/*************************************************************************
* (C) 2022 AITNET ltd - Sofia/Bulgaria - <misho@aitbg.com>
*  by Michael Pounov <misho@elwix.org>
*
* $Author: misho $
* $Id: read.c,v 1.1.2.2 2022/09/15 13:50:14 misho Exp $
*
**************************************************************************
The ELWIX and AITNET software is distributed under the following
terms:

All of the documentation and software included in the ELWIX and AITNET
Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>

Copyright 2004 - 2022
	by Michael Pounov <misho@elwix.org>.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by Michael Pounov <misho@elwix.org>
ELWIX - Embedded LightWeight unIX and its contributors.
4. Neither the name of AITNET nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY AITNET AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
*/
#include "global.h"


/* _mqtt_readHEADER() read fixed header from MQTT message */
static struct mqtthdr *
_mqtt_readHEADER(mqtt_msg_t * __restrict buf, u_char cmd, int *len, caddr_t *next)
{
	struct mqtthdr *hdr;
	int bytes;

	if (!buf || !buf->msg_base || !buf->msg_len)
		return NULL;

	hdr = (struct mqtthdr*) buf->msg_base;
	if (hdr->mqtt_msg.type != cmd) {
		mqtt_SetErr(EINVAL, "Error:: wrong command #%d should be %d", 
				hdr->mqtt_msg.type, cmd);
		return NULL;
	}

	if (len)
		*len = mqtt_decodeLen(hdr->mqtt_len, &bytes);

	if (next)
		*next = buf->msg_base + bytes + 1;

	return hdr;
}


/*
 * mqtt_readCONNECT() Read elements from CONNECT message
 *
 * @buf = Message buffer
 * @KASec = Keep Alive in seconds for current connection
 * @psConnID = ConnectID
 * @connLen = ConnectID length
 * @psUser = Username if !=NULL
 * @userLen = Username length
 * @psPass = Password for Username, only if csUser is set
 * @passLen = Password length
 * @psWillTopic = Will Topic if !=NULL Will Flags set into message and must be e_free()
 * @psWillMessage = Will Message, may be NULL if !NULL must be e_free() after use!
 * return: .reserved == 1 is error or == 0 connection flags & msg ok
 */
mqtthdr_connack_t
mqtt_readCONNECT(mqtt_msg_t * __restrict buf, u_short *KASec, char * __restrict psConnID, int connLen, 
		char * __restrict psUser, int userLen, char * __restrict psPass, int passLen,  
		char ** __restrict psWillTopic, char ** __restrict psWillMessage)
{
	mqtthdr_connflgs_t flg = { MQTT_CONNFLGS_INIT };
	mqtthdr_connack_t cack = { 1, MQTT_RETCODE_DENIED };
	struct mqtthdr *hdr;
	mqtthdr_var_t *var;
	mqtt_len_t *ka;
	int len;
	caddr_t pos;

	if (!buf || !buf->msg_base || !buf->msg_len || !psConnID || !connLen)
		return cack;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_CONNECT, &len, &pos);
	if (!hdr)
		return cack;
	if (len < 12) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return cack;
	} else
		var = (mqtthdr_var_t*) pos;

	/* check init string & protocol */
	if (var->var_sb.sb.l == 4 && !strcmp((char*) var->var_data, MQTT_PROTO_STR))
		pos += var->var_sb.sb.l + sizeof(mqtt_len_t);
	else if (var->var_sb.sb.l == 6 || strcmp((char*) var->var_data, MQTT_CONN_STR))
		pos += var->var_sb.sb.l + sizeof(mqtt_len_t);
	else {
		mqtt_SetErr(EINVAL, "Invalid init string %.6s(%d)", 
				var->var_data, var->var_sb.sb.l);
		cack.retcode = MQTT_RETCODE_REFUSE_UNAVAIL;
		return cack;
	}
	switch (*pos) {
		case MQTT_PROTO_VER_3:
		case MQTT_PROTO_VER_311:
		case MQTT_PROTO_VER_5:
			pos++;
			break;
		default:
			mqtt_SetErr(EINVAL, "Invalid protocol version %d", *pos);
			cack.retcode = MQTT_RETCODE_REFUSE_VER;
			return cack;
	}
	flg = *(mqtthdr_connflgs_t*) pos;
	pos++;
	ka = (mqtt_len_t*) pos;
	*KASec = ntohs(ka->val);
	pos += sizeof(mqtt_len_t);

	len -= pos - (caddr_t) var;

