src/core/utils/slaac_address.hpp

/*
 *  Copyright (c) 2016, The OpenThread Authors.
 *  All rights reserved.
 *
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 *  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. Neither the name of the copyright holder 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 THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER OR CONTRIBUTORS BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 */

/**
 * @file
 *   This file includes definitions for Thread global IPv6 address configuration with SLAAC.
 */

#ifndef SLAAC_ADDRESS_HPP_
#define SLAAC_ADDRESS_HPP_

#include "openthread-core-config.h"

#include "common/locator.hpp"
#include "common/notifier.hpp"
#include "net/netif.hpp"

namespace ot {
namespace Utils {

/**
 * @addtogroup core-slaac-address
 *
 * @brief
 *   This module includes definitions for Thread global IPv6 address configuration with SLAAC.
 *
 * @{
 */

/**
 * This class implements the SLAAC utility for Thread protocol.
 *
 */
class Slaac : public InstanceLocator
{
public:
    enum
    {
        kIidSecretKeySize = 32, ///< Number of bytes in secret key for generating semantically opaque IID.
    };

    /**
     * This type represents the secret key used for generating semantically opaque IID (per RFC 7217).
     *
     */
    struct IidSecretKey
    {
        uint8_t m8[kIidSecretKeySize];
    };

    /**
     * This constructor initializes the SLAAC manager object.
     *
     * Note that SLAAC module starts enabled.
     *
     * @param[in]  aInstance  A reference to the OpenThread instance.
     *
     */
    explicit Slaac(Instance &aInstance);

    /**
     * This method enables the SLAAC module.
     *
     * When enabled, new SLAAC addresses are generated and added from on-mesh prefixes in network data.
     *
     */
    void Enable(void);

    /**
     * This method disables the SLAAC module.
     *
     * When disabled, any previously added SLAAC address by this module is removed.
     *
     */
    void Disable(void);

    /**
     * This method indicates whether SLAAC module is enabled or not.
     *
     * @retval TRUE    SLAAC module is enabled.
     * @retval FALSE   SLAAC module is disabled.
     *
     */
    bool IsEnabled(void) const { return mEnabled; }

    /**
     * This methods sets a SLAAC prefix filter handler.
     *
     * The handler is invoked by SLAAC module when it is about to add a SLAAC address based on a prefix. The return
     * boolean value from handler determines whether the address is filtered or added (TRUE to filter the address,
     * FALSE to add address).
     *
     * The filter can be set to `NULL` to disable filtering (i.e., allow SLAAC addresses for all prefixes).
     *
     */
    void SetFilter(otIp6SlaacPrefixFilter aFilter);

private:
    enum
    {
        kMaxIidCreationAttempts = 1024, // Maximum number of attempts when generating IID.
    };

    // Values for `UpdateMode` input parameter in `Update()`.
    enum
    {
        kModeNone   = 0x0,    // No action.
        kModeAdd    = 1 << 0, // Add new SLAAC addresses for new prefixes in network data.
        kModeRemove = 1 << 1, // Remove SLAAC addresses.
                              // When SLAAC is enabled, remove addresses with no matching prefix in network data,
                              // When SLAAC is disabled, remove all previously added addresses.
    };

    typedef uint8_t UpdateMode;

    bool        ShouldFilter(const otIp6Prefix &aPrefix) const;
    void        Update(UpdateMode aMode);
    void        GenerateIid(Ip6::NetifUnicastAddress &aAddress) const;
    void        GetIidSecretKey(IidSecretKey &aKey) const;
    static void HandleStateChanged(Notifier::Callback &aCallback, otChangedFlags aFlags);
    void        HandleStateChanged(otChangedFlags aFlags);

    bool                     mEnabled;
    otIp6SlaacPrefixFilter   mFilter;
    Notifier::Callback       mNotifierCallback;
    Ip6::NetifUnicastAddress mAddresses[OPENTHREAD_CONFIG_IP6_SLAAC_NUM_ADDRESSES];
};

/**
 * @}
 */

} // namespace Utils
} // namespace ot

#endif // SLAAC_ADDRESS_HPP_