1 /*
2 * Copyright (c) 2018, 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 * This file implements OpenThread Time Synchronization Service.
32 */
33
34 #include "openthread-core-config.h"
35
36 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
37
38 #include "time_sync_service.hpp"
39
40 #include "instance/instance.hpp"
41
42 #define ABS(value) (((value) >= 0) ? (value) : -(value))
43
44 namespace ot {
45
46 RegisterLogModule("TimeSync");
47
TimeSync(Instance & aInstance)48 TimeSync::TimeSync(Instance &aInstance)
49 : InstanceLocator(aInstance)
50 , mTimeSyncRequired(false)
51 , mTimeSyncSeq(OT_TIME_SYNC_INVALID_SEQ)
52 , mTimeSyncPeriod(OPENTHREAD_CONFIG_TIME_SYNC_PERIOD)
53 , mXtalThreshold(OPENTHREAD_CONFIG_TIME_SYNC_XTAL_THRESHOLD)
54 #if OPENTHREAD_FTD
55 , mLastTimeSyncSent(0)
56 #endif
57 , mLastTimeSyncReceived(0)
58 , mNetworkTimeOffset(0)
59 , mTimer(aInstance)
60 , mCurrentStatus(kUnsynchronized)
61 {
62 CheckAndHandleChanges(false);
63 }
64
GetTime(uint64_t & aNetworkTime) const65 TimeSync::Status TimeSync::GetTime(uint64_t &aNetworkTime) const
66 {
67 aNetworkTime = static_cast<uint64_t>(static_cast<int64_t>(Get<Radio>().GetNow()) + mNetworkTimeOffset);
68
69 return mCurrentStatus;
70 }
71
HandleTimeSyncMessage(const Message & aMessage)72 void TimeSync::HandleTimeSyncMessage(const Message &aMessage)
73 {
74 const int64_t origNetworkTimeOffset = mNetworkTimeOffset;
75 int8_t timeSyncSeqDelta;
76
77 VerifyOrExit(aMessage.GetTimeSyncSeq() != OT_TIME_SYNC_INVALID_SEQ);
78
79 timeSyncSeqDelta = static_cast<int8_t>(aMessage.GetTimeSyncSeq() - mTimeSyncSeq);
80
81 if (mTimeSyncSeq != OT_TIME_SYNC_INVALID_SEQ && timeSyncSeqDelta < 0)
82 {
83 // An older time sync sequence was received. This indicates that there is a device that still needs to be
84 // synchronized with the current sequence, so forward it.
85 mTimeSyncRequired = true;
86
87 LogInfo("Older time sync seq received:%u. Forwarding current seq:%u", aMessage.GetTimeSyncSeq(), mTimeSyncSeq);
88 }
89 else if (Get<Mle::MleRouter>().IsLeader() && timeSyncSeqDelta > 0)
90 {
91 // Another device is forwarding a later time sync sequence, perhaps because it merged from a different
92 // partition. The leader is authoritative, so ensure all devices synchronize to the time being seeded by this
93 // leader instead.
94 mTimeSyncSeq = aMessage.GetTimeSyncSeq() + 1;
95 mTimeSyncRequired = true;
96
97 LogInfo("Newer time sync seq:%u received by leader. Setting current seq to:%u and forwarding",
98 aMessage.GetTimeSyncSeq(), mTimeSyncSeq);
99 }
100 else if (!Get<Mle::MleRouter>().IsLeader())
101 {
102 // For all devices aside from the leader, update network time in following three cases:
103 // 1. During first attach.
104 // 2. Already attached, and a newer time sync sequence was received.
105 // 3. During reattach or migration process.
106 if (mTimeSyncSeq == OT_TIME_SYNC_INVALID_SEQ || timeSyncSeqDelta > 0 || Get<Mle::MleRouter>().IsDetached())
107 {
108 // Update network time and forward it.
109 mLastTimeSyncReceived = TimerMilli::GetNow();
110 mTimeSyncSeq = aMessage.GetTimeSyncSeq();
111 mNetworkTimeOffset = aMessage.GetNetworkTimeOffset();
112 mTimeSyncRequired = true;
113
114 LogInfo("Newer time sync seq:%u received. Forwarding", mTimeSyncSeq);
115
116 // Only notify listeners of an update for network time offset jumps of more than
117 // OPENTHREAD_CONFIG_TIME_SYNC_JUMP_NOTIF_MIN_US but notify listeners regardless if the status changes.
