Merge "res_pjsip_history: Add a module that provides PJSIP history for debugging"

2 files changed, 1377 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index 9421f0ba2..e07f0e5a2 100644
--- a/CHANGES
+++ b/CHANGES
@@ -202,6 +202,31 @@ Queue
    the queue member was paused.
 
 ------------------------------------------------------------------------------
+--- Functionality changes from Asterisk 13.7.0 to Asterisk 13.8.0 ------------
+------------------------------------------------------------------------------
+
+res_pjsip_history
+------------------
+ * A new module, res_pjsip_history, has been added that provides SIP history
+   viewing/filtering from the CLI. The module is intended to be used on systems
+   with busy SIP traffic, where existing forms of viewing SIP messages - such
+   as the res_pjsip_logger - may be inadequate. The module provides two new
+   CLI commands:
+   - 'pjsip set history {on|off|clear}' - this enables/disables SIP history
+     capturing, as well as clears an existing history capture. Note that SIP
+     packets captured are stored in memory until cleared. As a result, the
+     history capture should only be used for debugging/viewing purposes, and
+     should *NOT* be left permanently enabled on a system.
+   - 'pjsip show history' - displays the captured SIP history. When invoked
+     with no options, the entire captured history is displayed. Two options
+     are available:
+     -- 'entry <num>' - display a detailed view of a single SIP message in
+        the history
+     -- 'where ...' - filter the history based on some expression. For more
+        information on filtering, view the current CLI help for the
+        'pjsip show history' command.
+
+------------------------------------------------------------------------------
 --- Functionality changes from Asterisk 13.6.0 to Asterisk 13.7.0 ------------
 ------------------------------------------------------------------------------
 
diff --git a/res/res_pjsip_history.c b/res/res_pjsip_history.c
new file mode 100644
index 000000000..339aecb74
--- /dev/null
+++ b/res/res_pjsip_history.c
@@ -0,0 +1,1352 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 1999 - 2015, Digium, Inc.
+ *
+ * Matt Jordan <mjordan@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 PJSIP History
+ *
+ * \author Matt Jordan <mjordan@digium.com>
+ *
+ */
+
+/*** MODULEINFO
+	<depend>pjproject</depend>
+	<depend>res_pjsip</depend>
+	<support_level>extended</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include <pjsip.h>
+#include <regex.h>
+
+#include "asterisk/res_pjsip.h"
+#include "asterisk/module.h"
+#include "asterisk/logger.h"
+#include "asterisk/cli.h"
+#include "asterisk/netsock2.h"
+#include "asterisk/vector.h"
+#include "asterisk/lock.h"
+
+#define HISTORY_INITIAL_SIZE 256
+
+/*! \brief Pool factory used by pjlib to allocate memory. */
+static pj_caching_pool cachingpool;
+
+/*! \brief Whether or not we are storing history */
+static int enabled;
+
+/*! \brief Packet count */
+static int packet_number;
+
+/*! \brief An item in the history */
+struct pjsip_history_entry {
+	/*! \brief Packet number */
+	int number;
+	/*! \brief Whether or not we transmitted the packet */
+	int transmitted;
+	/*! \brief Time the packet was transmitted/received */
+	struct timeval timestamp;
+	/*! \brief Source address */
+	pj_sockaddr_in src;
+	/*! \brief Destination address */
+	pj_sockaddr_in dst;
+	/*! \brief Memory pool used to allocate \c msg */
+	pj_pool_t *pool;
+	/*! \brief The actual SIP message */
+	pjsip_msg *msg;
+};
+
+/*! \brief Mutex that protects \ref vector_history */
+AST_MUTEX_DEFINE_STATIC(history_lock);
+
+/*! \brief The one and only history that we've captured */
+static AST_VECTOR(vector_history_t, struct pjsip_history_entry *) vector_history;
+
+struct expression_token;
+
+/*! \brief An operator that we understand in an expression */
+struct operator {
+	/*! \brief Our operator's symbol */
+	const char *symbol;
+	/*! \brief Precedence of the symbol */
+	int precedence;
+	/*! \brief Non-zero if the operator is evaluated right-to-left */
+	int right_to_left;
+	/*! \brief Number of operands the operator takes */
+	int operands;
+	/*!
+	 * \brief Evaluation function for unary operators
+	 *
+	 * \param op The operator being evaluated
+	 * \param type The type of value contained in \c operand
+	 * \param operand A pointer to the value to evaluate
+	 *
+	 * \retval -1 error
+	 * \retval 0 evaluation is False
+	 * \retval 1 evaluation is True
+	 */
+	int (* const evaluate_unary)(struct operator *op, enum aco_option_type type, void *operand);
+	/*!
+	 * \brief Evaluation function for binary operators
+	 *
+	 * \param op The operator being evaluated
+	 * \param type The type of value contained in \c op_left
+	 * \param op_left A pointer to the value to evaluate (a result or extracted from an entry)
+	 * \param op_right The expression token containing the other value (a result or user-provided)
+	 *
+	 * \retval -1 error
+	 * \retval 0 evaluation is False
+	 * \retval 1 evaluation is True
+	 */
+	int (* const evaluate)(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right);
+};
+
+/*! \brief A field that we understand and can perform operations on */
+struct allowed_field {
+	/*! \brief The representation of the field */
+	const char *symbol;
+	/*! \brief The type /c get_field returns */
+	enum aco_option_type return_type;
+	/*!
