main/pbx: Move variable routines to pbx_variables.c.

This is the third patch in a series meant to reduce the bulk of pbx.c.
This moves channel and global variable routines to their own source.

Change-Id: Ibe8fb4647db11598591d443a99e3f99200a56bc6

1 files changed, 1180 insertions, 0 deletions

diff --git a/main/pbx_variables.c b/main/pbx_variables.c
new file mode 100644
index 000000000..c02bdc8cc
--- /dev/null
+++ b/main/pbx_variables.c
@@ -0,0 +1,1180 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2016, CFWare, LLC
+ *
+ * Corey Farrell <git@cfware.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 PBX variables routines.
+ *
+ * \author Corey Farrell <git@cfware.com>
+ */
+
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include "asterisk/_private.h"
+#include "asterisk/app.h"
+#include "asterisk/ast_expr.h"
+#include "asterisk/chanvars.h"
+#include "asterisk/cli.h"
+#include "asterisk/linkedlists.h"
+#include "asterisk/lock.h"
+#include "asterisk/module.h"
+#include "asterisk/paths.h"
+#include "asterisk/pbx.h"
+#include "asterisk/stasis_channels.h"
+#include "pbx_private.h"
+
+/*** DOCUMENTATION
+	<application name="Set" language="en_US">
+		<synopsis>
+			Set channel variable or function value.
+		</synopsis>
+		<syntax argsep="=">
+			<parameter name="name" required="true" />
+			<parameter name="value" required="true" />
+		</syntax>
+		<description>
+			<para>This function can be used to set the value of channel variables or dialplan functions.
+			When setting variables, if the variable name is prefixed with <literal>_</literal>,
+			the variable will be inherited into channels created from the current channel.
+			If the variable name is prefixed with <literal>__</literal>, the variable will be
+			inherited into channels created from the current channel and all children channels.</para>
+			<note><para>If (and only if), in <filename>/etc/asterisk/asterisk.conf</filename>, you have
+			a <literal>[compat]</literal> category, and you have <literal>app_set = 1.4</literal> under that, then
+			the behavior of this app changes, and strips surrounding quotes from the right hand side as
+			it did previously in 1.4.
+			The advantages of not stripping out quoting, and not caring about the separator characters (comma and vertical bar)
+			were sufficient to make these changes in 1.6. Confusion about how many backslashes would be needed to properly
+			protect separators and quotes in various database access strings has been greatly
+			reduced by these changes.</para></note>
+		</description>
+		<see-also>
+			<ref type="application">MSet</ref>
+			<ref type="function">GLOBAL</ref>
+			<ref type="function">SET</ref>
+			<ref type="function">ENV</ref>
+		</see-also>
+	</application>
+	<application name="MSet" language="en_US">
+		<synopsis>
+			Set channel variable(s) or function value(s).
+		</synopsis>
+		<syntax>
+			<parameter name="set1" required="true" argsep="=">
+				<argument name="name1" required="true" />
+				<argument name="value1" required="true" />
+			</parameter>
+			<parameter name="set2" multiple="true" argsep="=">
+				<argument name="name2" required="true" />
+				<argument name="value2" required="true" />
+			</parameter>
+		</syntax>
+		<description>
+			<para>This function can be used to set the value of channel variables or dialplan functions.
+			When setting variables, if the variable name is prefixed with <literal>_</literal>,
+			the variable will be inherited into channels created from the current channel
+			If the variable name is prefixed with <literal>__</literal>, the variable will be
+			inherited into channels created from the current channel and all children channels.
+			MSet behaves in a similar fashion to the way Set worked in 1.2/1.4 and is thus
+			prone to doing things that you may not expect. For example, it strips surrounding
+			double-quotes from the right-hand side (value). If you need to put a separator
+			character (comma or vert-bar), you will need to escape them by inserting a backslash
+			before them. Avoid its use if possible.</para>
+		</description>
+		<see-also>
+			<ref type="application">Set</ref>
+		</see-also>
+	</application>
+ ***/
+
+AST_RWLOCK_DEFINE_STATIC(globalslock);
+static struct varshead globals = AST_LIST_HEAD_NOLOCK_INIT_VALUE;
+
+/*!
+ * \brief extract offset:length from variable name.
+ * \return 1 if there is a offset:length part, which is
+ * trimmed off (values go into variables)
+ */
+static int parse_variable_name(char *var, int *offset, int *length, int *isfunc)
+{
+	int parens = 0;
+
+	*offset = 0;
+	*length = INT_MAX;
+	*isfunc = 0;
+	for (; *var; var++) {
+		if (*var == '(') {
+			(*isfunc)++;
+			parens++;
+		} else if (*var == ')') {
+			parens--;
+		} else if (*var == ':' && parens == 0) {
+			*var++ = '\0';
+			sscanf(var, "%30d:%30d", offset, length);
+			return 1; /* offset:length valid */
+		}
+	}
+	return 0;
+}
+
+/*!
+ *\brief takes a substring. It is ok to call with value == workspace.
+ * \param value
+ * \param offset < 0 means start from the end of the string and set the beginning
+ *   to be that many characters back.
+ * \param length is the length of the substring, a value less than 0 means to leave
+ * that many off the end.
+ * \param workspace
+ * \param workspace_len
+ * Always return a copy in workspace.
