1 // Copyright (c) 2017 Cisco and/or its affiliates.
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at:
7 // http://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
22 "github.com/sirupsen/logrus"
25 // MessageType represents the type of a VPP message.
29 // RequestMessage represents a VPP request message
30 RequestMessage MessageType = iota
31 // ReplyMessage represents a VPP reply message
33 // EventMessage represents a VPP notification event message
35 // OtherMessage represents other VPP message (e.g. counters)
39 // Message is an interface that is implemented by all VPP Binary API messages generated by the binapigenerator.
40 type Message interface {
41 // GetMessageName returns the original VPP name of the message, as defined in the VPP API.
42 GetMessageName() string
44 // GetMessageType returns the type of the VPP message.
45 GetMessageType() MessageType
47 // GetCrcString returns the string with CRC checksum of the message definition (the string represents a hexadecimal number).
51 // DataType is an interface that is implemented by all VPP Binary API data types by the binapi_generator.
52 type DataType interface {
53 // GetTypeName returns the original VPP name of the data type, as defined in the VPP API.
56 // GetCrcString returns the string with CRC checksum of the data type definition (the string represents a hexadecimal number).
60 // ChannelProvider provides the communication channel with govpp core.
61 type ChannelProvider interface {
62 // NewAPIChannel returns a new channel for communication with VPP via govpp core.
63 // It uses default buffer sizes for the request and reply Go channels.
64 NewAPIChannel() (*Channel, error)
66 // NewAPIChannelBuffered returns a new channel for communication with VPP via govpp core.
67 // It allows to specify custom buffer sizes for the request and reply Go channels.
68 NewAPIChannelBuffered() (*Channel, error)
71 // MessageDecoder provides functionality for decoding binary data to generated API messages.
72 type MessageDecoder interface {
73 // DecodeMsg decodes binary-encoded data of a message into provided Message structure.
74 DecodeMsg(data []byte, msg Message) error
77 // MessageIdentifier provides identification of generated API messages.
78 type MessageIdentifier interface {
79 // GetMessageID returns message identifier of given API message.
80 GetMessageID(msg Message) (uint16, error)
81 // LookupByID looks up message name and crc by ID
82 LookupByID(ID uint16) (string, error)
85 // Channel is the main communication interface with govpp core. It contains two Go channels, one for sending the requests
86 // to VPP and one for receiving the replies from it. The user can access the Go channels directly, or use the helper
87 // methods provided inside of this package. Do not use the same channel from multiple goroutines concurrently,
88 // otherwise the responses could mix! Use multiple channels instead.
90 ID uint16 // channel ID
92 ReqChan chan *VppRequest // channel for sending the requests to VPP, closing this channel releases all resources in the ChannelProvider
93 ReplyChan chan *VppReply // channel where VPP replies are delivered to
95 NotifSubsChan chan *NotifSubscribeRequest // channel for sending notification subscribe requests
96 NotifSubsReplyChan chan error // channel where replies to notification subscribe requests are delivered to
98 MsgDecoder MessageDecoder // used to decode binary data to generated API messages
99 MsgIdentifier MessageIdentifier // used to retrieve message ID of a message
101 lastSeqNum uint16 // sequence number of the last sent request
103 delayedReply *VppReply // reply already taken from ReplyChan, buffered for later delivery
104 replyTimeout time.Duration // maximum time that the API waits for a reply from VPP before returning an error, can be set with SetReplyTimeout
107 // VppRequest is a request that will be sent to VPP.
108 type VppRequest struct {
109 SeqNum uint16 // sequence number
110 Message Message // binary API message to be send to VPP
111 Multipart bool // true if multipart response is expected, false otherwise
114 // VppReply is a reply received from VPP.
115 type VppReply struct {
116 MessageID uint16 // ID of the message
117 SeqNum uint16 // sequence number
118 Data []byte // encoded data with the message - MessageDecoder can be used for decoding
119 LastReplyReceived bool // in case of multipart replies, true if the last reply has been already received and this one should be ignored
120 Error error // in case of error, data is nil and this member contains error description
123 // NotifSubscribeRequest is a request to subscribe for delivery of specific notification messages.
