches the given time specification.\n"
   },

   { "Hangup", pbx_builtin_hangup,
   "Hang up the calling channel",
   "  Hangup([causecode]): This application will hang up the calling channel.\n"
   "If a causecode is given the channel's hangup cause will be set to the given\n"
   "value.\n"
   },

   { "NoOp", pbx_builtin_noop,
   "Do Nothing",
   "  NoOp(): This applicatiion does nothing. However, it is useful for debugging\n"
   "purposes. Any text that is provided as arguments to this application can be\n"
   "viewed at the Asterisk CLI. This method can be used to see the evaluations of\n"
   "variables or functions without having any effect."
   },

   { "Progress", pbx_builtin_progress,
   "Indicate progress",
   "  Progress(): This application will request that in-band progress information\n"
   "be provided to the calling channel.\n"
   },

   { "ResetCDR", pbx_builtin_resetcdr,
   "Resets the Call Data Record",
   "  ResetCDR([options]):  This application causes the Call Data Record to be\n"
   "reset.\n"
   "  Options:\n"
   "    w -- Store the current CDR record before resetting it.\n"
   "    a -- Store any stacked records.\n"
   "    v -- Save CDR variables.\n"
   },

   { "Ringing", pbx_builtin_ringing,
   "Indicate ringing tone",
   "  Ringing(): This application will request that the channel indicate a ringing\n"
   "tone to the user.\n"
   },

   { "SayNumber", pbx_builtin_saynumber,
   "Say Number",
   "  SayNumber(digits[,gender]): This application will play the sounds that\n"
   "correspond to the given number. Optionally, a gender may be specified.\n"
   "This will use the language that is currently set for the channel. See the\n"
   "LANGUAGE function for more information on setting the language for the channel.\n"
   },

   { "SayDigits", pbx_builtin_saydigits,
   "Say Digits",
   "  SayDigits(digits): This application will play the sounds that correspond\n"
   "to the digits of the given number. This will use the language that is currently\n"
   "set for the channel. See the LANGUAGE function for more information on setting\n"
   "the language for the channel.\n"
   },

   { "SayAlpha", pbx_builtin_saycharacters,
   "Say Alpha",
   "  SayAlpha(string): This application will play the sounds that correspond to\n"
   "the letters of the given string.\n"
   },

   { "SayPhonetic", pbx_builtin_sayphonetic,
   "Say Phonetic",
   "  SayPhonetic(string): This application will play the sounds from the phonetic\n"
   "alphabet that correspond to the letters in the given string.\n"
   },

   { "SetAMAFlags", pbx_builtin_setamaflags,
   "Set the AMA Flags",
   "  SetAMAFlags([flag]): This application will set the channel's AMA Flags for\n"
   "  billing purposes.\n"
   },

   { "SetGlobalVar", pbx_builtin_setglobalvar,
   "Set a global variable to a given value",
   "  SetGlobalVar(variable=value): This application sets a given global variable to\n"
   "the specified value.\n"
   "\n\nThis application is deprecated in favor of Set(GLOBAL(var)=value)\n"
   },

   { "Set", pbx_builtin_setvar,
   "Set channel variable(s) or function value(s)",
   "  Set(name1=value1|name2=value2|..[|options])\n"
   "This function can be used to set the value of channel variables or dialplan\n"
   "functions. It will accept up to 24 name/value pairs. When setting variables,\n"
   "if the variable name is prefixed with _, the variable will be inherited into\n"
   "channels created from the current channel. If the variable name is prefixed\n"
   "with __, the variable will be inherited into channels created from the current\n"
   "channel and all children channels.\n"
   "  Options:\n"
   "    g - Set variable globally instead of on the channel\n"
   "        (applies only to variables, not functions)\n"
   "\n\nThe use of Set to set multiple variables at once and the g flag have both\n"
   "been deprecated.  Please use multiple Set calls and the GLOBAL() dialplan\n"
   "function instead.\n"
   },

   { "ImportVar", pbx_builtin_importvar,
   "Import a variable from a channel into a new variable",
   "  ImportVar(newvar=channelname|variable): This application imports a variable\n"
   "from the specified channel (as opposed to the current one) and stores it as\n"
   "a variable in the current channel (the channel that is calling this\n"
   "application). Variables created by this application have the same inheritance\n"
   "properties as those created with the Set application. See the documentation for\n"
   "Set for more information.\n"
   },

