common_time_server_packets.h revision 9158825f9c41869689d6b1786d7c7aa8bdd524ce 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_COMMON_TIME_SERVER_PACKETS_H
18#define ANDROID_COMMON_TIME_SERVER_PACKETS_H
19
20#include <stdint.h>
21#include <common_time/ICommonClock.h>
22
23namespace android {
24
25/***** time sync protocol packets *****/
26
27enum TimeServicePacketType {
28    TIME_PACKET_WHO_IS_MASTER_REQUEST = 1,
29    TIME_PACKET_WHO_IS_MASTER_RESPONSE,
30    TIME_PACKET_SYNC_REQUEST,
31    TIME_PACKET_SYNC_RESPONSE,
32    TIME_PACKET_MASTER_ANNOUNCEMENT,
33};
34
35class TimeServicePacketHeader {
36  public:
37    friend class UniversalTimeServicePacket;
38    // magic number identifying the protocol
39    uint32_t magic;
40
41    // protocol version of the packet
42    uint16_t version;
43
44    // type of the packet
45    TimeServicePacketType packetType;
46
47    // the timeline ID
48    uint64_t timelineID;
49
50    // synchronization group this packet belongs to (used to operate multiple
51    // synchronization domains which all use the same master election endpoint)
52    uint64_t syncGroupID;
53
54    ssize_t serializePacket(uint8_t* data, uint32_t length);
55
56  protected:
57    void initHeader(TimeServicePacketType type,
58                    const uint64_t tlID,
59                    const uint64_t groupID) {
60        magic              = kMagic;
61        version            = kCurVersion;
62        packetType         = type;
63        timelineID         = tlID;
64        syncGroupID        = groupID;
65    }
66
67    bool checkPacket(uint64_t expectedSyncGroupID) const {
68        return ((magic       == kMagic) &&
69                (version     == kCurVersion) &&
70                (!expectedSyncGroupID || (syncGroupID == expectedSyncGroupID)));
71    }
72
73    ssize_t serializeHeader(uint8_t* data, uint32_t length);
74    ssize_t deserializeHeader(const uint8_t* data, uint32_t length);
75
76  private:
77    static const uint32_t kMagic;
78    static const uint16_t kCurVersion;
79};
80
81// packet querying for a suitable master
82class WhoIsMasterRequestPacket : public TimeServicePacketHeader {
83  public:
84    uint64_t senderDeviceID;
85    uint8_t senderDevicePriority;
86
87    void initHeader(const uint64_t groupID) {
88        TimeServicePacketHeader::initHeader(TIME_PACKET_WHO_IS_MASTER_REQUEST,
89                                            ICommonClock::kInvalidTimelineID,
90                                            groupID);
91    }
92
93    ssize_t serializePacket(uint8_t* data, uint32_t length);
94    ssize_t deserializePacket(const uint8_t* data, uint32_t length);
95};
96
97// response to a WhoIsMaster request
98class WhoIsMasterResponsePacket : public TimeServicePacketHeader {
99  public:
100    uint64_t deviceID;
101    uint8_t devicePriority;
102
103    void initHeader(const uint64_t tlID, const uint64_t groupID) {
104        TimeServicePacketHeader::initHeader(TIME_PACKET_WHO_IS_MASTER_RESPONSE,
105                                            tlID, groupID);
106    }
107
108    ssize_t serializePacket(uint8_t* data, uint32_t length);
109    ssize_t deserializePacket(const uint8_t* data, uint32_t length);
110};
111
112// packet sent by a client requesting correspondence between local
113// and common time
114class SyncRequestPacket : public TimeServicePacketHeader {
115  public:
116    // local time when this request was transmitted
117    int64_t clientTxLocalTime;
118
119    void initHeader(const uint64_t tlID, const uint64_t groupID) {
120        TimeServicePacketHeader::initHeader(TIME_PACKET_SYNC_REQUEST,
121                                            tlID, groupID);
122    }
123
124    ssize_t serializePacket(uint8_t* data, uint32_t length);
125    ssize_t deserializePacket(const uint8_t* data, uint32_t length);
126};
127
128// response to a sync request sent by the master
129class SyncResponsePacket : public TimeServicePacketHeader {
130  public:
131    // local time when this request was transmitted by the client
132    int64_t clientTxLocalTime;
133
134    // common time when the master received the request
135    int64_t masterRxCommonTime;
136
137    // common time when the master transmitted the response
138    int64_t masterTxCommonTime;
139
140    // flag that is set if the recipient of the sync request is not acting
141    // as a master for the requested timeline
142    uint32_t nak;
143
144    void initHeader(const uint64_t tlID, const uint64_t groupID) {
145        TimeServicePacketHeader::initHeader(TIME_PACKET_SYNC_RESPONSE,
146                                            tlID, groupID);
147    }
148
149    ssize_t serializePacket(uint8_t* data, uint32_t length);
150    ssize_t deserializePacket(const uint8_t* data, uint32_t length);
151};
152
153// announcement of the master's presence
154class MasterAnnouncementPacket : public TimeServicePacketHeader {
155  public:
156    // the master's device ID
157    uint64_t deviceID;
158    uint8_t devicePriority;
159
160    void initHeader(const uint64_t tlID, const uint64_t groupID) {
161        TimeServicePacketHeader::initHeader(TIME_PACKET_MASTER_ANNOUNCEMENT,
162                                            tlID, groupID);
163    }
164
165    ssize_t serializePacket(uint8_t* data, uint32_t length);
166    ssize_t deserializePacket(const uint8_t* data, uint32_t length);
167};
168
169class UniversalTimeServicePacket {
170  public:
171    uint16_t packetType;
172    union {
173        WhoIsMasterRequestPacket  who_is_master_request;
174        WhoIsMasterResponsePacket who_is_master_response;
175        SyncRequestPacket         sync_request;
176        SyncResponsePacket        sync_response;
177        MasterAnnouncementPacket  master_announcement;
178    } p;
179
180    ssize_t deserializePacket(const uint8_t* data,
181                              uint32_t       length,
182                              uint64_t       expectedSyncGroupID);
183};
184
185};  // namespace android
186
187#endif  // ANDROID_COMMON_TIME_SERVER_PACKETS_H
188
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190