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Validate SDP offers and answers

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itchyonion 2023-03-14 12:39:57 -07:00
parent 8e5ea82611
commit 07b5f07452
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GPG key ID: 4B87B720348500EA
3 changed files with 56 additions and 13 deletions
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23
client/lib/webrtc.go
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@ -4,8 +4,10 @@ import (
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"io"
"log"
"strings"
"sync"
"time"
@ -143,10 +145,10 @@ func (c *WebRTCPeer) checkForStaleness(timeout time.Duration) {
}
}
// connect does the bulk of the work: gather ICE candidates, send the SDP offer to broker,
// receive an answer from broker, and wait for data channel to open
func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel) error {
log.Println(c.id, " connecting...")
// TODO: When go-webrtc is more stable, it's possible that a new
// PeerConnection won't need to be re-prepared each time.
err := c.preparePeerConnection(config)
localDescription := c.pc.LocalDescription()
c.eventsLogger.OnNewSnowflakeEvent(event.EventOnOfferCreated{
@ -187,7 +189,7 @@ func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel
}
// preparePeerConnection creates a new WebRTC PeerConnection and returns it
// after ICE candidate gathering is complete..
// after non-trickle ICE candidate gathering is complete.
func (c *WebRTCPeer) preparePeerConnection(config *webrtc.Configuration) error {
var err error
s := webrtc.SettingEngine{}
@ -240,10 +242,8 @@ func (c *WebRTCPeer) preparePeerConnection(config *webrtc.Configuration) error {
})
c.transport = dc
c.open = make(chan struct{})
log.Println("WebRTC: DataChannel created.")
log.Println("WebRTC: DataChannel created")
// Allow candidates to accumulate until ICEGatheringStateComplete.
done := webrtc.GatheringCompletePromise(c.pc)
offer, err := c.pc.CreateOffer(nil)
// TODO: Potentially timeout and retry if ICE isn't working.
if err != nil {
@ -252,16 +252,23 @@ func (c *WebRTCPeer) preparePeerConnection(config *webrtc.Configuration) error {
return err
}
log.Println("WebRTC: Created offer")
// Allow candidates to accumulate until ICEGatheringStateComplete.
done := webrtc.GatheringCompletePromise(c.pc)
// Start gathering candidates
err = c.pc.SetLocalDescription(offer)
if err != nil {
log.Println("Failed to prepare offer", err)
log.Println("Failed to apply offer", err)
c.pc.Close()
return err
}
log.Println("WebRTC: Set local description")
<-done // Wait for ICE candidate gathering to complete.
log.Println("WebRTC: PeerConnection created.")
if !strings.Contains(c.pc.LocalDescription().SDP, "\na=candidate:") {
return fmt.Errorf("SDP offer contains no candidate")
}
return nil
}