+ */
+static char *substring(const char *value, int offset, int length, char *workspace, size_t workspace_len)
+{
+	char *ret = workspace;
+	int lr;	/* length of the input string after the copy */
+
+	ast_copy_string(workspace, value, workspace_len); /* always make a copy */
+
+	lr = strlen(ret); /* compute length after copy, so we never go out of the workspace */
+
+	/* Quick check if no need to do anything */
+	if (offset == 0 && length >= lr)	/* take the whole string */
+		return ret;
+
+	if (offset < 0)	{	/* translate negative offset into positive ones */
+		offset = lr + offset;
+		if (offset < 0) /* If the negative offset was greater than the length of the string, just start at the beginning */
+			offset = 0;
+	}
+
+	/* too large offset result in empty string so we know what to return */
+	if (offset >= lr)
+		return ret + lr;	/* the final '\0' */
+
+	ret += offset;		/* move to the start position */
+	if (length >= 0 && length < lr - offset)	/* truncate if necessary */
+		ret[length] = '\0';
+	else if (length < 0) {
+		if (lr > offset - length) /* After we remove from the front and from the rear, is there anything left? */
+			ret[lr + length - offset] = '\0';
+		else
+			ret[0] = '\0';
+	}
+
+	return ret;
+}
+
+static const char *ast_str_substring(struct ast_str *value, int offset, int length)
+{
+	int lr;	/* length of the input string after the copy */
+
+	lr = ast_str_strlen(value); /* compute length after copy, so we never go out of the workspace */
+
+	/* Quick check if no need to do anything */
+	if (offset == 0 && length >= lr)	/* take the whole string */
+		return ast_str_buffer(value);
+
+	if (offset < 0)	{	/* translate negative offset into positive ones */
+		offset = lr + offset;
+		if (offset < 0) /* If the negative offset was greater than the length of the string, just start at the beginning */
+			offset = 0;
+	}
+
+	/* too large offset result in empty string so we know what to return */
+	if (offset >= lr) {
+		ast_str_reset(value);
+		return ast_str_buffer(value);
+	}
+
+	if (offset > 0) {
+		/* Go ahead and chop off the beginning */
+		memmove(ast_str_buffer(value), ast_str_buffer(value) + offset, ast_str_strlen(value) - offset + 1);
+		lr -= offset;
+	}
+
+	if (length >= 0 && length < lr) {	/* truncate if necessary */
+		char *tmp = ast_str_buffer(value);
+		tmp[length] = '\0';
+		ast_str_update(value);
+	} else if (length < 0) {
+		if (lr > -length) { /* After we remove from the front and from the rear, is there anything left? */
+			char *tmp = ast_str_buffer(value);
+			tmp[lr + length] = '\0';
+			ast_str_update(value);
+		} else {
+			ast_str_reset(value);
+		}
+	} else {
+		/* Nothing to do, but update the buffer length */
+		ast_str_update(value);
+	}
+
+	return ast_str_buffer(value);
+}
+
+/*! \brief  Support for Asterisk built-in variables in the dialplan
+
+\note	See also
+	- \ref AstVar	Channel variables
+	- \ref AstCauses The HANGUPCAUSE variable
+ */
+void pbx_retrieve_variable(struct ast_channel *c, const char *var, char **ret, char *workspace, int workspacelen, struct varshead *headp)
+{
+	struct ast_str *str = ast_str_create(16);
+	const char *cret;
+
+	cret = ast_str_retrieve_variable(&str, 0, c, headp, var);
+	ast_copy_string(workspace, ast_str_buffer(str), workspacelen);
+	*ret = cret ? workspace : NULL;
+	ast_free(str);
+}
+
+const char *ast_str_retrieve_variable(struct ast_str **str, ssize_t maxlen, struct ast_channel *c, struct varshead *headp, const char *var)
+{
+	const char not_found = '\0';
+	char *tmpvar;
+	const char *ret;
+	const char *s;	/* the result */
+	int offset, length;
+	int i, need_substring;
+	struct varshead *places[2] = { headp, &globals };	/* list of places where we may look */
+	char workspace[20];
+
+	if (c) {
+		ast_channel_lock(c);
+		places[0] = ast_channel_varshead(c);
+	}
+	/*
+	 * Make a copy of var because parse_variable_name() modifies the string.
+	 * Then if called directly, we might need to run substring() on the result;
+	 * remember this for later in 'need_substring', 'offset' and 'length'
+	 */
+	tmpvar = ast_strdupa(var);	/* parse_variable_name modifies the string */
+	need_substring = parse_variable_name(tmpvar, &offset, &length, &i /* ignored */);
+
+	/*
+	 * Look first into predefined variables, then into variable lists.
+	 * Variable 's' points to the result, according to the following rules:
+	 * s == &not_found (set at the beginning) means that we did not find a
+	 *	matching variable and need to look into more places.
+	 * If s != &not_found, s is a valid result string as follows:
+	 * s = NULL if the variable does not have a value;
+	 *	you typically do this when looking for an unset predefined variable.
+	 * s = workspace if the result has been assembled there;
+	 *	typically done when the result is built e.g. with an snprintf(),
+	 *	so we don't need to do an additional copy.
+	 * s != workspace in case we have a string, that needs to be copied
+	 *	(the ast_copy_string is done once for all at the end).
+	 *	Typically done when the result is already available in some string.
