pbx.c

/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Core PBX routines.
 * 
 * Copyright (C) 1999, Mark Spencer
 *
 * Mark Spencer <markster@linux-support.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#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/term.h>
#include <asterisk/manager.h>
#include <asterisk/ast_expr.h>
#include <asterisk/channel_pvt.h>
#include <asterisk/linkedlists.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <setjmp.h>
#include <ctype.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include "asterisk.h"

/*
 * 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 ;-) 
 *
 */


struct ast_context;

struct ast_pbx {
	int dtimeout;					/* Timeout between digits (seconds) */
	int rtimeout;					/* Timeout for response (seconds) */
};

/* An extension */
struct ast_exten {
	char exten[AST_MAX_EXTENSION];
	int matchcid;
	char cidmatch[AST_MAX_EXTENSION];
	int priority;
	/* An extension */
	struct ast_context *parent;
	/* Application to execute */
	char app[AST_MAX_EXTENSION];
	/* Data to use */
	void *data;
	/* Data destructor */
	void (*datad)(void *);
	/* Next higher priority with our extension */
	struct ast_exten *peer;
	/* Registrar */
	char *registrar;
	/* Extension with a greater ID */
	struct ast_exten *next;
};

struct ast_include {
	char name[AST_MAX_EXTENSION];
	char rname[AST_MAX_EXTENSION];
	char *registrar;
	int hastime;
	unsigned int monthmask;
	unsigned int daymask;
	unsigned int dowmask;
	unsigned int minmask[24];
	struct ast_include *next;
};

struct ast_sw {
	char name[AST_MAX_EXTENSION];
	char *registrar;
	char data[AST_MAX_EXTENSION];
	struct ast_sw *next;
};

struct ast_ignorepat {
	char pattern[AST_MAX_EXTENSION];
	char *registrar;
	struct ast_ignorepat *next;
};

/* An extension context */
struct ast_context {
	/* Name of the context */
	char name[AST_MAX_EXTENSION];
	/* A lock to prevent multiple threads from clobbering the context */
	pthread_mutex_t lock;
	/* The root of the list of extensions */
	struct ast_exten *root;
	/* Link them together */
	struct ast_context *next;
	/* Include other contexts */
	struct ast_include *includes;
	/* Patterns for which to continue playing dialtone */
	struct ast_ignorepat *ignorepats;
	/* Registrar */
	char *registrar;
	/* Alternative switches */
	struct ast_sw *alts;
};


/* An application */
struct ast_app {
	/* Name of the application */
	char name[AST_MAX_APP];
	int (*execute)(struct ast_channel *chan, void *data);
	char *synopsis;
	char *description;
	struct ast_app *next;
};

static int pbx_builtin_prefix(struct ast_channel *, void *);
static int pbx_builtin_stripmsd(struct ast_channel *, void *);
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_dtimeout(struct ast_channel *, void *);
static int pbx_builtin_rtimeout(struct ast_channel *, void *);
static int pbx_builtin_atimeout(struct ast_channel *, void *);
static int pbx_builtin_wait(struct ast_channel *, void *);
static int pbx_builtin_setlanguage(struct ast_channel *, void *);
static int pbx_builtin_ringing(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_setvar(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 *);
void pbx_builtin_setvar_helper(struct ast_channel *chan, char *name, char *value);
char *pbx_builtin_getvar_helper(struct ast_channel *chan, char *name);

static struct varshead globals = AST_LIST_HEAD_INITIALIZER(varshead);

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(): If the channel is ringing, answer it, otherwise do nothing. \n"
"Returns 0 unless it tries to answer the channel and fails.\n"   },

	{ "Goto", pbx_builtin_goto, 
"Goto a particular priority, extension, or context",
"  Goto([[context|]extension|]priority):  Set the  priority to the specified\n"
"value, optionally setting the extension and optionally the context as well.\n"
"The extension BYEXTENSION is special in that it uses the current extension,\n"
"thus  permitting  you  to go to a different  context, without  specifying a\n"
"specific extension. Always returns 0, even if the given context, extension,\n"
"or priority is invalid.\n" },

