/*
 * Copyright (C) 2012 Andreas Steffen
 * HSR Hochschule fuer Technik Rapperswil
 *
 * This program 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program 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.
 */

#include "tnc_pdp_connections.h"

#include <collections/linked_list.h>
#include <utils/debug.h>
#include <threading/rwlock.h>
#include <processing/jobs/callback_job.h>

#include <daemon.h>

/**
 * Default PDP connection timeout, in s
 */
#define DEFAULT_TIMEOUT 30

typedef struct private_tnc_pdp_connections_t private_tnc_pdp_connections_t;
typedef struct entry_t entry_t;

/**
 * Private data of tnc_pdp_connections_t
 */
struct private_tnc_pdp_connections_t {

	/**
	 * Implements tnc_pdp_connections_t interface
	 */
	tnc_pdp_connections_t public;

	/**
	 * TNC PEP RADIUS Connections
	 */
	linked_list_t *list;

	/**
	 * Lock to access PEP connection list
	 */
	rwlock_t *lock;

	/**
	 * Connection timeout before we kill non-completed connections, in s
	 */
	int timeout;
};

/**
 * Data entry for a TNC PEP RADIUS connection
 */
struct entry_t {

	/**
	 * NAS identifier of PEP
	 */
	chunk_t nas_id;

	/**
	 * User name of TNC Client
	 */
	chunk_t user_name;

	/**
	 * EAP method state
	 */
	eap_method_t *method;

	/**
	 * IKE SA used for bus communication
	 */
	ike_sa_t *ike_sa;

	/**
	 * Timestamp this entry has been created
	 */
	time_t created;
};

/**
 * Free the memory allocated to a data entry
 */
static void free_entry(entry_t *this)
{
	this->method->destroy(this->method);
	this->ike_sa->destroy(this->ike_sa);
	free(this->nas_id.ptr);
	free(this->user_name.ptr);
	free(this);
}

/**
 * Find a matching data entry
 */
static bool equals_entry( entry_t *this, chunk_t nas_id, chunk_t user_name)
{
	bool no_nas_id = !this->nas_id.ptr && !nas_id.ptr;

	return (chunk_equals(this->nas_id, nas_id) || no_nas_id) &&
			chunk_equals(this->user_name, user_name);
}

/**
 * Find a matching data entry
 */
static void dbg_nas_user(chunk_t nas_id, chunk_t user_name, bool not, char *op)
{
	if (nas_id.len)
	{
		DBG1(DBG_CFG, "%s RADIUS connection for user '%.*s' NAS '%.*s'",
					   not ? "could not find" : op, (int)user_name.len,
					   user_name.ptr, (int)nas_id.len, nas_id.ptr);
	}
	else
	{
		DBG1(DBG_CFG, "%s RADIUS connection for user '%.*s'",
					   not ? "could not find" : op, (int)user_name.len,
					   user_name.ptr);
	}
}

/**
 * Check if any connection has timed out
 */
static job_requeue_t check_timeouts(private_tnc_pdp_connections_t *this)
{
	enumerator_t *enumerator;
	entry_t *entry;
	time_t now;

	now = time_monotonic(NULL);

	this->lock->write_lock(this->lock);
	enumerator = this->list->create_enumerator(this->list);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (entry->created + this->timeout <= now)
		{
			DBG1(DBG_CFG, "RADIUS connection timed out after %d seconds",
				 this->timeout);
			this->list->remove_at(this->list, enumerator);
			free_entry(entry);
		}
	}
	enumerator->destroy(enumerator);
	this->lock->unlock(this->lock);

	return JOB_REQUEUE_NONE;
}

METHOD(tnc_pdp_connections_t, add, void,
	private_tnc_pdp_connections_t *this, chunk_t nas_id, chunk_t user_name,
	identification_t *peer, eap_method_t *method)
{
	enumerator_t *enumerator;
	entry_t *entry;
	ike_sa_id_t *ike_sa_id;
	ike_sa_t *ike_sa;
	bool found = FALSE;

