mosquitto/libcommon/property_common.c

/*
Copyright (c) 2018-2021 Roger Light <roger@atchoo.org>

All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
and Eclipse Distribution License v1.0 which accompany this distribution.

The Eclipse Public License is available at
   https://www.eclipse.org/legal/epl-2.0/
and the Eclipse Distribution License is available at
  http://www.eclipse.org/org/documents/edl-v10.php.

SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause

Contributors:
   Roger Light - initial implementation and documentation.
*/

#include "config.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#ifndef WIN32
#  include <strings.h>
#endif

#include "mosquitto.h"
#include "property_common.h"


void mosquitto_property_free(mosquitto_property **property)
{
	if(!property || !(*property)) return;

	switch((*property)->property_type){
		case MQTT_PROP_TYPE_STRING:
			mosquitto_FREE((*property)->value.s.v);
			break;

		case MQTT_PROP_TYPE_BINARY:
			mosquitto_FREE((*property)->value.bin.v);
			break;

		case MQTT_PROP_TYPE_STRING_PAIR:
			mosquitto_FREE((*property)->name.v);
			mosquitto_FREE((*property)->value.s.v);
			break;

		case MQTT_PROP_TYPE_BYTE:
		case MQTT_PROP_TYPE_INT16:
		case MQTT_PROP_TYPE_INT32:
		case MQTT_PROP_TYPE_VARINT:
			/* Nothing to free */
			break;
	}

	free(*property);
	*property = NULL;
}


BROKER_EXPORT void mosquitto_property_free_all(mosquitto_property **property)
{
	mosquitto_property *p, *next;

	if(!property) return;

	p = *property;
	while(p){
		next = p->next;
		mosquitto_property_free(&p);
		p = next;
	}
	*property = NULL;
}


unsigned int mosquitto_property_get_length(const mosquitto_property *property)
{
	if(!property) return 0;

	switch(property->property_type){
		case MQTT_PROP_TYPE_BYTE:
			return 2; /* 1 (identifier) + 1 byte */

		case MQTT_PROP_TYPE_INT16:
			return 3; /* 1 (identifier) + 2 bytes */

		case MQTT_PROP_TYPE_INT32:
			return 5; /* 1 (identifier) + 4 bytes */

		case MQTT_PROP_TYPE_VARINT:
			if(property->value.varint < 128){
				return 2;
			}else if(property->value.varint < 16384){
				return 3;
			}else if(property->value.varint < 2097152){
				return 4;
			}else if(property->value.varint < 268435456){
				return 5;
			}else{
				return 0;
			}

		case MQTT_PROP_TYPE_BINARY:
			return 3U + property->value.bin.len; /* 1 + 2 bytes (len) + X bytes (payload) */

		case MQTT_PROP_TYPE_STRING:
			return 3U + property->value.s.len; /* 1 + 2 bytes (len) + X bytes (string) */

		case MQTT_PROP_TYPE_STRING_PAIR:
			return 5U + property->value.s.len + property->name.len; /* 1 + 2*(2 bytes (len) + X bytes (string))*/

		default:
			return 0;
	}
	return 0;
}


unsigned int mosquitto_property_get_length_all(const mosquitto_property *property)
{
	const mosquitto_property *p;
	unsigned int len = 0;

	p = property;
	while(p){
		len += mosquitto_property_get_length(p);
		p = p->next;
	}
	return len;
}