+	 * \brief Function that returns the field from a pjsip_history_entry
+	 *
+	 * Note that the function must return a pointer to the location in
+	 * \c pjsip_history_entry - no memory should be allocated as the caller
+	 * will not dispose of any
+	 */
+	void *(* const get_field)(struct pjsip_history_entry *entry);
+};
+
+/*! \brief The type of token that has been parsed out of an expression */
+enum expression_token_type {
+	/*! The \c expression_token contains a field */
+	TOKEN_TYPE_FIELD,
+	/*! The \c expression_token contains an operator */
+	TOKEN_TYPE_OPERATOR,
+	/*! The \c expression_token contains a previous result */
+	TOKEN_TYPE_RESULT
+};
+
+/*! \brief A token in the expression or an evaluated part of the expression */
+struct expression_token {
+	/*! \brief The next expression token in the queue */
+	struct expression_token *next;
+	/*! \brief The type of value stored in the expression token */
+	enum expression_token_type token_type;
+	/*! \brief An operator that evaluates expressions */
+	struct operator *op;
+	/*! \brief The result of an evaluated expression */
+	int result;
+	/*! \brief The field in the expression */
+	char field[];
+};
+
+/*!
+ * \brief Operator callback for determining equality
+ */
+static int evaluate_equal(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+	{
+		int right;
+
+		if (sscanf(op_right->field, "%30d", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not an integer\n", op_right->field);
+			return -1;
+		}
+		return (*(int *)op_left) == right;
+	}
+	case OPT_DOUBLE_T:
+	{
+		double right;
+
+		if (sscanf(op_right->field, "%lf", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a double\n", op_right->field);
+			return -1;
+		}
+		return (*(double *)op_left) == right;
+	}
+	case OPT_CHAR_ARRAY_T:
+	case OPT_STRINGFIELD_T:
+		/* In our case, we operate on pj_str_t */
+		return pj_strcmp2(op_left, op_right->field) == 0;
+	case OPT_NOOP_T:
+	/* Used for timeval */
+	{
+		struct timeval right = { 0, };
+
+		if (sscanf(op_right->field, "%ld", &right.tv_sec) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a timestamp\n", op_right->field);
+			return -1;
+		}
+
+		return ast_tvcmp(*(struct timeval *)op_left, right) == 0;
+	}
+	case OPT_SOCKADDR_T:
+	/* In our case, we operate only on pj_sockaddr_t */
+	{
+		pj_sockaddr right;
+		pj_str_t str_right;
+
+		pj_cstr(&str_right, op_right->field);
+		if (pj_sockaddr_parse(pj_AF_UNSPEC(), 0, &str_right, &right) != PJ_SUCCESS) {
+			ast_log(LOG_WARNING, "Unable to convert field '%s': not an IPv4 or IPv6 address\n", op_right->field);
+			return -1;
+		}
+
+		return pj_sockaddr_cmp(op_left, &right) == 0;
+	}
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate field '%s': invalid type for operator '%s'\n",
+			op_right->field, op->symbol);
+	}
+
+	return -1;
+}
+
+/*!
+ * \brief Operator callback for determining inequality
+ */
+static int evaluate_not_equal(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	return !evaluate_equal(op, type, op_left, op_right);
+}
+
+/*
+ * \brief Operator callback for determining if one operand is less than another
+ */
+static int evaluate_less_than(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+	{
+		int right;
+
+		if (sscanf(op_right->field, "%30d", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not an integer\n", op_right->field);
+			return -1;
+		}
+		return (*(int *)op_left) < right;
+	}
+	case OPT_DOUBLE_T:
+	{
+		double right;
+
+		if (sscanf(op_right->field, "%lf", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a double\n", op_right->field);
+			return -1;
+		}
+		return (*(double *)op_left) < right;
+	}
+	case OPT_NOOP_T:
+	/* Used for timeval */
+	{
+		struct timeval right = { 0, };
+
+		if (sscanf(op_right->field, "%ld", &right.tv_sec) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a timestamp\n", op_right->field);
+			return -1;
+		}
+
+		return ast_tvcmp(*(struct timeval *)op_left, right) == -1;
+	}
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate field '%s': invalid type for operator '%s'\n",
+			op_right->field, op->symbol);
+	}
+
+	return -1;
+}
+
+/*
+ * \brief Operator callback for determining if one operand is greater than another
+ */
+static int evaluate_greater_than(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+	{
+		int right;
+
+		if (sscanf(op_right->field, "%30d", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not an integer\n", op_right->field);
+			return -1;
+		}
+		return (*(int *)op_left) > right;
+	}
+	case OPT_DOUBLE_T:
+	{
+		double right;
+
+		if (sscanf(op_right->field, "%lf", &right) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a double\n", op_right->field);
+			return -1;
+		}
+		return (*(double *)op_left) > right;
+	}
+	case OPT_NOOP_T:
+	/* Used for timeval */
+	{
+		struct timeval right = { 0, };
+
+		if (sscanf(op_right->field, "%ld", &right.tv_sec) != 1) {
+			ast_log(LOG_WARNING, "Unable to extract field '%s': not a timestamp\n", op_right->field);
+			return -1;
+		}
+
+		return ast_tvcmp(*(struct timeval *)op_left, right) == 1;
+	}
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate field '%s': invalid type for operator '%s'\n",
+			op_right->field, op->symbol);
+	}
+
+	return -1;
+}
+
+/*
+ * \brief Operator callback for determining if one operand is less than or equal to another
+ */
+static int evaluate_less_than_or_equal(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	return !evaluate_greater_than(op, type, op_left, op_right);
+}
+
+/*
+ * \brief Operator callback for determining if one operand is greater than or equal to another
+ */
+static int evaluate_greater_than_or_equal(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	return !evaluate_less_than(op, type, op_left, op_right);
