summaryrefslogtreecommitdiffstats
path: root/core/channel.go
blob: a7d95fe1ecda271b622e58b2dc699af146224bac (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
// Copyright (c) 2018 Cisco and/or its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package core

import (
	"errors"
	"fmt"
	"reflect"
	"strings"
	"time"

	"git.fd.io/govpp.git/api"
	"github.com/sirupsen/logrus"
)

var (
	ErrInvalidRequestCtx = errors.New("invalid request context")
)

// MessageCodec provides functionality for decoding binary data to generated API messages.
type MessageCodec interface {
	//EncodeMsg encodes message into binary data.
	EncodeMsg(msg api.Message, msgID uint16) ([]byte, error)
	// DecodeMsg decodes binary-encoded data of a message into provided Message structure.
	DecodeMsg(data []byte, msg api.Message) error
}

// MessageIdentifier provides identification of generated API messages.
type MessageIdentifier interface {
	// GetMessageID returns message identifier of given API message.
	GetMessageID(msg api.Message) (uint16, error)
	// LookupByID looks up message name and crc by ID
	LookupByID(msgID uint16) (api.Message, error)
}

// vppRequest is a request that will be sent to VPP.
type vppRequest struct {
	seqNum uint16      // sequence number
	msg    api.Message // binary API message to be send to VPP
	multi  bool        // true if multipart response is expected
}

// vppReply is a reply received from VPP.
type vppReply struct {
	seqNum       uint16 // sequence number
	msgID        uint16 // ID of the message
	data         []byte // encoded data with the message
	lastReceived bool   // for multi request, true if the last reply has been already received
	err          error  // in case of error, data is nil and this member contains error
}

// requestCtx is a context for request with single reply
type requestCtx struct {
	ch     *Channel
	seqNum uint16
}

// multiRequestCtx is a context for request with multiple responses
type multiRequestCtx struct {
	ch     *Channel
	seqNum uint16
}

// subscriptionCtx is a context of subscription for delivery of specific notification messages.
type subscriptionCtx struct {
	ch         *Channel
	notifChan  chan api.Message   // channel where notification messages will be delivered to
	msgID      uint16             // message ID for the subscribed event message
	event      api.Message        // event message that this subscription is for
	msgFactory func() api.Message // function that returns a new instance of the specific message that is expected as a notification
}

// channel is the main communication interface with govpp core. It contains four Go channels, one for sending the requests
// to VPP, one for receiving the replies from it and the same set for notifications. The user can access the Go channels
// via methods provided by Channel interface in this package. Do not use the same channel from multiple goroutines
// concurrently, otherwise the responses could mix! Use multiple channels instead.
type Channel struct {
	id   uint16
	conn *Connection

	reqChan   chan *vppRequest // channel for sending the requests to VPP
	replyChan chan *vppReply   // channel where VPP replies are delivered to

	msgCodec      MessageCodec      // used to decode binary data to generated API messages
	msgIdentifier MessageIdentifier // used to retrieve message ID of a message

	lastSeqNum uint16 // sequence number of the last sent request

	delayedReply *vppReply     // reply already taken from ReplyChan, buffered for later delivery
	replyTimeout time.Duration // maximum time that the API waits for a reply from VPP before returning an error, can be set with SetReplyTimeout
}

func newChannel(id uint16, conn *Connection, codec MessageCodec, identifier MessageIdentifier, reqSize, replySize int) *Channel {
	return &Channel{
		id:            id,
		conn:          conn,
		msgCodec:      codec,
		msgIdentifier: identifier,
		reqChan:       make(chan *vppRequest, reqSize),
		replyChan:     make(chan *vppReply, replySize),
		replyTimeout:  DefaultReplyTimeout,
	}
}

func (ch *Channel) GetID() uint16 {
	return ch.id
}

func (ch *Channel) nextSeqNum() uint16 {
	ch.lastSeqNum++
	return ch.lastSeqNum
}

func (ch *Channel) SendRequest(msg api.Message) api.RequestCtx {
	seqNum := ch.nextSeqNum()
	ch.reqChan <- &vppRequest{
		msg:    msg,
		seqNum: seqNum,
	}
	return &requestCtx{ch: ch, seqNum: seqNum}
}

func (ch *Channel) SendMultiRequest(msg api.Message) api.MultiRequestCtx {
	seqNum := ch.nextSeqNum()
	ch.reqChan <- &vppRequest{
		msg:    msg,
		seqNum: seqNum,
		multi:  true,
	}
	return &multiRequestCtx{ch: ch, seqNum: seqNum}
}

func getMsgFactory(msg api.Message) func() api.Message {
	return func() api.Message {
		return reflect.New(reflect.TypeOf(msg).Elem()).Interface().(api.Message)
	}
}

func (ch *Channel) SubscribeNotification(notifChan chan api.Message, event api.Message) (api.SubscriptionCtx, error) {
	msgID, err := ch.msgIdentifier.GetMessageID(event)
	if err != nil {
		log.WithFields(logrus.Fields{
			"msg_name": event.GetMessageName(),
			"msg_crc":  event.GetCrcString(),
		}).Errorf("unable to retrieve message ID: %v", err)
		return nil, fmt.Errorf("unable to retrieve event message ID: %v", err)
	}

	sub := &subscriptionCtx{
		ch:         ch,
		notifChan:  notifChan,
		msgID:      msgID,
		event:      event,
		msgFactory: getMsgFactory(event),
	}

