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subscription.go
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subscription.go
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package upnpsub
import (
"context"
"errors"
"fmt"
"net/http"
"net/url"
"time"
"github.com/ItsNotGoodName/go-upnpsub/internal/status"
)
type subscription struct {
// Static fields.
callbackHeader string // callbackHeader is part of the UPnP header.
doneC chan struct{} // doneC is closed when the subscription is closed.
eventC chan Event // eventC is the events from UPnP event publisher.
eventURL string // eventURL is the event URL of the UPnP event publisher.
renewC chan struct{} // renewC forces a subscription renewal.
status *status.Status // status is the subscription status.
sid string // sid is the unique id set by the UPnP event publisher.
timeout int // timeout is the timeout in seconds received from UPnP event publisher.
}
func newSubscription(eventURL *url.URL, uri string, port int) (*subscription, error) {
callbackIP, err := findCallbackIP(eventURL)
if err != nil {
return nil, err
}
return &subscription{
callbackHeader: fmt.Sprintf("<http://%s:%d%s>", callbackIP, port, uri),
doneC: make(chan struct{}),
eventC: make(chan Event, 8),
eventURL: eventURL.String(),
renewC: make(chan struct{}),
timeout: minTimeout,
status: status.New(),
}, nil
}
func (sub *subscription) Renew() {
select {
case sub.renewC <- struct{}{}:
default:
}
}
func (sub *subscription) Events() <-chan Event {
return sub.eventC
}
func (sub *subscription) Done() <-chan struct{} {
return sub.doneC
}
func (sub *subscription) IsActive() bool {
select {
case <-sub.doneC:
return false
default:
return sub.status.Active()
}
}
func (sub *subscription) LastActive() time.Time {
return sub.status.LastActive()
}
// subscribe sends SUBSCRIBE request to UPnP event publisher.
func (sub *subscription) subscribe(ctx context.Context, sidHook func(oldSID, newSID string)) error {
success := false
defer func() {
if success {
sub.status.Activate(sub.timeout)
} else {
sub.status.Deactivate()
}
}()
// Create request
req, err := http.NewRequest("SUBSCRIBE", sub.eventURL, nil)
if err != nil {
return fmt.Errorf("subscribe: %w", err)
}
req = req.WithContext(ctx)
// Add headers to request
req.Header.Add("CALLBACK", sub.callbackHeader)
req.Header.Add("NT", headerNT)
req.Header.Add("TIMEOUT", headerTimeout)
// Execute request
res, err := http.DefaultClient.Do(req)
if err != nil {
return fmt.Errorf("subscribe: %w", err)
}
defer res.Body.Close()
// Check if request failed
if res.StatusCode != http.StatusOK {
return fmt.Errorf("subscribe: invalid response status %s", res.Status)
}
// Get sub's timeout
timeout, err := parseTimeout(res.Header.Get("timeout"))
if err != nil {
return fmt.Errorf("subscribe: %w", err)
}
// Get SID
sid := res.Header.Get("sid")
if sid == "" {
return errors.New("subscribe: response did not supply a sid")
}
sub.timeout = timeout
oldSID := sub.sid
sub.sid = sid
sidHook(oldSID, sub.sid)
success = true
return nil
}
// resubscribe sends a SUBSCRIBE request to UPnP event publisher that renews the existing subscription.
func (sub *subscription) resubscribe(ctx context.Context) error {
success := false
defer func() {
if success {
sub.status.Activate(sub.timeout)
} else {
sub.status.Deactivate()
}
}()
// Create request
req, err := http.NewRequest("SUBSCRIBE", sub.eventURL, nil)
if err != nil {
return fmt.Errorf("resubscribe: %w", err)
}
req = req.WithContext(ctx)
// Add headers to request
req.Header.Add("SID", sub.sid)
req.Header.Add("TIMEOUT", headerTimeout)
// Execute request
res, err := http.DefaultClient.Do(req)
if err != nil {
return fmt.Errorf("resubscribe: %w", err)
}
defer res.Body.Close()
// Check if request failed
if res.StatusCode != http.StatusOK {
return fmt.Errorf("resubscribe: invalid response status %s", res.Status)
}
// Check response's SID
sid := res.Header.Get("SID")
if sid == "" {
return errors.New("resubscribe: response did not supply a sid")
}
if sid != sub.sid {
return fmt.Errorf("resubscribe: response's sid does not match subscription's sid, %s != %s", sid, sub.sid)
}
// Get sub's timeout
timeout, err := parseTimeout(res.Header.Get("timeout"))
if err != nil {
return fmt.Errorf("resubscribe: %w", err)
}
sub.timeout = timeout
success = true
return nil
}
// unsubscribe sends an UNSUBSCRIBE request to UPnP event publisher.
func (sub *subscription) unsubscribe(ctx context.Context) error {
// Create request
req, err := http.NewRequest("UNSUBSCRIBE", sub.eventURL, nil)
if err != nil {
return fmt.Errorf("unsubscribe: %w", err)
}
req = req.WithContext(ctx)
// Add headers to request
req.Header.Add("SID", sub.sid)
// Execute request
res, err := http.DefaultClient.Do(req)
if err != nil {
return fmt.Errorf("unsubscribe: %w", err)
}
defer res.Body.Close()
// Check if request failed
if res.StatusCode != http.StatusOK {
return fmt.Errorf("unsubscribe: invalid response status %s", res.Status)
}
sub.status.Deactivate()
return nil
}