103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
// Copyright (c) Mainflux
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// SPDX-License-Identifier: Apache-2.0
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package coap
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import (
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"bytes"
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"context"
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"fmt"
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"sync/atomic"
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"github.com/mainflux/mainflux/logger"
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"github.com/mainflux/mainflux/pkg/errors"
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"github.com/mainflux/mainflux/pkg/messaging"
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"github.com/plgd-dev/go-coap/v2/message"
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"github.com/plgd-dev/go-coap/v2/message/codes"
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mux "github.com/plgd-dev/go-coap/v2/mux"
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)
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// Client wraps CoAP client.
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type Client interface {
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// In CoAP terminology, Token similar to the Session ID.
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Token() string
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Handle(m messaging.Message) error
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Cancel() error
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Done() <-chan struct{}
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}
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// ErrOption indicates an error when adding an option.
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var ErrOption = errors.New("unable to set option")
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type client struct {
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client mux.Client
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token message.Token
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observe uint32
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logger logger.Logger
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}
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// NewClient instantiates a new Observer.
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func NewClient(c mux.Client, tkn message.Token, l logger.Logger) Client {
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return &client{
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client: c,
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token: tkn,
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logger: l,
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observe: 0,
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}
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}
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func (c *client) Done() <-chan struct{} {
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return c.client.Done()
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}
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func (c *client) Cancel() error {
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m := message.Message{
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Code: codes.Content,
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Token: c.token,
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Context: context.Background(),
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Options: make(message.Options, 0, 16),
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}
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if err := c.client.WriteMessage(&m); err != nil {
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c.logger.Error(fmt.Sprintf("Error sending message: %s.", err))
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}
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return c.client.Close()
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}
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func (c *client) Token() string {
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return c.token.String()
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}
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func (c *client) Handle(msg messaging.Message) error {
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m := message.Message{
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Code: codes.Content,
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Token: c.token,
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Context: c.client.Context(),
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Body: bytes.NewReader(msg.Payload),
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}
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atomic.AddUint32(&c.observe, 1)
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var opts message.Options
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var buff []byte
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opts, n, err := opts.SetContentFormat(buff, message.TextPlain)
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if err == message.ErrTooSmall {
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buff = append(buff, make([]byte, n)...)
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_, _, err = opts.SetContentFormat(buff, message.TextPlain)
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}
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if err != nil {
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c.logger.Error(fmt.Sprintf("Can't set content format: %s.", err))
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return errors.Wrap(ErrOption, err)
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}
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opts = append(opts, message.Option{ID: message.Observe, Value: []byte{byte(c.observe)}})
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opts, n, err = opts.SetObserve(buff, uint32(c.observe))
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if err == message.ErrTooSmall {
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buff = append(buff, make([]byte, n)...)
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opts, _, err = opts.SetObserve(buff, uint32(c.observe))
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}
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if err != nil {
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return fmt.Errorf("cannot set options to response: %w", err)
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}
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m.Options = opts
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return c.client.WriteMessage(&m)
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}
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