/*
 *  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 <stdbool.h>
#include <stdint.h>

#include <openthread/error.h>
#include <openthread/instance.h>
#include <openthread/message.h>
#include <openthread/platform/radio.h>
#include <openthread/platform/toolchain.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)
#define OT_IP6_ADDRESS_BITSIZE (OT_IP6_ADDRESS_SIZE * 8) ///< Size of an IPv6 address (bits)
#define OT_IP6_HEADER_SIZE 40                            ///< Size of an IPv6 header (bytes)
#define OT_IP6_HEADER_PROTO_OFFSET 6                     ///< Offset of the proto field in the IPv6 header (bytes)

/**
 * @struct otIp6InterfaceIdentifier
 *
 * 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;

/**
 * Represents the Interface Identifier of an IPv6 address.
 */
typedef struct otIp6InterfaceIdentifier otIp6InterfaceIdentifier;

/**
 * @struct otIp6NetworkPrefix
 *
 * 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;

/**
 * Represents the Network Prefix of an IPv6 address (most significant 64 bits of the address).
 */
typedef struct otIp6NetworkPrefix otIp6NetworkPrefix;

/**
 * @struct otIp6AddressComponents
 *
 * 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;

/**
 * Represents the components of an IPv6 address.
 */
typedef struct otIp6AddressComponents otIp6AddressComponents;

/**
 * @struct otIp6Address
 *
 * 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;

/**
 * Represents an IPv6 address.
 */
typedef struct otIp6Address otIp6Address;

/**
 * @struct otIp6Prefix
 *
 * 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;

/**
 * Represents an IPv6 prefix.
 */
typedef struct otIp6Prefix otIp6Prefix;

/**
 * IPv6 Address origins
 */
enum
{
    OT_ADDRESS_ORIGIN_THREAD = 0, ///< Thread assigned (ALOC, RLOC, MLEID, etc.)
    OT_ADDRESS_ORIGIN_SLAAC  = 1, ///< SLAAC assigned (used in `otNetifAddress` and not in `otNetifMulticastAddress`).
    OT_ADDRESS_ORIGIN_DHCPV6 = 2, ///< DHCPv6 assigned (used in `otNetifAddress` and not in `otNetifMulticastAddress`).
    OT_ADDRESS_ORIGIN_MANUAL = 3, ///< Manually assigned address.
};

/**
 * 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 (OT_ADDRESS_ORIGIN_* values).
    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.
    bool         mMeshLocal : 1;          ///< TRUE if the address is mesh-local, FALSE otherwise.
    bool         mSrpRegistered : 1;      ///< Used by OT core only (indicates whether registered by SRP Client).
    const struct otNetifAddress *mNext;   ///< A pointer to the next network interface address.
} otNetifAddress;

/**
 * Represents an IPv6 network interface multicast address.
 *
 * The `mAddressOrigin` field is set to either `OT_ADDRESS_ORIGIN_THREAD` if the multicast address is subscribed by
 * OpenThread core or `OT_ADDRESS_ORIGIN_MANUAL` if it is subscribed manually using `otIp6SubscribeMulticastAddress()`.
 *
 * The multicast addresses subscribed by OpenThread core include addresses such as
 * - link-local all nodes (`ff02::01`),
 * - realm-local all nodes (`ff03::01`),
 * - link-local all routers (`ff02::02`),
 * - realm-local all routers (`ff03::02`),
 * - realm-local all MPL forwarders (`ff03::fc`),
 * - link-local all Thread nodes,
 * - realm-local all Thread nodes.
 */
typedef struct otNetifMulticastAddress
{
    otIp6Address                          mAddress;       ///< The IPv6 multicast address.
    const struct otNetifMulticastAddress *mNext;          ///< A pointer to the next multicast address.
    uint8_t                               mAddressOrigin; ///< The multicast address origin.
    uint8_t                               mData;          ///< Opaque data used by OpenThread core.
} otNetifMulticastAddress;

/**
 * Represents an IPv6 socket address.
 */
typedef struct otSockAddr
{
    otIp6Address mAddress; ///< An IPv6 address.
    uint16_t     mPort;    ///< A transport-layer port.
} otSockAddr;