+	 */
+	s = &not_found;	/* default value */
+	if (c) {	/* This group requires a valid channel */
+		/* Names with common parts are looked up a piece at a time using strncmp. */
+		if (!strncmp(var, "CALL", 4)) {
+			if (!strncmp(var + 4, "ING", 3)) {
+				if (!strcmp(var + 7, "PRES")) {			/* CALLINGPRES */
+					ast_str_set(str, maxlen, "%d",
+						ast_party_id_presentation(&ast_channel_caller(c)->id));
+					s = ast_str_buffer(*str);
+				} else if (!strcmp(var + 7, "ANI2")) {		/* CALLINGANI2 */
+					ast_str_set(str, maxlen, "%d", ast_channel_caller(c)->ani2);
+					s = ast_str_buffer(*str);
+				} else if (!strcmp(var + 7, "TON")) {		/* CALLINGTON */
+					ast_str_set(str, maxlen, "%d", ast_channel_caller(c)->id.number.plan);
+					s = ast_str_buffer(*str);
+				} else if (!strcmp(var + 7, "TNS")) {		/* CALLINGTNS */
+					ast_str_set(str, maxlen, "%d", ast_channel_dialed(c)->transit_network_select);
+					s = ast_str_buffer(*str);
+				}
+			}
+		} else if (!strcmp(var, "HINT")) {
+			s = ast_str_get_hint(str, maxlen, NULL, 0, c, ast_channel_context(c), ast_channel_exten(c)) ? ast_str_buffer(*str) : NULL;
+		} else if (!strcmp(var, "HINTNAME")) {
+			s = ast_str_get_hint(NULL, 0, str, maxlen, c, ast_channel_context(c), ast_channel_exten(c)) ? ast_str_buffer(*str) : NULL;
+		} else if (!strcmp(var, "EXTEN")) {
+			s = ast_channel_exten(c);
+		} else if (!strcmp(var, "CONTEXT")) {
+			s = ast_channel_context(c);
+		} else if (!strcmp(var, "PRIORITY")) {
+			ast_str_set(str, maxlen, "%d", ast_channel_priority(c));
+			s = ast_str_buffer(*str);
+		} else if (!strcmp(var, "CHANNEL")) {
+			s = ast_channel_name(c);
+		} else if (!strcmp(var, "UNIQUEID")) {
+			s = ast_channel_uniqueid(c);
+		} else if (!strcmp(var, "HANGUPCAUSE")) {
+			ast_str_set(str, maxlen, "%d", ast_channel_hangupcause(c));
+			s = ast_str_buffer(*str);
+		}
+	}
+	if (s == &not_found) { /* look for more */
+		if (!strcmp(var, "EPOCH")) {
+			ast_str_set(str, maxlen, "%d", (int) time(NULL));
+			s = ast_str_buffer(*str);
+		} else if (!strcmp(var, "SYSTEMNAME")) {
+			s = ast_config_AST_SYSTEM_NAME;
+		} else if (!strcmp(var, "ASTETCDIR")) {
+			s = ast_config_AST_CONFIG_DIR;
+		} else if (!strcmp(var, "ASTMODDIR")) {
+			s = ast_config_AST_MODULE_DIR;
+		} else if (!strcmp(var, "ASTVARLIBDIR")) {
+			s = ast_config_AST_VAR_DIR;
+		} else if (!strcmp(var, "ASTDBDIR")) {
+			s = ast_config_AST_DB;
+		} else if (!strcmp(var, "ASTKEYDIR")) {
+			s = ast_config_AST_KEY_DIR;
+		} else if (!strcmp(var, "ASTDATADIR")) {
+			s = ast_config_AST_DATA_DIR;
+		} else if (!strcmp(var, "ASTAGIDIR")) {
+			s = ast_config_AST_AGI_DIR;
+		} else if (!strcmp(var, "ASTSPOOLDIR")) {
+			s = ast_config_AST_SPOOL_DIR;
+		} else if (!strcmp(var, "ASTRUNDIR")) {
+			s = ast_config_AST_RUN_DIR;
+		} else if (!strcmp(var, "ASTLOGDIR")) {
+			s = ast_config_AST_LOG_DIR;
+		} else if (!strcmp(var, "ENTITYID")) {
+			ast_eid_to_str(workspace, sizeof(workspace), &ast_eid_default);
+			s = workspace;
+		}
+	}
+	/* if not found, look into chanvars or global vars */
+	for (i = 0; s == &not_found && i < ARRAY_LEN(places); i++) {
+		struct ast_var_t *variables;
+		if (!places[i])
+			continue;
+		if (places[i] == &globals)
+			ast_rwlock_rdlock(&globalslock);
+		AST_LIST_TRAVERSE(places[i], variables, entries) {
+			if (!strcmp(ast_var_name(variables), var)) {
+				s = ast_var_value(variables);
+				break;
+			}
+		}
+		if (places[i] == &globals)
+			ast_rwlock_unlock(&globalslock);
+	}
+	if (s == &not_found || s == NULL) {
+		ast_debug(5, "Result of '%s' is NULL\n", var);
+		ret = NULL;
+	} else {
+		ast_debug(5, "Result of '%s' is '%s'\n", var, s);
+		if (s != ast_str_buffer(*str)) {
+			ast_str_set(str, maxlen, "%s", s);
+		}
+		ret = ast_str_buffer(*str);
+		if (need_substring) {
+			ret = ast_str_substring(*str, offset, length);
+			ast_debug(2, "Final result of '%s' is '%s'\n", var, ret);
+		}
+	}
+
+	if (c) {
+		ast_channel_unlock(c);
+	}
+	return ret;
+}
+
+void ast_str_substitute_variables_full(struct ast_str **buf, ssize_t maxlen, struct ast_channel *c, struct varshead *headp, const char *templ, size_t *used)
+{
+	/* Substitutes variables into buf, based on string templ */
+	char *cp4 = NULL;
+	const char *whereweare;
+	int orig_size = 0;
+	int offset, offset2, isfunction;