	{ "Hangup", pbx_builtin_hangup,
"Unconditional hangup",
"  Hangup(): Unconditionally hangs up a given channel by returning -1 always.\n" },

	{ "DigitTimeout", pbx_builtin_dtimeout,
"Set maximum timeout between digits",
"  DigitTimeout(seconds): Set the  maximum  amount of time permitted between\n"
"digits when the user is typing in an extension.  When this timeout expires,\n"
"after the user has started to  type  in an extension, the extension will be\n"
"considered  complete, and  will be interpreted.  Note that if an  extension\n"
"typed in is valid, it will not have to timeout to be tested,  so  typically\n"
"at  the  expiry of  this timeout, the  extension will be considered invalid\n"
"(and  thus  control  would be passed to the 'i' extension, or if it doesn't\n"
"exist the call would be terminated).  Always returns 0.\n" },

	{ "ResponseTimeout", pbx_builtin_rtimeout,
"Set maximum timeout awaiting response",
"  ResponseTimeout(seconds): Set the maximum amount of time permitted after\n"
"falling through a series of priorities for a channel in which the user may\n"
"begin typing an extension.  If the user does not type an extension in this\n"
"amount of time, control will pass to the 't' extension if  it  exists, and\n"
"if not the call would be terminated.  Always returns 0.\n"  },

	{ "AbsoluteTimeout", pbx_builtin_atimeout,
"Set absolute maximum time of call",
"  AbsoluteTimeout(seconds): Set the absolute maximum amount of time permitted\n"
"for a call.  A setting of 0 disables the timeout.  Always returns 0.\n" },

	{ "BackGround", pbx_builtin_background,
"Play a file while awaiting extension",
"  Background(filename): Plays a given file, while simultaneously waiting for\n"
"the user to begin typing an extension. The  timeouts  do not count until the\n"
"last BackGround application as ended. Always returns 0.\n" },

	{ "Wait", pbx_builtin_wait, 
"Waits for some time", 
"  Wait(seconds): Waits for a specified number of seconds, then returns 0.\n" },

	{ "StripMSD", pbx_builtin_stripmsd,
"Strip leading digits",
"  StripMSD(count): Strips the leading  'count'  digits  from  the  channel's\n"
"associated extension. For example, the  number  5551212 when stripped with a\n"
"count of 3 would be changed to 1212.  This app always returns 0, and the PBX\n"
"will continue processing at the next priority for the *new* extension.\n"
"  So, for  example, if  priority 3 of 5551212  is  StripMSD 3, the next step\n"
"executed will be priority 4 of 1212.  If you switch into an  extension which\n"
"has no first step, the PBX will treat it as though the user dialed an\n"
"invalid extension.\n" },

	{ "Prefix", pbx_builtin_prefix, 
"Prepend leading digits",
"  Prefix(digits): Prepends the  digit  string  specified  by  digits to the\n"
"channel's associated extension. For example, the number 1212 when  prefixed\n"
"with '555' will become 5551212. This app always returns 0, and the PBX will\n"
"continue processing at the next priority for the *new* extension.\n"
"  So, for example, if priority  3  of 1212 is  Prefix  555, the  next  step\n"
"executed will be priority 4 of 5551212. If  you  switch  into an  extension\n"
"which has no first step, the PBX will treat it as though the user dialed an\n"
"invalid extension.\n" },

	{ "SetLanguage", pbx_builtin_setlanguage,
"Sets user language",
"  SetLanguage(language):  Set  the  channel  language to 'language'.  This\n"
"information is used for the generation of numbers, and to select a natural\n"
"language file when available.  For example, if language is set to 'fr' and\n"
"the file 'demo-congrats' is requested  to  be  played,  if the file 'demo-\n"
"congrats-fr' exists, then it will play that file, and if not will play the\n"
"normal 'demo-congrats'. Always returns 0.\n"  },