/**
 * ECN statuses, represented as in the IP header.
 */
enum
{
    OT_ECN_NOT_CAPABLE = 0x0, ///< Non-ECT
    OT_ECN_CAPABLE_0   = 0x2, ///< ECT(0)
    OT_ECN_CAPABLE_1   = 0x1, ///< ECT(1)
    OT_ECN_MARKED      = 0x3, ///< Congestion encountered (CE)
};

/**
 * 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.
    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.
    uint8_t mEcn : 2;       ///< The ECN status of the packet, represented as in the IPv6 header.
    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
};

/**
 * Initializes the IPv6 interface and its external address pools.
 *
 * Requires `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE`.
 *
 * It provides the memory buffers for the external unicast and multicast address pools and must be called before
 * enabling the IPv6 interface.
 *
 * The provided memory buffers MUST persist and remain valid as long as the OpenThread instance is initialized.
 * OpenThread will use these provided buffers to manage the pools of externally added unicast and multicast
 * addresses (i.e., those added via `otIp6AddUnicastAddress()` and `otIp6SubscribeMulticastAddress()`).
 *
 * This function can only be called once. Subsequent calls will return `OT_ERROR_ALREADY`.
 *
 * The `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE` feature and this function allow the external unicast/multicast
 * address pools to be configured at run-time after OpenThread instance initialization, rather than build-time.
 * When this feature is disabled, the build-time configs `OPENTHREAD_CONFIG_IP6_MAX_EXT_UCAST_ADDRS` and
 * `OPENTHREAD_CONFIG_IP6_MAX_EXT_MCAST_ADDRS` specify the pool sizes used by the OpenThread stack.
 *
 * This feature allows the OpenThread stack to be compiled as a library without specifying the address pool sizes.
 * It delegates the configuration of the pools to the next layer, allowing the OpenThread stack to be integrated into
 * various projects without requiring a new OpenThread stack configuration to be built.
 *
 * @param[in] aInstance               A pointer to an OpenThread instance.
 * @param[in] aUnicastAddrPool        A pointer to an array of `otNetifAddress`.
 * @param[in] aUnicastAddrPoolSize    The number of entries in @p aUnicastAddrPool.
 * @param[in] aMulticastAddrPool      A pointer to an array of `otNetifMulticastAddress`.
 * @param[in] aMulticastAddrPoolSize  The number of entries in @p aMulticastAddrPool.
 *
 * @retval OT_ERROR_NONE     Successfully initialized the IPv6 interface.
 * @retval OT_ERROR_ALREADY  The IPv6 interface is already initialized.
 */
otError otIp6Init(otInstance              *aInstance,
                  otNetifAddress          *aUnicastAddrPool,
                  uint16_t                 aUnicastAddrPoolSize,
                  otNetifMulticastAddress *aMulticastAddrPool,
                  uint16_t                 aMulticastAddrPoolSize);

/**
 * Brings the IPv6 interface up or down.
 *
 * Call this to enable or disable IPv6 communication.
 *
 * When `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE` is enabled, `otIp6Init()` MUST be called prior to calling
 * this function. If it is not, this function will return `OT_ERROR_INVALID_STATE`.
 *
 * @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),
 *                                  or not initialized under `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE`.
 */
otError otIp6SetEnabled(otInstance *aInstance, bool aEnabled);

/**
 * 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);

/**
 * Adds 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`
 * and `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE`.
 *
 * @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);

/**
 * Removes 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);

/**
 * Gets 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);

/**
 * Indicates whether or not a unicast IPv6 address is assigned to the Thread interface.
 *
 * @param[in]  aInstance A pointer to an OpenThread instance.
 * @param[in]  aAddress  A pointer to the unicast address.
 *
 * @retval TRUE   If @p aAddress is assigned to the Thread interface.
 * @retval FALSE  If @p aAddress is not assigned to the Thread interface.
 */
bool otIp6HasUnicastAddress(otInstance *aInstance, const otIp6Address *aAddress);

/**
 * Subscribes 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`
 * and `OPENTHREAD_CONFIG_IP6_INIT_EXT_ADDR_POOL_ENABLE`.
 *
 *
 * @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 an invalid multicast address.
 * @retval OT_ERROR_REJECTED       The IP Address indicated by @p aAddress is an internal multicast address.
 * @retval OT_ERROR_NO_BUFS        The Network Interface is already storing the maximum allowed external multicast
 *                                 addresses.
 */
otError otIp6SubscribeMulticastAddress(otInstance *aInstance, const otIp6Address *aAddress);