BROKER_EXPORT int mosquitto_property_check_command(int command, int identifier)
{
	switch(identifier){
		case MQTT_PROP_PAYLOAD_FORMAT_INDICATOR:
		case MQTT_PROP_MESSAGE_EXPIRY_INTERVAL:
		case MQTT_PROP_CONTENT_TYPE:
		case MQTT_PROP_RESPONSE_TOPIC:
		case MQTT_PROP_CORRELATION_DATA:
			if(command != CMD_PUBLISH && command != CMD_WILL){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_SUBSCRIPTION_IDENTIFIER:
			if(command != CMD_PUBLISH && command != CMD_SUBSCRIBE){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_SESSION_EXPIRY_INTERVAL:
			if(command != CMD_CONNECT && command != CMD_CONNACK && command != CMD_DISCONNECT){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_AUTHENTICATION_METHOD:
		case MQTT_PROP_AUTHENTICATION_DATA:
			if(command != CMD_CONNECT && command != CMD_CONNACK && command != CMD_AUTH){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER:
		case MQTT_PROP_SERVER_KEEP_ALIVE:
		case MQTT_PROP_RESPONSE_INFORMATION:
		case MQTT_PROP_MAXIMUM_QOS:
		case MQTT_PROP_RETAIN_AVAILABLE:
		case MQTT_PROP_WILDCARD_SUB_AVAILABLE:
		case MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE:
		case MQTT_PROP_SHARED_SUB_AVAILABLE:
			if(command != CMD_CONNACK){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_WILL_DELAY_INTERVAL:
			if(command != CMD_WILL){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_REQUEST_PROBLEM_INFORMATION:
		case MQTT_PROP_REQUEST_RESPONSE_INFORMATION:
			if(command != CMD_CONNECT){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_SERVER_REFERENCE:
			if(command != CMD_CONNACK && command != CMD_DISCONNECT){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_REASON_STRING:
			if(command == CMD_CONNECT || command == CMD_PUBLISH || command == CMD_SUBSCRIBE || command == CMD_UNSUBSCRIBE){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_RECEIVE_MAXIMUM:
		case MQTT_PROP_TOPIC_ALIAS_MAXIMUM:
		case MQTT_PROP_MAXIMUM_PACKET_SIZE:
			if(command != CMD_CONNECT && command != CMD_CONNACK){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_TOPIC_ALIAS:
			if(command != CMD_PUBLISH){
				return MOSQ_ERR_PROTOCOL;
			}
			break;

		case MQTT_PROP_USER_PROPERTY:
			break;

		default:
			return MOSQ_ERR_PROTOCOL;
	}
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT const char *mosquitto_property_identifier_to_string(int identifier)
{
	switch(identifier){
		case MQTT_PROP_PAYLOAD_FORMAT_INDICATOR:
			return "payload-format-indicator";
		case MQTT_PROP_MESSAGE_EXPIRY_INTERVAL:
			return "message-expiry-interval";
		case MQTT_PROP_CONTENT_TYPE:
			return "content-type";
		case MQTT_PROP_RESPONSE_TOPIC:
			return "response-topic";
		case MQTT_PROP_CORRELATION_DATA:
			return "correlation-data";
		case MQTT_PROP_SUBSCRIPTION_IDENTIFIER:
			return "subscription-identifier";
		case MQTT_PROP_SESSION_EXPIRY_INTERVAL:
			return "session-expiry-interval";
		case MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER:
			return "assigned-client-identifier";
		case MQTT_PROP_SERVER_KEEP_ALIVE:
			return "server-keep-alive";
		case MQTT_PROP_AUTHENTICATION_METHOD:
			return "authentication-method";
		case MQTT_PROP_AUTHENTICATION_DATA:
			return "authentication-data";
		case MQTT_PROP_REQUEST_PROBLEM_INFORMATION:
			return "request-problem-information";
		case MQTT_PROP_WILL_DELAY_INTERVAL:
			return "will-delay-interval";
		case MQTT_PROP_REQUEST_RESPONSE_INFORMATION:
			return "request-response-information";
		case MQTT_PROP_RESPONSE_INFORMATION:
			return "response-information";
		case MQTT_PROP_SERVER_REFERENCE:
			return "server-reference";
		case MQTT_PROP_REASON_STRING:
			return "reason-string";
		case MQTT_PROP_RECEIVE_MAXIMUM:
			return "receive-maximum";
		case MQTT_PROP_TOPIC_ALIAS_MAXIMUM:
			return "topic-alias-maximum";
		case MQTT_PROP_TOPIC_ALIAS:
			return "topic-alias";
		case MQTT_PROP_MAXIMUM_QOS:
			return "maximum-qos";
		case MQTT_PROP_RETAIN_AVAILABLE:
			return "retain-available";
		case MQTT_PROP_USER_PROPERTY:
			return "user-property";
		case MQTT_PROP_MAXIMUM_PACKET_SIZE:
			return "maximum-packet-size";
		case MQTT_PROP_WILDCARD_SUB_AVAILABLE:
			return "wildcard-subscription-available";
		case MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE:
			return "subscription-identifier-available";
		case MQTT_PROP_SHARED_SUB_AVAILABLE:
			return "shared-subscription-available";
		default:
			return NULL;
	}
}