+}
+
+/*
+ * \brief Operator callback for determining logical NOT
+ */
+static int evaluate_not(struct operator *op, enum aco_option_type type, void *operand)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+		return !(*(int *)operand);
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate: invalid operand type for operator '%s'\n", op->symbol);
+	}
+
+	return -1;
+}
+
+/*
+ * \brief Operator callback for determining logical AND
+ */
+static int evaluate_and(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+		return (*(int *)op_left && op_right->result);
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate: invalid operand type for operator '%s'\n", op->symbol);
+	}
+
+	return -1;
+}
+
+/*
+ * \brief Operator callback for determining logical OR
+ */
+static int evaluate_or(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_BOOL_T:
+	case OPT_BOOLFLAG_T:
+	case OPT_INT_T:
+	case OPT_UINT_T:
+		return (*(int *)op_left || op_right->result);
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate: invalid operand type for operator '%s'\n", op->symbol);
+	}
+
+	return -1;
+}
+
+/*
+ * \brief Operator callback for regex 'like'
+ */
+static int evaluate_like(struct operator *op, enum aco_option_type type, void *op_left, struct expression_token *op_right)
+{
+	switch (type) {
+	case OPT_CHAR_ARRAY_T:
+	case OPT_STRINGFIELD_T:
+	/* In our case, we operate on pj_str_t */
+	{
+		int result;
+		regex_t regexbuf;
+		char buf[pj_strlen(op_left) + 1];
+
+		ast_copy_pj_str(buf, op_left, pj_strlen(op_left));
+		if (regcomp(&regexbuf, op_right->field, REG_EXTENDED | REG_NOSUB)) {
+			ast_log(LOG_WARNING, "Failed to compile '%s' into a regular expression\n", op_right->field);
+			return -1;
+		}
+
+		result = (regexec(&regexbuf, buf, 0, NULL, 0) == 0);
+		regfree(&regexbuf);
+
+		return result;
+	}
+	default:
+		ast_log(LOG_WARNING, "Cannot evaluate: invalid operand type for operator '%s'\n", op->symbol);
+	}
+
+	return -1;
+}
+
+/*!
+ * \brief Operator token for a left parenthesis.
+ *
+ * While this is used by the shunting-yard algorithm implementation,
+ * it should never appear in the resulting RPN queue of expression tokens
+ */
+static struct operator left_paren = {
+	.symbol = "(",
+	.precedence = 15
+};
+
+/*!
+ * \brief Our allowed operations
+ */
+static struct operator allowed_operators[] = {
+	{ .symbol = "=", .precedence = 7, .operands = 2, .evaluate = evaluate_equal, },
+	{ .symbol = "==", .precedence = 7, .operands = 2, .evaluate = evaluate_equal, },
+	{ .symbol = "!=", .precedence = 7, .operands = 2, .evaluate = evaluate_not_equal, },
+	{ .symbol = "<", .precedence = 6, .operands = 2, .evaluate = evaluate_less_than, },
+	{ .symbol = ">", .precedence = 6, .operands = 2, .evaluate = evaluate_greater_than, },
+	{ .symbol = "<=", .precedence = 6, .operands = 2, .evaluate = evaluate_less_than_or_equal, },
+	{ .symbol = ">=", .precedence = 6, .operands = 2, .evaluate = evaluate_greater_than_or_equal, },
+	{ .symbol = "!", .precedence = 2, .operands = 1, .right_to_left = 1, .evaluate_unary = evaluate_not, },
+	{ .symbol = "&&", .precedence = 11, .operands = 2, .evaluate = evaluate_and, },
+	{ .symbol = "||", .precedence = 12, .operands = 2, .evaluate = evaluate_or, },
+	{ .symbol = "like", .precedence = 7, .operands = 2, .evaluate = evaluate_like, },
+	{ .symbol = "and", .precedence = 11, .operands = 2, .evaluate = evaluate_and, },
+	{ .symbol = "or", .precedence = 11, .operands = 2, .evaluate = evaluate_or, },
+	{ .symbol = "not", .precedence = 2, .operands = 1, .right_to_left = 1, .evaluate_unary = evaluate_not, },
+};
+
+/*! \brief Callback to retrieve the entry index number */
+static void *entry_get_number(struct pjsip_history_entry *entry)
+{
+	return &entry->number;
+}
+
+/*! \brief Callback to retrieve the entry's timestamp */
+static void *entry_get_timestamp(struct pjsip_history_entry *entry)
+{
+	return &entry->timestamp;
+}
+
+/*! \brief Callback to retrieve the entry's destination address */
+static void *entry_get_addr(struct pjsip_history_entry *entry)
+{
+	if (entry->transmitted) {
+		return &entry->dst;
+	} else {
+		return &entry->src;
+	}
+}
+
+/*! \brief Callback to retrieve the entry's SIP request method type */
+static void *entry_get_sip_msg_request_method(struct pjsip_history_entry *entry)
+{
+	if (entry->msg->type != PJSIP_REQUEST_MSG) {
+		return NULL;
+	}
+
+	return &entry->msg->line.req.method.name;
+}
+
+/*! \brief Callback to retrieve the entry's SIP Call-ID header */
+static void *entry_get_sip_msg_call_id(struct pjsip_history_entry *entry)
+{
+	pjsip_cid_hdr *cid_hdr;
+
+	cid_hdr = PJSIP_MSG_CID_HDR(entry->msg);
+
+	return &cid_hdr->id;
+}
+
+/*! \brief The fields we allow */
+static struct allowed_field allowed_fields[] = {
+	{ .symbol = "number", .return_type = OPT_INT_T, .get_field = entry_get_number, },
+	/* We co-op the NOOP type here for timeval */
+	{ .symbol = "timestamp", .return_type = OPT_NOOP_T, .get_field = entry_get_timestamp, },
+	{ .symbol = "addr", .return_type = OPT_SOCKADDR_T, .get_field = entry_get_addr, },
+	{ .symbol = "sip.msg.request.method", .return_type = OPT_CHAR_ARRAY_T, .get_field = entry_get_sip_msg_request_method, },
+	{ .symbol = "sip.msg.call-id", .return_type = OPT_CHAR_ARRAY_T, .get_field = entry_get_sip_msg_call_id, },
+};
+
+/*! \brief Free an expression token and all others it references */
+static struct expression_token *expression_token_free(struct expression_token *token)
+{
+	struct expression_token *it_token;
+
+	it_token = token;
+	while (it_token) {
+		struct expression_token *prev = it_token;
+
+		it_token = it_token->next;
+		ast_free(prev);
+	}
+
+	return NULL;
+}
+
+/*!