/**
 * Unsubscribes 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_REJECTED      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);

/**
 * Gets 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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.
    bool                mMeshLocal : 1; ///< Whether this is a mesh-local unicast/anycast address.
} otIp6AddressInfo;

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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.
 * @retval OT_ERROR_INVALID_ARGS            The message's metadata is invalid, e.g. the message uses
 *                                          `OT_MESSAGE_ORIGIN_THREAD_NETIF` as the origin.
 */
otError otIp6Send(otInstance *aInstance, otMessage *aMessage);

/**
 * 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);

/**
 * 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);

/**
 * Removes all ports from the allowed unsecure port list.
 *
 * @param[in]  aInstance A pointer to an OpenThread instance.
 */
void otIp6RemoveAllUnsecurePorts(otInstance *aInstance);

/**
 * 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);

/**
 * Sets whether to allow link-local unsecure IPv6 datagrams when the Thread role is disabled.
 *
 * Available only when `OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE` is enabled. This is intended for testing. By default,
 * this is disabled (i.e., unsecure traffic is always dropped regardless of the device's role).
 *
 * @param[in] aInstance  A pointer to an OpenThread instance.
 * @param[in] aAllow     TRUE to allow, FALSE otherwise.
 */
void otIp6SetAllowUnsecureWhenDisabled(otInstance *aInstance, bool aAllow);

/**
 * Indicates whether allowing link-local unsecure IPv6 datagrams when the Thread role is disabled is enabled.
 *
 * Available only when `OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE` is enabled.
 *
 * @param[in] aInstance  A pointer to an OpenThread instance.
 *
 * @retval TRUE   Does allow unsecure IPv6 datagrams when the Thread role is disabled.
 * @retval FALSE  Does not allow unsecure IPv6 datagrams when the Thread role is disabled.
 */
bool otIp6IsUnsecureAllowedWhenDisabled(otInstance *aInstance);

/**
 * 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 whether or not the IPv6 address is a link-local unicast address.
 *
 * @param[in]  aAddress   A pointer to the IPv6 address to test.
 *
 * @retval TRUE   If the IPv6 address is a link-local unicast address.
 * @retval FALSE  If the IPv6 address is not a link-local unicast address.
 */
bool otIp6IsLinkLocalUnicast(const otIp6Address *aAddress);

/**
 * Forms a link-local unicast IPv6 address from the Interface Identifier generated from the given
 * MAC Extended Address with the universal/local bit inverted.
 *
 * @param[in]  aExtAddress  A pointer to the MAC Extended Address (used to generate the IID).
 * @param[out] aAddress     A pointer to output the IPv6 link-local unicast address.
 */
void otIp6FormLinkLocalAddressFromExtAddress(const otExtAddress *aExtAddress, otIp6Address *aAddress);

/**
 * Extracts the MAC Extended Address from the Interface Identifier of the given IPv6 address.
 *
 * @param[in]  aAddress     A pointer to the IPv6 address.
 * @param[out] aExtAddress  A pointer to output the MAC Extended Address (generated from the IID).
 */
void otIp6ExtractExtAddressFromIp6AddressIid(const otIp6Address *aAddress, otExtAddress *aExtAddress);

/**
 * 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);

/**
 * 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 @p aString and updated @p aAddress.
 * @retval OT_ERROR_PARSE  Failed to parse @p aString as an IPv6 address.
 */
otError otIp6AddressFromString(const char *aString, otIp6Address *aAddress);

/**
 * Converts a human-readable IPv6 prefix string into a binary representation.
 *
 * The @p aString parameter should be a string in the format "<address>/<plen>", where `<address>` is an IPv6
 * address and `<plen>` is a prefix length.
 *
 * @param[in]   aString  A pointer to a NULL-terminated string.
 * @param[out]  aPrefix  A pointer to an IPv6 prefix.
 *
 * @retval OT_ERROR_NONE   Successfully parsed the string as an IPv6 prefix and updated @p aPrefix.
 * @retval OT_ERROR_PARSE  Failed to parse @p aString as an IPv6 prefix.
 */
otError otIp6PrefixFromString(const char *aString, otIp6Prefix *aPrefix);

#define OT_IP6_ADDRESS_STRING_SIZE 40 ///< Recommended size for string representation of an IPv6 address.