	ike_sa_id = ike_sa_id_create(IKEV2_MAJOR_VERSION, 0, 0, FALSE);
	ike_sa = ike_sa_create(ike_sa_id, FALSE, IKEV2);
	ike_sa_id->destroy(ike_sa_id);
	ike_sa->set_other_id(ike_sa, peer);

	this->lock->read_lock(this->lock);
	enumerator = this->list->create_enumerator(this->list);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (equals_entry(entry, nas_id, user_name))
		{
			found = TRUE;
			entry->method->destroy(entry->method);
			entry->ike_sa->destroy(entry->ike_sa);
			DBG1(DBG_CFG, "removed stale RADIUS connection");
			entry->method = method;
			entry->ike_sa = ike_sa;
			entry->created = time_monotonic(NULL);
			break;
		}
	}
	enumerator->destroy(enumerator);
	this->lock->unlock(this->lock);

	if (!found)
	{
		INIT(entry,
			.nas_id = chunk_clone(nas_id),
			.user_name = chunk_clone(user_name),
			.method = method,
			.ike_sa = ike_sa,
			.created = time_monotonic(NULL),
		);
		this->lock->write_lock(this->lock);
		this->list->insert_last(this->list, entry);
		this->lock->unlock(this->lock);
	}

	/* schedule timeout checking */
	lib->scheduler->schedule_job_ms(lib->scheduler,
				(job_t*)callback_job_create((callback_job_cb_t)check_timeouts,
					this, NULL, (callback_job_cancel_t)return_false),
				this->timeout * 1000);

	dbg_nas_user(nas_id, user_name, FALSE, "created");
}

METHOD(tnc_pdp_connections_t, remove_, void,
	private_tnc_pdp_connections_t *this, chunk_t nas_id, chunk_t user_name)
{
	enumerator_t *enumerator;
	entry_t *entry;

	this->lock->write_lock(this->lock);
	enumerator = this->list->create_enumerator(this->list);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (equals_entry(entry, nas_id, user_name))
		{
			free_entry(entry);
			this->list->remove_at(this->list, enumerator);
			dbg_nas_user(nas_id, user_name, FALSE, "removed");
			break;
		}
	}
	enumerator->destroy(enumerator);
	this->lock->unlock(this->lock);
}

METHOD(tnc_pdp_connections_t, get_state, eap_method_t*,
	private_tnc_pdp_connections_t *this, chunk_t nas_id, chunk_t user_name,
	ike_sa_t **ike_sa)
{
	enumerator_t *enumerator;
	entry_t *entry;
	eap_method_t *found = NULL;

	this->lock->read_lock(this->lock);
	enumerator = this->list->create_enumerator(this->list);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (equals_entry(entry, nas_id, user_name))
		{
			found = entry->method;
			*ike_sa = entry->ike_sa;
			break;
		}
	}
	enumerator->destroy(enumerator);
	if (!found)
	{
		this->lock->unlock(this->lock);
	}

	dbg_nas_user(nas_id, user_name, !found, "found");
	return found;
}

METHOD(tnc_pdp_connections_t, unlock, void,
	private_tnc_pdp_connections_t *this)
{
	this->lock->unlock(this->lock);
}

METHOD(tnc_pdp_connections_t, destroy, void,
	private_tnc_pdp_connections_t *this)
{
	this->lock->destroy(this->lock);
	this->list->destroy_function(this->list, (void*)free_entry);
	free(this);
}

/*
 * see header file
 */
tnc_pdp_connections_t *tnc_pdp_connections_create(void)
{
	private_tnc_pdp_connections_t *this;

	INIT(this,
		.public = {
			.add = _add,
			.remove = _remove_,
			.get_state = _get_state,
			.unlock = _unlock,
			.destroy = _destroy,
		},
		.list = linked_list_create(),
		.lock = rwlock_create(RWLOCK_TYPE_DEFAULT),
		.timeout = lib->settings->get_int(lib->settings,
						"%s.plugins.tnc-pdp.timeout", DEFAULT_TIMEOUT, lib->ns),
	);

	return &this->public;
}