+ * \brief Allocate an expression token
+ *
+ * \param token_type The type of token in the expression
+ * \param value The value/operator/result to pack into the token
+ *
+ * \retval NULL on failure
+ * \retval \c expression_token on success
+ */
+static struct expression_token *expression_token_alloc(enum expression_token_type token_type, void *value)
+{
+	struct expression_token *token;
+
+	switch (token_type) {
+	case TOKEN_TYPE_RESULT:
+	case TOKEN_TYPE_OPERATOR:
+		token = ast_calloc(1, sizeof(*token));
+		break;
+	case TOKEN_TYPE_FIELD:
+		token = ast_calloc(1, sizeof(*token) + strlen((const char *)value) + 1);
+		break;
+	default:
+		ast_assert(0);
+		return NULL;
+	}
+
+	if (!token) {
+		return NULL;
+	}
+	token->token_type = token_type;
+
+	switch (token_type) {
+	case TOKEN_TYPE_RESULT:
+		token->result = *(int *)value;
+		break;
+	case TOKEN_TYPE_OPERATOR:
+		token->op = value;
+		break;
+	case TOKEN_TYPE_FIELD:
+		strcpy(token->field, value); /* safe */
+		break;
+	default:
+		ast_assert(0);
+	}
+
+	return token;
+}
+
+/*! \brief Determine if the expression token matches a field in \c allowed_fields */
+static struct allowed_field *get_allowed_field(struct expression_token *token)
+{
+	int i;
+
+	ast_assert(token->token_type == TOKEN_TYPE_FIELD);
+
+	for (i = 0; i < ARRAY_LEN(allowed_fields); i++) {
+		if (strcasecmp(allowed_fields[i].symbol, token->field)) {
+			continue;
+		}
+
+		return &allowed_fields[i];
+	}
+
+	return NULL;
+}
+
+/*! \brief AO2 destructor for \c pjsip_history_entry */
+static void pjsip_history_entry_dtor(void *obj)
+{
+	struct pjsip_history_entry *entry = obj;
+
+	if (entry->pool) {
+		pj_pool_release(entry->pool);
+		entry->pool = NULL;
+	}
+}
+
+/*!
+ * \brief Create a \c pjsip_history_entry AO2 object
+ *
+ * \param msg The PJSIP message that this history entry wraps
+ *
+ * \retval An AO2 \c pjsip_history_entry object on success
+ * \retval NULL on failure
+ */
+static struct pjsip_history_entry *pjsip_history_entry_alloc(pjsip_msg *msg)
+{
+	struct pjsip_history_entry *entry;
+
+	entry = ao2_alloc_options(sizeof(*entry), pjsip_history_entry_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
+	if (!entry) {
+		return NULL;
+	}
+	entry->number = ast_atomic_fetchadd_int(&packet_number, 1);
+	entry->timestamp = ast_tvnow();
+	entry->timestamp.tv_usec = 0;
+
+	entry->pool = pj_pool_create(&cachingpool.factory, NULL, PJSIP_POOL_RDATA_LEN,
+	                             PJSIP_POOL_RDATA_INC, NULL);
+	if (!entry->pool) {
+		ao2_ref(entry, -1);
+		return NULL;
+	}
+
+	entry->msg = pjsip_msg_clone(entry->pool, msg);
+	if (!entry->msg) {
+		ao2_ref(entry, -1);
+		return NULL;
+	}
+
+	return entry;
+}
+
+/*! \brief PJSIP callback when a SIP message is transmitted */
+static pj_status_t history_on_tx_msg(pjsip_tx_data *tdata)
+{
+	struct pjsip_history_entry *entry;
+
+	if (!enabled) {
+		return PJ_SUCCESS;
+	}
+
+	entry = pjsip_history_entry_alloc(tdata->msg);
+	if (!entry) {
+		return PJ_SUCCESS;
+	}
+	entry->transmitted = 1;
+	pj_sockaddr_cp(&entry->src, &tdata->tp_info.transport->local_addr);
+	pj_sockaddr_cp(&entry->dst, &tdata->tp_info.dst_addr);
+
+	ast_mutex_lock(&history_lock);
+	AST_VECTOR_APPEND(&vector_history, entry);
+	ast_mutex_unlock(&history_lock);
+
+	return PJ_SUCCESS;
+}
+
+/*! \brief PJSIP callback when a SIP message is received */
+static pj_bool_t history_on_rx_msg(pjsip_rx_data *rdata)
+{
+	struct pjsip_history_entry *entry;
+
+	if (!enabled) {
+		return PJ_FALSE;
+	}
+
+	if (!rdata->msg_info.msg) {
+		return PJ_FALSE;
+	}
+
+	entry = pjsip_history_entry_alloc(rdata->msg_info.msg);
+	if (!entry) {
+		return PJ_FALSE;
+	}
+
+	if (rdata->tp_info.transport->addr_len) {
+		pj_sockaddr_cp(&entry->dst, &rdata->tp_info.transport->local_addr);
+	}
+
+	if (rdata->pkt_info.src_addr_len) {
+		pj_sockaddr_cp(&entry->src, &rdata->pkt_info.src_addr);
+	}
+
+	ast_mutex_lock(&history_lock);
+	AST_VECTOR_APPEND(&vector_history, entry);
+	ast_mutex_unlock(&history_lock);
+
+	return PJ_FALSE;
+}
+
+/*! \brief Vector callback that releases the reference for the entry in a history vector */
+static void clear_history_entry_cb(struct pjsip_history_entry *entry)
+{
+	ao2_ref(entry, -1);
+}
+
+/*!