	// add the subscription into map
	ch.conn.subscriptionsLock.Lock()
	defer ch.conn.subscriptionsLock.Unlock()

	ch.conn.subscriptions[msgID] = append(ch.conn.subscriptions[msgID], sub)

	return sub, nil
}

func (ch *Channel) SetReplyTimeout(timeout time.Duration) {
	ch.replyTimeout = timeout
}

func (ch *Channel) Close() {
	if ch.reqChan != nil {
		close(ch.reqChan)
		ch.reqChan = nil
	}
}

func (req *requestCtx) ReceiveReply(msg api.Message) error {
	if req == nil || req.ch == nil {
		return ErrInvalidRequestCtx
	}

	lastReplyReceived, err := req.ch.receiveReplyInternal(msg, req.seqNum)
	if err != nil {
		return err
	} else if lastReplyReceived {
		return errors.New("multipart reply recieved while a single reply expected")
	}

	return nil
}

func (req *multiRequestCtx) ReceiveReply(msg api.Message) (lastReplyReceived bool, err error) {
	if req == nil || req.ch == nil {
		return false, ErrInvalidRequestCtx
	}

	return req.ch.receiveReplyInternal(msg, req.seqNum)
}

func (sub *subscriptionCtx) Unsubscribe() error {
	log.WithFields(logrus.Fields{
		"msg_name": sub.event.GetMessageName(),
		"msg_id":   sub.msgID,
	}).Debug("Removing notification subscription.")

	// remove the subscription from the map
	sub.ch.conn.subscriptionsLock.Lock()
	defer sub.ch.conn.subscriptionsLock.Unlock()

	for i, item := range sub.ch.conn.subscriptions[sub.msgID] {
		if item == sub {
			// remove i-th item in the slice
			sub.ch.conn.subscriptions[sub.msgID] = append(sub.ch.conn.subscriptions[sub.msgID][:i], sub.ch.conn.subscriptions[sub.msgID][i+1:]...)
			return nil
		}
	}

	return fmt.Errorf("subscription for %q not found", sub.event.GetMessageName())
}

// receiveReplyInternal receives a reply from the reply channel into the provided msg structure.
func (ch *Channel) receiveReplyInternal(msg api.Message, expSeqNum uint16) (lastReplyReceived bool, err error) {
	if msg == nil {
		return false, errors.New("nil message passed in")
	}

	var ignore bool

	if vppReply := ch.delayedReply; vppReply != nil {
		// try the delayed reply
		ch.delayedReply = nil
		ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
		if !ignore {
			return lastReplyReceived, err
		}
	}

	timer := time.NewTimer(ch.replyTimeout)
	for {
		select {
		// blocks until a reply comes to ReplyChan or until timeout expires
		case vppReply := <-ch.replyChan:
			ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
			if ignore {
				continue
			}
			return lastReplyReceived, err

		case <-timer.C:
			err = fmt.Errorf("no reply received within the timeout period %s", ch.replyTimeout)
			return false, err
		}
	}
	return
}

func (ch *Channel) processReply(reply *vppReply, expSeqNum uint16, msg api.Message) (ignore bool, lastReplyReceived bool, err error) {
	// check the sequence number
	cmpSeqNums := compareSeqNumbers(reply.seqNum, expSeqNum)
	if cmpSeqNums == -1 {
		// reply received too late, ignore the message
		logrus.WithField("seqNum", reply.seqNum).Warn(
			"Received reply to an already closed binary API request")
		ignore = true
		return
	}
	if cmpSeqNums == 1 {
		ch.delayedReply = reply
		err = fmt.Errorf("missing binary API reply with sequence number: %d", expSeqNum)
		return
	}

	if reply.err != nil {
		err = reply.err
		return
	}
	if reply.lastReceived {
		lastReplyReceived = true
		return
	}

	// message checks
	var expMsgID uint16
	expMsgID, err = ch.msgIdentifier.GetMessageID(msg)
	if err != nil {
		err = fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
			msg.GetMessageName(), msg.GetCrcString())
		return
	}

	if reply.msgID != expMsgID {
		var msgNameCrc string
		if replyMsg, err := ch.msgIdentifier.LookupByID(reply.msgID); err != nil {
			msgNameCrc = err.Error()
		} else {
			msgNameCrc = getMsgNameWithCrc(replyMsg)
		}

		err = fmt.Errorf("received invalid message ID (seqNum=%d), expected %d (%s), but got %d (%s) "+
			"(check if multiple goroutines are not sharing single GoVPP channel)",
			reply.seqNum, expMsgID, msg.GetMessageName(), reply.msgID, msgNameCrc)
		return
	}

	// decode the message
	if err = ch.msgCodec.DecodeMsg(reply.data, msg); err != nil {
		return
	}

	// check Retval and convert it into VnetAPIError error
	if strings.HasSuffix(msg.GetMessageName(), "_reply") {
		// TODO: use categories for messages to avoid checking message name
		if f := reflect.Indirect(reflect.ValueOf(msg)).FieldByName("Retval"); f.IsValid() {
			retval := int32(f.Int())
			err = api.RetvalToVPPApiError(retval)
		}
	}

	return
}