text: /*
   *  Copyright (c) 2016, The OpenThread Authors.
   *  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. 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
   *  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.
   */
  
  /**
   * @file
   * @brief
   *  This file defines the OpenThread IPv6 API.
   */
  
  #ifndef OPENTHREAD_IP6_H_
  #define OPENTHREAD_IP6_H_
  
  #include <openthread/message.h>
  #include <openthread/platform/radio.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @addtogroup api-ip6
   *
   * @brief
   *   This module includes functions that control IPv6 communication.
   *
   * @{
   *
   */
  
  #define OT_IP6_PREFIX_SIZE 8                           ///< Size of an IPv6 prefix (bytes)
  #define OT_IP6_PREFIX_BITSIZE (OT_IP6_PREFIX_SIZE * 8) ///< Size of an IPv6 prefix (bits)
  #define OT_IP6_IID_SIZE 8                              ///< Size of an IPv6 Interface Identifier (bytes)
  #define OT_IP6_ADDRESS_SIZE 16                         ///< Size of an IPv6 address (bytes)
  
  /**
   * @struct otIp6InterfaceIdentifier
   *
   * This structure represents the Interface Identifier of an IPv6 address.
   *
   */
  OT_TOOL_PACKED_BEGIN
  struct otIp6InterfaceIdentifier
  {
      union OT_TOOL_PACKED_FIELD
      {
          uint8_t  m8[OT_IP6_IID_SIZE];                     ///< 8-bit fields
          uint16_t m16[OT_IP6_IID_SIZE / sizeof(uint16_t)]; ///< 16-bit fields
          uint32_t m32[OT_IP6_IID_SIZE / sizeof(uint32_t)]; ///< 32-bit fields
      } mFields;                                            ///< The Interface Identifier accessor fields
  } OT_TOOL_PACKED_END;
  
  /**
   * This structure represents the Interface Identifier of an IPv6 address.
   *
   */
  typedef struct otIp6InterfaceIdentifier otIp6InterfaceIdentifier;
  
  /**
   * @struct otIp6NetworkPrefix
   *
   * This structure represents the Network Prefix of an IPv6 address (most significant 64 bits of the address).
   *
   */
  OT_TOOL_PACKED_BEGIN
  struct otIp6NetworkPrefix
  {
      uint8_t m8[OT_IP6_PREFIX_SIZE]; ///< The Network Prefix.
  } OT_TOOL_PACKED_END;
  
  /**
   * This structure represents the Network Prefix of an IPv6 address (most significant 64 bits of the address).
   *
   */
  typedef struct otIp6NetworkPrefix otIp6NetworkPrefix;
  
  /**
   * @struct otIp6AddressComponents
   *
   * This structure represents the components of an IPv6 address.
   *
   */
  OT_TOOL_PACKED_BEGIN
  struct otIp6AddressComponents
  {
      otIp6NetworkPrefix       mNetworkPrefix; ///< The Network Prefix (most significant 64 bits of the address)
      otIp6InterfaceIdentifier mIid;           ///< The Interface Identifier (least significant 64 bits of the address)
  } OT_TOOL_PACKED_END;
  
  /**
   * This structure represents the components of an IPv6 address.
   *
   */
  typedef struct otIp6AddressComponents otIp6AddressComponents;
  
  /**
   * @struct otIp6Address
   *
   * This structure represents an IPv6 address.
   *
   */
  OT_TOOL_PACKED_BEGIN
  struct otIp6Address
  {
      union OT_TOOL_PACKED_FIELD
      {
          uint8_t                m8[OT_IP6_ADDRESS_SIZE];                     ///< 8-bit fields
          uint16_t               m16[OT_IP6_ADDRESS_SIZE / sizeof(uint16_t)]; ///< 16-bit fields
          uint32_t               m32[OT_IP6_ADDRESS_SIZE / sizeof(uint32_t)]; ///< 32-bit fields
          otIp6AddressComponents mComponents;                                 ///< IPv6 address components
      } mFields;                                                              ///< IPv6 accessor fields
  } OT_TOOL_PACKED_END;
  
  /**
   * This structure represents an IPv6 address.
   *
   */
  typedef struct otIp6Address otIp6Address;
  
  /**
   * This structure represents an IPv6 prefix.
   *
   */
  OT_TOOL_PACKED_BEGIN
  struct otIp6Prefix
  {
      otIp6Address mPrefix; ///< The IPv6 prefix.
      uint8_t      mLength; ///< The IPv6 prefix length (in bits).
  } OT_TOOL_PACKED_END;
  