+ * \brief Remove all entries from \ref vector_history
+ *
+ * This must be called from a registered PJSIP thread
+ */
+static int clear_history_entries(void *obj)
+{
+	ast_mutex_lock(&history_lock);
+	AST_VECTOR_RESET(&vector_history, clear_history_entry_cb);
+	packet_number = 0;
+	ast_mutex_unlock(&history_lock);
+
+	return 0;
+}
+
+/*!
+ * \brief Build a reverse polish notation expression queue
+ *
+ * This function is an implementation of the Shunting-Yard Algorithm. It takes
+ * a user provided infix-notation expression and converts it into a reverse
+ * polish notation expression, which is a queue of tokens that can be easily
+ * parsed.
+ *
+ * \params a The CLI arguments provided by the User, containing the infix expression
+ *
+ * \retval NULL error
+ * \retval expression_token A 'queue' of expression tokens in RPN
+ */
+static struct expression_token *build_expression_queue(struct ast_cli_args *a)
+{
+	AST_VECTOR(, struct operator *) operators; /* A stack of saved operators */
+	struct expression_token *output = NULL;    /* The output queue */
+	struct expression_token *head = NULL;      /* Pointer to the head of /c output */
+	int i;
+
+#define APPEND_TO_OUTPUT(output, token) do { \
+	if ((output)) { \
+		(output)->next = (token); \
+		(output) = (token); \
+	} else { \
+		(output) = (token); \
+		head = (output); \
+	} \
+} while (0)
+
+	if (AST_VECTOR_INIT(&operators, 8)) {
+		return NULL;
+	}
+
+	for (i = 4; i < a->argc; i++) {
+		struct expression_token *out_token;
+		char *token = ast_strdupa(a->argv[i]);
+		int j;
+
+		/* Strip off and append any left parentheses */
+		if (token[0] == '(') {
+			AST_VECTOR_APPEND(&operators, &left_paren);
+			if (!token[1]) {
+				continue;
+			}
+			token = &token[1];
+		}
+
+		/* Handle the case where the token is an operator */
+		for (j = 0; j < ARRAY_LEN(allowed_operators); j++) {
+			int k;
+
+			if (strcasecmp(token, allowed_operators[j].symbol)) {
+				continue;
+			}
+
+			for (k = AST_VECTOR_SIZE(&operators) - 1; k >= 0; k--) {
+				struct operator *top = AST_VECTOR_GET(&operators, k);
+
+				/* Remove and push queued up operators, if they are of
+				 * less precedence than this operator
+				 */
+				if ((allowed_operators[j].right_to_left && allowed_operators[j].precedence >= top->precedence)
+					|| (!allowed_operators[j].right_to_left && allowed_operators[j].precedence > top->precedence)) {
+
+					if (!(out_token = expression_token_alloc(TOKEN_TYPE_OPERATOR, top))) {
+						goto error;
+					}
+					APPEND_TO_OUTPUT(output, out_token);
+					AST_VECTOR_REMOVE(&operators, k, 1);
+				}
+			}
+
+			AST_VECTOR_APPEND(&operators, &allowed_operators[j]);
+			token = NULL;
+			break;
+		}
+
+		/* Token was an operator; continue to next token */
+		if (!token) {
+			continue;
+		}
+
+		/* Handle a right parentheses either by itself or as part of the token.
+		 * If part of the token, push the token onto the output queue first
+		 */
+		if (token[0] == ')' || token[strlen(token) - 1] == ')') {
+
+			if (token[strlen(token) - 1] == ')') {
+				token[strlen(token) - 1] = '\0';
+
+				if (!(out_token = expression_token_alloc(TOKEN_TYPE_FIELD, token))) {
+					goto error;
+				}
+				APPEND_TO_OUTPUT(output, out_token);
+				token = NULL;
+			}
+
+			for (j = AST_VECTOR_SIZE(&operators) - 1; j >= 0; j--) {
+				struct operator *top = AST_VECTOR_GET(&operators, j);
+
+				AST_VECTOR_REMOVE(&operators, j, 1);
+				if (top == &left_paren) {
+					break;
+				}
+
+				if (!(out_token = expression_token_alloc(TOKEN_TYPE_OPERATOR, top))) {
+					goto error;
+				}
+				APPEND_TO_OUTPUT(output, out_token);
+			}
+		}
+
+		/* Just a plain token, push to the output queue */
+		if (token) {
+			if (!(out_token = expression_token_alloc(TOKEN_TYPE_FIELD, token))) {
+				goto error;
+			}
+			APPEND_TO_OUTPUT(output, out_token);
+		}
+	}
+
+	/* Remove any non-applied operators that remain, applying them
+	 * to the output queue
+	 */
+	for (i = AST_VECTOR_SIZE(&operators) - 1; i >= 0; i--) {
+		struct operator *top = AST_VECTOR_GET(&operators, i);
+		struct expression_token *out_token;
+
+		AST_VECTOR_REMOVE(&operators, i, 1);
+		if (top == &left_paren) {
+			ast_log(LOG_WARNING, "Unbalanced '(' parentheses in expression!\n");
+			continue;
+		}
+
+		if (!(out_token = expression_token_alloc(TOKEN_TYPE_OPERATOR, top))) {
+			goto error;
+		}
+		APPEND_TO_OUTPUT(output, out_token);
+	}
+
+	AST_VECTOR_FREE(&operators);
+	return head;
+
+error:
+	AST_VECTOR_FREE(&operators);
+	expression_token_free(output);
+	return NULL;
+}
+
+/*!