	{ "Ringing", pbx_builtin_ringing,
"Indicate ringing tone",
"  Ringing(): Request that the channel indicate ringing tone to the user.\n"
"Always returns 0.\n" },

	{ "Congestion", pbx_builtin_congestion,
"Indicate congestion and stop",
"  Congestion(): Requests that the channel indicate congestion and then\n"
"waits for the user to hang up.  Always returns -1." },

	{ "Busy", pbx_builtin_busy,
"Indicate busy condition and stop",
"  Busy(): Requests that the channel indicate busy condition and then waits\n"
"for the user to hang up.  Always returns -1." },

	{ "SetVar", pbx_builtin_setvar,
"Set variable to value",
"  Setvar(#n=value): Sets variable n to value" },

	{ "SetGlobalVar", pbx_builtin_setglobalvar,
"Set variable to value",
"  Setvar(#n=value): Sets global variable n to value" },

	{ "NoOp", pbx_builtin_noop,
"No operation",
"  NoOp(): No-operation; Does nothing." },

	{ "GotoIf", pbx_builtin_gotoif,
"Conditional goto",
"  GotoIf(Condition?label1:label2): Go to label 1 if condition is\n"
"true, to label2 if condition is false. Either label1 or label2 may be\n"
"omitted (in that case, we just don't take the particular branch) but not\n"
"both.  Look for the condition syntax in examples or documentation." },

};

/* Lock for the application list */
static pthread_mutex_t applock = AST_MUTEX_INITIALIZER;
static struct ast_context *contexts = NULL;
/* Lock for the ast_context list */
static pthread_mutex_t conlock = AST_MUTEX_INITIALIZER;
static struct ast_app *apps = NULL;

/* Lock for switches */
static pthread_mutex_t switchlock = AST_MUTEX_INITIALIZER;
struct ast_switch *switches = NULL;

int pbx_exec(struct ast_channel *c, /* Channel */
					struct ast_app *app,
					void *data,				/* Data for execution */
					int newstack)			/* Force stack increment */
{
	/* 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 res;
	int stack = c->stack;
	int (*execute)(struct ast_channel *chan, void *data) = app->execute; 
	if (newstack && stack > AST_CHANNEL_MAX_STACK - 2) {
		/* Don't allow us to go over the max number of stacks we
		   permit saving. */
		ast_log(LOG_WARNING, "Stack overflow, cannot create another stack\n");
		return -1;
	}
	if (newstack && (res = setjmp(c->jmp[++c->stack]))) {
		/* Okay, here's where it gets weird.  If newstack is non-zero, 
		   then we increase the stack increment, but setjmp is not going
		   to return until longjmp is called -- when the application
		   exec'd is finished running. */
		if (res == 1)
			res = 0;
		if (c->stack != stack + 1) 
			ast_log(LOG_WARNING, "Stack returned to an unexpected place!\n");
		else if (c->app[c->stack])
			ast_log(LOG_WARNING, "Application may have forgotten to free its memory\n");
		c->stack = stack;
		return res;
	} else {
		if (c->cdr)
			ast_cdr_setapp(c->cdr, app->name, data);
		c->appl = app->name;
		c->data = data;		
		res = execute(c, data);
		c->appl = NULL;
		c->data = NULL;		
		/* Any application that returns, we longjmp back, just in case. */
		if (c->stack != stack + 1)
			ast_log(LOG_WARNING, "Stack is not at expected value\n");
		longjmp(c->jmp[stack+1], res);
		/* Never returns */
	}
}


/* Go no deeper than this through includes (not counting loops) */
#define AST_PBX_MAX_STACK	64