BROKER_EXPORT int mosquitto_string_to_property_info(const char *propname, int *identifier, int *type)
{
	if(!propname) return MOSQ_ERR_INVAL;

	if(!strcasecmp(propname, "payload-format-indicator")){
		*identifier = MQTT_PROP_PAYLOAD_FORMAT_INDICATOR;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "message-expiry-interval")){
		*identifier = MQTT_PROP_MESSAGE_EXPIRY_INTERVAL;
		*type = MQTT_PROP_TYPE_INT32;
	}else if(!strcasecmp(propname, "content-type")){
		*identifier = MQTT_PROP_CONTENT_TYPE;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "response-topic")){
		*identifier = MQTT_PROP_RESPONSE_TOPIC;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "correlation-data")){
		*identifier = MQTT_PROP_CORRELATION_DATA;
		*type = MQTT_PROP_TYPE_BINARY;
	}else if(!strcasecmp(propname, "subscription-identifier")){
		*identifier = MQTT_PROP_SUBSCRIPTION_IDENTIFIER;
		*type = MQTT_PROP_TYPE_VARINT;
	}else if(!strcasecmp(propname, "session-expiry-interval")){
		*identifier = MQTT_PROP_SESSION_EXPIRY_INTERVAL;
		*type = MQTT_PROP_TYPE_INT32;
	}else if(!strcasecmp(propname, "assigned-client-identifier")){
		*identifier = MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "server-keep-alive")){
		*identifier = MQTT_PROP_SERVER_KEEP_ALIVE;
		*type = MQTT_PROP_TYPE_INT16;
	}else if(!strcasecmp(propname, "authentication-method")){
		*identifier = MQTT_PROP_AUTHENTICATION_METHOD;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "authentication-data")){
		*identifier = MQTT_PROP_AUTHENTICATION_DATA;
		*type = MQTT_PROP_TYPE_BINARY;
	}else if(!strcasecmp(propname, "request-problem-information")){
		*identifier = MQTT_PROP_REQUEST_PROBLEM_INFORMATION;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "will-delay-interval")){
		*identifier = MQTT_PROP_WILL_DELAY_INTERVAL;
		*type = MQTT_PROP_TYPE_INT32;
	}else if(!strcasecmp(propname, "request-response-information")){
		*identifier = MQTT_PROP_REQUEST_RESPONSE_INFORMATION;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "response-information")){
		*identifier = MQTT_PROP_RESPONSE_INFORMATION;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "server-reference")){
		*identifier = MQTT_PROP_SERVER_REFERENCE;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "reason-string")){
		*identifier = MQTT_PROP_REASON_STRING;
		*type = MQTT_PROP_TYPE_STRING;
	}else if(!strcasecmp(propname, "receive-maximum")){
		*identifier = MQTT_PROP_RECEIVE_MAXIMUM;
		*type = MQTT_PROP_TYPE_INT16;
	}else if(!strcasecmp(propname, "topic-alias-maximum")){
		*identifier = MQTT_PROP_TOPIC_ALIAS_MAXIMUM;
		*type = MQTT_PROP_TYPE_INT16;
	}else if(!strcasecmp(propname, "topic-alias")){
		*identifier = MQTT_PROP_TOPIC_ALIAS;
		*type = MQTT_PROP_TYPE_INT16;
	}else if(!strcasecmp(propname, "maximum-qos")){
		*identifier = MQTT_PROP_MAXIMUM_QOS;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "retain-available")){
		*identifier = MQTT_PROP_RETAIN_AVAILABLE;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "user-property")){
		*identifier = MQTT_PROP_USER_PROPERTY;
		*type = MQTT_PROP_TYPE_STRING_PAIR;
	}else if(!strcasecmp(propname, "maximum-packet-size")){
		*identifier = MQTT_PROP_MAXIMUM_PACKET_SIZE;
		*type = MQTT_PROP_TYPE_INT32;
	}else if(!strcasecmp(propname, "wildcard-subscription-available")){
		*identifier = MQTT_PROP_WILDCARD_SUB_AVAILABLE;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "subscription-identifier-available")){
		*identifier = MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE;
		*type = MQTT_PROP_TYPE_BYTE;
	}else if(!strcasecmp(propname, "shared-subscription-available")){
		*identifier = MQTT_PROP_SHARED_SUB_AVAILABLE;
		*type = MQTT_PROP_TYPE_BYTE;
	}else{
		return MOSQ_ERR_INVAL;
	}
	return MOSQ_ERR_SUCCESS;
}