+	const char *nextvar, *nextexp, *nextthing;
+	const char *vars, *vare;
+	char *finalvars;
+	int pos, brackets, needsub, len;
+	struct ast_str *substr1 = ast_str_create(16), *substr2 = NULL, *substr3 = ast_str_create(16);
+
+	ast_str_reset(*buf);
+	whereweare = templ;
+	while (!ast_strlen_zero(whereweare)) {
+		/* reset our buffer */
+		ast_str_reset(substr3);
+
+		/* Assume we're copying the whole remaining string */
+		pos = strlen(whereweare);
+		nextvar = NULL;
+		nextexp = NULL;
+		nextthing = strchr(whereweare, '$');
+		if (nextthing) {
+			switch (nextthing[1]) {
+			case '{':
+				nextvar = nextthing;
+				pos = nextvar - whereweare;
+				break;
+			case '[':
+				nextexp = nextthing;
+				pos = nextexp - whereweare;
+				break;
+			default:
+				pos = 1;
+			}
+		}
+
+		if (pos) {
+			/* Copy that many bytes */
+			ast_str_append_substr(buf, maxlen, whereweare, pos);
+
+			templ += pos;
+			whereweare += pos;
+		}
+
+		if (nextvar) {
+			/* We have a variable.  Find the start and end, and determine
+			   if we are going to have to recursively call ourselves on the
+			   contents */
+			vars = vare = nextvar + 2;
+			brackets = 1;
+			needsub = 0;
+
+			/* Find the end of it */
+			while (brackets && *vare) {
+				if ((vare[0] == '$') && (vare[1] == '{')) {
+					needsub++;
+				} else if (vare[0] == '{') {
+					brackets++;
+				} else if (vare[0] == '}') {
+					brackets--;
+				} else if ((vare[0] == '$') && (vare[1] == '['))
+					needsub++;
+				vare++;
+			}
+			if (brackets)
+				ast_log(LOG_WARNING, "Error in extension logic (missing '}')\n");
+			len = vare - vars - 1;
+
+			/* Skip totally over variable string */
+			whereweare += (len + 3);
+
+			/* Store variable name (and truncate) */
+			ast_str_set_substr(&substr1, 0, vars, len);
+			ast_debug(5, "Evaluating '%s' (from '%s' len %d)\n", ast_str_buffer(substr1), vars, len);
+
+			/* Substitute if necessary */
+			if (needsub) {
+				size_t my_used;
+
+				if (!substr2) {
+					substr2 = ast_str_create(16);
+				}
+				ast_str_substitute_variables_full(&substr2, 0, c, headp, ast_str_buffer(substr1), &my_used);
+				finalvars = ast_str_buffer(substr2);
+			} else {
+				finalvars = ast_str_buffer(substr1);
+			}
+
+			parse_variable_name(finalvars, &offset, &offset2, &isfunction);
+			if (isfunction) {
+				/* Evaluate function */
+				if (c || !headp) {
+					cp4 = ast_func_read2(c, finalvars, &substr3, 0) ? NULL : ast_str_buffer(substr3);
+				} else {
+					struct varshead old;
+					struct ast_channel *bogus = ast_dummy_channel_alloc();
+					if (bogus) {
+						memcpy(&old, ast_channel_varshead(bogus), sizeof(old));
+						memcpy(ast_channel_varshead(bogus), headp, sizeof(*ast_channel_varshead(bogus)));
+						cp4 = ast_func_read2(c, finalvars, &substr3, 0) ? NULL : ast_str_buffer(substr3);
+						/* Don't deallocate the varshead that was passed in */
+						memcpy(ast_channel_varshead(bogus), &old, sizeof(*ast_channel_varshead(bogus)));
+						ast_channel_unref(bogus);
+					} else {
+						ast_log(LOG_ERROR, "Unable to allocate bogus channel for variable substitution.  Function results may be blank.\n");
+					}
+				}
+				ast_debug(2, "Function %s result is '%s'\n", finalvars, cp4 ? cp4 : "(null)");
+			} else {
+				/* Retrieve variable value */
+				ast_str_retrieve_variable(&substr3, 0, c, headp, finalvars);
+				cp4 = ast_str_buffer(substr3);
+			}
+			if (cp4) {
+				ast_str_substring(substr3, offset, offset2);
+				ast_str_append(buf, maxlen, "%s", ast_str_buffer(substr3));
+			}
+		} else if (nextexp) {
+			/* We have an expression.  Find the start and end, and determine
+			   if we are going to have to recursively call ourselves on the
+			   contents */
+			vars = vare = nextexp + 2;
+			brackets = 1;
+			needsub = 0;
+
+			/* Find the end of it */
+			while (brackets && *vare) {
+				if ((vare[0] == '$') && (vare[1] == '[')) {
+					needsub++;
+					brackets++;
+					vare++;
+				} else if (vare[0] == '[') {
+					brackets++;
+				} else if (vare[0] == ']') {
+					brackets--;
+				} else if ((vare[0] == '$') && (vare[1] == '{')) {
+					needsub++;
+					vare++;
+				}
+				vare++;
+			}
+			if (brackets)
+				ast_log(LOG_WARNING, "Error in extension logic (missing ']')\n");
+			len = vare - vars - 1;
+