  /**
   * This structure represents an IPv6 prefix.
   *
   */
  typedef struct otIp6Prefix otIp6Prefix;
  
  /**
   * IPv6 Address origins
   *
   */
  enum
  {
      OT_ADDRESS_ORIGIN_THREAD = 0, ///< Thread assigned address (ALOC, RLOC, MLEID, etc)
      OT_ADDRESS_ORIGIN_SLAAC  = 1, ///< SLAAC assigned address
      OT_ADDRESS_ORIGIN_DHCPV6 = 2, ///< DHCPv6 assigned address
      OT_ADDRESS_ORIGIN_MANUAL = 3, ///< Manually assigned address
  };
  
  /**
   * This structure represents an IPv6 network interface unicast address.
   *
   */
  typedef struct otNetifAddress
  {
      otIp6Address           mAddress;                ///< The IPv6 unicast address.
      uint8_t                mPrefixLength;           ///< The Prefix length (in bits).
      uint8_t                mAddressOrigin;          ///< The IPv6 address origin.
      bool                   mPreferred : 1;          ///< TRUE if the address is preferred, FALSE otherwise.
      bool                   mValid : 1;              ///< TRUE if the address is valid, FALSE otherwise.
      bool                   mScopeOverrideValid : 1; ///< TRUE if the mScopeOverride value is valid, FALSE otherwise.
      unsigned int           mScopeOverride : 4;      ///< The IPv6 scope of this address.
      bool                   mRloc : 1;               ///< TRUE if the address is an RLOC, FALSE otherwise.
      struct otNetifAddress *mNext;                   ///< A pointer to the next network interface address.
  } otNetifAddress;
  
  /**
   * This structure represents an IPv6 network interface multicast address.
   *
   */
  typedef struct otNetifMulticastAddress
  {
      otIp6Address                          mAddress; ///< The IPv6 multicast address.
      const struct otNetifMulticastAddress *mNext;    ///< A pointer to the next network interface multicast address.
  } otNetifMulticastAddress;
  
  /**
   * This structure represents an IPv6 socket address.
   *
   */
  typedef struct otSockAddr
  {
      otIp6Address mAddress; ///< An IPv6 address.
      uint16_t     mPort;    ///< A transport-layer port.
  } otSockAddr;
  
  /**
   * This structure represents the local and peer IPv6 socket addresses.
   *
   */
  typedef struct otMessageInfo
  {
      otIp6Address mSockAddr;      ///< The local IPv6 address.
      otIp6Address mPeerAddr;      ///< The peer IPv6 address.
      uint16_t     mSockPort;      ///< The local transport-layer port.
      uint16_t     mPeerPort;      ///< The peer transport-layer port.
      const void * mLinkInfo;      ///< A pointer to link-specific information.
      uint8_t      mHopLimit;      ///< The IPv6 Hop Limit value. Only applies if `mAllowZeroHopLimit` is FALSE.
                                   ///< If `0`, IPv6 Hop Limit is default value `OPENTHREAD_CONFIG_IP6_HOP_LIMIT_DEFAULT`.
                                   ///< Otherwise, specifies the IPv6 Hop Limit.
      bool mIsHostInterface : 1;   ///< TRUE if packets sent/received via host interface, FALSE otherwise.
      bool mAllowZeroHopLimit : 1; ///< TRUE to allow IPv6 Hop Limit 0 in `mHopLimit`, FALSE otherwise.
      bool mMulticastLoop : 1;     ///< TRUE to allow looping back multicast, FALSE otherwise.
  } otMessageInfo;
  
  /**
   * Internet Protocol Numbers.
   *
   */
  enum
  {
      OT_IP6_PROTO_HOP_OPTS = 0,  ///< IPv6 Hop-by-Hop Option
      OT_IP6_PROTO_TCP      = 6,  ///< Transmission Control Protocol
      OT_IP6_PROTO_UDP      = 17, ///< User Datagram
      OT_IP6_PROTO_IP6      = 41, ///< IPv6 encapsulation
      OT_IP6_PROTO_ROUTING  = 43, ///< Routing Header for IPv6
      OT_IP6_PROTO_FRAGMENT = 44, ///< Fragment Header for IPv6
      OT_IP6_PROTO_ICMP6    = 58, ///< ICMP for IPv6
      OT_IP6_PROTO_NONE     = 59, ///< No Next Header for IPv6
      OT_IP6_PROTO_DST_OPTS = 60, ///< Destination Options for IPv6
  };
  
