/*
 * Copyright (C) 2012 Smile Communications, jason.penton@smilecoms.com
 * Copyright (C) 2012 Smile Communications, richard.good@smilecoms.com
 *
 * The initial version of this code was written by Dragos Vingarzan
 * (dragos(dot)vingarzan(at)fokus(dot)fraunhofer(dot)de and the
 * Fraunhofer FOKUS Institute. It was and still is maintained in a separate
 * branch of the original SER. We are therefore migrating it to
 * Kamailio/SR and look forward to maintaining it from here on out.
 * 2011/2012 Smile Communications, Pty. Ltd.
 * ported/maintained/improved by
 * Jason Penton (jason(dot)penton(at)smilecoms.com and
 * Richard Good (richard(dot)good(at)smilecoms.com) as part of an
 * effort to add full IMS support to Kamailio/SR using a new and
 * improved architecture
 *
 * NB: A lot of this code was originally part of OpenIMSCore,
 * FhG Fokus.
 * Copyright (C) 2004-2006 FhG Fokus
 * Thanks for great work! This is an effort to
 * break apart the various CSCF functions into logically separate
 * components. We hope this will drive wider use. We also feel
 * that in this way the architecture is more complete and thereby easier
 * to manage in the Kamailio/SR environment
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * Kamailio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * Kamailio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "diameter.h"
#include "diameter_api.h"


#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>

#include "utils.h"
#include "globals.h"

#include "config.h"
#include "peermanager.h"
#include "diameter_epc_code_cmd.h"

extern dp_config *config; /**< Configuration for this diameter peer */


/**
 * This function encodes an AAAMessage to its network representation (encoder).
 *  From an AAAMessage structure, a buffer to be sent is built.
 * @param msg - the message to encode
 * @returns 1 on success, -1 on error
 * \note This function is taken from DISC http://developer.berlios.de/projects/disc/
 */
AAAReturnCode AAABuildMsgBuffer(AAAMessage *msg)
{
	unsigned char *p;
	AAA_AVP *avp;

	/* first let's comput the length of the buffer */
	msg->buf.len = AAA_MSG_HDR_SIZE; /* AAA message header size */
	/* count and add the avps */
	for(avp = msg->avpList.head; avp; avp = avp->next) {
		msg->buf.len += AVP_HDR_SIZE(avp->flags) + to_32x_len(avp->data.len);
		//LM_DBG("AVP code: %d, data %.*s\n", avp->code, avp->data.len, avp->data.s);
	}

	LM_DBG("len=%d\n", msg->buf.len);
	/* allocate some memory */
	msg->buf.s = (char *)shm_malloc(msg->buf.len);
	if(!msg->buf.s) {
		LM_ERR("no more free memory!\n");
		goto error;
	}
	memset(msg->buf.s, 0, msg->buf.len);

	/* fill in the buffer */
	p = (unsigned char *)msg->buf.s;
	/* DIAMETER HEADER */
	/* message length */
	((unsigned int *)p)[0] = htonl(msg->buf.len);
	/* Diameter Version */
	*p = 1;
	p += VER_SIZE + MESSAGE_LENGTH_SIZE;
	/* command code */
	((unsigned int *)p)[0] = htonl(msg->commandCode);
	/* flags */
	*p = (unsigned char)msg->flags;
	p += FLAGS_SIZE + COMMAND_CODE_SIZE;
	/* application-ID */
	((unsigned int *)p)[0] = htonl(msg->applicationId);
	p += APPLICATION_ID_SIZE;
	/* hop by hop id */
	((unsigned int *)p)[0] = htonl(msg->hopbyhopId);
	p += HOP_BY_HOP_IDENTIFIER_SIZE;
	/* end to end id */
	((unsigned int *)p)[0] = htonl(msg->endtoendId);
	p += END_TO_END_IDENTIFIER_SIZE;