/**
 * 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.

/**
 * 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,
 * for example "[%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.

/**
 * 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);

/**
 * 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);

/**
 * Gets a prefix with @p aLength from @p aAddress.
 *
 * @param[in]  aAddress   A pointer to an IPv6 address.
 * @param[in]  aLength    The length of prefix in bits.
 * @param[out] aPrefix    A pointer to output the IPv6 prefix.
 */
void otIp6GetPrefix(const otIp6Address *aAddress, uint8_t aLength, otIp6Prefix *aPrefix);

/**
 * 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);

/**
 * Perform OpenThread source address selection.
 *
 * @param[in]      aInstance     A pointer to an OpenThread instance.
 * @param[in,out]  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);

/**
 * Indicates whether the SLAAC module is enabled or not.
 *
 * `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` build-time feature must be enabled.
 *
 * @retval TRUE    SLAAC module is enabled.
 * @retval FALSE   SLAAC module is disabled.
 */
bool otIp6IsSlaacEnabled(otInstance *aInstance);

/**
 * Enables/disables the SLAAC module.
 *
 * `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` build-time feature must 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);

/**
 * 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] aInstance   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);

/**
 * Sets the SLAAC module filter handler.
 *
 * `OPENTHREAD_CONFIG_IP6_SLAAC_ENABLE` build-time feature must 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);

/**
 * 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);

#define OT_IP6_MAX_MLR_ADDRESSES 15 ///< Max number of IPv6 addresses supported by Multicast Listener Registration.

/**
 * Registers Multicast Listeners to Primary Backbone Router.
 *
 * `OPENTHREAD_CONFIG_TMF_PROXY_MLR_ENABLE` and `OPENTHREAD_CONFIG_COMMISSIONER_ENABLE`
 * must be 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);

/**
 * Sets the Mesh Local IID (for test purpose).
 *
 * Requires `OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE`.
 *
 * @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);

/**
 * 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);

/**
 * Represents the counters for packets and bytes.
 */
typedef struct otPacketsAndBytes
{
    uint64_t mPackets; ///< The number of packets.
    uint64_t mBytes;   ///< The number of bytes.
} otPacketsAndBytes;

/**
 * Represents the counters of packets forwarded via Border Routing.
 */
typedef struct otBorderRoutingCounters
{
    otPacketsAndBytes mInboundUnicast;    ///< The counters for inbound unicast.
    otPacketsAndBytes mInboundMulticast;  ///< The counters for inbound multicast.
    otPacketsAndBytes mOutboundUnicast;   ///< The counters for outbound unicast.
    otPacketsAndBytes mOutboundMulticast; ///< The counters for outbound multicast.
    otPacketsAndBytes mInboundInternet;   ///< The counters for inbound Internet when DHCPv6 PD enabled.
    otPacketsAndBytes mOutboundInternet;  ///< The counters for outbound Internet when DHCPv6 PD enabled.
    uint32_t          mRaRx;              ///< The number of received RA packets.
    uint32_t          mRaTxSuccess;       ///< The number of RA packets successfully transmitted.
    uint32_t          mRaTxFailure;       ///< The number of RA packets failed to transmit.
    uint32_t          mRsRx;              ///< The number of received RS packets.
    uint32_t          mRsTxSuccess;       ///< The number of RS packets successfully transmitted.
    uint32_t          mRsTxFailure;       ///< The number of RS packets failed to transmit.
} otBorderRoutingCounters;

/**
 * Gets the Border Routing counters.
 *
 * `OPENTHREAD_CONFIG_IP6_BR_COUNTERS_ENABLE` build-time feature must be enabled.
 *
 * @param[in]  aInstance  A pointer to an OpenThread instance.
 *
 * @returns A pointer to the Border Routing counters.
 */
const otBorderRoutingCounters *otIp6GetBorderRoutingCounters(otInstance *aInstance);

/**
 * Resets the Border Routing counters.
 *
 * @param[in]  aInstance  A pointer to an OpenThread instance.
 */
void otIp6ResetBorderRoutingCounters(otInstance *aInstance);

/**
 * @}
 */

#ifdef __cplusplus
} // extern "C"
#endif

#endif // OPENTHREAD_IP6_H_