static void property__add(mosquitto_property **proplist, struct mqtt5__property *prop)
{
	mosquitto_property *p;

	if(!(*proplist)){
		*proplist = prop;
	}

	p = *proplist;
	while(p->next){
		p = p->next;
	}
	p->next = prop;
	prop->next = NULL;
}


BROKER_EXPORT int mosquitto_property_add_byte(mosquitto_property **proplist, int identifier, uint8_t value)
{
	mosquitto_property *prop;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_PAYLOAD_FORMAT_INDICATOR
			&& identifier != MQTT_PROP_REQUEST_PROBLEM_INFORMATION
			&& identifier != MQTT_PROP_REQUEST_RESPONSE_INFORMATION
			&& identifier != MQTT_PROP_MAXIMUM_QOS
			&& identifier != MQTT_PROP_RETAIN_AVAILABLE
			&& identifier != MQTT_PROP_WILDCARD_SUB_AVAILABLE
			&& identifier != MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE
			&& identifier != MQTT_PROP_SHARED_SUB_AVAILABLE){
		return MOSQ_ERR_INVAL;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->value.i8 = value;
	prop->property_type = MQTT_PROP_TYPE_BYTE;

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_int16(mosquitto_property **proplist, int identifier, uint16_t value)
{
	mosquitto_property *prop;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_SERVER_KEEP_ALIVE
			&& identifier != MQTT_PROP_RECEIVE_MAXIMUM
			&& identifier != MQTT_PROP_TOPIC_ALIAS_MAXIMUM
			&& identifier != MQTT_PROP_TOPIC_ALIAS){
		return MOSQ_ERR_INVAL;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->value.i16 = value;
	prop->property_type = MQTT_PROP_TYPE_INT16;

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_int32(mosquitto_property **proplist, int identifier, uint32_t value)
{
	mosquitto_property *prop;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_MESSAGE_EXPIRY_INTERVAL
			&& identifier != MQTT_PROP_SESSION_EXPIRY_INTERVAL
			&& identifier != MQTT_PROP_WILL_DELAY_INTERVAL
			&& identifier != MQTT_PROP_MAXIMUM_PACKET_SIZE){

		return MOSQ_ERR_INVAL;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->value.i32 = value;
	prop->property_type = MQTT_PROP_TYPE_INT32;

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_varint(mosquitto_property **proplist, int identifier, uint32_t value)
{
	mosquitto_property *prop;

	if(!proplist || value > 268435455) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_SUBSCRIPTION_IDENTIFIER) return MOSQ_ERR_INVAL;

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->value.varint = value;
	prop->property_type = MQTT_PROP_TYPE_VARINT;

