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1 /*
2  *  Copyright (c) 2021-22, The OpenThread Authors.
3  *  All rights reserved.
4  *
5  *  Redistribution and use in source and binary forms, with or without
6  *  modification, are permitted provided that the following conditions are met:
7  *  1. Redistributions of source code must retain the above copyright
8  *     notice, this list of conditions and the following disclaimer.
9  *  2. Redistributions in binary form must reproduce the above copyright
10  *     notice, this list of conditions and the following disclaimer in the
11  *     documentation and/or other materials provided with the distribution.
12  *  3. Neither the name of the copyright holder nor the
13  *     names of its contributors may be used to endorse or promote products
14  *     derived from this software without specific prior written permission.
15  *
16  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20  *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24  *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26  *  POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 /**
30  * @file
31  * @brief
32  *  This file defines the OpenThread Border Routing Manager API.
33  */
34 
35 #ifndef OPENTHREAD_BORDER_ROUTING_H_
36 #define OPENTHREAD_BORDER_ROUTING_H_
37 
38 #include <openthread/error.h>
39 #include <openthread/ip6.h>
40 #include <openthread/netdata.h>
41 
42 #ifdef __cplusplus
43 extern "C" {
44 #endif
45 
46 /**
47  * @addtogroup api-border-routing
48  *
49  * @brief
50  *  This module includes definitions related to Border Routing Manager.
51  *
52  *
53  * @{
54  *
55  * All the functions in this module require `OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE` to be enabled.
56  *
57  * Border Routing Manager handles bi-directional routing between Thread network and adjacent infrastructure link (AIL).
58  *
59  * It emits ICMRv6 ND Router Advertisement (RA) messages on AIL to advertise on-link and route prefixes. It also
60  * processes received RA messages from infrastructure and mirrors the discovered prefixes on the Thread Network Data to
61  * ensure devices on Thread mesh can reach AIL through the Border Router.
62  *
63  * Routing Manager manages the Off-Mesh Routable (OMR) prefix on the Thread Network data which configures Thread
64  * devices with a suitable Off-Mesh Routable IPv6 address. It announces the reachability of this prefix on AIL by
65  * including it in the emitted RA messages as an IPv6 Route Information Option (RIO).
66  *
67  * Routing Manager also monitors and adds on-link prefix on the infrastructure network. If a router on AIL is already
68  * providing RA messages containing an IPv6 Prefix Information Option (PIO) that enables IPv6 devices on the link to
69  * self-configure their own routable unicast IPv6 address, this address can be used by Thread devices to reach AIL. If
70  * Border Router finds no such RA message on AIL, it generates a ULA on-link prefix which it then advertises on AIL in
71  * the emitted RA messages.
72  */
73 
74 /**
75  * Represents an iterator to iterate through the Border Router's discovered prefix table.
76  *
77  * The fields in this type are opaque (intended for use by OpenThread core only) and therefore should not be
78  * accessed or used by caller.
79  *
80  * Before using an iterator, it MUST be initialized using `otBorderRoutingPrefixTableInitIterator()`.
81  */
82 typedef struct otBorderRoutingPrefixTableIterator
83 {
84     const void *mPtr1;
85     const void *mPtr2;
86     uint32_t    mData0;
87     uint32_t    mData1;
88     uint8_t     mData2;
89     uint8_t     mData3;
90 } otBorderRoutingPrefixTableIterator;
91 
92 /**
93  * Represents a discovered router on the infrastructure link.
94  *
95  * The `mIsPeerBr` field requires `OPENTHREAD_CONFIG_BORDER_ROUTING_TRACK_PEER_BR_INFO_ENABLE`. Routing Manager
96  * determines whether the router is a peer BR (connected to the same Thread mesh network) by comparing its advertised
97  * PIO/RIO prefixes with the entries in the Thread Network Data. While this method is generally effective, it may not
98  * be 100% accurate in all scenarios, so the `mIsPeerBr` flag should be used with caution.
99  */
100 typedef struct otBorderRoutingRouterEntry
101 {
102     otIp6Address mAddress;                      ///< IPv6 address of the router.