  /**
   * This function brings up/down the IPv6 interface.
   *
   * Call this function to enable/disable IPv6 communication.
   *
   * @param[in] aInstance A pointer to an OpenThread instance.
   * @param[in] aEnabled  TRUE to enable IPv6, FALSE otherwise.
   *
   * @retval OT_ERROR_NONE            Successfully brought the IPv6 interface up/down.
   * @retval OT_ERROR_INVALID_STATE   IPv6 interface is not available since device is operating in raw-link mode
   *                                  (applicable only when `OPENTHREAD_CONFIG_LINK_RAW_ENABLE` feature is enabled).
   *
   */
  otError otIp6SetEnabled(otInstance *aInstance, bool aEnabled);
  
  /**
   * This function indicates whether or not the IPv6 interface is up.
   *
   * @param[in] aInstance A pointer to an OpenThread instance.
   *
   * @retval TRUE   The IPv6 interface is enabled.
   * @retval FALSE  The IPv6 interface is disabled.
   *
   */
  bool otIp6IsEnabled(otInstance *aInstance);
  
  /**
   * Add a Network Interface Address to the Thread interface.
   *
   * The passed-in instance @p aAddress is copied by the Thread interface. The Thread interface only
   * supports a fixed number of externally added unicast addresses. See OPENTHREAD_CONFIG_IP6_MAX_EXT_UCAST_ADDRS.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aAddress  A pointer to a Network Interface Address.
   *
   * @retval OT_ERROR_NONE          Successfully added (or updated) the Network Interface Address.
   * @retval OT_ERROR_INVALID_ARGS  The IP Address indicated by @p aAddress is an internal address.
   * @retval OT_ERROR_NO_BUFS       The Network Interface is already storing the maximum allowed external addresses.
   */
  otError otIp6AddUnicastAddress(otInstance *aInstance, const otNetifAddress *aAddress);
  
  /**
   * Remove a Network Interface Address from the Thread interface.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aAddress  A pointer to an IP Address.
   *
   * @retval OT_ERROR_NONE          Successfully removed the Network Interface Address.
   * @retval OT_ERROR_INVALID_ARGS  The IP Address indicated by @p aAddress is an internal address.
   * @retval OT_ERROR_NOT_FOUND     The IP Address indicated by @p aAddress was not found.
   */
  otError otIp6RemoveUnicastAddress(otInstance *aInstance, const otIp6Address *aAddress);
  
  /**
   * Get the list of IPv6 addresses assigned to the Thread interface.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   *
   * @returns A pointer to the first Network Interface Address.
   */
  const otNetifAddress *otIp6GetUnicastAddresses(otInstance *aInstance);
  
  /**
   * Subscribe the Thread interface to a Network Interface Multicast Address.
   *
   * The passed in instance @p aAddress will be copied by the Thread interface. The Thread interface only
   * supports a fixed number of externally added multicast addresses. See OPENTHREAD_CONFIG_IP6_MAX_EXT_MCAST_ADDRS.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aAddress  A pointer to an IP Address.
   *
   * @retval OT_ERROR_NONE           Successfully subscribed to the Network Interface Multicast Address.
   * @retval OT_ERROR_ALREADY        The multicast address is already subscribed.
   * @retval OT_ERROR_INVALID_ARGS   The IP Address indicated by @p aAddress is invalid address.
   * @retval OT_ERROR_INVALID_STATE  The Network Interface is not up.
   * @retval OT_ERROR_NO_BUFS        The Network Interface is already storing the maximum allowed external multicast
   *                                 addresses.
   *
   */
  otError otIp6SubscribeMulticastAddress(otInstance *aInstance, const otIp6Address *aAddress);
  
  /**
   * Unsubscribe the Thread interface to a Network Interface Multicast Address.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aAddress  A pointer to an IP Address.
   *
   * @retval OT_ERROR_NONE          Successfully unsubscribed to the Network Interface Multicast Address.
   * @retval OT_ERROR_INVALID_ARGS  The IP Address indicated by @p aAddress is an internal address.
   * @retval OT_ERROR_NOT_FOUND     The IP Address indicated by @p aAddress was not found.
   */
  otError otIp6UnsubscribeMulticastAddress(otInstance *aInstance, const otIp6Address *aAddress);
  
