initial commit

Signed-off-by: Rastislav Szabo <raszabo@cisco.com>

1 files changed, 280 insertions, 0 deletions

diff --git a/api/api.go b/api/api.go
new file mode 100644
index 0000000..783f97a
--- /dev/null
+++ b/api/api.go
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+// Copyright (c) 2017 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 api
+
+import (
+	"errors"
+	"fmt"
+	"time"
+)
+
+// MessageType represents the type of a VPP message.
+type MessageType int
+
+const (
+	// RequestMessage represents a VPP request message
+	RequestMessage MessageType = iota
+	// ReplyMessage represents a VPP reply message
+	ReplyMessage
+	// OtherMessage represents other VPP message (e.g. counters)
+	OtherMessage
+)
+
+// Message is an interface that is implemented by all VPP Binary API messages generated by the binapi_generator.
+type Message interface {
+	// GetMessageName returns the original VPP name of the message, as defined in the VPP API.
+	GetMessageName() string
+
+	// GetMessageType returns the type of the VPP message.
+	GetMessageType() MessageType
+
+	// GetCrcString returns the string with CRC checksum of the message definition (the string represents a hexadecimal number).
+	GetCrcString() string
+}
+
+// DataType is an interface that is implemented by all VPP Binary API data types by the binapi_generator.
+type DataType interface {
+	// GetTypeName returns the original VPP name of the data type, as defined in the VPP API.
+	GetTypeName() string
+
+	// GetCrcString returns the string with CRC checksum of the data type definition (the string represents a hexadecimal number).
+	GetCrcString() string
+}
+
+// ChannelProvider provides the communication channel with govpp core.
+type ChannelProvider interface {
+	// NewAPIChannel returns a new channel for communication with VPP via govpp core.
+	// It uses default buffer sizes for the request and reply Go channels.
+	NewAPIChannel() (*Channel, error)
+
+	// NewAPIChannel returns a new channel for communication with VPP via govpp core.
+	// It allows to specify custom buffer sizes for the request and reply Go channels.
+	NewAPIChannelBuffered() (*Channel, error)
+}
+
+// MessageDecoder provides functionality for decoding binary data to generated API messages.
+type MessageDecoder interface {
+	// DecodeMsg decodes binary-encoded data of a message into provided Message structure.
+	DecodeMsg(data []byte, msg Message) error
+}
+
+// MessageIdentifier provides identification of generated API messages.
+type MessageIdentifier interface {
+	// GetMessageID returns message identifier of given API message.
+	GetMessageID(msg Message) (uint16, error)
+}
+
+// Channel is the main communication interface with govpp core. It contains two Go channels, one for sending the requests
+// to VPP and one for receiving the replies from it. The user can access the Go channels directly, or use the helper
+// methods  provided inside of this package.
+type Channel struct {
+	ReqChan   chan *VppRequest // channel for sending the requests to VPP, closing this channel releases all resources in the ChannelProvider
+	ReplyChan chan *VppReply   // channel where VPP replies are delivered to
+
+	NotifSubsChan      chan *NotifSubscribeRequest // channel for sending notification subscribe requests
+	NotifSubsReplyChan chan error                  // channel where replies to notification subscribe requests are delivered to
+
+	MsgDecoder    MessageDecoder    // used to decode binary data to generated API messages
+	MsgIdentifier MessageIdentifier // used to retrieve message ID of a message
+
+	replyTimeout time.Duration // maximum time that the API waits for a reply from VPP before returning an error, can be set with SetReplyTimeout
+	metadata     interface{}   // opaque metadata of the API channel
+}
+
+// VppRequest is a request that will be sent to VPP.
+type VppRequest struct {
+	Message   Message // binary API message to be send to VPP
+	Multipart bool    // true if multipart response is expected, false otherwise
+}
+
+// VppReply is a reply received from VPP.
+type VppReply struct {
+	MessageID         uint16 // ID of the message
+	Data              []byte // encoded data with the message - MessageDecoder can be used for decoding
+	LastReplyReceived bool   // in case of multipart replies, true if the last reply has been already received and this one should be ignored
+	Error             error  // in case of error, data is nil and this member contains error description
+}
+
+// NotifSubscribeRequest is a request to subscribe for delivery of specific notification messages.
+type NotifSubscribeRequest struct {
+	Subscription *NotifSubscription // subscription details
+	Subscribe    bool               // true if this is a request to subscribe, false if unsubscribe
+}
+
+// NotifSubscription represents a subscription for delivery of specific notification messages.
+type NotifSubscription struct {
+	NotifChan  chan Message   // channel where notification messages will be delivered to
+	MsgFactory func() Message // function that returns a new instance of the specific message that is expected as a notification
+}
+
+// RequestCtx is a context of a ongoing request (simple one - only one response is expected).
+type RequestCtx struct {
+	ch *Channel
+}
+
+// MultiRequestCtx is a context of a ongoing multipart request (multiple responses are expected).
+type MultiRequestCtx struct {
+	ch *Channel
+}
+
+const defaultReplyTimeout = time.Second * 1 // default timeout for replies from VPP, can be changed with SetReplyTimeout