#define HELPER_EXISTS 0
#define HELPER_SPAWN 1
#define HELPER_EXEC 2
#define HELPER_CANMATCH 3
#define HELPER_MATCHMORE 4

struct ast_app *pbx_findapp(char *app) 
{
	struct ast_app *tmp;
	if (ast_pthread_mutex_lock(&applock)) {
		ast_log(LOG_WARNING, "Unable to obtain application lock\n");
		return NULL;
	}
	tmp = apps;
	while(tmp) {
		if (!strcasecmp(tmp->name, app))
			break;
		tmp = tmp->next;
	}
	ast_pthread_mutex_unlock(&applock);
	return tmp;
}

static struct ast_switch *pbx_findswitch(char *sw)
{
	struct ast_switch *asw;
	if (ast_pthread_mutex_lock(&switchlock)) {
		ast_log(LOG_WARNING, "Unable to obtain application lock\n");
		return NULL;
	}
	asw = switches;
	while(asw) {
		if (!strcasecmp(asw->name, sw))
			break;
		asw = asw->next;
	}
	ast_pthread_mutex_unlock(&switchlock);
	return asw;
}

static inline int include_valid(struct ast_include *i)
{
	struct tm *tm;
	time_t t;
	if (!i->hastime)
		return 1;
	time(&t);
	tm = localtime(&t);
	if (!tm) {
		ast_log(LOG_WARNING, "Failed to get local time\n");
		return 0;
	}

	/* If it's not the right month, return */
	if (!(i->monthmask & (1 << tm->tm_mon))) {
		return 0;
	}

	/* If it's not that time of the month.... */
	/* Warning, tm_mday has range 1..31! */
	if (!(i->daymask & (1 << (tm->tm_mday-1))))
		return 0;

	/* If it's not the right day of the week */
	if (!(i->dowmask & (1 << tm->tm_wday)))
		return 0;

	/* Sanity check the hour just to be safe */
	if ((tm->tm_hour < 0) || (tm->tm_hour > 23)) {
		ast_log(LOG_WARNING, "Insane time...\n");
		return 0;
	}

	/* Now the tough part, we calculate if it fits
	   in the right time based on min/hour */
	if (!(i->minmask[tm->tm_hour] & (1 << (tm->tm_min / 2))))
		return 0;

	/* If we got this far, then we're good */
	return 1;
}

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

#define EXTENSION_MATCH_CORE(data,pattern,match) {\
	/* All patterns begin with _ */\
	if (pattern[0] != '_') \
		return 0;\
	/* Start optimistic */\
	match=1;\
	pattern++;\
	while(match && *data && *pattern && (*pattern != '/')) {\
		switch(toupper(*pattern)) {\
		case '[': \
		{\
			int i,border=0;\
			char *where;\
			match=0;\
			pattern++;\
			where=strchr(pattern,']');\
			if (where)\
				border=(int)(where-pattern);\
			if (!where || border > strlen(pattern)) {\
				ast_log(LOG_WARNING, "Wrong usage of [] in the extension\n");\
				return match;\
			}\
			for (i=0; i<border; i++) {\
				int res=0;\
				if (i+2<border)\
					if (pattern[i+1]=='-') {\
						if (*data >= pattern[i] && *data <= pattern[i+2]) {\
							res=1;\
						} else {\
							i+=2;\
							continue;\
						}\
					}\
				if (res==1 || *data==pattern[i]) {\
					match = 1;\
					break;\
				}\
			}\
			pattern+=border;\
			break;\
		}\
		case 'N':\
			if ((*data < '2') || (*data > '9'))\
				match=0;\
			break;\
		case 'X':\
			if ((*data < '0') || (*data > '9'))\
				match = 0;\
			break;\
		case 'Z':\
			if ((*data < '1') || (*data > '9'))\
				match = 0;\
			break;\
		case '.':\
			/* Must match */\
			return 1;\
		case ' ':\
		case '-':\
			/* Ignore these characters */\
			data--;\
			break;\
		default:\
			if (*data != *pattern)\
				match =0;\
		}\
		data++;\
		pattern++;\
	}\
}

int ast_extension_match(char *pattern, char *data)
{
	int match;
	/* If they're the same return */
	if (!strcasecmp(pattern, data))
		return 1;
	EXTENSION_MATCH_CORE(data,pattern,match);
	/* Must be at the end of both */
	if (*data || (*pattern && (*pattern != '/')))
		match = 0;
	return match;
}