118 CheckAndHandleChanges(ABS(mNetworkTimeOffset - origNetworkTimeOffset) >=
119 OPENTHREAD_CONFIG_TIME_SYNC_JUMP_NOTIF_MIN_US);
120 }
121 }
122
123 exit:
124 return;
125 }
126
IncrementTimeSyncSeq(void)127 void TimeSync::IncrementTimeSyncSeq(void)
128 {
129 if (++mTimeSyncSeq == OT_TIME_SYNC_INVALID_SEQ)
130 {
131 ++mTimeSyncSeq;
132 }
133 }
134
NotifyTimeSyncCallback(void)135 void TimeSync::NotifyTimeSyncCallback(void) { mTimeSyncCallback.InvokeIfSet(); }
136
137 #if OPENTHREAD_FTD
ProcessTimeSync(void)138 void TimeSync::ProcessTimeSync(void)
139 {
140 if (Get<Mle::MleRouter>().IsLeader() &&
141 (TimerMilli::GetNow() - mLastTimeSyncSent > Time::SecToMsec(mTimeSyncPeriod)))
142 {
143 IncrementTimeSyncSeq();
144 mTimeSyncRequired = true;
145
146 LogInfo("Leader seeding new time sync seq:%u", mTimeSyncSeq);
147 }
148
149 if (mTimeSyncRequired)
150 {
151 VerifyOrExit(Get<Mle::MleRouter>().SendTimeSync() == kErrorNone);
152
153 mLastTimeSyncSent = TimerMilli::GetNow();
154 mTimeSyncRequired = false;
155 }
156
157 exit:
158 return;
159 }
160 #endif // OPENTHREAD_FTD
161
HandleNotifierEvents(Events aEvents)162 void TimeSync::HandleNotifierEvents(Events aEvents)
163 {
164 bool stateChanged = false;
165
166 if (aEvents.Contains(kEventThreadRoleChanged))
167 {
168 stateChanged = true;
169 }
170
171 if (aEvents.Contains(kEventThreadPartitionIdChanged) && !Get<Mle::MleRouter>().IsLeader())
172 {
173 // Partition has changed. Accept any network time currently being seeded on the new partition
174 // and don't attempt to forward the currently held network time from the previous partition.
175 mTimeSyncSeq = OT_TIME_SYNC_INVALID_SEQ;
176 mTimeSyncRequired = false;
177
178 // Network time status will become kUnsychronized because no network time has yet been received
179 // on the new partition.
180 mLastTimeSyncReceived.SetValue(0);
181
182 stateChanged = true;
183
184 LogInfo("Resetting time sync seq, partition changed");
185 }
186
187 if (stateChanged)
188 {
189 CheckAndHandleChanges(false);
190 }
191 }
192
HandleTimeout(void)193 void TimeSync::HandleTimeout(void) { CheckAndHandleChanges(false); }
194
CheckAndHandleChanges(bool aTimeUpdated)195 void TimeSync::CheckAndHandleChanges(bool aTimeUpdated)
196 {
197 Status networkTimeStatus = kSynchronized;
198 const uint32_t resyncNeededThresholdMs = 2 * Time::SecToMsec(mTimeSyncPeriod);
199 const uint32_t timeSyncLastSyncMs = TimerMilli::GetNow() - mLastTimeSyncReceived;
200
201 mTimer.Stop();
202
203 switch (Get<Mle::MleRouter>().GetRole())
204 {
205 case Mle::kRoleDisabled:
206 case Mle::kRoleDetached:
207 networkTimeStatus = kUnsynchronized;
208 LogInfo("Time sync status UNSYNCHRONIZED as role:DISABLED/DETACHED");
209 break;
210
211 case Mle::kRoleChild:
212 case Mle::kRoleRouter:
213 if (mLastTimeSyncReceived.GetValue() == 0)
214 {
215 // Haven't yet received any time sync
216 networkTimeStatus = kUnsynchronized;
217 LogInfo("Time sync status UNSYNCHRONIZED as mLastTimeSyncReceived:0");
218 }
219 else if (timeSyncLastSyncMs > resyncNeededThresholdMs)
220 {
221 // The device hasn’t received time sync for more than two periods time.
222 networkTimeStatus = kResyncNeeded;
223 LogInfo("Time sync status RESYNC_NEEDED as timeSyncLastSyncMs:%lu > resyncNeededThresholdMs:%lu",
224 ToUlong(timeSyncLastSyncMs), ToUlong(resyncNeededThresholdMs));
225 }
226 else
227 {
228 // Schedule a check 1 millisecond after two periods of time
229 OT_ASSERT(resyncNeededThresholdMs >= timeSyncLastSyncMs);
230 mTimer.Start(resyncNeededThresholdMs - timeSyncLastSyncMs + 1);
231 LogInfo("Time sync status SYNCHRONIZED");
232 }
233 break;
234
235 case Mle::kRoleLeader:
236 LogInfo("Time sync status SYNCHRONIZED as role:LEADER");
237 break;
238 }
239
240 if (networkTimeStatus != mCurrentStatus || aTimeUpdated)
241 {
242 mCurrentStatus = networkTimeStatus;
243
244 NotifyTimeSyncCallback();
245 }
246 }
247
248 } // namespace ot
249
250 #endif // OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
251