install go2rtc on bob

installs_on_host/go2rtc/pkg/webtorrent/server.go

@@ -0,0 +1,228 @@
+package webtorrent
+
+import (
+	"encoding/base64"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/gorilla/websocket"
+)
+
+type Server struct {
+	core.Listener
+
+	URL      string
+	Exchange func(src, offer string) (answer string, err error)
+
+	shares   map[string]*Share
+	mu       sync.Mutex
+	announce *core.Worker
+}
+
+type Share struct {
+	name string
+	pwd  string
+	src  string
+}
+
+func (s *Server) AddShare(name, pwd, src string) {
+	s.mu.Lock()
+
+	if s.shares == nil {
+		s.shares = map[string]*Share{}
+	}
+
+	if len(s.shares) == 0 {
+		go s.Serve()
+	}
+
+	hash := InfoHash(name)
+	s.shares[hash] = &Share{
+		name: name,
+		pwd:  pwd,
+		src:  src,
+	}
+
+	s.announce.Do()
+
+	s.mu.Unlock()
+}
+
+func (s *Server) GetSharePwd(name string) (pwd string) {
+	hash := InfoHash(name)
+	s.mu.Lock()
+	if share, ok := s.shares[hash]; ok {
+		pwd = share.pwd
+	}
+	s.mu.Unlock()
+	return
+}
+
+func (s *Server) RemoveShare(name string) {
+	hash := InfoHash(name)
+	s.mu.Lock()
+	if _, ok := s.shares[hash]; ok {
+		delete(s.shares, hash)
+	}
+	s.mu.Unlock()
+}
+
+// Serve - run reconnection loop, will exit on??
+func (s *Server) Serve() error {
+	for s.HasShares() {
+		s.Fire("connect to tracker: " + s.URL)
+
+		ws, _, err := websocket.DefaultDialer.Dial(s.URL, nil)
+		if err != nil {
+			s.Fire(err)
+			time.Sleep(time.Minute)
+			continue
+		}
+
+		peerID := core.RandString(16, 36)
+
+		// instant run announce worker
+		s.announce = core.NewWorker(0, func() time.Duration {
+			if err = s.writer(ws, peerID); err != nil {
+				return 0
+			}
+			return time.Minute
+		})
+
+		// run reader forewer
+		for {
+			if err = s.reader(ws, peerID); err != nil {
+				break
+			}
+		}
+
+		// stop announcing worker
+		s.announce.Stop()
+
+		// ensure ws is stopped
+		_ = ws.Close()
+
+		time.Sleep(time.Minute)
+	}
+
+	s.Fire("disconnect")
+
+	return nil
+}
+
+// reader - receive offers in the loop, will exit on ws.Close
+func (s *Server) reader(ws *websocket.Conn, peerID string) error {
+	var v Message
+	if err := ws.ReadJSON(&v); err != nil {
+		return err
+	}
+
+	s.Fire(&v)
+
+	s.mu.Lock()
+	share, ok := s.shares[v.InfoHash]
+	s.mu.Unlock()
+
+	// skip any unknown shares
+	if !ok || v.OfferId == "" || v.Offer == nil {
+		return nil
+	}
+
+	s.Fire("new offer: " + v.OfferId)
+
+	cipher, err := NewCipher(share.name, share.pwd, v.OfferId)
+	if err != nil {
+		s.Fire(err)
+		return nil
+	}
+
+	enc, err := base64.StdEncoding.DecodeString(v.Offer.SDP)
+	if err != nil {
+		s.Fire(err)
+		return nil
+	}
+
+	offer, err := cipher.Decrypt(enc)
+	if err != nil {
+		s.Fire(err)
+		return nil
+	}
+
+	answer, err := s.Exchange(share.src, string(offer))
+	if err != nil {
+		s.Fire(err)
+		return nil
+	}
+
+	enc = cipher.Encrypt([]byte(answer))
+
+	raw := fmt.Sprintf(
+		`{"action":"announce","info_hash":"%s","peer_id":"%s","offer_id":"%s","answer":{"type":"answer","sdp":"%s"},"to_peer_id":"%s"}`,
+		v.InfoHash, peerID, v.OfferId, base64.StdEncoding.EncodeToString(enc), v.PeerId,
+	)
+	return ws.WriteMessage(websocket.TextMessage, []byte(raw))
+}
+
+func (s *Server) writer(ws *websocket.Conn, peerID string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if len(s.shares) == 0 {
+		return ws.Close()
+	}
+
+	for hash := range s.shares {
+		msg := fmt.Sprintf(
+			`{"action":"announce","info_hash":"%s","peer_id":"%s","offers":[],"numwant":10}`,
+			hash, peerID,
+		)
+		if err := ws.WriteMessage(websocket.TextMessage, []byte(msg)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (s *Server) HasShares() bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return len(s.shares) > 0
+}
+
+type Message struct {
+	Action   string `json:"action"`
+	InfoHash string `json:"info_hash"`
+
+	// Announce msg
+	Numwant int    `json:"numwant,omitempty"`
+	PeerId  string `json:"peer_id,omitempty"`
+	Offers  []struct {
+		OfferId string `json:"offer_id"`
+		Offer   struct {
+			Type string `json:"type"`
+			SDP  string `json:"sdp"`
+		} `json:"offer"`
+	} `json:"offers,omitempty"`
+
+	// Interval msg
+	Interval   int `json:"interval,omitempty"`
+	Complete   int `json:"complete,omitempty"`
+	Incomplete int `json:"incomplete,omitempty"`
+
+	// Offer msg
+	OfferId string `json:"offer_id,omitempty"`
+	Offer   *struct {
+		Type string `json:"type"`
+		SDP  string `json:"sdp"`
+	} `json:"offer,omitempty"`
+
+	// Answer msg
+	ToPeerId string `json:"to_peer_id,omitempty"`
+	Answer   *struct {
+		Type string `json:"type"`
+		SDP  string `json:"sdp"`
+	} `json:"answer,omitempty"`
+}