+ * \brief Evaluate a single entry in this history using a RPN expression
+ *
+ * \param entry The entry in the history to evaluate
+ * \param queue The RPN expression
+ *
+ * \retval 0 The expression evaluated FALSE on \c entry
+ * \retval 1 The expression evaluated TRUE on \c entry
+ * \retval -1 The expression errored
+ */
+static int evaluate_history_entry(struct pjsip_history_entry *entry, struct expression_token *queue)
+{
+	AST_VECTOR(, struct expression_token *) stack; /* Our stack of results and operands */
+	struct expression_token *it_queue;
+	struct expression_token *final;
+	int result;
+	int i;
+
+	if (AST_VECTOR_INIT(&stack, 16)) {
+		return -1;
+	}
+
+	for (it_queue = queue; it_queue; it_queue = it_queue->next) {
+		struct expression_token *op_one;
+		struct expression_token *op_two = NULL;
+		struct expression_token *result;
+		int res = 0;
+
+		/* If this is not an operator, push it to the stack */
+		if (!it_queue->op) {
+			AST_VECTOR_APPEND(&stack, it_queue);
+			continue;
+		}
+
+		if (AST_VECTOR_SIZE(&stack) < it_queue->op->operands) {
+			ast_log(LOG_WARNING, "Unable to evaluate expression operator '%s': not enough operands\n",
+				it_queue->op->symbol);
+			goto error;
+		}
+
+		if (it_queue->op->operands == 1) {
+			/* Unary operators currently consist only of 'not', which can only act
+			 * upon an evaluated condition result.
+			 */
+			ast_assert(it_queue->op->evaluate_unary != NULL);
+
+			op_one = AST_VECTOR_REMOVE(&stack, AST_VECTOR_SIZE(&stack) - 1, 1);
+			if (op_one->token_type != TOKEN_TYPE_RESULT) {
+				ast_log(LOG_WARNING, "Unable to evaluate '%s': operand is not the result of an operation\n",
+					it_queue->op->symbol);
+				goto error;
+			}
+
+			res = it_queue->op->evaluate_unary(it_queue->op, OPT_INT_T, &op_one->result) == 0 ? 0 : 1;
+		} else if (it_queue->op->operands == 2) {
+			struct allowed_field *field;
+			enum aco_option_type type;
+			void *value;
+
+			ast_assert(it_queue->op->evaluate != NULL);
+
+			op_one = AST_VECTOR_REMOVE(&stack, AST_VECTOR_SIZE(&stack) - 1, 1);
+			op_two = AST_VECTOR_REMOVE(&stack, AST_VECTOR_SIZE(&stack) - 1, 1);
+
+			/* If operand two is a field, then it must be a field we recognize. */
+			if (op_two->token_type == TOKEN_TYPE_FIELD) {
+				field = get_allowed_field(op_two);
+				if (!field) {
+					ast_log(LOG_WARNING, "Unknown or unrecognized field: %s\n", op_two->field);
+					goto error;
+				}
+
+				type = field->return_type;
+				value = field->get_field(entry);
+			} else if (op_two->token_type == TOKEN_TYPE_RESULT) {
+				type = OPT_INT_T;
+				value = &op_two->result;
+			} else {
+				ast_log(LOG_WARNING, "Attempting to evaluate an operator: %s\n", op_two->op->symbol);
+				goto error;
+			}
+
+			if (value) {
+				res = it_queue->op->evaluate(it_queue->op, type, value, op_one) == 0 ? 0 : 1;
+			} else {
+				res = 0;
+			}
+		} else {
+			ast_log(LOG_WARNING, "Operator '%s' has an invalid number of operands\n", it_queue->op->symbol);
+			ast_assert(0);
+			goto error;
+		}
+
+		/* Results are temporary; clean used ones up */
+		if (op_one && op_one->token_type == TOKEN_TYPE_RESULT) {
+			ast_free(op_one);
+		}
+		if (op_two && op_two->token_type == TOKEN_TYPE_RESULT) {
+			ast_free(op_two);
+		}
+
+		/* Push the result onto the stack */
+		result = expression_token_alloc(TOKEN_TYPE_RESULT, &res);
+		if (!result) {
+			goto error;
+		}
+		AST_VECTOR_APPEND(&stack, result);
+	}
+
+	/*
+	 * When the evaluation is complete, we must have:
+	 *  - A single result remaining on the stack
+	 *  - An actual result
+	 */
+	if (AST_VECTOR_SIZE(&stack) != 1) {
+		ast_log(LOG_WARNING, "Expression was unbalanced: %zu results remained after evaluation\n",
+			AST_VECTOR_SIZE(&stack));
+		goto error;
+	}
+
+	final = AST_VECTOR_GET(&stack, 0);
+	if (final->token_type != TOKEN_TYPE_RESULT) {
+		ast_log(LOG_WARNING, "Expression did not create a usable result\n");
+		goto error;
+	}
+	result = final->result;
+	ast_free(final);
+
+	return result;
+
+error:
+	/* Clean out any remaining result expression tokens */
+	for (i = 0; i < AST_VECTOR_SIZE(&stack); i++) {
+		struct expression_token *failed_token = AST_VECTOR_GET(&stack, i);
+
+		if (failed_token->token_type == TOKEN_TYPE_RESULT) {
+			ast_free(failed_token);
+		}
+	}
+	AST_VECTOR_FREE(&stack);
+	return -1;
+}
+
+/*!