  /**
   * Get the list of IPv6 multicast addresses subscribed to the Thread interface.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   *
   * @returns A pointer to the first Network Interface Multicast Address.
   *
   */
  const otNetifMulticastAddress *otIp6GetMulticastAddresses(otInstance *aInstance);
  
  /**
   * Check if multicast promiscuous mode is enabled on the Thread interface.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   *
   * @sa otIp6SetMulticastPromiscuousEnabled
   *
   */
  bool otIp6IsMulticastPromiscuousEnabled(otInstance *aInstance);
  
  /**
   * Enable multicast promiscuous mode on the Thread interface.
   *
   * @param[in]  aInstance  A pointer to an OpenThread instance.
   * @param[in]  aEnabled   TRUE to enable Multicast Promiscuous mode, FALSE otherwise.
   *
   * @sa otIp6IsMulticastPromiscuousEnabled
   *
   */
  void otIp6SetMulticastPromiscuousEnabled(otInstance *aInstance, bool aEnabled);
  
  /**
   * Allocate a new message buffer for sending an IPv6 message.
   *
   * @note If @p aSettings is 'NULL', the link layer security is enabled and the message priority is set to
   * OT_MESSAGE_PRIORITY_NORMAL by default.
   *
   * @param[in]  aInstance  A pointer to an OpenThread instance.
   * @param[in]  aSettings  A pointer to the message settings or NULL to set default settings.
   *
   * @returns A pointer to the message buffer or NULL if no message buffers are available or parameters are invalid.
   *
   * @sa otMessageFree
   *
   */
  otMessage *otIp6NewMessage(otInstance *aInstance, const otMessageSettings *aSettings);
  
  /**
   * Allocate a new message buffer and write the IPv6 datagram to the message buffer for sending an IPv6 message.
   *
   * @note If @p aSettings is NULL, the link layer security is enabled and the message priority is obtained from IPv6
   *       message itself.
   *       If @p aSettings is not NULL, the @p aSetting->mPriority is ignored and obtained from IPv6 message itself.
   *
   * @param[in]  aInstance    A pointer to an OpenThread instance.
   * @param[in]  aData        A pointer to the IPv6 datagram buffer.
   * @param[in]  aDataLength  The size of the IPv6 datagram buffer pointed by @p aData.
   * @param[in]  aSettings    A pointer to the message settings or NULL to set default settings.
   *
   * @returns A pointer to the message or NULL if malformed IPv6 header or insufficient message buffers are available.
   *
   * @sa otMessageFree
   *
   */
  otMessage *otIp6NewMessageFromBuffer(otInstance *             aInstance,
                                       const uint8_t *          aData,
                                       uint16_t                 aDataLength,
                                       const otMessageSettings *aSettings);
  
  /**
   * This function pointer is called when an IPv6 datagram is received.
   *
   * @param[in]  aMessage  A pointer to the message buffer containing the received IPv6 datagram. This function transfers
   *                       the ownership of the @p aMessage to the receiver of the callback. The message should be
   *                       freed by the receiver of the callback after it is processed (see otMessageFree()).
   * @param[in]  aContext  A pointer to application-specific context.
   *
   */
  typedef void (*otIp6ReceiveCallback)(otMessage *aMessage, void *aContext);
  
  /**
   * This function registers a callback to provide received IPv6 datagrams.
   *
   * By default, this callback does not pass Thread control traffic.  See otIp6SetReceiveFilterEnabled() to
   * change the Thread control traffic filter setting.
   *
   * @param[in]  aInstance         A pointer to an OpenThread instance.
   * @param[in]  aCallback         A pointer to a function that is called when an IPv6 datagram is received or
   *                               NULL to disable the callback.
   * @param[in]  aCallbackContext  A pointer to application-specific context.
   *
   * @sa otIp6IsReceiveFilterEnabled
   * @sa otIp6SetReceiveFilterEnabled
   *
   */
  void otIp6SetReceiveCallback(otInstance *aInstance, otIp6ReceiveCallback aCallback, void *aCallbackContext);
  
  /**
   * @struct otIp6AddressInfo
   *
   * This structure represents IPv6 address information.
   *
   */
  typedef struct otIp6AddressInfo
  {
      const otIp6Address *mAddress;       ///< A pointer to the IPv6 address.
      uint8_t             mPrefixLength;  ///< The prefix length of mAddress if it is a unicast address.
      uint8_t             mScope : 4;     ///< The scope of this address.
      bool                mPreferred : 1; ///< Whether this is a preferred address.
  } otIp6AddressInfo;
  