   { "Wait", pbx_builtin_wait,
   "Waits for some time",
   "  Wait(seconds): This application waits for a specified number of seconds.\n"
   "Then, dialplan execution will continue at the next priority.\n"
   "  Note that the seconds can be passed with fractions of a second. For example,\n"
   "'1.5' will ask the application to wait for 1.5 seconds.\n"
   },

   { "WaitExten", pbx_builtin_waitexten,
   "Waits for an extension to be entered",
   "  WaitExten([seconds][|options]): This application waits for the user to enter\n"
   "a new extension for a specified number of seconds.\n"
   "  Note that the seconds can be passed with fractions of a second. For example,\n"
   "'1.5' will ask the application to wait for 1.5 seconds.\n"
   "  Options:\n"
   "    m[(x)] - Provide music on hold to the caller while waiting for an extension.\n"
   "               Optionally, specify the class for music on hold within parenthesis.\n"
   "See Also: Playback(application), Background(application).\n"
   },

};

static struct ast_context *contexts;
AST_RWLOCK_DEFINE_STATIC(conlock);     /*!< Lock for the ast_context list */

static AST_LIST_HEAD_STATIC(apps, ast_app);

static AST_LIST_HEAD_STATIC(switches, ast_switch);

static int stateid = 1;
/* WARNING:
   When holding this list's lock, do _not_ do anything that will cause conlock
   to be taken, unless you _already_ hold it. The ast_merge_contexts_and_delete
   function will take the locks in conlock/hints order, so any other
   paths that require both locks must also take them in that order.
*/
static AST_LIST_HEAD_STATIC(hints, ast_hint);
struct ast_state_cb *statecbs;

/*
   \note This function is special. It saves the stack so that no matter
   how many times it is called, it returns to the same place */
int pbx_exec(struct ast_channel *c,       /*!< Channel */
        struct ast_app *app,     /*!< Application */
        void *data)        /*!< Data for execution */
{
   int res;

   const char *saved_c_appl;
   const char *saved_c_data;

   if (c->cdr && !ast_check_hangup(c))
      ast_cdr_setapp(c->cdr, app->name, data);

   /* save channel values */
   saved_c_appl= c->appl;
   saved_c_data= c->data;

   c->appl = app->name;
   c->data = data;
   /* XXX remember what to to when we have linked apps to modules */
   if (app->module) {
      /* XXX LOCAL_USER_ADD(app->module) */
   }
   res = app->execute(c, S_OR(data, ""));
   if (app->module) {
      /* XXX LOCAL_USER_REMOVE(app->module) */
   }
   /* restore channel values */
   c->appl = saved_c_appl;
   c->data = saved_c_data;
   return res;
}


/*! Go no deeper than this through includes (not counting loops) */
#define AST_PBX_MAX_STACK  128

/*! \brief Find application handle in linked list
 */
struct ast_app *pbx_findapp(const char *app)
{
   struct ast_app *tmp;

   AST_LIST_LOCK(&apps);
   AST_LIST_TRAVERSE(&apps, tmp, list) {
      if (!strcasecmp(tmp->name, app))
         break;
   }
   AST_LIST_UNLOCK(&apps);

   return tmp;
}

static struct ast_switch *pbx_findswitch(const char *sw)
{
   struct ast_switch *asw;

   AST_LIST_LOCK(&switches);
   AST_LIST_TRAVERSE(&switches, asw, list) {
      if (!strcasecmp(asw->name, sw))
         break;
   }
   AST_LIST_UNLOCK(&switches);

   return asw;
}

static inline int include_valid(struct ast_include *i)
{
   if (!i->hastime)
      return 1;