static int extension_close(char *pattern, char *data, int needmore)
{
	int match;
	/* If "data" is longer, it can'be a subset of pattern unless
	   pattern is a pattern match */
	if ((strlen(pattern) < strlen(data)) && (pattern[0] != '_'))
		return 0;
	
	if ((!strlen((char *)data) || !strncasecmp(pattern, data, strlen(data))) && 
		(!needmore || (strlen(pattern) > strlen(data)))) {
		return 1;
	}
	EXTENSION_MATCH_CORE(data,pattern,match);
	/* If there's more or we don't care about more, return non-zero, otlherwise it's a miss */
	if (!needmore || *pattern) {
		return match;
	} else
		return 0;
}

struct ast_context *ast_context_find(char *name)
{
	struct ast_context *tmp;
	ast_pthread_mutex_lock(&conlock);
	if (name) {
		tmp = contexts;
		while(tmp) {
			if (!strcasecmp(name, tmp->name))
				break;
			tmp = tmp->next;
		}
	} else
		tmp = contexts;
	ast_pthread_mutex_unlock(&conlock);
	return tmp;
}

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

static int matchcid(char *cidpattern, char *callerid)
{
	char tmp[AST_MAX_EXTENSION];
	int failresult;
	char *name, *num;
	
	/* 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 (strlen(cidpattern))
		failresult = 0;
	else
		failresult = 1;

	if (!callerid)
		return failresult;

	/* Copy original Caller*ID */
	strncpy(tmp, callerid, sizeof(tmp)-1);
	/* Parse Number */
	if (ast_callerid_parse(tmp, &name, &num)) 
		return failresult;
	if (!num)
		return failresult;
	ast_shrink_phone_number(num);
	return ast_extension_match(cidpattern, num);
}

static struct ast_exten *pbx_find_extension(struct ast_channel *chan, char *context, char *exten, int priority, char *callerid, int action, char *incstack[], int *stacklen, int *status, struct ast_switch **swo, char **data)
{
	int x, res;
	struct ast_context *tmp;
	struct ast_exten *e, *eroot;
	struct ast_include *i;
	struct ast_sw *sw;
	struct ast_switch *asw;
	/* Initialize status if appropriate */
	if (!*stacklen) {
		*status = STATUS_NO_CONTEXT;
		*swo = NULL;
		*data = NULL;
	}
	/* Check for stack overflow */
	if (*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<*stacklen;x++) {
		if (!strcasecmp(incstack[x], context))
			return NULL;
	}
	tmp = contexts;
	while(tmp) {
		/* Match context */
		if (!strcasecmp(tmp->name, context)) {
			if (*status < STATUS_NO_EXTENSION)
				*status = STATUS_NO_EXTENSION;
			eroot = tmp->root;
			while(eroot) {
				/* Match extension */
				if ((((action != HELPER_MATCHMORE) && ast_extension_match(eroot->exten, exten)) ||
						((action == HELPER_CANMATCH) && (extension_close(eroot->exten, exten, 0))) ||
						((action == HELPER_MATCHMORE) && (extension_close(eroot->exten, exten, 1)))) &&
						(!eroot->matchcid || matchcid(eroot->cidmatch, callerid))) {
						e = eroot;
						if (*status < STATUS_NO_PRIORITY)
							*status = STATUS_NO_PRIORITY;
						while(e) {
							/* Match priority */
							if (e->priority == priority) {
								*status = STATUS_SUCCESS;
								return e;
							}
							e = e->peer;
						}
				}
				eroot = eroot->next;
			}
			/* Check alternative switches */
			sw = tmp->alts;
			while(sw) {
				if ((asw = pbx_findswitch(sw->name))) {
					if (action == HELPER_CANMATCH)
						res = asw->canmatch ? asw->canmatch(chan, context, exten, priority, callerid, sw->data) : 0;
					else if (action == HELPER_MATCHMORE)
						res = asw->matchmore ? asw->matchmore(chan, context, exten, priority, callerid, sw->data) : 0;
					else
						res = asw->exists ? asw->exists(chan, context, exten, priority, callerid, sw->data) : 0;
					if (res) {
						/* Got a match */
						*swo = asw;
						*data = sw->data;
						return NULL;
					}
				} else {
					ast_log(LOG_WARNING, "No such switch '%s'\n", sw->name);
				}
				sw = sw->next;
			}
			/* Setup the stack */
			incstack[*stacklen] = tmp->name;
			(*stacklen)++;
			/* Now try any includes we have in this context */
			i = tmp->includes;
			while(i) {
				if (include_valid(i)) {
					if ((e = pbx_find_extension(chan, i->rname, exten, priority, callerid, action, incstack, stacklen, status, swo, data))) 
						return e;
					if (*swo) 
						return NULL;
				}
				i = i->next;
			}
		}
		tmp = tmp->next;
	}
	return NULL;
}