	/* AVPS */
	for(avp = msg->avpList.head; avp; avp = avp->next) {
		/* AVP HEADER */
		/* avp code */
		set_4bytes(p, avp->code);
		p += 4;
		/* flags */
		(*p++) = (unsigned char)avp->flags;
		/* avp length */
		set_3bytes(p, (AVP_HDR_SIZE(avp->flags) + avp->data.len));
		p += 3;
		/* vendor id */
		if((avp->flags & 0x80) != 0) {
			set_4bytes(p, avp->vendorId);
			p += 4;
		}
		/* data */
		memcpy(p, avp->data.s, avp->data.len);
		p += to_32x_len(avp->data.len);
	}

	if((char *)p - msg->buf.s != msg->buf.len) {
		LM_ERR("BUG: build_buf_from_msg: mismatch between len and buf!\n");
		shm_free(msg->buf.s);
		msg->buf.s = 0;
		msg->buf.len = 0;
		goto error;
	}

	return 1;
error:
	return -1;
}


/**
 *  Allocates a new AAAMessage.
 * @param commandCode - the command code for this message
 * @param applicationId - application id to be set
 * @param sessionId - session id to be set
 * @param request - if you want to create a response, put the request here. If you want a
 * request, call with NULL
 * @returns the AAAMessage* or NULL on error
 * \note This function is taken from DISC http://developer.berlios.de/projects/disc/
 */
AAAMessage *AAANewMessage(AAACommandCode commandCode,
		AAAApplicationId applicationId, AAASession *session,
		AAAMessage *request)
{
	AAAMessage *msg;
	AAA_AVP *avp;
	AAA_AVP *avp_t;
	str *sessionId = 0;
#if 0
	unsigned int code;
#endif
	// str dest_host={"?",1};
	str dest_realm = {"?", 1};

	msg = 0;
	if(!session || !session->id.s) {
		if(request) {
			/* copy old session id from AVP */
			if(request->sessionId)
				sessionId = &(request->sessionId->data);
		} else {
			if(commandCode != Code_DW)
				LM_DBG("param session received null and it's a request!!\n");
		}
	} else {
		sessionId = &(session->id);
	}

	/* allocated a new AAAMessage structure and set it to 0 */
	msg = (AAAMessage *)shm_malloc(sizeof(AAAMessage));
	if(!msg) {
		LM_ERR("no more free memory!!\n");
		goto error;
	}
	memset(msg, 0, sizeof(AAAMessage));

	/* command code */
	msg->commandCode = commandCode;
	/* application ID */
	msg->applicationId = applicationId;

	/*add session ID */
	if(sessionId) {
		avp = AAACreateAVP(
				263, 0, 0, sessionId->s, sessionId->len, AVP_DUPLICATE_DATA);
		if(!avp || AAAAddAVPToMessage(msg, avp, 0) != AAA_ERR_SUCCESS) {
			LM_ERR("cannot create/add Session-Id avp\n");
			if(avp)
				AAAFreeAVP(&avp);
			goto error;
		}
		msg->sessionId = avp;
	}

	/* add origin host AVP */
	/* changed by cristian to comply with rfc3588:
	 * 6.3.  Origin-Host AVP
	 *
	 *    The Origin-Host AVP (AVP Code 264) is of type
	 *    DiameterIdentity... */
	avp = AAACreateAVP(
			264, 0, 0, config->fqdn.s, config->fqdn.len, AVP_DUPLICATE_DATA);
	if(!avp
			|| AAAAddAVPToMessage(msg, avp, msg->avpList.tail)
					   != AAA_ERR_SUCCESS) {
		LM_ERR("cannot create/add Origin-Host avp\n");
		if(avp)
			AAAFreeAVP(&avp);
		goto error;
	}
	msg->orig_host = avp;
	/* add origin realm AVP */
	avp = AAACreateAVP(
			296, 0, 0, config->realm.s, config->realm.len, AVP_DUPLICATE_DATA);
	if(!avp
			|| AAAAddAVPToMessage(msg, avp, msg->avpList.tail)
					   != AAA_ERR_SUCCESS) {
		LM_ERR("cannot create/add Origin-Realm avp\n");
		if(avp)
			AAAFreeAVP(&avp);
		goto error;
	}
	msg->orig_realm = avp;

	if(!request) {
		/* it's a new request -> set the flag */
		msg->flags = 0x80;
	} else {
		/* link the incoming peer to the answer */
		msg->in_peer = request->in_peer;
		/* set the P flag as in request */
		msg->flags |= request->flags & 0x40;
		/**/
		msg->endtoendId = request->endtoendId;
		msg->hopbyhopId = request->hopbyhopId;