  /**
   * This function pointer is called when an internal IPv6 address is added or removed.
   *
   * @param[in]   aAddressInfo        A pointer to the IPv6 address information.
   * @param[in]   aIsAdded            TRUE if the @p aAddress was added, FALSE if @p aAddress was removed.
   * @param[in]   aContext            A pointer to application-specific context.
   *
   */
  typedef void (*otIp6AddressCallback)(const otIp6AddressInfo *aAddressInfo, bool aIsAdded, void *aContext);
  
  /**
   * This function registers a callback to notify internal IPv6 address changes.
   *
   * @param[in]   aInstance           A pointer to an OpenThread instance.
   * @param[in]   aCallback           A pointer to a function that is called when an internal IPv6 address is added or
   *                                  removed. NULL to disable the callback.
   * @param[in]   aCallbackContext    A pointer to application-specific context.
   *
   */
  void otIp6SetAddressCallback(otInstance *aInstance, otIp6AddressCallback aCallback, void *aCallbackContext);
  
  /**
   * This function indicates whether or not Thread control traffic is filtered out when delivering IPv6 datagrams
   * via the callback specified in otIp6SetReceiveCallback().
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   *
   * @returns  TRUE if Thread control traffic is filtered out, FALSE otherwise.
   *
   * @sa otIp6SetReceiveCallback
   * @sa otIp6SetReceiveFilterEnabled
   *
   */
  bool otIp6IsReceiveFilterEnabled(otInstance *aInstance);
  
  /**
   * This function sets whether or not Thread control traffic is filtered out when delivering IPv6 datagrams
   * via the callback specified in otIp6SetReceiveCallback().
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aEnabled  TRUE if Thread control traffic is filtered out, FALSE otherwise.
   *
   * @sa otIp6SetReceiveCallback
   * @sa otIsReceiveIp6FilterEnabled
   *
   */
  void otIp6SetReceiveFilterEnabled(otInstance *aInstance, bool aEnabled);
  
  /**
   * This function sends an IPv6 datagram via the Thread interface.
   *
   * The caller transfers ownership of @p aMessage when making this call. OpenThread will free @p aMessage when
   * processing is complete, including when a value other than `OT_ERROR_NONE` is returned.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aMessage  A pointer to the message buffer containing the IPv6 datagram.
   *
   * @retval OT_ERROR_NONE                    Successfully processed the message.
   * @retval OT_ERROR_DROP                    Message was well-formed but not fully processed due to packet processing
   * rules.
   * @retval OT_ERROR_NO_BUFS                 Could not allocate necessary message buffers when processing the datagram.
   * @retval OT_ERROR_NO_ROUTE                No route to host.
   * @retval OT_ERROR_INVALID_SOURCE_ADDRESS  Source address is invalid, e.g. an anycast address or a multicast address.
   * @retval OT_ERROR_PARSE                   Encountered a malformed header when processing the message.
   *
   */
  otError otIp6Send(otInstance *aInstance, otMessage *aMessage);
  
  /**
   * This function adds a port to the allowed unsecured port list.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aPort     The port value.
   *
   * @retval OT_ERROR_NONE         The port was successfully added to the allowed unsecure port list.
   * @retval OT_ERROR_INVALID_ARGS The port is invalid (value 0 is reserved for internal use).
   * @retval OT_ERROR_NO_BUFS      The unsecure port list is full.
   *
   */
  otError otIp6AddUnsecurePort(otInstance *aInstance, uint16_t aPort);
  
  /**
   * This function removes a port from the allowed unsecure port list.
   *
   * @note This function removes @p aPort by overwriting @p aPort with the element after @p aPort in the internal port
   *       list. Be careful when calling otIp6GetUnsecurePorts() followed by otIp6RemoveUnsecurePort() to remove unsecure
   *       ports.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   * @param[in]  aPort     The port value.
   *
   * @retval OT_ERROR_NONE         The port was successfully removed from the allowed unsecure port list.
   * @retval OT_ERROR_INVALID_ARGS The port is invalid (value 0 is reserved for internal use).
   * @retval OT_ERROR_NOT_FOUND    The port was not found in the unsecure port list.
   *
   */
  otError otIp6RemoveUnsecurePort(otInstance *aInstance, uint16_t aPort);
  