static void pbx_substitute_variables_temp(struct ast_channel *c,char *cp3,char **cp4)
{
	int offset;
	struct ast_var_t *variables;
	char *name, *num; /* for callerid name + num variables */
	struct varshead *headp;
	char pri[80];
        headp=&c->varshead;
        *cp4=NULL;
	        		/* Now we have the variable name on cp3 */
				if (!strcmp(cp3, "CALLERIDNUM")) {
						char cid[256] = "";
						if (c->callerid)
							strncpy(cid, c->callerid, sizeof(cid) - 1);
						ast_callerid_parse(cid, &name, &num);
						if (num) {
							ast_shrink_phone_number(num);
							*cp4 = num;
						} else
							*cp4 = "";
					} else if (!strcmp(cp3, "CALLERIDNAME")) {
						char cid[256] = "";
						if (c->callerid)
							strncpy(cid, c->callerid, sizeof(cid) - 1);
						ast_callerid_parse(cid, &name, &num);
						if (name)
							*cp4 = name;
						else
							*cp4 = "";
	        			} else if (!strcmp(cp3, "CALLERID")) {
						*cp4 = c->callerid;
						if (!(*cp4))
							*cp4 = "";
					} else if (!strcmp(cp3, "EXTEN")) {
						*cp4 = c->exten;
					} else if (!strncmp(cp3, "EXTEN-", strlen("EXTEN-")) && 
						/* XXX Remove me eventually */
						(sscanf(cp3 + strlen("EXTEN-"), "%d", &offset) == 1)) {
						if (offset < 0)
							offset=0;
						if (offset > strlen(c->exten))
							offset = strlen(c->exten);
						*cp4 = c->exten + offset;
						ast_log(LOG_WARNING, "The use of 'EXTEN-foo' has been derprecated in favor of 'EXTEN:foo'\n");
					} else if (!strncmp(cp3, "EXTEN:", strlen("EXTEN:")) && 
						(sscanf(cp3 + strlen("EXTEN:"), "%d", &offset) == 1)) {
						if (offset < 0)
							offset=0;
						if (offset > strlen(c->exten))
							offset = strlen(c->exten);
						*cp4 = c->exten + offset;
					} else if (!strcmp(cp3, "RDNIS")) {
						*cp4 = c->rdnis;
						if (!(*cp4))
							*cp4 = "";
					} else if (!strcmp(cp3, "CONTEXT")) {
						*cp4 = c->context;
					} else if (!strcmp(cp3, "PRIORITY")) {
						snprintf(pri, sizeof(pri), "%d", c->priority);
						*cp4 = pri;
					} else {
		        		AST_LIST_TRAVERSE(headp,variables,entries) {
#if 0
		        			ast_log(LOG_WARNING,"Comparing variable '%s' with '%s'\n",cp3,ast_var_name(variables));
#endif
							if (strcasecmp(ast_var_name(variables),cp3)==0)
								*cp4=ast_var_value(variables);
						}
						if (!(*cp4)) {
							/* Try globals */
			        		AST_LIST_TRAVERSE(&globals,variables,entries) {
#if 0
			        			ast_log(LOG_WARNING,"Comparing variable '%s' with '%s'\n",cp3,ast_var_name(variables));
#endif
								if (strcasecmp(ast_var_name(variables),cp3)==0)
									*cp4=ast_var_value(variables);
							}
						}
						if (!(*cp4)) {
							int len=strlen(cp3);
							int len_env=strlen("ENV(");
							if (len > (len_env+1) && !strncasecmp(cp3,"ENV(",len_env) && !strcmp(cp3+len-1,")")) {
								cp3[len-1]='\0';
								*cp4=getenv(cp3+len_env);
							}
						}
					}
}