		//TODO: aon:move this information in the AAASession structure, do not add these fields for

		if(msg->commandCode == Code_CE || msg->commandCode == Code_DP
				|| msg->commandCode == Code_DW
				|| msg->commandCode == Diameter_CCR
				|| msg->commandCode == Diameter_RAR) {
			// Don't add Destination Host/Realm because some stacks are way to picky and will just refuse it
		} else {

			/* Mirror the old originhost/realm to destinationhost/realm*/
			//avp = AAAFindMatchingAVP(request,0,AVP_Origin_Host,0,0);
			//if (avp) dest_host = avp->data;
			/* add destination host and destination realm */
			//avp = AAACreateAVP(AVP_Destination_Host,AAA_AVP_FLAG_MANDATORY,0,
			//	dest_host.s,dest_host.len,AVP_DUPLICATE_DATA);
			//if (!avp) {
			//		LM_ERR("Failed creating Destination Host avp\n");
			//		goto error;
			//	}
			//	if (AAAAddAVPToMessage(msg,avp,msg->avpList.tail)!=AAA_ERR_SUCCESS) {
			//		LM_ERR("Failed adding Destination Host avp to message\n");
			//		AAAFreeAVP(&avp);
			//		goto error;
			//	}

			avp = AAAFindMatchingAVP(request, 0, AVP_Origin_Realm, 0, 0);
			if(avp)
				dest_realm = avp->data;
			avp = AAACreateAVP(AVP_Destination_Realm, AAA_AVP_FLAG_MANDATORY, 0,
					dest_realm.s, dest_realm.len, AVP_DUPLICATE_DATA);
			if(!avp) {
				LM_ERR("Failed creating Destination Realm avp\n");
				goto error;
			}
			if(AAAAddAVPToMessage(msg, avp, msg->avpList.tail)
					!= AAA_ERR_SUCCESS) {
				LM_ERR("Failed adding Destination Realm avp to message\n");
				AAAFreeAVP(&avp);
				goto error;
			}
		}

		msg->res_code = 0;
		/* mirror all the proxy-info avp in the same order */
		avp_t = request->avpList.head;
		while((avp_t = AAAFindMatchingAVP(
					   request, avp_t, 284, 0, AAA_FORWARD_SEARCH))
				!= 0) {
			if((avp = AAACloneAVP(avp_t, 1)) == 0
					|| AAAAddAVPToMessage(msg, avp, msg->avpList.tail)
							   != AAA_ERR_SUCCESS)
				goto error;
		}
	}

	return msg;
error:
	LM_ERR("failed to create a new AAA message!\n");
	AAAFreeMessage(&msg);
	return 0;
}

/**
 * Create a Diameter Request.
 * @param app_id - application id to be set
 * @param command_code - the command code for this message
 * @param flags - flags to be set
 * @param sessId - session id to be set
 * @returns the AAAMessage* or NULL on error
 */
AAAMessage *AAACreateRequest(AAAApplicationId app_id,
		AAACommandCode command_code, AAAMsgFlag flags, AAASession *session)
{
	AAAMessage *msg;
	AAA_AVP *avp;

	msg = AAANewMessage(command_code, app_id, session, 0);
	if(!msg)
		return 0;
	msg->hopbyhopId = next_hopbyhop();
	msg->endtoendId = next_endtoend();
	msg->flags |= flags;

	if(session) {
		/* add destination host and destination realm */
		/*if(session->dest_host.s){//TODO: check spec about removing this across the board (jason)
			avp = AAACreateAVP(AVP_Destination_Host,AAA_AVP_FLAG_MANDATORY,0,
			session->dest_host.s,session->dest_host.len,AVP_DUPLICATE_DATA);
			if (!avp) {
				LM_ERR("Failed creating Destination Host avp\n");
				goto error;
			}
			if (AAAAddAVPToMessage(msg,avp,msg->avpList.tail)!=AAA_ERR_SUCCESS) {
				LM_ERR("Failed adding Destination Host avp to message\n");
				AAAFreeAVP(&avp);
				goto error;
			}
		}*/