+			/* Skip totally over expression */
+			whereweare += (len + 3);
+
+			/* Store variable name (and truncate) */
+			ast_str_set_substr(&substr1, 0, vars, len);
+
+			/* Substitute if necessary */
+			if (needsub) {
+				size_t my_used;
+
+				if (!substr2) {
+					substr2 = ast_str_create(16);
+				}
+				ast_str_substitute_variables_full(&substr2, 0, c, headp, ast_str_buffer(substr1), &my_used);
+				finalvars = ast_str_buffer(substr2);
+			} else {
+				finalvars = ast_str_buffer(substr1);
+			}
+
+			if (ast_str_expr(&substr3, 0, c, finalvars)) {
+				ast_debug(2, "Expression result is '%s'\n", ast_str_buffer(substr3));
+			}
+			ast_str_append(buf, maxlen, "%s", ast_str_buffer(substr3));
+		}
+	}
+	*used = ast_str_strlen(*buf) - orig_size;
+	ast_free(substr1);
+	ast_free(substr2);
+	ast_free(substr3);
+}
+
+void ast_str_substitute_variables(struct ast_str **buf, ssize_t maxlen, struct ast_channel *chan, const char *templ)
+{
+	size_t used;
+	ast_str_substitute_variables_full(buf, maxlen, chan, NULL, templ, &used);
+}
+
+void ast_str_substitute_variables_varshead(struct ast_str **buf, ssize_t maxlen, struct varshead *headp, const char *templ)
+{
+	size_t used;
+	ast_str_substitute_variables_full(buf, maxlen, NULL, headp, templ, &used);
+}
+
+void pbx_substitute_variables_helper_full(struct ast_channel *c, struct varshead *headp, const char *cp1, char *cp2, int count, size_t *used)
+{
+	/* Substitutes variables into cp2, based on string cp1, cp2 NO LONGER NEEDS TO BE ZEROED OUT!!!!  */
+	char *cp4 = NULL;
+	const char *whereweare, *orig_cp2 = cp2;
+	int length, offset, offset2, isfunction;
+	char *workspace = NULL;
+	char *ltmp = NULL, *var = NULL;
+	char *nextvar, *nextexp, *nextthing;
+	char *vars, *vare;
+	int pos, brackets, needsub, len;
+
+	*cp2 = 0; /* just in case nothing ends up there */
+	whereweare = cp1;
+	while (!ast_strlen_zero(whereweare) && count) {
+		/* Assume we're copying the whole remaining string */
+		pos = strlen(whereweare);
+		nextvar = NULL;
+		nextexp = NULL;
+		nextthing = strchr(whereweare, '$');
+		if (nextthing) {
+			switch (nextthing[1]) {
+			case '{':
+				nextvar = nextthing;
+				pos = nextvar - whereweare;
+				break;
+			case '[':
+				nextexp = nextthing;
+				pos = nextexp - whereweare;
+				break;
+			default:
+				pos = 1;
+			}
+		}
+
+		if (pos) {
+			/* Can't copy more than 'count' bytes */
+			if (pos > count)
+				pos = count;
+
+			/* Copy that many bytes */
+			memcpy(cp2, whereweare, pos);
+
+			count -= pos;
+			cp2 += pos;
+			whereweare += pos;
+			*cp2 = 0;
+		}
+
+		if (nextvar) {
+			/* We have a variable.  Find the start and end, and determine
+			   if we are going to have to recursively call ourselves on the
+			   contents */
+			vars = vare = nextvar + 2;
+			brackets = 1;
+			needsub = 0;
+
+			/* Find the end of it */
+			while (brackets && *vare) {
+				if ((vare[0] == '$') && (vare[1] == '{')) {
+					needsub++;
+				} else if (vare[0] == '{') {
+					brackets++;
+				} else if (vare[0] == '}') {
+					brackets--;
+				} else if ((vare[0] == '$') && (vare[1] == '['))
+					needsub++;
+				vare++;
+			}
+			if (brackets)
+				ast_log(LOG_WARNING, "Error in extension logic (missing '}')\n");
+			len = vare - vars - 1;
+
+			/* Skip totally over variable string */
+			whereweare += (len + 3);
+
+			if (!var)
+				var = ast_alloca(VAR_BUF_SIZE);
+
+			/* Store variable name (and truncate) */
+			ast_copy_string(var, vars, len + 1);
+
+			/* Substitute if necessary */
+			if (needsub) {
+				size_t my_used;
+
+				if (!ltmp) {
+					ltmp = ast_alloca(VAR_BUF_SIZE);
+				}
+				pbx_substitute_variables_helper_full(c, headp, var, ltmp, VAR_BUF_SIZE - 1, &my_used);
+				vars = ltmp;
+			} else {
+				vars = var;
+			}
+
+			if (!workspace)
+				workspace = ast_alloca(VAR_BUF_SIZE);
+
+			workspace[0] = '\0';
+
+			parse_variable_name(vars, &offset, &offset2, &isfunction);
+			if (isfunction) {
+				/* Evaluate function */
+				if (c || !headp)
+					cp4 = ast_func_read(c, vars, workspace, VAR_BUF_SIZE) ? NULL : workspace;
+				else {
+					struct varshead old;
+					struct ast_channel *c = ast_dummy_channel_alloc();
+					if (c) {
+						memcpy(&old, ast_channel_varshead(c), sizeof(old));
+						memcpy(ast_channel_varshead(c), headp, sizeof(*ast_channel_varshead(c)));