103     uint32_t     mMsecSinceLastUpdate;          ///< Milliseconds since last update (any message rx) from this router.
104     uint32_t     mAge;                          ///< The router's age in seconds (duration since its first discovery).
105     bool         mManagedAddressConfigFlag : 1; ///< The router's Managed Address Config flag (`M` flag).
106     bool         mOtherConfigFlag : 1;          ///< The router's Other Config flag (`O` flag).
107     bool         mSnacRouterFlag : 1;           ///< The router's SNAC Router flag (`S` flag).
108     bool         mIsLocalDevice : 1;            ///< This router is the local device (this BR).
109     bool         mIsReachable : 1;              ///< This router is reachable.
110     bool         mIsPeerBr : 1;                 ///< This router is (likely) a peer BR.
111 } otBorderRoutingRouterEntry;
112 
113 /**
114  * Represents an entry from the discovered prefix table.
115  *
116  * The entries in the discovered table track the Prefix/Route Info Options in the received Router Advertisement messages
117  * from other routers on the infrastructure link.
118  */
119 typedef struct otBorderRoutingPrefixTableEntry
120 {
121     otBorderRoutingRouterEntry mRouter;              ///< Information about the router advertising this prefix.
122     otIp6Prefix                mPrefix;              ///< The discovered IPv6 prefix.
123     bool                       mIsOnLink;            ///< Indicates whether the prefix is on-link or route prefix.
124     uint32_t                   mMsecSinceLastUpdate; ///< Milliseconds since last update of this prefix.
125     uint32_t                   mValidLifetime;       ///< Valid lifetime of the prefix (in seconds).
126     otRoutePreference          mRoutePreference;     ///< Route preference when `mIsOnlink` is false.
127     uint32_t                   mPreferredLifetime;   ///< Preferred lifetime of the on-link prefix when `mIsOnLink`.
128 } otBorderRoutingPrefixTableEntry;
129 
130 /**
131  * Represents information about a peer Border Router found in the Network Data.
132  */
133 typedef struct otBorderRoutingPeerBorderRouterEntry
134 {
135     uint16_t mRloc16; ///< The RLOC16 of BR.
136     uint32_t mAge;    ///< Seconds since the BR appeared in the Network Data.
137 } otBorderRoutingPeerBorderRouterEntry;
138 
139 /**
140  * Represents a group of data of platform-generated RA messages processed.
141  */
142 typedef struct otPdProcessedRaInfo
143 {
144     uint32_t mNumPlatformRaReceived;   ///< The number of platform generated RA handled by ProcessPlatformGeneratedRa.
145     uint32_t mNumPlatformPioProcessed; ///< The number of PIO processed for adding OMR prefixes.
146     uint32_t mLastPlatformRaMsec;      ///< The timestamp of last processed RA message.
147 } otPdProcessedRaInfo;
148 
149 /**
150  * Represents the state of Border Routing Manager.
151  */
152 typedef enum
153 {
154     OT_BORDER_ROUTING_STATE_UNINITIALIZED, ///< Routing Manager is uninitialized.
155     OT_BORDER_ROUTING_STATE_DISABLED,      ///< Routing Manager is initialized but disabled.
156     OT_BORDER_ROUTING_STATE_STOPPED,       ///< Routing Manager in initialized and enabled but currently stopped.
157     OT_BORDER_ROUTING_STATE_RUNNING,       ///< Routing Manager is initialized, enabled, and running.
158 } otBorderRoutingState;
159 
160 /**
161  * This enumeration represents the state of DHCPv6 Prefix Delegation State.
162  */
163 typedef enum
164 {
165     OT_BORDER_ROUTING_DHCP6_PD_STATE_DISABLED, ///< DHCPv6 PD is disabled on the border router.
166     OT_BORDER_ROUTING_DHCP6_PD_STATE_STOPPED,  ///< DHCPv6 PD in enabled but won't try to request and publish a prefix.
167     OT_BORDER_ROUTING_DHCP6_PD_STATE_RUNNING,  ///< DHCPv6 PD is enabled and will try to request and publish a prefix.