		if(session->dest_realm.s) {
			avp = AAACreateAVP(AVP_Destination_Realm, AAA_AVP_FLAG_MANDATORY, 0,
					session->dest_realm.s, session->dest_realm.len,
					AVP_DUPLICATE_DATA);
			if(!avp) {
				LM_ERR("Failed creating Destination Realm avp\n");
				goto error;
			}
			if(AAAAddAVPToMessage(msg, avp, msg->avpList.tail)
					!= AAA_ERR_SUCCESS) {
				LM_ERR("Failed adding Destination Realm avp to message\n");
				AAAFreeAVP(&avp);
				goto error;
			}
		}
	}

	return msg;
error:
	AAAFreeMessage(&msg);
	return NULL;
}

/**
 * Create a Diameter Response to a given Request.
 * @param request - the request that this response is for
 * @returns the AAAMessage* or NULL on error
 */
AAAMessage *AAACreateResponse(AAAMessage *request)
{
	AAAMessage *msg;
	msg = AAANewMessage(
			request->commandCode, request->applicationId, 0, request);

	return msg;
}


/**
 *  Frees an AVP List and all the members
 * @param avpList - list to be freed
 * @returns AAA_ERR_SUCCESS
 */
AAAReturnCode AAAFreeAVPList(AAA_AVP_LIST *avpList)
{
	AAA_AVP *avp_t;
	AAA_AVP *avp;
	/* free the avp list */
	avp = avpList->head;
	while(avp) {
		avp_t = avp;
		avp = avp->next;
		/*free the avp*/
		AAAFreeAVP(&avp_t);
	}
	avpList->head = 0;
	avpList->tail = 0;
	return AAA_ERR_SUCCESS;
}

/**
 *  Frees completely a message allocated through AAANewMessage()
 * @param msg - pointer to the pointer containing the message.
 * @returns AAA_ERR_SUCCESS
 */
AAAReturnCode AAAFreeMessage(AAAMessage **msg)
{
	LM_DBG("Freeing message (%p) %d\n", *msg, (*msg)->commandCode);
	/* param check */
	if(!msg || !(*msg))
		goto done;

	/* free the avp list */
	AAAFreeAVPList(&((*msg)->avpList));

	/* free the buffer (if any) */
	if((*msg)->buf.s)
		shm_free((*msg)->buf.s);

	/* free the AAA msg */
	shm_free(*msg);
	*msg = 0;

done:
	return AAA_ERR_SUCCESS;
}

/**
 *  Sets the proper result_code into the Result-Code AVP; ths avp must already
 * exists into the reply messge.
 * @param message - the message to set the Result-Code to
 * @param resultCode - code to set as result
 * \note This function is taken from DISC http://developer.berlios.de/projects/disc/
 */
AAAReturnCode AAASetMessageResultCode(
		AAAMessage *message, AAAResultCode resultCode)
{
	if(!is_req(message) && message->res_code) {
		*((unsigned int *)(message->res_code->data.s)) = htonl(resultCode);
		return AAA_ERR_SUCCESS;
	}
	return AAA_ERR_FAILURE;
}


/**
 *  This function converts message from the network format to the AAAMessage structure (decoder).
 * @param source - the source char buffer
 * @param sourceLen - the length of the input buffer
 * @param attach_buf - whether to attach the input buffer to the message
 * @returns the AAAMessage* or NULL on error
 * \note This function is taken from DISC http://developer.berlios.de/projects/disc/
 */
AAAMessage *AAATranslateMessage(
		unsigned char *source, unsigned int sourceLen, int attach_buf)
{
	unsigned char *ptr;
	AAAMessage *msg = 0;
	unsigned char version;
	unsigned int msg_len;
	AAA_AVP *avp;
	unsigned int avp_code;
	unsigned char avp_flags;
	unsigned int avp_len;
	unsigned int avp_vendorID;
	unsigned int avp_data_len;

	/* check the params */
	if(!source || !sourceLen || sourceLen < AAA_MSG_HDR_SIZE) {
		LM_ERR("invalid buffered received!\n");
		goto error;
	}

	/* inits */
	msg = 0;
	avp = 0;
	ptr = source;

	/* alloc a new message structure */
	msg = (AAAMessage *)shm_malloc(sizeof(AAAMessage));
	if(!msg) {
		LM_ERR("no more free memory!!\n");
		goto error;
	}
	memset(msg, 0, sizeof(AAAMessage));