+						cp4 = ast_func_read(c, vars, workspace, VAR_BUF_SIZE) ? NULL : workspace;
+						/* Don't deallocate the varshead that was passed in */
+						memcpy(ast_channel_varshead(c), &old, sizeof(*ast_channel_varshead(c)));
+						c = ast_channel_unref(c);
+					} else {
+						ast_log(LOG_ERROR, "Unable to allocate bogus channel for variable substitution.  Function results may be blank.\n");
+					}
+				}
+				ast_debug(2, "Function %s result is '%s'\n", vars, cp4 ? cp4 : "(null)");
+			} else {
+				/* Retrieve variable value */
+				pbx_retrieve_variable(c, vars, &cp4, workspace, VAR_BUF_SIZE, headp);
+			}
+			if (cp4) {
+				cp4 = substring(cp4, offset, offset2, workspace, VAR_BUF_SIZE);
+
+				length = strlen(cp4);
+				if (length > count)
+					length = count;
+				memcpy(cp2, cp4, length);
+				count -= length;
+				cp2 += length;
+				*cp2 = 0;
+			}
+		} else if (nextexp) {
+			/* We have an expression.  Find the start and end, and determine
+			   if we are going to have to recursively call ourselves on the
+			   contents */
+			vars = vare = nextexp + 2;
+			brackets = 1;
+			needsub = 0;
+
+			/* Find the end of it */
+			while (brackets && *vare) {
+				if ((vare[0] == '$') && (vare[1] == '[')) {
+					needsub++;
+					brackets++;
+					vare++;
+				} else if (vare[0] == '[') {
+					brackets++;
+				} else if (vare[0] == ']') {
+					brackets--;
+				} else if ((vare[0] == '$') && (vare[1] == '{')) {
+					needsub++;
+					vare++;
+				}
+				vare++;
+			}
+			if (brackets)
+				ast_log(LOG_WARNING, "Error in extension logic (missing ']')\n");
+			len = vare - vars - 1;
+
+			/* Skip totally over expression */
+			whereweare += (len + 3);
+
+			if (!var)
+				var = ast_alloca(VAR_BUF_SIZE);
+
+			/* Store variable name (and truncate) */
+			ast_copy_string(var, vars, len + 1);
+
+			/* Substitute if necessary */
+			if (needsub) {
+				size_t my_used;
+
+				if (!ltmp) {
+					ltmp = ast_alloca(VAR_BUF_SIZE);
+				}
+				pbx_substitute_variables_helper_full(c, headp, var, ltmp, VAR_BUF_SIZE - 1, &my_used);
+				vars = ltmp;
+			} else {
+				vars = var;
+			}
+
+			length = ast_expr(vars, cp2, count, c);
+
+			if (length) {
+				ast_debug(1, "Expression result is '%s'\n", cp2);
+				count -= length;
+				cp2 += length;
+				*cp2 = 0;
+			}
+		}
+	}
+	*used = cp2 - orig_cp2;
+}
+
+void pbx_substitute_variables_helper(struct ast_channel *c, const char *cp1, char *cp2, int count)
+{
+	size_t used;
+	pbx_substitute_variables_helper_full(c, (c) ? ast_channel_varshead(c) : NULL, cp1, cp2, count, &used);
+}
+
+void pbx_substitute_variables_varshead(struct varshead *headp, const char *cp1, char *cp2, int count)
+{
+	size_t used;
+	pbx_substitute_variables_helper_full(NULL, headp, cp1, cp2, count, &used);
+}
+
+/*! \brief CLI support for listing global variables in a parseable way */
+static char *handle_show_globals(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	int i = 0;
+	struct ast_var_t *newvariable;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "dialplan show globals";
+		e->usage =
+			"Usage: dialplan show globals\n"
+			"       List current global dialplan variables and their values\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	ast_rwlock_rdlock(&globalslock);
+	AST_LIST_TRAVERSE (&globals, newvariable, entries) {
+		i++;
+		ast_cli(a->fd, "   %s=%s\n", ast_var_name(newvariable), ast_var_value(newvariable));
+	}
+	ast_rwlock_unlock(&globalslock);
+	ast_cli(a->fd, "\n    -- %d variable(s)\n", i);
+
+	return CLI_SUCCESS;
+}
+
+/*! \brief CLI support for listing chanvar's variables in a parseable way */
+static char *handle_show_chanvar(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct ast_channel *chan;
+	struct ast_var_t *var;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "dialplan show chanvar";
+		e->usage =
+			"Usage: dialplan show chanvar <channel>\n"
+			"       List current channel variables and their values\n";
+		return NULL;
+	case CLI_GENERATE:
+		return ast_complete_channels(a->line, a->word, a->pos, a->n, 3);
+	}
+
+	if (a->argc != e->args + 1) {
+		return CLI_SHOWUSAGE;
+	}
+
+	chan = ast_channel_get_by_name(a->argv[e->args]);
+	if (!chan) {
+		ast_cli(a->fd, "Channel '%s' not found\n", a->argv[e->args]);
+		return CLI_FAILURE;
+	}
+
+	ast_channel_lock(chan);