124 type NotifSubscribeRequest struct {
125 Subscription *NotifSubscription // subscription details
126 Subscribe bool // true if this is a request to subscribe, false if unsubscribe
129 // NotifSubscription represents a subscription for delivery of specific notification messages.
130 type NotifSubscription struct {
131 NotifChan chan Message // channel where notification messages will be delivered to
132 MsgFactory func() Message // function that returns a new instance of the specific message that is expected as a notification
135 // RequestCtx is a context of a ongoing request (simple one - only one response is expected).
136 type RequestCtx struct {
141 // MultiRequestCtx is a context of a ongoing multipart request (multiple responses are expected).
142 type MultiRequestCtx struct {
147 const defaultReplyTimeout = time.Second * 1 // default timeout for replies from VPP, can be changed with SetReplyTimeout
149 // NewChannelInternal returns a new channel structure.
150 // Note that this is just a raw channel not yet connected to VPP, it is not intended to be used directly.
151 // Use ChannelProvider to get an API channel ready for communication with VPP.
152 func NewChannelInternal(id uint16) *Channel {
155 replyTimeout: defaultReplyTimeout,
159 // SetReplyTimeout sets the timeout for replies from VPP. It represents the maximum time the API waits for a reply
160 // from VPP before returning an error.
161 func (ch *Channel) SetReplyTimeout(timeout time.Duration) {
162 ch.replyTimeout = timeout
165 // Close closes the API channel and releases all API channel-related resources in the ChannelProvider.
166 func (ch *Channel) Close() {
167 if ch.ReqChan != nil {
172 // SendRequest asynchronously sends a request to VPP. Returns a request context, that can be used to call ReceiveReply.
173 // In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
174 func (ch *Channel) SendRequest(msg Message) *RequestCtx {
176 ch.ReqChan <- &VppRequest{
178 SeqNum: ch.lastSeqNum,
180 return &RequestCtx{ch: ch, seqNum: ch.lastSeqNum}
183 // ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
184 // The reply will be decoded into the msg argument. Error will be returned if the response cannot be received or decoded.
185 func (req *RequestCtx) ReceiveReply(msg Message) error {
186 if req == nil || req.ch == nil {
187 return errors.New("invalid request context")
190 lastReplyReceived, err := req.ch.receiveReplyInternal(msg, req.seqNum)
192 if lastReplyReceived {
193 err = errors.New("multipart reply recieved while a simple reply expected")
198 // SendMultiRequest asynchronously sends a multipart request (request to which multiple responses are expected) to VPP.
199 // Returns a multipart request context, that can be used to call ReceiveReply.
200 // In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
201 func (ch *Channel) SendMultiRequest(msg Message) *MultiRequestCtx {
203 ch.ReqChan <- &VppRequest{
206 SeqNum: ch.lastSeqNum,
208 return &MultiRequestCtx{ch: ch, seqNum: ch.lastSeqNum}
211 // ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
212 // The reply will be decoded into the msg argument. If the last reply has been already consumed, lastReplyReceived is
213 // set to true. Do not use the message itself if lastReplyReceived is true - it won't be filled with actual data.
214 // Error will be returned if the response cannot be received or decoded.
215 func (req *MultiRequestCtx) ReceiveReply(msg Message) (lastReplyReceived bool, err error) {
216 if req == nil || req.ch == nil {
217 return false, errors.New("invalid request context")
220 return req.ch.receiveReplyInternal(msg, req.seqNum)
223 // receiveReplyInternal receives a reply from the reply channel into the provided msg structure.