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_binary(mosquitto_property **proplist, int identifier, const void *value, uint16_t len)
{
	mosquitto_property *prop;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_CORRELATION_DATA
			&& identifier != MQTT_PROP_AUTHENTICATION_DATA){

		return MOSQ_ERR_INVAL;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->property_type = MQTT_PROP_TYPE_BINARY;

	if(len){
		prop->value.bin.v = mosquitto_malloc(len);
		if(!prop->value.bin.v){
			mosquitto_FREE(prop);
			return MOSQ_ERR_NOMEM;
		}

		memcpy(prop->value.bin.v, value, len);
		prop->value.bin.len = len;
	}

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_string(mosquitto_property **proplist, int identifier, const char *value)
{
	mosquitto_property *prop;
	size_t slen = 0;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(value){
		slen = strlen(value);
		if(mosquitto_validate_utf8(value, (int)slen)) return MOSQ_ERR_MALFORMED_UTF8;
	}

	if(identifier != MQTT_PROP_CONTENT_TYPE
			&& identifier != MQTT_PROP_RESPONSE_TOPIC
			&& identifier != MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER
			&& identifier != MQTT_PROP_AUTHENTICATION_METHOD
			&& identifier != MQTT_PROP_RESPONSE_INFORMATION
			&& identifier != MQTT_PROP_SERVER_REFERENCE
			&& identifier != MQTT_PROP_REASON_STRING){

		return MOSQ_ERR_INVAL;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->property_type = MQTT_PROP_TYPE_STRING;
	if(value && slen > 0){
		prop->value.s.v = mosquitto_strdup(value);
		if(!prop->value.s.v){
			mosquitto_FREE(prop);
			return MOSQ_ERR_NOMEM;
		}
		prop->value.s.len = (uint16_t)slen;
	}

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}


BROKER_EXPORT int mosquitto_property_add_string_pair(mosquitto_property **proplist, int identifier, const char *name, const char *value)
{
	mosquitto_property *prop;
	size_t slen_name = 0, slen_value = 0;

	if(!proplist) return MOSQ_ERR_INVAL;
	if(identifier != MQTT_PROP_USER_PROPERTY) return MOSQ_ERR_INVAL;
	if(name){
		slen_name = strlen(name);
		if(mosquitto_validate_utf8(name, (int)slen_name)) return MOSQ_ERR_MALFORMED_UTF8;
	}
	if(value){
		if(mosquitto_validate_utf8(value, (int)slen_value)) return MOSQ_ERR_MALFORMED_UTF8;
	}

	prop = mosquitto_calloc(1, sizeof(mosquitto_property));
	if(!prop) return MOSQ_ERR_NOMEM;

	prop->client_generated = true;
	prop->identifier = identifier;
	prop->property_type = MQTT_PROP_TYPE_STRING_PAIR;

	if(name){
		prop->name.v = mosquitto_strdup(name);
		if(!prop->name.v){
			mosquitto_FREE(prop);
			return MOSQ_ERR_NOMEM;
		}
		prop->name.len = (uint16_t)strlen(name);
	}

	if(value){
		prop->value.s.v = mosquitto_strdup(value);
		if(!prop->value.s.v){
			mosquitto_FREE(prop->name.v);
			mosquitto_FREE(prop);
			return MOSQ_ERR_NOMEM;
		}
		prop->value.s.len = (uint16_t)strlen(value);
	}

	property__add(proplist, prop);
	return MOSQ_ERR_SUCCESS;
}

BROKER_EXPORT int mosquitto_property_check_all(int command, const mosquitto_property *properties)
{
	const mosquitto_property *p, *tail;
	int rc;

	p = properties;

	while(p){
		/* Validity checks */
		if(p->identifier == MQTT_PROP_REQUEST_PROBLEM_INFORMATION
				|| p->identifier == MQTT_PROP_PAYLOAD_FORMAT_INDICATOR
				|| p->identifier == MQTT_PROP_REQUEST_RESPONSE_INFORMATION
				|| p->identifier == MQTT_PROP_MAXIMUM_QOS
				|| p->identifier == MQTT_PROP_RETAIN_AVAILABLE
				|| p->identifier == MQTT_PROP_WILDCARD_SUB_AVAILABLE
				|| p->identifier == MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE
				|| p->identifier == MQTT_PROP_SHARED_SUB_AVAILABLE){