	/* get ConnID */
	var = (mqtthdr_var_t*) pos;
	len -= MQTTHDR_VAR_SIZEOF(var);
	if (len < 0 || var->var_sb.sb.l >= MQTT_CONNID_MAX) {
		mqtt_SetErr(EINVAL, "Unexpected EOM at Connection ID %d", len);
		cack.retcode = MQTT_RETCODE_REFUSE_ID;
		return cack;
	} else {
		memset(psConnID, 0, connLen--);
		memcpy(psConnID, var->var_data, 
				ntohs(var->var_sb.val) > connLen ? connLen : ntohs(var->var_sb.val));
		pos += MQTTHDR_VAR_SIZEOF(var);
	}

	/* get Willz */
	if (flg.will_flg) {
		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var);
		if (len < 0) {
			mqtt_SetErr(EINVAL, "Unexpected EOM at Will Topic %d", len);
			cack.retcode = MQTT_RETCODE_REFUSE_ID;
			return cack;
		} else {
			if (psWillTopic) {
				*psWillTopic = e_malloc(ntohs(var->var_sb.val) + 1);
				if (!*psWillTopic) {
					LOGERR;
					cack.retcode = MQTT_RETCODE_REFUSE_UNAVAIL;
					return cack;
				} else
					memset(*psWillTopic, 0, ntohs(var->var_sb.val) + 1);
				memcpy(*psWillTopic, var->var_data, ntohs(var->var_sb.val));
			}
			pos += MQTTHDR_VAR_SIZEOF(var);
		}

		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var);
		if (len < 0) {
			mqtt_SetErr(EINVAL, "Unexpected EOM at Will Message %d", len);
			e_free(psWillTopic);
			cack.retcode = MQTT_RETCODE_REFUSE_ID;
			return cack;
		} else {
			if (psWillMessage) {
				*psWillMessage = e_malloc(ntohs(var->var_sb.val) + 1);
				if (!*psWillMessage) {
					LOGERR;
					e_free(psWillTopic);
					cack.retcode = MQTT_RETCODE_REFUSE_UNAVAIL;
					return cack;
				} else
					memset(*psWillMessage, 0, ntohs(var->var_sb.val) + 1);
				memcpy(*psWillMessage, var->var_data, ntohs(var->var_sb.val));
			}
			pos += MQTTHDR_VAR_SIZEOF(var);
		}
	}

	/* get User/Pass */
	if (flg.username) {
		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var);
		if (len < 0 || var->var_sb.sb.l > 12) {
			mqtt_SetErr(EINVAL, "Unexpected EOM at Username %d", len);
			if (flg.will_flg) {
				if (psWillTopic)
					e_free(psWillTopic);
				if (psWillMessage)
					e_free(psWillMessage);
			}
			cack.retcode = MQTT_RETCODE_REFUSE_USERPASS;
			return cack;
		} else {
			if (psUser && userLen) {
				memset(psUser, 0, userLen--);
				memcpy(psUser, var->var_data, 
						ntohs(var->var_sb.val) > userLen ? userLen : ntohs(var->var_sb.val));
			}
			pos += MQTTHDR_VAR_SIZEOF(var);
		}
	}
	if (flg.password) {
		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var);
		if (len < 0 || var->var_sb.sb.l > 12) {
			mqtt_SetErr(EINVAL, "Unexpected EOM at Password %d", len);
			if (flg.will_flg) {
				if (psWillTopic)
					e_free(psWillTopic);
				if (psWillMessage)
					e_free(psWillMessage);
			}
			cack.retcode = MQTT_RETCODE_REFUSE_USERPASS;
			return cack;
		} else {
			if (psPass && passLen) {
				memset(psPass, 0, passLen--);
				memcpy(psPass, var->var_data, 
						ntohs(var->var_sb.val) > passLen ? passLen : ntohs(var->var_sb.val));
			}
			pos += MQTTHDR_VAR_SIZEOF(var);
		}
	}

	flg.reserved = 0;
	cack.reserved = flg.flags;
	cack.retcode = MQTT_RETCODE_ACCEPTED;
	return cack;
}