  /**
   * This function removes all ports from the allowed unsecure port list.
   *
   * @param[in]  aInstance A pointer to an OpenThread instance.
   *
   */
  void otIp6RemoveAllUnsecurePorts(otInstance *aInstance);
  
  /**
   * This function returns a pointer to the unsecure port list.
   *
   * @note Port value 0 is used to indicate an invalid entry.
   *
   * @param[in]   aInstance    A pointer to an OpenThread instance.
   * @param[out]  aNumEntries  The number of entries in the list.
   *
   * @returns A pointer to the unsecure port list.
   *
   */
  const uint16_t *otIp6GetUnsecurePorts(otInstance *aInstance, uint8_t *aNumEntries);
  
  /**
   * Test if two IPv6 addresses are the same.
   *
   * @param[in]  aFirst   A pointer to the first IPv6 address to compare.
   * @param[in]  aSecond  A pointer to the second IPv6 address to compare.
   *
   * @retval TRUE   The two IPv6 addresses are the same.
   * @retval FALSE  The two IPv6 addresses are not the same.
   *
   */
  bool otIp6IsAddressEqual(const otIp6Address *aFirst, const otIp6Address *aSecond);
  
  /**
   * Test if two IPv6 prefixes are the same.
   *
   * @param[in]  aFirst   A pointer to the first IPv6 prefix to compare.
   * @param[in]  aSecond  A pointer to the second IPv6 prefix to compare.
   *
   * @retval TRUE   The two IPv6 prefixes are the same.
   * @retval FALSE  The two IPv6 prefixes are not the same.
   *
   */
  bool otIp6ArePrefixesEqual(const otIp6Prefix *aFirst, const otIp6Prefix *aSecond);
  
  /**
   * This function converts a human-readable IPv6 address string into a binary representation.
   *
   * @param[in]   aString   A pointer to a NULL-terminated string.
   * @param[out]  aAddress  A pointer to an IPv6 address.
   *
   * @retval OT_ERROR_NONE          Successfully parsed the string.
   * @retval OT_ERROR_INVALID_ARGS  Failed to parse the string.
   *
   */
  otError otIp6AddressFromString(const char *aString, otIp6Address *aAddress);
  
  #define OT_IP6_ADDRESS_STRING_SIZE 40 ///< Recommended size for string representation of an IPv6 address.
  
  /**
   * This function converts a given IPv6 address to a human-readable string.
   *
   * The IPv6 address string is formatted as 16 hex values separated by ':' (i.e., "%x:%x:%x:...:%x").
   *
   * If the resulting string does not fit in @p aBuffer (within its @p aSize characters), the string will be truncated
   * but the outputted string is always null-terminated.
   *
   * @param[in]  aAddress  A pointer to an IPv6 address (MUST NOT be NULL).
   * @param[out] aBuffer   A pointer to a char array to output the string (MUST NOT be NULL).
   * @param[in]  aSize     The size of @p aBuffer (in bytes). Recommended to use `OT_IP6_ADDRESS_STRING_SIZE`.
   *
   */
  void otIp6AddressToString(const otIp6Address *aAddress, char *aBuffer, uint16_t aSize);
  
  #define OT_IP6_SOCK_ADDR_STRING_SIZE 48 ///< Recommended size for string representation of an IPv6 socket address.
  
  /**
   * This function converts a given IPv6 socket address to a human-readable string.
   *
   * The IPv6 socket address string is formatted as "[<address>]:<port>" where `<address> is shown as 16 hex values
   * separated by ':' and `<port>` is the port number in decimal format (i.e., "[%x:%x:...:%x]:%u")
   *
   * If the resulting string does not fit in @p aBuffer (within its @p aSize characters), the string will be truncated
   * but the outputted string is always null-terminated.
   *
   * @param[in]  aSockAddr A pointer to an IPv6 socket address (MUST NOT be NULL).
   * @param[out] aBuffer   A pointer to a char array to output the string (MUST NOT be NULL).
   * @param[in]  aSize     The size of @p aBuffer (in bytes). Recommended to use `OT_IP6_SOCK_ADDR_STRING_SIZE`.
   *
   */
  void otIp6SockAddrToString(const otSockAddr *aSockAddr, char *aBuffer, uint16_t aSize);
  
  #define OT_IP6_PREFIX_STRING_SIZE 45 ///< Recommended size for string representation of an IPv6 prefix.
  