168     OT_BORDER_ROUTING_DHCP6_PD_STATE_IDLE,     ///< DHCPv6 PD is idle; Higher-prf prefix published by other BRs.
169 } otBorderRoutingDhcp6PdState;
170 
171 /**
172  * Initializes the Border Routing Manager on given infrastructure interface.
173  *
174  * @note  This method MUST be called before any other otBorderRouting* APIs.
175  * @note  This method can be re-called to change the infrastructure interface, but the Border Routing Manager should be
176  *        disabled first, and re-enabled after.
177  *
178  * @param[in]  aInstance          A pointer to an OpenThread instance.
179  * @param[in]  aInfraIfIndex      The infrastructure interface index.
180  * @param[in]  aInfraIfIsRunning  A boolean that indicates whether the infrastructure
181  *                                interface is running.
182  *
183  * @retval  OT_ERROR_NONE           Successfully started the Border Routing Manager on given infrastructure.
184  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is in a state other than disabled or uninitialized.
185  * @retval  OT_ERROR_INVALID_ARGS   The index of the infrastructure interface is not valid.
186  * @retval  OT_ERROR_FAILED         Internal failure. Usually due to failure in generating random prefixes.
187  *
188  * @sa otPlatInfraIfStateChanged.
189  * @sa otBorderRoutingSetEnabled.
190  */
191 otError otBorderRoutingInit(otInstance *aInstance, uint32_t aInfraIfIndex, bool aInfraIfIsRunning);
192 
193 /**
194  * Enables or disables the Border Routing Manager.
195  *
196  * @note  The Border Routing Manager is disabled by default.
197  *
198  * @param[in]  aInstance  A pointer to an OpenThread instance.
199  * @param[in]  aEnabled   A boolean to enable/disable the routing manager.
200  *
201  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
202  * @retval  OT_ERROR_NONE           Successfully enabled/disabled the Border Routing Manager.
203  */
204 otError otBorderRoutingSetEnabled(otInstance *aInstance, bool aEnabled);
205 
206 /**
207  * Gets the current state of Border Routing Manager.
208  *
209  * @param[in]  aInstance  A pointer to an OpenThread instance.
210  *
211  * @returns The current state of Border Routing Manager.
212  */
213 otBorderRoutingState otBorderRoutingGetState(otInstance *aInstance);
214 
215 /**
216  * Gets the current preference used when advertising Route Info Options (RIO) in Router Advertisement
217  * messages sent over the infrastructure link.
218  *
219  * The RIO preference is determined as follows:
220  *
221  * - If explicitly set by user by calling `otBorderRoutingSetRouteInfoOptionPreference()`, the given preference is
222  *   used.
223  * - Otherwise, it is determined based on device's current role: Medium preference when in router/leader role and
224  *   low preference when in child role.
225  *
226  * @returns The current Route Info Option preference.
227  */
228 otRoutePreference otBorderRoutingGetRouteInfoOptionPreference(otInstance *aInstance);
229 
230 /**
231  * Explicitly sets the preference to use when advertising Route Info Options (RIO) in Router
232  * Advertisement messages sent over the infrastructure link.
233  *
234  * After a call to this function, BR will use the given preference for all its advertised RIOs. The preference can be
235  * cleared by calling `otBorderRoutingClearRouteInfoOptionPreference()`.
236  *
237  * @param[in] aInstance     A pointer to an OpenThread instance.
238  * @param[in] aPreference   The route preference to use.
239  */
240 void otBorderRoutingSetRouteInfoOptionPreference(otInstance *aInstance, otRoutePreference aPreference);
241 
242 /**
243  * Clears a previously set preference value for advertised Route Info Options.
244  *
245  * After a call to this function, BR will use device's role to determine the RIO preference: Medium preference when
246  * in router/leader role and low preference when in child role.
247  *
248  * @param[in] aInstance     A pointer to an OpenThread instance.
249  */
250 void otBorderRoutingClearRouteInfoOptionPreference(otInstance *aInstance);
251 
252 /**
253  * Sets additional options to append at the end of emitted Router Advertisement (RA) messages.