			if(p->value.i8 > 1){
				return MOSQ_ERR_PROTOCOL;
			}
		}else if(p->identifier == MQTT_PROP_MAXIMUM_PACKET_SIZE){
			if( p->value.i32 == 0){
				return MOSQ_ERR_PROTOCOL;
			}
		}else if(p->identifier == MQTT_PROP_RECEIVE_MAXIMUM
				|| p->identifier == MQTT_PROP_TOPIC_ALIAS){

			if(p->value.i16 == 0){
				return MOSQ_ERR_PROTOCOL;
			}
		}

		/* Check for properties on incorrect commands */
		rc = mosquitto_property_check_command(command, p->identifier);
		if(rc) return rc;

		/* Check for duplicates */
		if(p->identifier != MQTT_PROP_USER_PROPERTY){
			tail = p->next;
			while(tail){
				if(p->identifier == tail->identifier){
					return MOSQ_ERR_DUPLICATE_PROPERTY;
				}
				tail = tail->next;
			}
		}

		p = p->next;
	}

	return MOSQ_ERR_SUCCESS;
}

static const mosquitto_property *property__get_property(const mosquitto_property *proplist, int identifier, bool skip_first)
{
	const mosquitto_property *p;
	bool is_first = true;

	p = proplist;

	while(p){
		if(p->identifier == identifier){
			if(!is_first || !skip_first){
				return p;
			}
			is_first = false;
		}
		p = p->next;
	}
	return NULL;
}


BROKER_EXPORT int mosquitto_property_identifier(const mosquitto_property *property)
{
	if(property == NULL) return 0;

	return property->identifier;
}


BROKER_EXPORT int mosquitto_property_type(const mosquitto_property *property)
{
	if(property == NULL) return 0;

	return property->property_type;
}


BROKER_EXPORT mosquitto_property *mosquitto_property_next(const mosquitto_property *proplist)
{
	if(proplist == NULL) return NULL;

	return proplist->next;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_byte(const mosquitto_property *proplist, int identifier, uint8_t *value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_PAYLOAD_FORMAT_INDICATOR
			&& p->identifier != MQTT_PROP_REQUEST_PROBLEM_INFORMATION
			&& p->identifier != MQTT_PROP_REQUEST_RESPONSE_INFORMATION
			&& p->identifier != MQTT_PROP_MAXIMUM_QOS
			&& p->identifier != MQTT_PROP_RETAIN_AVAILABLE
			&& p->identifier != MQTT_PROP_WILDCARD_SUB_AVAILABLE
			&& p->identifier != MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE
			&& p->identifier != MQTT_PROP_SHARED_SUB_AVAILABLE){
		return NULL;
	}

	if(value) *value = p->value.i8;

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_int16(const mosquitto_property *proplist, int identifier, uint16_t *value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_SERVER_KEEP_ALIVE
			&& p->identifier != MQTT_PROP_RECEIVE_MAXIMUM
			&& p->identifier != MQTT_PROP_TOPIC_ALIAS_MAXIMUM
			&& p->identifier != MQTT_PROP_TOPIC_ALIAS){
		return NULL;
	}

	if(value) *value = p->value.i16;

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_int32(const mosquitto_property *proplist, int identifier, uint32_t *value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_MESSAGE_EXPIRY_INTERVAL
			&& p->identifier != MQTT_PROP_SESSION_EXPIRY_INTERVAL
			&& p->identifier != MQTT_PROP_WILL_DELAY_INTERVAL
			&& p->identifier != MQTT_PROP_MAXIMUM_PACKET_SIZE){

		return NULL;
	}

	if(value) *value = p->value.i32;

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_varint(const mosquitto_property *proplist, int identifier, uint32_t *value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_SUBSCRIPTION_IDENTIFIER){
		return NULL;
	}

	if(value) *value = p->value.varint;