  /**
   * This function converts a given IPv6 prefix to a human-readable string.
   *
   * The IPv6 address string is formatted as "%x:%x:%x:...[::]/plen".
   *
   * If the resulting string does not fit in @p aBuffer (within its @p aSize characters), the string will be truncated
   * but the outputted string is always null-terminated.
   *
   * @param[in]  aPrefix   A pointer to an IPv6 prefix (MUST NOT be NULL).
   * @param[out] aBuffer   A pointer to a char array to output the string (MUST NOT be NULL).
   * @param[in]  aSize     The size of @p aBuffer (in bytes). Recommended to use `OT_IP6_PREFIX_STRING_SIZE`.
   *
   */
  void otIp6PrefixToString(const otIp6Prefix *aPrefix, char *aBuffer, uint16_t aSize);
  
  /**
   * This function returns the prefix match length (bits) for two IPv6 addresses.
   *
   * @param[in]  aFirst   A pointer to the first IPv6 address.
   * @param[in]  aSecond  A pointer to the second IPv6 address.
   *
   * @returns  The prefix match length in bits.
   *
   */
  uint8_t otIp6PrefixMatch(const otIp6Address *aFirst, const otIp6Address *aSecond);
  
  /**
   * This function indicates whether or not a given IPv6 address is the Unspecified Address.
   *
   * @param[in]  aAddress   A pointer to an IPv6 address.
   *
   * @retval TRUE   If the IPv6 address is the Unspecified Address.
   * @retval FALSE  If the IPv6 address is not the Unspecified Address.
   *
   */
  bool otIp6IsAddressUnspecified(const otIp6Address *aAddress);
  
  /**
   * This function perform OpenThread source address selection.
   *
   * @param[in]     aInstance     A pointer to an OpenThread instance.
   * @param[inout]  aMessageInfo  A pointer to the message information.
   *
   * @retval  OT_ERROR_NONE       Found a source address and is filled into mSockAddr of @p aMessageInfo.
   * @retval  OT_ERROR_NOT_FOUND  No source address was found and @p aMessageInfo is unchanged.
   *
   */
  otError otIp6SelectSourceAddress(otInstance *aInstance, otMessageInfo *aMessageInfo);
  
  /**
   * This function indicates whether the SLAAC module is enabled or not.
   *
   * This function requires the build-time feature `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` to be enabled.
   *
   * @retval TRUE    SLAAC module is enabled.
   * @retval FALSE   SLAAC module is disabled.
   *
   */
  bool otIp6IsSlaacEnabled(otInstance *aInstance);
  
  /**
   * This function enables/disables the SLAAC module.
   *
   * This function requires the build-time feature `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` to be enabled.
   *
   * When SLAAC module is enabled, SLAAC addresses (based on on-mesh prefixes in Network Data) are added to the interface.
   * When SLAAC module is disabled any previously added SLAAC address is removed.
   *
   * @param[in] aInstance A pointer to an OpenThread instance.
   * @param[in] aEnabled  TRUE to enable, FALSE to disable.
   *
   */
  void otIp6SetSlaacEnabled(otInstance *aInstance, bool aEnabled);
  
  /**
   * This function pointer allows user to filter prefixes and not allow an SLAAC address based on a prefix to be added.
   *
   * `otIp6SetSlaacPrefixFilter()` can be used to set the filter handler. The filter handler is invoked by SLAAC module
   * when it is about to add a SLAAC address based on a prefix. Its boolean return value determines whether the address
   * is filtered (not added) or not.
   *
   * @param[in] aInstacne   A pointer to an OpenThread instance.
   * @param[in] aPrefix     A pointer to prefix for which SLAAC address is about to be added.
   *
   * @retval TRUE    Indicates that the SLAAC address based on the prefix should be filtered and NOT added.
   * @retval FALSE   Indicates that the SLAAC address based on the prefix should be added.
   *
   */
  typedef bool (*otIp6SlaacPrefixFilter)(otInstance *aInstance, const otIp6Prefix *aPrefix);
  
  /**
   * This function sets the SLAAC module filter handler.
   *
   * This function requires the build-time feature `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` to be enabled.
   *
   * The filter handler is called by SLAAC module when it is about to add a SLAAC address based on a prefix to decide
   * whether the address should be added or not.
   *
   * A NULL filter handler disables filtering and allows all SLAAC addresses to be added.
   *
   * If this function is not called, the default filter used by SLAAC module will be NULL (filtering is disabled).
   *
   * @param[in] aInstance    A pointer to an OpenThread instance.
   * @param[in] aFilter      A pointer to SLAAC prefix filter handler, or NULL to disable filtering.
   *
   */
  void otIp6SetSlaacPrefixFilter(otInstance *aInstance, otIp6SlaacPrefixFilter aFilter);
  