254  *
255  * The content of @p aOptions is copied internally, so it can be a temporary buffer (e.g., a stack allocated array).
256  *
257  * Subsequent calls to this function overwrite the previously set value.
258  *
259  * @param[in] aOptions   A pointer to the encoded options. Can be `NULL` to clear.
260  * @param[in] aLength    Number of bytes in @p aOptions.
261  *
262  * @retval OT_ERROR_NONE     Successfully set the extra option bytes.
263  * @retval OT_ERROR_NO_BUFS  Could not allocate buffer to save the buffer.
264  */
265 otError otBorderRoutingSetExtraRouterAdvertOptions(otInstance *aInstance, const uint8_t *aOptions, uint16_t aLength);
266 
267 /**
268  * Gets the current preference used for published routes in Network Data.
269  *
270  * The preference is determined as follows:
271  *
272  * - If explicitly set by user by calling `otBorderRoutingSetRoutePreference()`, the given preference is used.
273  * - Otherwise, it is determined automatically by `RoutingManager` based on the device's role and link quality.
274  *
275  * @param[in] aInstance     A pointer to an OpenThread instance.
276  *
277  * @returns The current published route preference.
278  */
279 otRoutePreference otBorderRoutingGetRoutePreference(otInstance *aInstance);
280 
281 /**
282  * Explicitly sets the preference of published routes in Network Data.
283  *
284  * After a call to this function, BR will use the given preference. The preference can be cleared by calling
285  * `otBorderRoutingClearRoutePreference()`.
286  *
287  * @param[in] aInstance     A pointer to an OpenThread instance.
288  * @param[in] aPreference   The route preference to use.
289  */
290 void otBorderRoutingSetRoutePreference(otInstance *aInstance, otRoutePreference aPreference);
291 
292 /**
293  * Clears a previously set preference value for published routes in Network Data.
294  *
295  * After a call to this function, BR will determine the preference automatically based on the device's role and
296  * link quality (to the parent when acting as end-device).
297  *
298  * @param[in] aInstance     A pointer to an OpenThread instance.
299  */
300 void otBorderRoutingClearRoutePreference(otInstance *aInstance);
301 
302 /**
303  * Gets the local Off-Mesh-Routable (OMR) Prefix, for example `fdfc:1ff5:1512:5622::/64`.
304  *
305  * An OMR Prefix is a randomly generated 64-bit prefix that's published in the
306  * Thread network if there isn't already an OMR prefix. This prefix can be reached
307  * from the local Wi-Fi or Ethernet network.
308  *
309  * Note: When DHCPv6 PD is enabled, the border router may publish the prefix from
310  * DHCPv6 PD.
311  *
312  * @param[in]   aInstance  A pointer to an OpenThread instance.
313  * @param[out]  aPrefix    A pointer to where the prefix will be output to.
314  *
315  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
316  * @retval  OT_ERROR_NONE           Successfully retrieved the OMR prefix.
317  *
318  * @sa otBorderRoutingGetPdOmrPrefix
319  */
320 otError otBorderRoutingGetOmrPrefix(otInstance *aInstance, otIp6Prefix *aPrefix);
321 
322 /**
323  * Gets the DHCPv6 Prefix Delegation (PD) provided off-mesh-routable (OMR) prefix.
324  *
325  * Only mPrefix, mValidLifetime and mPreferredLifetime fields are used in the returned prefix info.
326  *
327  * `OPENTHREAD_CONFIG_BORDER_ROUTING_DHCP6_PD_ENABLE` must be enabled.
328  *
329  * @param[in]   aInstance    A pointer to an OpenThread instance.
330  * @param[out]  aPrefixInfo  A pointer to where the prefix info will be output to.
331  *
332  * @retval  OT_ERROR_NONE           Successfully retrieved the OMR prefix.
333  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
334  * @retval  OT_ERROR_NOT_FOUND      There are no valid PD prefix on this BR.