	/* get the version */
	version = (unsigned char)*ptr;
	ptr += VER_SIZE;
	if(version != 1) {
		LM_ERR("invalid version [%d]in AAA msg\n", version);
		goto error;
	}

	/* message length */
	msg_len = get_3bytes(ptr);
	ptr += MESSAGE_LENGTH_SIZE;
	if(msg_len > sourceLen) {
		LM_ERR("AAA message len [%d] bigger than buffer len [%d]\n", msg_len,
				sourceLen);
		goto error;
	}

	/* command flags */
	msg->flags = *ptr;
	ptr += FLAGS_SIZE;

	/* command code */
	msg->commandCode = get_3bytes(ptr);
	ptr += COMMAND_CODE_SIZE;

	/* application-Id */
	msg->applicationId = get_4bytes(ptr);
	ptr += APPLICATION_ID_SIZE;

	/* Hop-by-Hop-Id */
	msg->hopbyhopId = ntohl(*((unsigned int *)ptr));
	ptr += HOP_BY_HOP_IDENTIFIER_SIZE;

	/* End-to-End-Id */
	msg->endtoendId = ntohl(*((unsigned int *)ptr));
	ptr += END_TO_END_IDENTIFIER_SIZE;

	/* start decoding the AVPS */
	while(ptr < source + msg_len) {
		if(ptr + AVP_HDR_SIZE(0x80) > source + msg_len) {
			LM_ERR("source buffer to short!! "
				   "Cannot read the whole AVP header!\n");
			goto error;
		}
		/* avp code */
		avp_code = get_4bytes(ptr);
		ptr += AVP_CODE_SIZE;
		/* avp flags */
		avp_flags = (unsigned char)*ptr;
		ptr += AVP_FLAGS_SIZE;
		/* avp length */
		avp_len = get_3bytes(ptr);
		ptr += AVP_LENGTH_SIZE;
		if(avp_len < 1) {
			LM_ERR("invalid AVP len [%d]\n", avp_len);
			goto error;
		}
		/* avp vendor-ID */
		avp_vendorID = 0;
		if(avp_flags & AAA_AVP_FLAG_VENDOR_SPECIFIC) {
			avp_vendorID = get_4bytes(ptr);
			ptr += AVP_VENDOR_ID_SIZE;
		}
		/* data length */
		avp_data_len = avp_len - AVP_HDR_SIZE(avp_flags);
		/*check the data length */
		if(source + msg_len < ptr + avp_data_len) {
			LM_ERR("source buffer to short!! "
				   "Cannot read a whole data for AVP!\n");
			goto error;
		}

		/* create the AVP */
		avp = AAACreateAVP(avp_code, avp_flags, avp_vendorID, (char *)ptr,
				avp_data_len, AVP_DONT_FREE_DATA);
		if(!avp)
			goto error;

		/* link the avp into aaa message to the end */
		AAAAddAVPToMessage(msg, avp, msg->avpList.tail);

		ptr += to_32x_len(avp_data_len);
	}

	/* link the buffer to the message */
	if(attach_buf) {
		msg->buf.s = (char *)source;
		msg->buf.len = msg_len;
	}

	msg->sessionId = AAAFindMatchingAVP(msg, 0, AVP_Session_Id, 0, 0);

	//AAAPrintMessage( msg );
	return msg;
error:
	LM_ERR("message conversion dropped!!\n");
	AAAFreeMessage(&msg);
	return 0;
}


/**
 *  print as debug all info contained by an aaa message + AVPs
 * @param msg - the AAAMessage to print
 * \note This function is taken from DISC http://developer.berlios.de/projects/disc/
 */
void AAAPrintMessage(AAAMessage *msg)
{
	char buf[1024];
	AAA_AVP *avp;

	/* print msg info */
	LM_DBG("AAA_MESSAGE - %p\n", msg);
	LM_DBG("\tCode = %u\n", msg->commandCode);
	LM_DBG("\tFlags = %x\n", msg->flags);

	/*print the AVPs */
	avp = msg->avpList.head;
	while(avp) {
		AAAConvertAVPToString(avp, buf, 1024);
		LM_DBG("\n%s\n", buf);
		avp = avp->next;
	}
}