+
+// NewChannelInternal returns a new channel structure with metadata field filled in with the provided argument.
+// Note that this is just a raw channel not yet connected to VPP, it is not intended to be used directly.
+// Use ChannelProvider to get an API channel ready for communication with VPP.
+func NewChannelInternal(metadata interface{}) *Channel {
+	return &Channel{
+		replyTimeout: defaultReplyTimeout,
+		metadata:     metadata,
+	}
+}
+
+// Metadata returns the metadata stored within the channel structure by the NewChannelInternal call.
+func (ch *Channel) Metadata() interface{} {
+	return ch.metadata
+}
+
+// SetReplyTimeout sets the timeout for replies from VPP. It represents the maximum time the API waits for a reply
+// from VPP before returning an error.
+func (ch *Channel) SetReplyTimeout(timeout time.Duration) {
+	ch.replyTimeout = timeout
+}
+
+// Close closes the API channel and releases all API channel-related resources in the ChannelProvider.
+func (ch *Channel) Close() {
+	if ch.ReqChan != nil {
+		close(ch.ReqChan)
+	}
+}
+
+// SendRequest asynchronously sends a request to VPP. Returns a request context, that can be used to call ReceiveReply.
+// In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
+func (ch *Channel) SendRequest(msg Message) *RequestCtx {
+	ch.ReqChan <- &VppRequest{
+		Message: msg,
+	}
+	return &RequestCtx{ch: ch}
+}
+
+// ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
+// The reply will be decoded into the msg argument. Error will be returned if the response cannot be received or decoded.
+func (req *RequestCtx) ReceiveReply(msg Message) error {
+	if req == nil || req.ch == nil {
+		return errors.New("invalid request context")
+	}
+
+	lastReplyReceived, err := req.ch.receiveReplyInternal(msg)
+
+	if lastReplyReceived {
+		err = errors.New("multipart reply recieved while a simple reply expected")
+	}
+	return err
+}
+
+// SendMultiRequest asynchronously sends a multipart request (request to which multiple responses are expected) to VPP.
+// Returns a multipart request context, that can be used to call ReceiveReply.
+// In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
+func (ch *Channel) SendMultiRequest(msg Message) *MultiRequestCtx {
+	ch.ReqChan <- &VppRequest{
+		Message:   msg,
+		Multipart: true,
+	}
+	return &MultiRequestCtx{ch: ch}
+}
+
+// ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
+// The reply will be decoded into the msg argument. If the last reply has been already consumed, LastReplyReceived is
+// set to true. Do not use the message itself if LastReplyReceived is true - it won't be filled with actual data.
+// Error will be returned if the response cannot be received or decoded.
+func (req *MultiRequestCtx) ReceiveReply(msg Message) (LastReplyReceived bool, err error) {
+	if req == nil || req.ch == nil {
+		return false, errors.New("invalid request context")
+	}
+
+	return req.ch.receiveReplyInternal(msg)
+}
+
+// receiveReplyInternal receives a reply from the reply channel into the provided msg structure.
+func (ch *Channel) receiveReplyInternal(msg Message) (LastReplyReceived bool, err error) {
+	if msg == nil {
+		return false, errors.New("nil message passed in")
+	}
+	select {
+	// blocks until a reply comes to ReplyChan or until timeout expires
+	case vppReply := <-ch.ReplyChan:
+		if vppReply.Error != nil {
+			err = vppReply.Error
+			return
+		}
+		if vppReply.LastReplyReceived {
+			LastReplyReceived = true
+			return
+		}
+		// message checks
+		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 false, err
+		}
+		if vppReply.MessageID != expMsgID {
+			err = fmt.Errorf("invalid message ID %d, expected %d", vppReply.MessageID, expMsgID)
+			return false, err
+		}
+		// decode the message
+		err = ch.MsgDecoder.DecodeMsg(vppReply.Data, msg)
+
+	case <-time.After(ch.replyTimeout):
+		err = fmt.Errorf("no reply received within the timeout period %ds", ch.replyTimeout/time.Second)
+	}
+	return
+}
+
+// SubscribeNotification subscribes for receiving of the specified notification messages via provided Go channel.
+// Note that the caller is responsible for creating the Go channel with preferred buffer size. If the channel's
+// buffer is full, the notifications will not be delivered into it.
+func (ch *Channel) SubscribeNotification(notifChan chan Message, msgFactory func() Message) (*NotifSubscription, error) {
+	subscription := &NotifSubscription{
+		NotifChan:  notifChan,
+		MsgFactory: msgFactory,
+	}
+	ch.NotifSubsChan <- &NotifSubscribeRequest{
+		Subscription: subscription,
+		Subscribe:    true,
+	}
+	return subscription, <-ch.NotifSubsReplyChan
+}
+
+// UnsubscribeNotification unsubscribes from receiving the notifications tied to the provided notification subscription.
+func (ch *Channel) UnsubscribeNotification(subscription *NotifSubscription) error {
+	ch.NotifSubsChan <- &NotifSubscribeRequest{
+		Subscription: subscription,
+		Subscribe:    false,
+	}
+	return <-ch.NotifSubsReplyChan
+}
+
+// CheckMessageCompatibility checks whether provided messages are compatible with the version of VPP
+// which the library is connected to.
+func (ch *Channel) CheckMessageCompatibility(messages ...Message) error {
+	for _, msg := range messages {
+		_, err := ch.MsgIdentifier.GetMessageID(msg)
+		if err != nil {
+			return fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
+				msg.GetMessageName(), msg.GetCrcString())
+		}
+	}
+	return nil
+}