335  *
336  * @sa otBorderRoutingGetOmrPrefix
337  * @sa otPlatBorderRoutingProcessIcmp6Ra
338  */
339 otError otBorderRoutingGetPdOmrPrefix(otInstance *aInstance, otBorderRoutingPrefixTableEntry *aPrefixInfo);
340 
341 /**
342  * Gets the data of platform generated RA message processed..
343  *
344  * `OPENTHREAD_CONFIG_BORDER_ROUTING_DHCP6_PD_ENABLE` must be enabled.
345  *
346  * @param[in]   aInstance    A pointer to an OpenThread instance.
347  * @param[out]  aPrefixInfo  A pointer to where the prefix info will be output to.
348  *
349  * @retval  OT_ERROR_NONE           Successfully retrieved the Info.
350  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
351  * @retval  OT_ERROR_NOT_FOUND      There are no valid Info on this BR.
352  */
353 otError otBorderRoutingGetPdProcessedRaInfo(otInstance *aInstance, otPdProcessedRaInfo *aPdProcessedRaInfo);
354 
355 /**
356  * Gets the currently favored Off-Mesh-Routable (OMR) Prefix.
357  *
358  * The favored OMR prefix can be discovered from Network Data or can be this device's local OMR prefix.
359  *
360  * @param[in]   aInstance    A pointer to an OpenThread instance.
361  * @param[out]  aPrefix      A pointer to output the favored OMR prefix.
362  * @param[out]  aPreference  A pointer to output the preference associated the favored prefix.
363  *
364  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not running yet.
365  * @retval  OT_ERROR_NONE           Successfully retrieved the favored OMR prefix.
366  */
367 otError otBorderRoutingGetFavoredOmrPrefix(otInstance *aInstance, otIp6Prefix *aPrefix, otRoutePreference *aPreference);
368 
369 /**
370  * Gets the local On-Link Prefix for the adjacent infrastructure link.
371  *
372  * The local On-Link Prefix is a 64-bit prefix that's advertised on the infrastructure link if there isn't already a
373  * usable on-link prefix being advertised on the link.
374  *
375  * @param[in]   aInstance  A pointer to an OpenThread instance.
376  * @param[out]  aPrefix    A pointer to where the prefix will be output to.
377  *
378  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
379  * @retval  OT_ERROR_NONE           Successfully retrieved the local on-link prefix.
380  */
381 otError otBorderRoutingGetOnLinkPrefix(otInstance *aInstance, otIp6Prefix *aPrefix);
382 
383 /**
384  * Gets the currently favored On-Link Prefix.
385  *
386  * The favored prefix is either a discovered on-link prefix on the infrastructure link or the local on-link prefix.
387  *
388  * @param[in]   aInstance  A pointer to an OpenThread instance.
389  * @param[out]  aPrefix    A pointer to where the prefix will be output to.
390  *
391  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
392  * @retval  OT_ERROR_NONE           Successfully retrieved the favored on-link prefix.
393  */
394 otError otBorderRoutingGetFavoredOnLinkPrefix(otInstance *aInstance, otIp6Prefix *aPrefix);
395 
396 /**
397  * Gets the local NAT64 Prefix of the Border Router.
398  *
399  * NAT64 Prefix might not be advertised in the Thread network.
400  *
401  * `OPENTHREAD_CONFIG_NAT64_BORDER_ROUTING_ENABLE` must be enabled.
402  *
403  * @param[in]   aInstance   A pointer to an OpenThread instance.
404  * @param[out]  aPrefix     A pointer to where the prefix will be output to.
405  *
406  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
407  * @retval  OT_ERROR_NONE           Successfully retrieved the NAT64 prefix.
408  */
409 otError otBorderRoutingGetNat64Prefix(otInstance *aInstance, otIp6Prefix *aPrefix);
410 
411 /**
412  * Gets the currently favored NAT64 prefix.
413  *
414  * The favored NAT64 prefix can be discovered from infrastructure link or can be this device's local NAT64 prefix.
415  *
416  * @param[in]   aInstance    A pointer to an OpenThread instance.
417  * @param[out]  aPrefix      A pointer to output the favored NAT64 prefix.
418  * @param[out]  aPreference  A pointer to output the preference associated the favored prefix.