+	AST_LIST_TRAVERSE(ast_channel_varshead(chan), var, entries) {
+		ast_cli(a->fd, "%s=%s\n", ast_var_name(var), ast_var_value(var));
+	}
+	ast_channel_unlock(chan);
+
+	ast_channel_unref(chan);
+	return CLI_SUCCESS;
+}
+
+static char *handle_set_global(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "dialplan set global";
+		e->usage =
+			"Usage: dialplan set global <name> <value>\n"
+			"       Set global dialplan variable <name> to <value>\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	if (a->argc != e->args + 2)
+		return CLI_SHOWUSAGE;
+
+	pbx_builtin_setvar_helper(NULL, a->argv[3], a->argv[4]);
+	ast_cli(a->fd, "\n    -- Global variable '%s' set to '%s'\n", a->argv[3], a->argv[4]);
+
+	return CLI_SUCCESS;
+}
+
+static char *handle_set_chanvar(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct ast_channel *chan;
+	const char *chan_name, *var_name, *var_value;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "dialplan set chanvar";
+		e->usage =
+			"Usage: dialplan set chanvar <channel> <varname> <value>\n"
+			"       Set channel variable <varname> to <value>\n";
+		return NULL;
+	case CLI_GENERATE:
+		return ast_complete_channels(a->line, a->word, a->pos, a->n, 3);
+	}
+
+	if (a->argc != e->args + 3)
+		return CLI_SHOWUSAGE;
+
+	chan_name = a->argv[e->args];
+	var_name = a->argv[e->args + 1];
+	var_value = a->argv[e->args + 2];
+
+	if (!(chan = ast_channel_get_by_name(chan_name))) {
+		ast_cli(a->fd, "Channel '%s' not found\n", chan_name);
+		return CLI_FAILURE;
+	}
+
+	pbx_builtin_setvar_helper(chan, var_name, var_value);
+
+	chan = ast_channel_unref(chan);
+
+	ast_cli(a->fd, "\n    -- Channel variable '%s' set to '%s' for '%s'\n",  var_name, var_value, chan_name);
+
+	return CLI_SUCCESS;
+}
+
+int pbx_builtin_serialize_variables(struct ast_channel *chan, struct ast_str **buf)
+{
+	struct ast_var_t *variables;
+	const char *var, *val;
+	int total = 0;
+
+	if (!chan)
+		return 0;
+
+	ast_str_reset(*buf);
+
+	ast_channel_lock(chan);
+
+	AST_LIST_TRAVERSE(ast_channel_varshead(chan), variables, entries) {
+		if ((var = ast_var_name(variables)) && (val = ast_var_value(variables))
+		   /* && !ast_strlen_zero(var) && !ast_strlen_zero(val) */
+		   ) {
+			if (ast_str_append(buf, 0, "%s=%s\n", var, val) < 0) {
+				ast_log(LOG_ERROR, "Data Buffer Size Exceeded!\n");
+				break;
+			} else
+				total++;
+		} else
+			break;
+	}
+
+	ast_channel_unlock(chan);
+
+	return total;
+}
+
+const char *pbx_builtin_getvar_helper(struct ast_channel *chan, const char *name)
+{
+	struct ast_var_t *variables;
+	const char *ret = NULL;
+	int i;
+	struct varshead *places[2] = { NULL, &globals };
+
+	if (!name)
+		return NULL;
+
+	if (chan) {
+		ast_channel_lock(chan);
+		places[0] = ast_channel_varshead(chan);
+	}
+
+	for (i = 0; i < 2; i++) {
+		if (!places[i])
+			continue;
+		if (places[i] == &globals)
+			ast_rwlock_rdlock(&globalslock);
+		AST_LIST_TRAVERSE(places[i], variables, entries) {
+			if (!strcmp(name, ast_var_name(variables))) {
+				ret = ast_var_value(variables);
+				break;
+			}
+		}
+		if (places[i] == &globals)
+			ast_rwlock_unlock(&globalslock);
+		if (ret)
+			break;
+	}
+
+	if (chan)
+		ast_channel_unlock(chan);
+
+	return ret;
+}
+
+void pbx_builtin_pushvar_helper(struct ast_channel *chan, const char *name, const char *value)
+{
+	struct ast_var_t *newvariable;
+	struct varshead *headp;
+
+	if (name[strlen(name)-1] == ')') {
+		char *function = ast_strdupa(name);
+
+		ast_log(LOG_WARNING, "Cannot push a value onto a function\n");
+		ast_func_write(chan, function, value);
+		return;
+	}
+
+	if (chan) {
+		ast_channel_lock(chan);
+		headp = ast_channel_varshead(chan);
+	} else {
+		ast_rwlock_wrlock(&globalslock);
+		headp = &globals;
+	}
+
+	if (value && (newvariable = ast_var_assign(name, value))) {
+		if (headp == &globals)
+			ast_verb(2, "Setting global variable '%s' to '%s'\n", name, value);
+		AST_LIST_INSERT_HEAD(headp, newvariable, entries);
+	}
+
+	if (chan)
+		ast_channel_unlock(chan);
+	else
+		ast_rwlock_unlock(&globalslock);
+}
+
+int pbx_builtin_setvar_helper(struct ast_channel *chan, const char *name, const char *value)
+{
+	struct ast_var_t *newvariable;
+	struct varshead *headp;
+	const char *nametail = name;
+	/*! True if the old value was not an empty string. */