/*
 * mqtt_readCONNACK() Read CONNACK message
 *
 * @buf = Message buffer
 * return: -1 error or >-1 CONNECT message return code
 */
u_char
mqtt_readCONNACK(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtthdr_connack_t *ack;
	caddr_t pos;

	if (!buf || !buf->msg_base || !buf->msg_len)
		return (u_char) -1;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_CONNACK, &len, &pos);
	if (!hdr)
		return (u_char) -1;
	if (len < sizeof(mqtthdr_connack_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_char) -1;
	} else
		ack = (mqtthdr_connack_t*) pos;

	if (ack->retcode > MQTT_RETCODE_DENIED) {
		mqtt_SetErr(EINVAL, "Invalid retcode %u", ack->retcode);
		return (u_char) -1;
	}

	return ack->retcode;
}

/*
 * mqtt_readDISCONNECT() Read DISCONNECT message
 *
 * @buf = Message buffer
 * return: -1 error, 0 ok, >0 undefined result
 */
int
mqtt_readDISCONNECT(mqtt_msg_t * __restrict buf)
{
	int len;

	if (!_mqtt_readHEADER(buf, MQTT_TYPE_DISCONNECT, &len, NULL))
		return -1;

	return len;
}

/*
 * mqtt_readPINGREQ() Read PINGREQ message
 *
 * @buf = Message buffer
 * return: -1 error, 0 ok, >0 undefined result
 */
int
mqtt_readPINGREQ(mqtt_msg_t * __restrict buf)
{
	int len;

	if (!_mqtt_readHEADER(buf, MQTT_TYPE_PINGREQ, &len, NULL))
		return -1;

	return len;
}

/*
 * mqtt_readPINGRESP() Read PINGRESP message
 *
 * @buf = Message buffer
 * return: -1 error, 0 ok, >0 undefined result
 */
int
mqtt_readPINGRESP(mqtt_msg_t * __restrict buf)
{
	int len;

	if (!_mqtt_readHEADER(buf, MQTT_TYPE_PINGRESP, &len, NULL))
		return -1;

	return len;
}

/*
 * mqtt_readPUBLISH() Read PUBLISH message
 *
 * @buf = Message buffer
 * @psTopic = Topic
 * @topicLen = Topic length
 * @msgID = MessageID
 * @pData = Data buffer, may be NULL
 * return: -1 error or !=-1 allocated data buffer length
 */
int
mqtt_readPUBLISH(mqtt_msg_t * __restrict buf, char * __restrict psTopic, int topicLen, 
		u_short *msgID, void ** __restrict pData)
{
	int len;
	struct mqtthdr *hdr;
	mqtthdr_var_t *var;
	mqtt_len_t *v;
	caddr_t pos;

	if (!buf || !psTopic || !msgID)
		return -1;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_PUBLISH, &len, &pos);
	if (!hdr)
		return -1;
	else
		var = (mqtthdr_var_t*) pos;

	/* topic */
	len -= MQTTHDR_VAR_SIZEOF(var);
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else {
		memset(psTopic, 0, topicLen--);
		memcpy(psTopic, var->var_data, ntohs(var->var_sb.val) > topicLen ? 
				topicLen : ntohs(var->var_sb.val));
		pos += MQTTHDR_VAR_SIZEOF(var);
		v = (mqtt_len_t*) pos;
	}

	len -= sizeof(mqtt_len_t);
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else {
		*msgID = ntohs(v->val);
		pos += sizeof(mqtt_len_t);
	}