   return ast_check_timing(&(i->timing));
}

static void pbx_destroy(struct ast_pbx *p)
{
   free(p);
}

/*
 * Special characters used in patterns:
 * '_'   underscore is the leading character of a pattern.
 *    In other position it is treated as a regular char.
 * ' ' '-'  space and '-' are separator and ignored.
 * .  one or more of any character. Only allowed at the end of
 *    a pattern.
 * !  zero or more of anything. Also impacts the result of CANMATCH
 *    and MATCHMORE. Only allowed at the end of a pattern.
 *    In the core routine, ! causes a match with a return code of 2.
 *    In turn, depending on the search mode: (XXX check if it is implemented)
 *    - E_MATCH retuns 1 (does match)
 *    - E_MATCHMORE returns 0 (no match)
 *    - E_CANMATCH returns 1 (does match)
 *
 * /  should not appear as it is considered the separator of the CID info.
 *    XXX at the moment we may stop on this char.
 *
 * X Z N match ranges 0-9, 1-9, 2-9 respectively.
 * [  denotes the start of a set of character. Everything inside
 *    is considered literally. We can have ranges a-d and individual
 *    characters. A '[' and '-' can be considered literally if they
 *    are just before ']'.
 *    XXX currently there is no way to specify ']' in a range, nor \ is
 *    considered specially.
 *
 * When we compare a pattern with a specific extension, all characters in the extension
 * itself are considered literally with the only exception of '-' which is considered
 * as a separator and thus ignored.
 * XXX do we want to consider space as a separator as well ?
 * XXX do we want to consider the separators in non-patterns as well ?
 */

/*!
 * \brief helper functions to sort extensions and patterns in the desired way,
 * so that more specific patterns appear first.
 *
 * ext_cmp1 compares individual characters (or sets of), returning
 * an int where bits 0-7 are the ASCII code of the first char in the set,
 * while bit 8-15 are the cardinality of the set minus 1.
 * This way more specific patterns (smaller cardinality) appear first.
 * Wildcards have a special value, so that we can directly compare them to
 * sets by subtracting the two values. In particular:
 *    0x000xx     one character, xx
 *    0x0yyxx     yy character set starting with xx
 *    0x10000     '.' (one or more of anything)
 *    0x20000     '!' (zero or more of anything)
 *    0x30000     NUL (end of string)
 *    0x40000     error in set.
 * The pointer to the string is advanced according to needs.
 * NOTES:
 * 1. the empty set is equivalent to NUL.
 * 2. given that a full set has always 0 as the first element,
 *    we could encode the special cases as 0xffXX where XX
 *    is 1, 2, 3, 4 as used above.
 */
static int ext_cmp1(const char **p)
{
   uint32_t chars[8];
   int c, cmin = 0xff, count = 0;
   const char *end;

   /* load, sign extend and advance pointer until we find
    * a valid character.
    */
   while ( (c = *(*p)++) && (c == ' ' || c == '-') )
      ;  /* ignore some characters */

   /* always return unless we have a set of chars */
   switch (c) {
   default: /* ordinary character */
      return 0x0000 | (c & 0xff);

   case 'N':   /* 2..9 */
      return 0x0700 | '2' ;

   case 'X':   /* 0..9 */
      return 0x0900 | '0';

   case 'Z':   /* 1..9 */
      return 0x0800 | '1';

   case '.':   /* wildcard */
      return 0x10000;

   case '!':   /* earlymatch */
      return 0x20000;   /* less specific than NULL */

   case '\0':  /* empty string */
      *p = NULL;
      return 0x30000;

   case '[':   /* pattern */
      break;
   }
   /* locate end of set */
   end = strchr(*p, ']');  

   if (end == NULL) {
      ast_log(LOG_WARNING, "Wrong usage of [] in the extension\n");
      return 0x40000;   /* XXX make this entry go last... */
   }

   bzero(chars, sizeof(chars));  /* clear all chars in the set */
   for (; *p < end  ; (*p)++) {
      unsigned char c1, c2;   /* first-last char in range */
      c1 = (unsigned char)((*p)[0]);
      if (*p + 2 < end && (*p)[1] == '-') { /* this is a range */
         c2 = (unsigned char)((*p)[2]);
         *p += 2; /* skip a total of 3 chars */
      } else         /* individual character */
         c2 = c1;
      if (c1 < cmin)
         cmin = c1;
      for (; c1 <= c2; c1++) {
         uint32_t mask = 1 << (c1 % 32);
         if ( (chars[ c1 / 32 ] & mask) == 0)
            count += 0x100;
         chars[ c1 / 32 ] |= mask;
      }
   }
   (*p)++;
   return count == 0 ? 0x30000 : (count | cmin);
}

/*!
 * \brief the full routine to compare extensions in rules.
 */
static int ext_cmp(const char *a, const char *b)
{
   /* make sure non-patterns come first.
    * If a is not a pattern, it either comes first or
    * we use strcmp to compare the strings.
    */
   int ret = 0;

   if (a[0] != '_')
      return (b[0] == '_') ? -1 : strcmp(a, b);