+ * \brief Create a filtered history based on a user provided expression
+ *
+ * \param a The CLI arguments containing the expression
+ *
+ * \retval NULL on error
+ * \retval A vector containing the filtered history on success
+ */
+static struct vector_history_t *filter_history(struct ast_cli_args *a)
+{
+	struct vector_history_t *output;
+	struct expression_token *queue;
+	int i;
+
+	output = ast_malloc(sizeof(*output));
+	if (!output) {
+		return NULL;
+	}
+
+	if (AST_VECTOR_INIT(output, HISTORY_INITIAL_SIZE / 2)) {
+		ast_free(output);
+		return NULL;
+	}
+
+	queue = build_expression_queue(a);
+	if (!queue) {
+		return NULL;
+	}
+
+	ast_mutex_lock(&history_lock);
+	for (i = 0; i < AST_VECTOR_SIZE(&vector_history); i++) {
+		struct pjsip_history_entry *entry = AST_VECTOR_GET(&vector_history, i);
+		int res;
+
+		res = evaluate_history_entry(entry, queue);
+		if (res == -1) {
+			/* Error in expression evaluation; bail */
+			ast_mutex_unlock(&history_lock);
+			AST_VECTOR_RESET(output, clear_history_entry_cb);
+			AST_VECTOR_FREE(output);
+			ast_free(output);
+			expression_token_free(queue);
+			return NULL;
+		} else if (!res) {
+			continue;
+		} else {
+			AST_VECTOR_APPEND(output, ao2_bump(entry));
+		}
+	}
+	ast_mutex_unlock(&history_lock);
+
+	expression_token_free(queue);
+
+	return output;
+}
+
+/*! \brief Print a detailed view of a single entry in the history to the CLI */
+static void display_single_entry(struct ast_cli_args *a, struct pjsip_history_entry *entry)
+{
+	char addr[64];
+	char *buf;
+
+	buf = ast_calloc(1, PJSIP_MAX_PKT_LEN * sizeof(char));
+	if (!buf) {
+		return;
+	}
+
+	if (pjsip_msg_print(entry->msg, buf, PJSIP_MAX_PKT_LEN) == -1) {
+		ast_log(LOG_WARNING, "Unable to print SIP message %d: packet too large!\n", entry->number);
+		ast_free(buf);
+		return;
+	}
+
+	if (entry->transmitted) {
+		pj_sockaddr_print(&entry->dst, addr, sizeof(addr), 3);
+	} else {
+		pj_sockaddr_print(&entry->src, addr, sizeof(addr), 3);
+	}
+
+	ast_cli(a->fd, "<--- History Entry %d %s %s at %-10.10ld --->\n",
+		entry->number,
+		entry->transmitted ? "Sent to" : "Received from",
+		addr,
+		entry->timestamp.tv_sec);
+	ast_cli(a->fd, "%s\n", buf);
+
+	ast_free(buf);
+}
+
+/*! \brief Print a list of the entries to the CLI */
+static void display_entry_list(struct ast_cli_args *a, struct vector_history_t *vec)
+{
+	int i;
+
+	ast_cli(a->fd, "%-5.5s %-10.10s %-30.30s %-35.35s\n",
+		"No.",
+		"Timestamp",
+		"(Dir) Address",
+		"SIP Message");
+	ast_cli(a->fd, "===== ========== ============================== ===================================\n");
+
+	for (i = 0; i < AST_VECTOR_SIZE(vec); i++) {
+		struct pjsip_history_entry *entry;
+		char addr[64];
+		char line[256];
+
+		entry = AST_VECTOR_GET(vec, i);
+
+		if (entry->transmitted) {
+			pj_sockaddr_print(&entry->dst, addr, sizeof(addr), 3);
+		} else {
+			pj_sockaddr_print(&entry->src, addr, sizeof(addr), 3);
+		}
+
+		if (entry->msg->type == PJSIP_REQUEST_MSG) {
+			char uri[128];
+
+			pjsip_uri_print(PJSIP_URI_IN_REQ_URI, entry->msg->line.req.uri, uri, sizeof(uri));
+			snprintf(line, sizeof(line), "%.*s %s SIP/2.0",
+				(int)pj_strlen(&entry->msg->line.req.method.name),
+				pj_strbuf(&entry->msg->line.req.method.name),
+				uri);
+		} else {
+			snprintf(line, sizeof(line), "SIP/2.0 %u %.*s",
+				entry->msg->line.status.code,
+				(int)pj_strlen(&entry->msg->line.status.reason),
+				pj_strbuf(&entry->msg->line.status.reason));
+		}
+
+		ast_cli(a->fd, "%-5.5d %-10.10ld %-5.5s %-24.24s %s\n",
+			entry->number,
+			entry->timestamp.tv_sec,
+			entry->transmitted ? "* ==>" : "* <==",
+			addr,
+			line);
+	}
+}
+
+/*! \brief Cleanup routine for a history vector, serviced on a registered PJSIP thread */
+static int safe_vector_cleanup(void *obj)
+{
+	struct vector_history_t *vec = obj;
+
+	AST_VECTOR_RESET(vec, clear_history_entry_cb);
+	AST_VECTOR_FREE(vec);
+	ast_free(vec);
+
+	return 0;
+}
+
+static char *pjsip_show_history(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct vector_history_t *vec = &vector_history;
+	struct pjsip_history_entry *entry = NULL;
+
+	if (cmd == CLI_INIT) {
+		e->command = "pjsip show history";
+		e->usage =
+			"Usage: pjsip show history [entry <num>|where [...]]\n"
+			"       Displays the currently collected history or an\n"
+			"       entry within the history.\n\n"
+			"       * Running the command with no options will display\n"
+			"         the entire history.\n"
+			"       * Providing 'entry <num>' will display the full\n"
+			"         detail of a particular entry in this history.\n"
+			"       * Providing 'where ...' will allow for filtering\n"
+			"         the history. The history can be filtered using\n"
+			"         any of the following fields:\n"
+			"         - number: The history entry number\n"