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_binary(const mosquitto_property *proplist, int identifier, void **value, uint16_t *len, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist || (value && !len) || (!value && len)) return NULL;

	if(value) *value = NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_CORRELATION_DATA
			&& p->identifier != MQTT_PROP_AUTHENTICATION_DATA){

		return NULL;
	}

	if(value){
		*len = p->value.bin.len;
		if(p->value.bin.len){
			*value = calloc(1, *len + 1U);
			if(!(*value)) return NULL;

			memcpy(*value, p->value.bin.v, *len);
		}else{
			*value = NULL;
		}
	}

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_string(const mosquitto_property *proplist, int identifier, char **value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_CONTENT_TYPE
			&& p->identifier != MQTT_PROP_RESPONSE_TOPIC
			&& p->identifier != MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER
			&& p->identifier != MQTT_PROP_AUTHENTICATION_METHOD
			&& p->identifier != MQTT_PROP_RESPONSE_INFORMATION
			&& p->identifier != MQTT_PROP_SERVER_REFERENCE
			&& p->identifier != MQTT_PROP_REASON_STRING){

		return NULL;
	}

	if(value){
		if(p->value.s.len){
			*value = calloc(1, (size_t)p->value.s.len+1);
			if(!(*value)) return NULL;

			memcpy(*value, p->value.s.v, p->value.s.len);
		}else{
			*value = NULL;
		}
	}

	return p;
}


BROKER_EXPORT const mosquitto_property *mosquitto_property_read_string_pair(const mosquitto_property *proplist, int identifier, char **name, char **value, bool skip_first)
{
	const mosquitto_property *p;
	if(!proplist) return NULL;

	if(name) *name = NULL;
	if(value) *value = NULL;

	p = property__get_property(proplist, identifier, skip_first);
	if(!p) return NULL;
	if(p->identifier != MQTT_PROP_USER_PROPERTY) return NULL;

	if(name){
		if(p->name.len){
			*name = calloc(1, (size_t)p->name.len+1);
			if(!(*name)) return NULL;
			memcpy(*name, p->name.v, p->name.len);
		}else{
			*name = NULL;
		}
	}

	if(value){
		if(p->value.s.len){
			*value = calloc(1, (size_t)p->value.s.len+1);
			if(!(*value)){
				if(name){
					free(*name);
					*name = NULL;
				}
				return NULL;
			}
			memcpy(*value, p->value.s.v, p->value.s.len);
		}else{
			*value = NULL;
		}
	}

	return p;
}


BROKER_EXPORT int mosquitto_property_remove(mosquitto_property **proplist, const mosquitto_property *property)
{
	mosquitto_property *item, *item_prev = NULL;

	if(proplist == NULL || property == NULL){
		return MOSQ_ERR_INVAL;
	}

	item = *proplist;
	while(item){
		if(item == property){
			if(item_prev == NULL){
				*proplist = (*proplist)->next;
			}else{
				item_prev->next = item->next;
			}
			item->next = NULL;
			return MOSQ_ERR_SUCCESS;
		}
		item_prev = item;
		item = item->next;
	}

	return MOSQ_ERR_NOT_FOUND;
}


BROKER_EXPORT int mosquitto_property_copy_all(mosquitto_property **dest, const mosquitto_property *src)
{
	mosquitto_property *pnew, *plast = NULL;

	if(!src) return MOSQ_ERR_SUCCESS;
	if(!dest) return MOSQ_ERR_INVAL;

	*dest = NULL;

	while(src){
		pnew = calloc(1, sizeof(mosquitto_property));
		if(!pnew){
			mosquitto_property_free_all(dest);
			return MOSQ_ERR_NOMEM;
		}
		if(plast){
			plast->next = pnew;
		}else{
			*dest = pnew;
		}
		plast = pnew;

		pnew->client_generated = src->client_generated;
		pnew->identifier = src->identifier;
		pnew->property_type = src->property_type;
		switch(pnew->property_type){
			case MQTT_PROP_TYPE_BYTE:
				pnew->value.i8 = src->value.i8;
				break;

			case MQTT_PROP_TYPE_INT16:
				pnew->value.i16 = src->value.i16;
				break;