  /**
   * This function pointer is called with results of `otIp6RegisterMulticastListeners`.
   *
   * @param[in]  aContext  A pointer to the user context.
   * @param[in]  aError    OT_ERROR_NONE when successfully sent MLR.req and received MLR.rsp,
   *                       OT_ERROR_RESPONSE_TIMEOUT when failed to receive MLR.rsp,
   *                       OT_ERROR_PARSE when failed to parse MLR.rsp.
   * @param[in]  aMlrStatus         The Multicast Listener Registration status when @p aError is OT_ERROR_NONE.
   * @param[in]  aFailedAddresses   A pointer to the failed IPv6 addresses when @p aError is OT_ERROR_NONE.
   * @param[in]  aFailedAddressNum  The number of failed IPv6 addresses when @p aError is OT_ERROR_NONE.
   *
   * @sa otIp6RegisterMulticastListeners
   *
   */
  typedef void (*otIp6RegisterMulticastListenersCallback)(void *              aContext,
                                                          otError             aError,
                                                          uint8_t             aMlrStatus,
                                                          const otIp6Address *aFailedAddresses,
                                                          uint8_t             aFailedAddressNum);
  
  /**
   * This function registers Multicast Listeners to Primary Backbone Router.
   *
   * Note: only available when both `OPENTHREAD_CONFIG_TMF_PROXY_MLR_ENABLE` and
   * `OPENTHREAD_CONFIG_COMMISSIONER_ENABLE` are enabled)
   *
   * @param[in]  aInstance    A pointer to an OpenThread instance.
   * @param[in]  aAddresses   A Multicast Address Array to register.
   * @param[in]  aAddressNum  The number of Multicast Address to register (0 if @p aAddresses is NULL).
   * @param[in]  aTimeout     A pointer to the timeout value (in seconds) to be included in MLR.req. A timeout value of 0
   *                          removes the corresponding Multicast Listener. If NULL, MLR.req would have no Timeout Tlv by
   *                          default.
   * @param[in]  aCallback    A pointer to the callback function.
   * @param[in]  aContext     A pointer to the user context.
   *
   * @retval OT_ERROR_NONE           Successfully sent MLR.req. The @p aCallback will be called iff this method
   *                                 returns OT_ERROR_NONE.
   * @retval OT_ERROR_BUSY           If a previous registration was ongoing.
   * @retval OT_ERROR_INVALID_ARGS   If one or more arguments are invalid.
   * @retval OT_ERROR_INVALID_STATE  If the device was not in a valid state to send MLR.req (e.g. Commissioner not
   *                                 started, Primary Backbone Router not found).
   * @retval OT_ERROR_NO_BUFS        If insufficient message buffers available.
   *
   * @sa otIp6RegisterMulticastListenersCallback
   *
   */
  otError otIp6RegisterMulticastListeners(otInstance *                            aInstance,
                                          const otIp6Address *                    aAddresses,
                                          uint8_t                                 aAddressNum,
                                          const uint32_t *                        aTimeout,
                                          otIp6RegisterMulticastListenersCallback aCallback,
                                          void *                                  aContext);
  
  /**
   * This function sets the Mesh Local IID (for test purpose).
   *
   * Only available when `OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE` is enabled.
   *
   * @param[in]   aInstance   A pointer to an OpenThread instance.
   * @param[in]   aIid        A pointer to the Mesh Local IID to set.
   *
   * @retval  OT_ERROR_NONE           Successfully set the Mesh Local IID.
   * @retval  OT_ERROR_INVALID_STATE  Thread protocols are enabled.
   *
   */
  otError otIp6SetMeshLocalIid(otInstance *aInstance, const otIp6InterfaceIdentifier *aIid);
  
  /**
   * This function converts a given IP protocol number to a human-readable string.
   *
   * @param[in] aIpProto   An IP protocol number (`OT_IP6_PROTO_*` enumeration).
   *
   * @returns A string representing @p aIpProto.
   *
   */
  const char *otIp6ProtoToString(uint8_t aIpProto);
  
  /**
   * @}
   *
   */
  
  #ifdef __cplusplus
  } // extern "C"
  #endif
  
  #endif // OPENTHREAD_IP6_H_
  