+	int old_value_existed = 0;
+
+	if (name[strlen(name) - 1] == ')') {
+		char *function = ast_strdupa(name);
+
+		return ast_func_write(chan, function, value);
+	}
+
+	if (chan) {
+		ast_channel_lock(chan);
+		headp = ast_channel_varshead(chan);
+	} else {
+		ast_rwlock_wrlock(&globalslock);
+		headp = &globals;
+	}
+
+	/* For comparison purposes, we have to strip leading underscores */
+	if (*nametail == '_') {
+		nametail++;
+		if (*nametail == '_')
+			nametail++;
+	}
+
+	AST_LIST_TRAVERSE_SAFE_BEGIN(headp, newvariable, entries) {
+		if (strcmp(ast_var_name(newvariable), nametail) == 0) {
+			/* there is already such a variable, delete it */
+			AST_LIST_REMOVE_CURRENT(entries);
+			old_value_existed = !ast_strlen_zero(ast_var_value(newvariable));
+			ast_var_delete(newvariable);
+			break;
+		}
+	}
+	AST_LIST_TRAVERSE_SAFE_END;
+
+	if (value && (newvariable = ast_var_assign(name, value))) {
+		if (headp == &globals) {
+			ast_verb(2, "Setting global variable '%s' to '%s'\n", name, value);
+		}
+		AST_LIST_INSERT_HEAD(headp, newvariable, entries);
+		ast_channel_publish_varset(chan, name, value);
+	} else if (old_value_existed) {
+		/* We just deleted a non-empty dialplan variable. */
+		ast_channel_publish_varset(chan, name, "");
+	}
+
+	if (chan)
+		ast_channel_unlock(chan);
+	else
+		ast_rwlock_unlock(&globalslock);
+	return 0;
+}
+
+int pbx_builtin_setvar(struct ast_channel *chan, const char *data)
+{
+	char *name, *value, *mydata;
+
+	if (ast_strlen_zero(data)) {
+		ast_log(LOG_WARNING, "Set requires one variable name/value pair.\n");
+		return 0;
+	}
+
+	mydata = ast_strdupa(data);
+	name = strsep(&mydata, "=");
+	value = mydata;
+	if (!value) {
+		ast_log(LOG_WARNING, "Set requires an '=' to be a valid assignment.\n");
+		return 0;
+	}
+
+	if (strchr(name, ' ')) {
+		ast_log(LOG_WARNING, "Please avoid unnecessary spaces on variables as it may lead to unexpected results ('%s' set to '%s').\n", name, mydata);
+	}
+
+	pbx_builtin_setvar_helper(chan, name, value);
+
+	return 0;
+}
+
+int pbx_builtin_setvar_multiple(struct ast_channel *chan, const char *vdata)
+{
+	char *data;
+	int x;
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(pair)[24];
+	);
+	AST_DECLARE_APP_ARGS(pair,
+		AST_APP_ARG(name);
+		AST_APP_ARG(value);
+	);
+
+	if (ast_strlen_zero(vdata)) {
+		ast_log(LOG_WARNING, "MSet requires at least one variable name/value pair.\n");
+		return 0;
+	}
+
+	data = ast_strdupa(vdata);
+	AST_STANDARD_APP_ARGS(args, data);
+
+	for (x = 0; x < args.argc; x++) {
+		AST_NONSTANDARD_APP_ARGS(pair, args.pair[x], '=');
+		if (pair.argc == 2) {
+			pbx_builtin_setvar_helper(chan, pair.name, pair.value);
+			if (strchr(pair.name, ' '))
+				ast_log(LOG_WARNING, "Please avoid unnecessary spaces on variables as it may lead to unexpected results ('%s' set to '%s').\n", pair.name, pair.value);
+		} else if (!chan) {
+			ast_log(LOG_WARNING, "MSet: ignoring entry '%s' with no '='\n", pair.name);
+		} else {
+			ast_log(LOG_WARNING, "MSet: ignoring entry '%s' with no '=' (in %s@%s:%d\n", pair.name, ast_channel_exten(chan), ast_channel_context(chan), ast_channel_priority(chan));
+		}
+	}
+
+	return 0;
+}
+
+void pbx_builtin_clear_globals(void)
+{
+	struct ast_var_t *vardata;
+
+	ast_rwlock_wrlock(&globalslock);
+	while ((vardata = AST_LIST_REMOVE_HEAD(&globals, entries)))
+		ast_var_delete(vardata);
+	ast_rwlock_unlock(&globalslock);
+}
+
+static struct ast_cli_entry vars_cli[] = {
+	AST_CLI_DEFINE(handle_show_globals, "Show global dialplan variables"),
+	AST_CLI_DEFINE(handle_show_chanvar, "Show channel variables"),
+	AST_CLI_DEFINE(handle_set_global, "Set global dialplan variable"),
+	AST_CLI_DEFINE(handle_set_chanvar, "Set a channel variable"),
+};
+
+static void unload_pbx_variables(void)
+{
+	ast_cli_unregister_multiple(vars_cli, ARRAY_LEN(vars_cli));
+	ast_unregister_application("Set");
+	ast_unregister_application("MSet");
+	pbx_builtin_clear_globals();
+}
+
+int load_pbx_variables(void)
+{
+	int res = 0;
+
+	res |= ast_cli_register_multiple(vars_cli, ARRAY_LEN(vars_cli));
+	res |= ast_register_application2("Set", pbx_builtin_setvar, NULL, NULL, NULL);
+	res |= ast_register_application2("MSet", pbx_builtin_setvar_multiple, NULL, NULL, NULL);
+	ast_register_cleanup(unload_pbx_variables);
+
+	return res;
+}