			case MQTT_PROP_TYPE_INT32:
				pnew->value.i32 = src->value.i32;
				break;

			case MQTT_PROP_TYPE_VARINT:
				pnew->value.varint = src->value.varint;
				break;

			case MQTT_PROP_TYPE_STRING:
				pnew->value.s.len = src->value.s.len;
				pnew->value.s.v = src->value.s.v ? strdup(src->value.s.v) : (char*)calloc(1,1);
				if(!pnew->value.s.v){
					mosquitto_property_free_all(dest);
					return MOSQ_ERR_NOMEM;
				}
				break;

			case MQTT_PROP_TYPE_BINARY:
				pnew->value.bin.len = src->value.bin.len;
				if(src->value.bin.len){
					pnew->value.bin.v = malloc(pnew->value.bin.len);
					if(!pnew->value.bin.v){
						mosquitto_property_free_all(dest);
						return MOSQ_ERR_NOMEM;
					}
					memcpy(pnew->value.bin.v, src->value.bin.v, pnew->value.bin.len);
				}
				break;

			case MQTT_PROP_TYPE_STRING_PAIR:
				pnew->value.s.len = src->value.s.len;
				pnew->value.s.v = src->value.s.v ? strdup(src->value.s.v) : (char*)calloc(1,1);
				if(!pnew->value.s.v){
					mosquitto_property_free_all(dest);
					return MOSQ_ERR_NOMEM;
				}

				pnew->name.len = src->name.len;
				pnew->name.v = src->name.v ? strdup(src->name.v) : (char*)calloc(1,1);
				if(!pnew->name.v){
					mosquitto_property_free_all(dest);
					return MOSQ_ERR_NOMEM;
				}
				break;

			default:
				mosquitto_property_free_all(dest);
				return MOSQ_ERR_INVAL;
		}

		src = mosquitto_property_next(src);
	}

	return MOSQ_ERR_SUCCESS;
}


uint8_t mosquitto_property_byte_value(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_BYTE){
		return property->value.i8;
	}else{
		return 0;
	}
}


uint16_t mosquitto_property_int16_value(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_INT16){
		return property->value.i16;
	}else{
		return 0;
	}
}


uint32_t mosquitto_property_int32_value(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_INT32){
		return property->value.i32;
	}else{
		return 0;
	}
}


uint32_t mosquitto_property_varint_value(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_VARINT){
		return property->value.varint;
	}else{
		return 0;
	}
}


const void *mosquitto_property_binary_value(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_BINARY){
		return property->value.bin.v;
	}else{
		return NULL;
	}
}


uint16_t mosquitto_property_binary_value_length(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_BINARY){
		return property->value.bin.len;
	}else{
		return 0;
	}
}


const char *mosquitto_property_string_value(const mosquitto_property *property)
{
	if(property && (property->property_type == MQTT_PROP_TYPE_STRING || property->property_type == MQTT_PROP_TYPE_STRING_PAIR)){
		return property->value.s.v;
	}else{
		return NULL;
	}
}


uint16_t mosquitto_property_string_value_length(const mosquitto_property *property)
{
	if(property && (property->property_type == MQTT_PROP_TYPE_STRING || property->property_type == MQTT_PROP_TYPE_STRING_PAIR)){
		return property->value.s.len;
	}else{
		return 0;
	}
}


const char *mosquitto_property_string_name(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_STRING_PAIR){
		return property->name.v;
	}else{
		return NULL;
	}
}


uint16_t mosquitto_property_string_name_length(const mosquitto_property *property)
{
	if(property && property->property_type == MQTT_PROP_TYPE_STRING_PAIR){
		return property->name.len;
	}else{
		return 0;
	}
}

/* Return the number of bytes we need to add on to the remaining length when
 * encoding these properties. */
unsigned int mosquitto_property_get_remaining_length(const mosquitto_property *props)
{
	unsigned int proplen, varbytes;

	proplen = mosquitto_property_get_length_all(props);
	varbytes = mosquitto_varint_bytes(proplen);
	return proplen + varbytes;
}