static void pbx_substitute_variables_helper(struct ast_channel *c,char *cp1,char **ecp2,int count)
{
	char *cp4,*cp2;
	char *tmp,*wherearewe,*finish,*ltmp,*lval,*nextvar;
	int length,variables=0;

	wherearewe=tmp=cp1;
	cp2=*ecp2;
	*cp2='\0';
	do {
		char *start,*start2;
		if ((tmp=strstr(wherearewe,"${"))) {
			variables++;
			length=(int)(tmp-wherearewe);
			strncat(cp2,wherearewe,length);
			wherearewe=tmp;
			
			ltmp=malloc(sizeof(char)*256);
			start=start2=tmp+1;
			do {
				if (variables==0) {
					nextvar=strstr(start2,"${");
					if (nextvar) {
						if ((int)(finish-nextvar)>0) {
							variables++;
							start2=nextvar+1;
						} else break;
					} else break;
				}
				finish=strchr(start,'}');
				if (finish) {
					variables--;
					start=finish+1;
				} else {
					if (variables>0) {
						ast_log(LOG_NOTICE, "Error in extension logic\n");
						cp2[0]='\0';
						return;
					}
					break;
				}
			} while (1);
			
			length=(int)(finish-tmp);
			wherearewe+=length+1;
			lval=strndup(tmp+2,length-2);
			pbx_substitute_variables_helper(c,lval,&ltmp,count+1);
			free(lval);
			if (ltmp) {
				length=strlen(ltmp);
				strncat(cp2,ltmp,length);
			}
		} else {
			if (wherearewe!=cp1) {
				if (*wherearewe) {
					length=strlen(wherearewe);
					strncat(cp2,wherearewe,length);
				}
				strcat(cp2,"\0");
				
				cp1=cp2;
			}
			if (count) {			
				pbx_substitute_variables_temp(c,cp1,&cp4);
				if (cp4) {
					/* reset output variable so we could store the result */
					*cp2='\0';
					length=strlen(cp4);
					strncat(cp2,cp4,length);
				} else
					cp2[0]='\0';
			}
			break;
		}
	} while(1);
}

static void *pbx_substitute_variables(struct ast_channel *c, struct ast_exten *e) {
	char *cp1,*cp3,*cp4,*cp5;
	char *cp2;
	char c1,c2;
	int m,mve,origlen,quoted,dolsign,docopy;
        
	/* No variables or expressions in e->data, so why scan it? */
	if (!strstr(e->data,"${") && !strstr(e->data,"$[")) {
		return strndup(e->data,strlen(e->data)+1);
	}
	
	cp1=e->data;
	cp2=malloc(sizeof(char)*256);
	pbx_substitute_variables_helper(c,cp1,(char **)&cp2,0);

	/* Second stage, expression evaluation */
	if ((strstr(cp2,"$[")==NULL)) {
		/* No expressions in cp2, return it */
		return(cp2);
	}
	/* else, do expression evaluation */
	
	dolsign=0;
	docopy=1;
	origlen=strlen(cp2)+1;
	
	cp5=malloc(origlen);
	memset(cp5,0,origlen);
	cp4=NULL;
	cp1=cp2;
	quoted=0;
	
	do {
		c1=*cp1;
		mve=0;
	        switch (c1) {
	        	case '$' : 
	        		dolsign=1;
	        		docopy=0;
	        		break;
	        	case '[' :
	        		if (dolsign==0) {
	        			docopy=1;
	        			dolsign=0;
	        			break;
	        		}
	        		dolsign=0;
	        		docopy=0;
	        		m=0;
	        		mve=1;
	        		cp1++;
	        		
