install go2rtc on bob

installs_on_host/go2rtc/pkg/webtorrent/client.go

@@ -0,0 +1,94 @@
+package webtorrent
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/webrtc"
+	"github.com/gorilla/websocket"
+	pion "github.com/pion/webrtc/v4"
+)
+
+func NewClient(tracker, share, pwd string, pc *pion.PeerConnection) (*webrtc.Conn, error) {
+	// 1. Create WebRTC producer
+	prod := webrtc.NewConn(pc)
+	prod.FormatName = "webtorrent"
+	prod.Mode = core.ModeActiveProducer
+	prod.Protocol = "ws"
+
+	medias := []*core.Media{
+		{Kind: core.KindVideo, Direction: core.DirectionRecvonly},
+		{Kind: core.KindAudio, Direction: core.DirectionRecvonly},
+	}
+
+	// 2. Create offer
+	offer, err := prod.CreateCompleteOffer(medias)
+	if err != nil {
+		return nil, err
+	}
+
+	// 3. Encrypt offer
+	nonce := strconv.FormatInt(time.Now().UnixNano(), 36)
+
+	cipher, err := NewCipher(share, pwd, nonce)
+	if err != nil {
+		return nil, err
+	}
+
+	enc := cipher.Encrypt([]byte(offer))
+
+	// 4. Connect to Tracker
+	ws, _, err := websocket.DefaultDialer.Dial(tracker, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	defer ws.Close()
+
+	// 5. Send offer
+	msg := fmt.Sprintf(
+		`{"action":"announce","info_hash":"%s","peer_id":"%s","offers":[{"offer_id":"%s","offer":{"type":"offer","sdp":"%s"}}],"numwant":1}`,
+		InfoHash(share), core.RandString(16, 36), nonce, base64.StdEncoding.EncodeToString(enc),
+	)
+	if err = ws.WriteMessage(websocket.TextMessage, []byte(msg)); err != nil {
+		return nil, err
+	}
+
+	// wait 30 seconds until full answer
+	if err = ws.SetReadDeadline(time.Now().Add(time.Second * 30)); err != nil {
+		return nil, err
+	}
+
+	for {
+		// 6. Read answer
+		var v Message
+		if err = ws.ReadJSON(&v); err != nil {
+			return nil, err
+		}
+
+		if v.Answer == nil {
+			continue
+		}
+
+		// 7. Decrypt answer
+		enc, err = base64.StdEncoding.DecodeString(v.Answer.SDP)
+		if err != nil {
+			return nil, err
+		}
+
+		answer, err := cipher.Decrypt(enc)
+		if err != nil {
+			return nil, err
+		}
+
+		// 8. Set answer
+		if err = prod.SetAnswer(string(answer)); err != nil {
+			return nil, err
+		}
+
+		return prod, nil
+	}
+}