+			"         - timestamp: The time associated with the history entry\n"
+			"         - addr: The source/destination address of the SIP message\n"
+			"         - sip.msg.request.method: The request method type\n"
+			"         - sip.msg.call-id: The Call-ID header of the SIP message\n"
+			"\n"
+			"         When filtering, standard Boolean operators can be used,\n"
+			"         as well as 'like' for regexs.\n"
+			"\n"
+			"         Example:\n"
+			"         'pjsip show history where number > 5 and (addr = \"192.168.0.3:5060\" or addr = \"192.168.0.5:5060\")'\n";
+		return NULL;
+	} else if (cmd == CLI_GENERATE) {
+		return NULL;
+	}
+
+	if (a->argc > 3) {
+		if (!strcasecmp(a->argv[3], "entry") && a->argc == 5) {
+			int num;
+
+			if (sscanf(a->argv[4], "%30d", &num) != 1) {
+				ast_cli(a->fd, "'%s' is not a valid entry number\n", a->argv[4]);
+				return CLI_FAILURE;
+			}
+
+			/* Get the entry at the provided position */
+			ast_mutex_lock(&history_lock);
+			if (num >= AST_VECTOR_SIZE(&vector_history) || num < 0) {
+				ast_cli(a->fd, "Entry '%d' does not exist\n", num);
+				ast_mutex_unlock(&history_lock);
+				return CLI_FAILURE;
+			}
+			entry = ao2_bump(AST_VECTOR_GET(&vector_history, num));
+			ast_mutex_unlock(&history_lock);
+		} else if (!strcasecmp(a->argv[3], "where")) {
+			vec = filter_history(a);
+			if (!vec) {
+				return CLI_FAILURE;
+			}
+		} else {
+			return CLI_SHOWUSAGE;
+		}
+	}
+
+	if (AST_VECTOR_SIZE(vec) == 1) {
+		if (vec == &vector_history) {
+			ast_mutex_lock(&history_lock);
+		}
+		entry = ao2_bump(AST_VECTOR_GET(vec, 0));
+		if (vec == &vector_history) {
+			ast_mutex_lock(&history_lock);
+		}
+	}
+
+	if (entry) {
+		display_single_entry(a, entry);
+	} else {
+		if (vec == &vector_history) {
+			ast_mutex_lock(&history_lock);
+		}
+
+		display_entry_list(a, vec);
+
+		if (vec == &vector_history) {
+			ast_mutex_unlock(&history_lock);
+		}
+	}
+
+	if (vec != &vector_history) {
+		ast_sip_push_task(NULL, safe_vector_cleanup, vec);
+	}
+	ao2_cleanup(entry);
+
+	return CLI_SUCCESS;
+}
+
+static char *pjsip_set_history(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	const char *what;
+
+	if (cmd == CLI_INIT) {
+		e->command = "pjsip set history {on|off|clear}";
+		e->usage =
+			"Usage: pjsip set history {on|off|clear}\n"
+			"       Enables/disables/clears the PJSIP history.\n\n"
+			"       Enabling the history will start recording transmitted/received\n"
+			"       packets. Disabling the history will stop recording, but keep\n"
+			"       the already received packets. Clearing the history will wipe\n"
+			"       the received packets from memory.\n\n"
+			"       As the PJSIP history is maintained in memory, and includes\n"
+			"       all received/transmitted requests and responses, it should\n"
+			"       only be enabled for debugging purposes, and cleared when done.\n";
+		return NULL;
+	} else if (cmd == CLI_GENERATE) {
+		return NULL;
+	}
+
+	what = a->argv[e->args - 1];	/* Guaranteed to exist */
+
+	if (a->argc == e->args) {
+		if (!strcasecmp(what, "on")) {
+			enabled = 1;
+			ast_cli(a->fd, "PJSIP History enabled\n");
+			return CLI_SUCCESS;
+		} else if (!strcasecmp(what, "off")) {
+			enabled = 0;
+			ast_cli(a->fd, "PJSIP History disabled\n");
+			return CLI_SUCCESS;
+		} else if (!strcasecmp(what, "clear")) {
+			ast_sip_push_task(NULL, clear_history_entries, NULL);
+			ast_cli(a->fd, "PJSIP History cleared\n");
+			return CLI_SUCCESS;
+		}
+	}
+
+	return CLI_SHOWUSAGE;
+}
+
+static pjsip_module logging_module = {
+	.name = { "History Module", 14 },
+	.priority = 0,
+	.on_rx_request = history_on_rx_msg,
+	.on_rx_response = history_on_rx_msg,
+	.on_tx_request = history_on_tx_msg,
+	.on_tx_response = history_on_tx_msg,
+};
+
+static struct ast_cli_entry cli_pjsip[] = {
+	AST_CLI_DEFINE(pjsip_set_history, "Enable/Disable PJSIP History"),
+	AST_CLI_DEFINE(pjsip_show_history, "Display PJSIP History"),
+};
+
+static int load_module(void)
+{
+	CHECK_PJSIP_MODULE_LOADED();
+
+	pj_caching_pool_init(&cachingpool, &pj_pool_factory_default_policy, 0);
+
+	AST_VECTOR_INIT(&vector_history, HISTORY_INITIAL_SIZE);
+
+	ast_sip_register_service(&logging_module);
+	ast_cli_register_multiple(cli_pjsip, ARRAY_LEN(cli_pjsip));
+
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	ast_cli_unregister_multiple(cli_pjsip, ARRAY_LEN(cli_pjsip));
+	ast_sip_unregister_service(&logging_module);
+
+	ast_sip_push_task_synchronous(NULL, clear_history_entries, NULL);
+	AST_VECTOR_FREE(&vector_history);
+
+	pj_caching_pool_destroy(&cachingpool);
+
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP History",
+		.support_level = AST_MODULE_SUPPORT_EXTENDED,
+		.load = load_module,
+		.unload = unload_module,
+		.load_pri = AST_MODPRI_APP_DEPEND,
+	);