	/* data */
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else if (pData) {
		if (!(*pData = e_malloc(len + 1))) {
			LOGERR;
			return -1;
		} else
			((char*) (*pData))[len] = 0;

		memcpy(*pData, pos, len);
	}

	return len;
}

/*
 * mqtt_readPUBACK() Read PUBACK message
 *
 * @buf = Message buffer
 * return: -1 error or MessageID
 */
u_short
mqtt_readPUBACK(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_PUBACK, &len, &pos);
	if (!hdr)
		return (u_short) -1;
	if (len < sizeof(mqtt_len_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_short) -1;
	} else
		v = (mqtt_len_t*) pos;

	return ntohs(v->val);
}

/*
 * mqtt_readPUBREC() Read PUBREC message
 *
 * @buf = Message buffer
 * return: -1 error or MessageID
 */
u_short
mqtt_readPUBREC(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_PUBREC, &len, &pos);
	if (!hdr)
		return (u_short) -1;
	if (len < sizeof(mqtt_len_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_short) -1;
	} else
		v = (mqtt_len_t*) pos;

	return ntohs(v->val);
}

/*
 * mqtt_readPUBREL() Read PUBREL message
 *
 * @buf = Message buffer
 * return: -1 error or MessageID
 */
u_short
mqtt_readPUBREL(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_PUBREL, &len, &pos);
	if (!hdr)
		return (u_short) -1;
	if (len < sizeof(mqtt_len_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_short) -1;
	} else
		v = (mqtt_len_t*) pos;

	return ntohs(v->val);
}

/*
 * mqtt_readPUBCOMP() Read PUBCOMP message
 *
 * @buf = Message buffer
 * return: -1 error or MessageID
 */
u_short
mqtt_readPUBCOMP(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_PUBCOMP, &len, &pos);
	if (!hdr)
		return (u_short) -1;
	if (len < sizeof(mqtt_len_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_short) -1;
	} else
		v = (mqtt_len_t*) pos;

	return ntohs(v->val);
}

/*
 * mqtt_readSUBSCRIBE() Read SUBSCRIBE message
 *
 * @buf = Message buffe
 * @msgID = MessageID
 * @subscr = Subscriptions, must be free after use with mqtt_subFree()
 * return: -1 error or >-1 elements into subscr
 */
int
mqtt_readSUBSCRIBE(mqtt_msg_t * __restrict buf, u_short *msgID, mqtt_subscr_t **subscr)
{
	register int i;
	int len;
	struct mqtthdr *hdr;
	mqtthdr_var_t *var;
	mqtt_subscr_t *subs;
	mqtt_len_t *v;
	caddr_t pos;

	if (!buf || !msgID || !subscr)
		return -1;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_SUBSCRIBE, &len, &pos);
	if (!hdr)
		return -1;
	else
		v = (mqtt_len_t*) pos;

	/* MessageID */
	len -= sizeof(mqtt_len_t);
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else {
		*msgID = ntohs(v->val);
		pos += sizeof(mqtt_len_t);
	}

	subs = mqtt_subAlloc(0);
	if (!subs)
		return -1;
	else
		*subscr = subs;

	/* Subscribes */
	for (i = 0; len > 0; i++) {
		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var) + 1;
		if (len < 0) {
			mqtt_subFree(subscr);
			mqtt_SetErr(EINVAL, "Short message length %d", len);
			return -1;
		}
		if (!mqtt_subRealloc(&subs, i + 1)) {
			mqtt_subFree(subscr);
			return -1;
		} else
			*subscr = subs;

		memset(&subs[i], 0, sizeof subs[i]);
		subs[i].sub_topic.msg_len = ntohs(var->var_sb.val);
		subs[i].sub_topic.msg_base = e_malloc(subs[i].sub_topic.msg_len + 1);
		if (!subs[i].sub_topic.msg_base) {
			LOGERR;
			mqtt_subFree(subscr);
			return -1;
		} else {
			memcpy(subs[i].sub_topic.msg_base, var->var_data, subs[i].sub_topic.msg_len);
			((char*) subs[i].sub_topic.msg_base)[subs[i].sub_topic.msg_len] = 0;
		}
		pos += MQTTHDR_VAR_SIZEOF(var);

		subs[i].sub_qos = *pos;
		pos++;
	}

	return i;
}

/*
 * mqtt_readSUBACK() Read SUBACK message
 *
 * @buf = Message buffer
 * @msgID = MessageID
 * @subqos = Subscribes QoS, must be free after use with e_free()
 * return: -1 error or >-1 readed subscribes QoS elements
 */
int
mqtt_readSUBACK(mqtt_msg_t * __restrict buf, u_short *msgID, u_char **subqos)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	if (!buf || !msgID || !subqos)
		return -1;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_SUBACK, &len, &pos);
	if (!hdr)
		return -1;
	else
		v = (mqtt_len_t*) pos;