   /* Now we know a is a pattern; if b is not, a comes first */
   if (b[0] != '_')
      return 1;
#if 0 /* old mode for ext matching */
   return strcmp(a, b);
#endif
   /* ok we need full pattern sorting routine */
   while (!ret && a && b)
      ret = ext_cmp1(&a) - ext_cmp1(&b);
   if (ret == 0)
      return 0;
   else
      return (ret > 0) ? 1 : -1;
}

/*!
 * When looking up extensions, we can have different requests
 * identified by the 'action' argument, as follows.
 * Note that the coding is such that the low 4 bits are the
 * third argument to extension_match_core.
 */
enum ext_match_t {
   E_MATCHMORE =  0x00, /* extension can match but only with more 'digits' */
   E_CANMATCH =   0x01, /* extension can match with or without more 'digits' */
   E_MATCH =   0x02, /* extension is an exact match */
   E_MATCH_MASK = 0x03, /* mask for the argument to extension_match_core() */
   E_SPAWN =   0x12, /* want to spawn an extension. Requires exact match */
   E_FINDLABEL =  0x22  /* returns the priority for a given label. Requires exact match */
};

/*
 * Internal function for ast_extension_{match|close}
 * return 0 on no-match, 1 on match, 2 on early match.
 * mode is as follows:
 * E_MATCH     success only on exact match
 * E_MATCHMORE success only on partial match (i.e. leftover digits in pattern)
 * E_CANMATCH  either of the above.
 */

static int _extension_match_core(const char *pattern, const char *data, enum ext_match_t mode)
{
   mode &= E_MATCH_MASK;   /* only consider the relevant bits */

   if ( (mode == E_MATCH) && (pattern[0] == '_') && (strcasecmp(pattern,data)==0) ) /* note: if this test is left out, then _x. will not match _x. !!! */
      return 1;

   if (pattern[0] != '_') { /* not a pattern, try exact or partial match */
      int ld = strlen(data), lp = strlen(pattern);

      if (lp < ld)      /* pattern too short, cannot match */
         return 0;
      /* depending on the mode, accept full or partial match or both */
      if (mode == E_MATCH)
         return !strcmp(pattern, data); /* 1 on match, 0 on fail */
      if (ld == 0 || !strncasecmp(pattern, data, ld)) /* partial or full match */
         return (mode == E_MATCHMORE) ? lp > ld : 1; /* XXX should consider '!' and '/' ? */
      else
         return 0;
   }
   pattern++; /* skip leading _ */
   /*
    * XXX below we stop at '/' which is a separator for the CID info. However we should
    * not store '/' in the pattern at all. When we insure it, we can remove the checks.
    */
   while (*data && *pattern && *pattern != '/') {
      const char *end;

      if (*data == '-') { /* skip '-' in data (just a separator) */
         data++;
         continue;
      }
      switch (toupper(*pattern)) {
      case '[':   /* a range */
         end = strchr(pattern+1, ']'); /* XXX should deal with escapes ? */
         if (end == NULL) {
            ast_log(LOG_WARNING, "Wrong usage of [] in the extension\n");
            return 0;   /* unconditional failure */
         }
         for (pattern++; pattern != end; pattern++) {
            if (pattern+2 < end && pattern[1] == '-') { /* this is a range */
               if (*data >= pattern[0] && *data <= pattern[2])
                  break;   /* match found */
               else {
                  pattern += 2; /* skip a total of 3 chars */
                  continue;
               }
            } else if (*data == pattern[0])
               break;   /* match found */
         }
         if (pattern == end)
            return 0;
         pattern = end; /* skip and continue */
         break;
      case 'N':
         if (*data < '2' || *data > '9')
            return 0;
         break;
      case 'X':
         if (*data < '0' || *data > '9')
            return 0;
         break;
      case 'Z':
         if (*data < '1' || *data > '9')
            return 0;
         break;
      case '.':   /* Must match, even with more digits */
         return 1;
      case '!':   /* Early match */
         return 2;
      case ' ':
      case '-':   /* Ignore these in patterns */
         data--; /* compensate the final data++ */
         break;
      default:
         if (*data != *pattern)
            return 0;
      }
      data++;
      pattern++;
   }
   if (*data)        /* data longer than pattern, no match */
      return 0;
   /*
    * match so far, but ran off the end of the data.
    * Depending on what is next, determine match or not.
    */
   if (*pattern == '\0' || *pattern == '/')  /* exact match */
      return (mode == E_MATCHMORE) ? 0 : 1;  /* this is a failure for E_MATCHMORE */
   else if (*pattern == '!')        /* early match */
      return 2;
   else                 /* partial match */
      return (mode == E_MATCH) ? 0 : 1;   /* this is a failure for E_MATCH */
}