224 func (ch *Channel) receiveReplyInternal(msg Message, expSeqNum uint16) (lastReplyReceived bool, err error) {
227 return false, errors.New("nil message passed in")
230 if ch.delayedReply != nil {
231 // try the delayed reply
232 vppReply := ch.delayedReply
233 ch.delayedReply = nil
234 ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
236 return lastReplyReceived, err
240 timer := time.NewTimer(ch.replyTimeout)
243 // blocks until a reply comes to ReplyChan or until timeout expires
244 case vppReply := <-ch.ReplyChan:
245 ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
249 return lastReplyReceived, err
252 err = fmt.Errorf("no reply received within the timeout period %s", ch.replyTimeout)
259 func (ch *Channel) processReply(reply *VppReply, expSeqNum uint16, msg Message) (ignore bool, lastReplyReceived bool, err error) {
260 // check the sequence number
261 cmpSeqNums := compareSeqNumbers(reply.SeqNum, expSeqNum)
262 if cmpSeqNums == -1 {
263 // reply received too late, ignore the message
264 logrus.WithField("sequence-number", reply.SeqNum).Warn(
265 "Received reply to an already closed binary API request")
270 ch.delayedReply = reply
271 err = fmt.Errorf("missing binary API reply with sequence number: %d", expSeqNum)
275 if reply.Error != nil {
279 if reply.LastReplyReceived {
280 lastReplyReceived = true
286 expMsgID, err = ch.MsgIdentifier.GetMessageID(msg)
288 err = fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
289 msg.GetMessageName(), msg.GetCrcString())
293 if reply.MessageID != expMsgID {
294 var msgNameCrc string
295 if nameCrc, err := ch.MsgIdentifier.LookupByID(reply.MessageID); err != nil {
296 msgNameCrc = err.Error()
301 err = fmt.Errorf("received invalid message ID (seq-num=%d), expected %d (%s), but got %d (%s) "+
302 "(check if multiple goroutines are not sharing single GoVPP channel)",
303 reply.SeqNum, expMsgID, msg.GetMessageName(), reply.MessageID, msgNameCrc)
307 // decode the message
308 err = ch.MsgDecoder.DecodeMsg(reply.Data, msg)
312 // compareSeqNumbers returns -1, 0, 1 if sequence number <seqNum1> precedes, equals to,
313 // or succeeds seq. number <seqNum2>.
314 // Since sequence numbers cycle in the finite set of size 2^16, the function
315 // must assume that the distance between compared sequence numbers is less than
316 // (2^16)/2 to determine the order.
317 func compareSeqNumbers(seqNum1, seqNum2 uint16) int {
318 // calculate distance from seqNum1 to seqNum2
320 if seqNum1 <= seqNum2 {
321 dist = seqNum2 - seqNum1
323 dist = 0xffff - (seqNum1 - seqNum2 - 1)
327 } else if dist <= 0x8000 {
333 // SubscribeNotification subscribes for receiving of the specified notification messages via provided Go channel.
334 // Note that the caller is responsible for creating the Go channel with preferred buffer size. If the channel's
335 // buffer is full, the notifications will not be delivered into it.
336 func (ch *Channel) SubscribeNotification(notifChan chan Message, msgFactory func() Message) (*NotifSubscription, error) {
337 subscription := &NotifSubscription{
338 NotifChan: notifChan,
339 MsgFactory: msgFactory,
341 ch.NotifSubsChan <- &NotifSubscribeRequest{
342 Subscription: subscription,
345 return subscription, <-ch.NotifSubsReplyChan
348 // UnsubscribeNotification unsubscribes from receiving the notifications tied to the provided notification subscription.
349 func (ch *Channel) UnsubscribeNotification(subscription *NotifSubscription) error {
350 ch.NotifSubsChan <- &NotifSubscribeRequest{
351 Subscription: subscription,
354 return <-ch.NotifSubsReplyChan
357 // CheckMessageCompatibility checks whether provided messages are compatible with the version of VPP
358 // which the library is connected to.
359 func (ch *Channel) CheckMessageCompatibility(messages ...Message) error {
360 for _, msg := range messages {
361 _, err := ch.MsgIdentifier.GetMessageID(msg)
363 return fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
364 msg.GetMessageName(), msg.GetCrcString())