	        		while (((c2=*(cp1+m))!=']') && (c2!='\0')) {
	        			m++;
	        		}
	        		cp3=malloc(m+2);
	        		strncpy(cp3,cp1,m);
	        		cp3[m]='\0';
	        		cp1+=m;
	        		/* Now we have the expression to evaluate on cp3 */
	        		cp4=ast_expr(cp3);
	        		free(cp3);
	        		break;
	        	default :
	        		if (dolsign==1) {
	        			strncat((char *)cp5,"$",1);
	        		}
	        		dolsign=0;
	        		docopy=1;
	        		mve=0;
	        		break;
	        }
	        if (cp1!='\0') {
	        	if (mve==0) {
	        		if (docopy==1) {
		        		strncat((char *)cp5,&c1,1);
		        	}
	        	} else {
	        		if (cp4!=NULL) {
		        		cp5=realloc(cp5,origlen+strlen(cp4)+1);
		        		strncat((char *)cp5,cp4,strlen(cp4));
		        		free(cp4);
		        	} else {
		        		ast_log(LOG_WARNING,"mve!=0 and cp4=NULL, something gone astray\n");
		        	}
	        	}
	        }
	                
	} while (*cp1++!='\0');
	free(cp2);
	return(cp5);
}
	        		
	        	
		                                                

static int pbx_extension_helper(struct ast_channel *c, char *context, char *exten, int priority, char *callerid, int action) 
{
	struct ast_exten *e;
	struct ast_app *app;
	struct ast_switch *sw;
	char *data;
	char *newdata;
	int newstack = 0;
	int res;
	int status = 0;
	char *incstack[AST_PBX_MAX_STACK];
	int stacklen = 0;
	char tmp[80];
	char tmp2[80];
	char tmp3[256];
	if (ast_pthread_mutex_lock(&conlock)) {
		ast_log(LOG_WARNING, "Unable to obtain lock\n");
		if ((action == HELPER_EXISTS) || (action == HELPER_CANMATCH) || (action == HELPER_MATCHMORE))
			return 0;
		else
			return -1;
	}
	e = pbx_find_extension(c, context, exten, priority, callerid, action, incstack, &stacklen, &status, &sw, &data);
	if (e) {
		switch(action) {
		case HELPER_CANMATCH:
			pthread_mutex_unlock(&conlock);
			return -1;
		case HELPER_EXISTS:
			pthread_mutex_unlock(&conlock);
			return -1;
		case HELPER_MATCHMORE:
			pthread_mutex_unlock(&conlock);
			return -1;
		case HELPER_SPAWN:
			newstack++;
			/* Fall through */
		case HELPER_EXEC:
			app = pbx_findapp(e->app);
			pthread_mutex_unlock(&conlock);
			if (app) {
				strncpy(c->context, context, sizeof(c->context-1));
				strncpy(c->exten, exten, sizeof(c->exten)-1);
				c->priority = priority;
				newdata=pbx_substitute_variables(c,e);
				if (option_debug)
						ast_log(LOG_DEBUG, "Launching '%s'\n", app->name);
				else if (option_verbose > 2)
						ast_verbose( VERBOSE_PREFIX_3 "Executing %s(\"%s\", \"%s\") %s\n", 
								term_color(tmp, app->name, COLOR_BRCYAN, 0, sizeof(tmp)),
								term_color(tmp2, c->name, COLOR_BRMAGENTA, 0, sizeof(tmp2)),
								term_color(tmp3, (newdata ? (char *)newdata : NULL), COLOR_BRMAGENTA, 0, sizeof(tmp3)),
								(newstack ? "in new stack" : "in same stack"));
				res = pbx_exec(c, app, newdata, newstack);
				free(newdata);
				return res;
			} else {
				ast_log(LOG_WARNING, "No application '%s' for extension (%s, %s, %d)\n", e->app, context, exten, priority);
				return -1;
			}