419  *
420  * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
421  * @retval  OT_ERROR_NONE           Successfully retrieved the favored NAT64 prefix.
422  */
423 otError otBorderRoutingGetFavoredNat64Prefix(otInstance        *aInstance,
424                                              otIp6Prefix       *aPrefix,
425                                              otRoutePreference *aPreference);
426 
427 /**
428  * Initializes an `otBorderRoutingPrefixTableIterator`.
429  *
430  * An iterator MUST be initialized before it is used.
431  *
432  * An iterator can be initialized again to restart from the beginning of the table.
433  *
434  * When iterating over entries in the table, to ensure the update times `mMsecSinceLastUpdate` of entries are
435  * consistent, they are given relative to the time the iterator was initialized.
436  *
437  * @param[in]  aInstance  The OpenThread instance.
438  * @param[out] aIterator  A pointer to the iterator to initialize.
439  */
440 void otBorderRoutingPrefixTableInitIterator(otInstance *aInstance, otBorderRoutingPrefixTableIterator *aIterator);
441 
442 /**
443  * Iterates over the entries in the Border Router's discovered prefix table.
444  *
445  * Prefix entries associated with the same discovered router on an infrastructure link are guaranteed to be grouped
446  * together (retrieved back-to-back).
447  *
448  * @param[in]     aInstance    The OpenThread instance.
449  * @param[in,out] aIterator    A pointer to the iterator.
450  * @param[out]    aEntry       A pointer to the entry to populate.
451  *
452  * @retval OT_ERROR_NONE        Iterated to the next entry, @p aEntry and @p aIterator are updated.
453  * @retval OT_ERROR_NOT_FOUND   No more entries in the table.
454  */
455 otError otBorderRoutingGetNextPrefixTableEntry(otInstance                         *aInstance,
456                                                otBorderRoutingPrefixTableIterator *aIterator,
457                                                otBorderRoutingPrefixTableEntry    *aEntry);
458 
459 /**
460  * Iterates over the discovered router entries on the infrastructure link.
461  *
462  * @param[in]     aInstance    The OpenThread instance.
463  * @param[in,out] aIterator    A pointer to the iterator.
464  * @param[out]    aEntry       A pointer to the entry to populate.
465  *
466  * @retval OT_ERROR_NONE        Iterated to the next router, @p aEntry and @p aIterator are updated.
467  * @retval OT_ERROR_NOT_FOUND   No more router entries.
468  */
469 otError otBorderRoutingGetNextRouterEntry(otInstance                         *aInstance,
470                                           otBorderRoutingPrefixTableIterator *aIterator,
471                                           otBorderRoutingRouterEntry         *aEntry);
472 
473 /**
474  * Iterates over the peer BRs found in the Network Data.
475  *
476  * Requires `OPENTHREAD_CONFIG_BORDER_ROUTING_TRACK_PEER_BR_INFO_ENABLE`.
477  *
478  * Peer BRs are other devices within the Thread mesh that provide external IP connectivity. A device is considered
479  * to provide external IP connectivity if at least one of the following conditions is met regarding its Network Data
480  * entries:
481  *
482  * - It has added at least one external route entry.
483  * - It has added at least one prefix entry with both the default-route and on-mesh flags set.
484  * - It has added at least one domain prefix (with both the domain and on-mesh flags set).
485  *
486  * The list of peer BRs specifically excludes the current device, even if it is itself acting as a BR.
487  *
488  * @param[in]     aInstance    The OpenThread instance.
489  * @param[in,out] aIterator    A pointer to the iterator.
490  * @param[out]    aEntry       A pointer to the entry to populate.
491  *
492  * @retval OT_ERROR_NONE        Iterated to the next entry, @p aEntry and @p aIterator are updated.
493  * @retval OT_ERROR_NOT_FOUND   No more entries.
494  */
495 otError otBorderRoutingGetNextPeerBrEntry(otInstance                           *aInstance,
496                                           otBorderRoutingPrefixTableIterator   *aIterator,
497                                           otBorderRoutingPeerBorderRouterEntry *aEntry);
498 
499 /**
500  * Returns the number of peer BRs found in the Network Data.