	/* MessageID */
	len -= sizeof(mqtt_len_t);
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else {
		*msgID = ntohs(v->val);
		pos += sizeof(mqtt_len_t);
	}

	/* Subscribes */
	*subqos = e_malloc(len);
	if (!*subqos) {
		LOGERR;
		return -1;
	} else
		memcpy(*subqos, pos, len);

	return len;
}

/*
 * mqtt_readUNSUBSCRIBE() Read UNSUBSCRIBE message
 *
 * @buf = Message buffer
 * @msgID = MessageID
 * @subscr = Subscriptions, must be free after use with mqtt_subFree()
 * return: -1 error or >-1 elements into subscr
 */
int
mqtt_readUNSUBSCRIBE(mqtt_msg_t * __restrict buf, u_short *msgID, mqtt_subscr_t **subscr)
{
	register int i;
	int len;
	struct mqtthdr *hdr;
	mqtthdr_var_t *var;
	mqtt_subscr_t *subs;
	mqtt_len_t *v;
	caddr_t pos;

	if (!buf || !msgID || !subscr)
		return -1;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_UNSUBSCRIBE, &len, &pos);
	if (!hdr)
		return -1;
	else
		v = (mqtt_len_t*) pos;

	/* MessageID */
	len -= sizeof(mqtt_len_t);
	if (len < 0) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return -1;
	} else {
		*msgID = ntohs(v->val);
		pos += sizeof(mqtt_len_t);
	}

	subs = mqtt_subAlloc(0);
	if (!subs)
		return -1;
	else
		*subscr = subs;

	/* Subscribes */
	for (i = 0; len > 0; i++) {
		var = (mqtthdr_var_t*) pos;
		len -= MQTTHDR_VAR_SIZEOF(var);
		if (len < 0) {
			mqtt_subFree(subscr);
			mqtt_SetErr(EINVAL, "Short message length %d", len);
			return -1;
		}
		if (!mqtt_subRealloc(&subs, i + 1)) {
			mqtt_subFree(subscr);
			return -1;
		} else
			*subscr = subs;

		memset(&subs[i], 0, sizeof subs[i]);
		subs[i].sub_topic.msg_len = ntohs(var->var_sb.val);
		subs[i].sub_topic.msg_base = e_malloc(subs[i].sub_topic.msg_len + 1);
		if (!subs[i].sub_topic.msg_base) {
			LOGERR;
			mqtt_subFree(subscr);
			return -1;
		} else {
			memcpy(subs[i].sub_topic.msg_base, var->var_data, subs[i].sub_topic.msg_len);
			((char*) subs[i].sub_topic.msg_base)[subs[i].sub_topic.msg_len] = 0;
		}
		pos += MQTTHDR_VAR_SIZEOF(var);
	}

	return i;
}

/*
 * mqtt_readUNSUBACK() Read UNSUBACK message
 *
 * @buf = Message buffer
 * return: -1 error or MessageID
 */
u_short
mqtt_readUNSUBACK(mqtt_msg_t * __restrict buf)
{
	int len;
	struct mqtthdr *hdr;
	mqtt_len_t *v;
	caddr_t pos;

	hdr = _mqtt_readHEADER(buf, MQTT_TYPE_UNSUBACK, &len, &pos);
	if (!hdr)
		return (u_short) -1;
	if (len < sizeof(mqtt_len_t)) {
		mqtt_SetErr(EINVAL, "Short message length %d", len);
		return (u_short) -1;
	} else
		v = (mqtt_len_t*) pos;

	return ntohs(v->val);
}