/*
 * Wrapper around _extension_match_core() to do performance measurement
 * using the profiling code.
 */
static int extension_match_core(const char *pattern, const char *data, enum ext_match_t mode)
{
   int i;
   static int prof_id = -2;   /* marker for 'unallocated' id */
   if (prof_id == -2)
      prof_id = ast_add_profile("ext_match", 0);
   ast_mark(prof_id, 1);
   i = _extension_match_core(pattern, data, mode);
   ast_mark(prof_id, 0);
   return i;
}

int ast_extension_match(const char *pattern, const char *data)
{
   return extension_match_core(pattern, data, E_MATCH);
}

int ast_extension_close(const char *pattern, const char *data, int needmore)
{
   if (needmore != E_MATCHMORE && needmore != E_CANMATCH)
      ast_log(LOG_WARNING, "invalid argument %d\n", needmore);
   return extension_match_core(pattern, data, needmore);
}

struct ast_context *ast_context_find(const char *name)
{
   struct ast_context *tmp = NULL;

   ast_rdlock_contexts();

   while ( (tmp = ast_walk_contexts(tmp)) ) {
      if (!name || !strcasecmp(name, tmp->name))
         break;
   }

   ast_unlock_contexts();

   return tmp;
}

#define STATUS_NO_CONTEXT  1
#define STATUS_NO_EXTENSION   2
#define STATUS_NO_PRIORITY 3
#define STATUS_NO_LABEL    4
#define STATUS_SUCCESS     5

static int matchcid(const char *cidpattern, const char *callerid)
{
   /* If the Caller*ID pattern is empty, then we're matching NO Caller*ID, so
      failing to get a number should count as a match, otherwise not */

   if (ast_strlen_zero(callerid))
      return ast_strlen_zero(cidpattern) ? 1 : 0;

   return ast_extension_match(cidpattern, callerid);
}

/* request and result for pbx_find_extension */
struct pbx_find_info {
#if 0
   const char *context;
   const char *exten;
   int priority;
#endif

   char *incstack[AST_PBX_MAX_STACK];      /* filled during the search */
   int stacklen;                   /* modified during the search */
   int status;                     /* set on return */
   struct ast_switch *swo;         /* set on return */
   const char *data;               /* set on return */
   const char *foundcontext;       /* set on return */
};

static struct ast_exten *pbx_find_extension(struct ast_channel *chan,
   struct ast_context *bypass, struct pbx_find_info *q,
   const char *context, const char *exten, int priority,
   const char *label, const char *callerid, enum ext_match_t action)
{
   int x, res;
   struct ast_context *tmp;
   struct ast_exten *e, *eroot;
   struct ast_include *i;
   struct ast_sw *sw;
   char *tmpdata = NULL;

   /* Initialize status if appropriate */
   if (q->stacklen == 0) {
      q->status = STATUS_NO_CONTEXT;
      q->swo = NULL;
      q->data = NULL;
      q->foundcontext = NULL;
   }
   /* Check for stack overflow */
   if (q->stacklen >= AST_PBX_MAX_STACK) {
      ast_log(LOG_WARNING, "Maximum PBX stack exceeded\n");
      return NULL;
   }
   /* Check first to see if we've already been checked */
   for (x = 0; x < q->stacklen; x++) {
      if (!strcasecmp(q->incstack[x], context))
         return NULL;
   }
   if (bypass) /* bypass means we only look there */
      tmp = bypass;
   else {   /* look in contexts */
      tmp = NULL;
      while ((tmp = ast_walk_contexts(tmp)) ) {
         if (!strcmp(tmp->name, context))
            break;
      }
      if (!tmp)
         return NULL;
   }
   if (q->status < STATUS_NO_EXTENSION)
      q->status = STATUS_NO_EXTENSION;

   /* scan the list trying to match extension and CID */
   eroot = NULL;
   while ( (eroot = ast_walk_context_extensions(tmp, eroot)) ) {
      int