501  *
502  * Requires `OPENTHREAD_CONFIG_BORDER_ROUTING_TRACK_PEER_BR_INFO_ENABLE`.
503  *
504  * Peer BRs are other devices within the Thread mesh that provide external IP connectivity. A device is considered
505  * to provide external IP connectivity if at least one of the following conditions is met regarding its Network Data
506  * entries:
507  *
508  * - It has added at least one external route entry.
509  * - It has added at least one prefix entry with both the default-route and on-mesh flags set.
510  * - It has added at least one domain prefix (with both the domain and on-mesh flags set).
511  *
512  * The list of peer BRs specifically excludes the current device, even if it is itself acting as a BR.
513  *
514  * @param[in]  aInstance    The OpenThread instance.
515  * @param[out] aMinAge      Pointer to an `uint32_t` to return the minimum age among all peer BRs.
516  *                          Can be NULL if the caller does not need this information.
517  *                          Age is represented as seconds since appearance of the BR entry in the Network Data.
518  *
519  * @returns The number of peer BRs.
520  */
521 uint16_t otBorderRoutingCountPeerBrs(otInstance *aInstance, uint32_t *aMinAge);
522 
523 /**
524  * Enables / Disables DHCPv6 Prefix Delegation.
525  *
526  * `OPENTHREAD_CONFIG_BORDER_ROUTING_DHCP6_PD_ENABLE` must be enabled.
527  *
528  * @param[in] aInstance A pointer to an OpenThread instance.
529  * @param[in] aEnabled  Whether to accept platform generated RA messages.
530  */
531 void otBorderRoutingDhcp6PdSetEnabled(otInstance *aInstance, bool aEnabled);
532 
533 /**
534  * Gets the current state of DHCPv6 Prefix Delegation.
535  *
536  * Requires `OPENTHREAD_CONFIG_BORDER_ROUTING_DHCP6_PD_ENABLE` to be enabled.
537  *
538  * @param[in]  aInstance  A pointer to an OpenThread instance.
539  *
540  * @returns The current state of DHCPv6 Prefix Delegation.
541  */
542 otBorderRoutingDhcp6PdState otBorderRoutingDhcp6PdGetState(otInstance *aInstance);
543 
544 /**
545  * When the state of a DHCPv6 Prefix Delegation (PD) on the Thread interface changes, this callback notifies processes
546  * in the OS of this changed state.
547  *
548  * @param[in] aState    The state of DHCPv6 Prefix Delegation State.
549  * @param[in] aContext  A pointer to arbitrary context information.
550  */
551 typedef void (*otBorderRoutingRequestDhcp6PdCallback)(otBorderRoutingDhcp6PdState aState, void *aContext);
552 
553 /**
554  * Sets the callback whenever the DHCPv6 PD state changes on the Thread interface.
555  *
556  * Subsequent calls to this function replace the previously set callback.
557  *
558  * @param[in] aInstance  A pointer to an OpenThread instance.
559  * @param[in] aCallback  A pointer to a function that is called whenever the DHCPv6 PD state changes.
560  * @param[in] aContext   A pointer to arbitrary context information.
561  */
562 void otBorderRoutingDhcp6PdSetRequestCallback(otInstance                           *aInstance,
563                                               otBorderRoutingRequestDhcp6PdCallback aCallback,
564                                               void                                 *aContext);
565 
566 /**
567  * Sets the local on-link prefix.
568  *
569  * Requires `OPENTHREAD_CONFIG_BORDER_ROUTING_TESTING_API_ENABLE`.
570  *
571  * This is intended for testing only and using it will make the BR non-compliant with the Thread Specification.
572  *
573  * @param[in]  aPrefix      The on-link prefix to use.
574  */
575 void otBorderRoutingSetOnLinkPrefix(otInstance *aInstance, const otIp6Prefix *aPrefix);
576 
577 /**
578  * @}
579  */
580 
581 #ifdef __cplusplus
582 } // extern "C"
583 #endif
584 
585 #endif // OPENTHREAD_BORDER_ROUTING_H_
586