install go2rtc on bob

installs_on_host/go2rtc/pkg/hap/conn.go

@@ -0,0 +1,173 @@
+package hap
+
+import (
+	"bufio"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"io"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/hap/chacha20poly1305"
+	"github.com/AlexxIT/go2rtc/pkg/hap/hkdf"
+)
+
+type Conn struct {
+	conn net.Conn
+	rw   *bufio.ReadWriter
+	wmu  sync.Mutex
+
+	encryptKey []byte
+	decryptKey []byte
+	encryptCnt uint64
+	decryptCnt uint64
+
+	//ClientID  string
+	SharedKey []byte
+
+	recv int
+	send int
+}
+
+func (c *Conn) MarshalJSON() ([]byte, error) {
+	conn := core.Connection{
+		ID:         core.ID(c),
+		FormatName: "homekit",
+		Protocol:   "hap",
+		RemoteAddr: c.conn.RemoteAddr().String(),
+		Recv:       c.recv,
+		Send:       c.send,
+	}
+	return json.Marshal(conn)
+}
+
+func NewConn(conn net.Conn, rw *bufio.ReadWriter, sharedKey []byte, isClient bool) (*Conn, error) {
+	key1, err := hkdf.Sha512(sharedKey, "Control-Salt", "Control-Read-Encryption-Key")
+	if err != nil {
+		return nil, err
+	}
+
+	key2, err := hkdf.Sha512(sharedKey, "Control-Salt", "Control-Write-Encryption-Key")
+	if err != nil {
+		return nil, err
+	}
+
+	c := &Conn{
+		conn: conn,
+		rw:   rw,
+
+		SharedKey: sharedKey,
+	}
+
+	if isClient {
+		c.encryptKey, c.decryptKey = key2, key1
+	} else {
+		c.encryptKey, c.decryptKey = key1, key2
+	}
+
+	return c, nil
+}
+
+const (
+	// packetSizeMax is the max length of encrypted packets
+	packetSizeMax = 0x400
+
+	VerifySize = 2
+	NonceSize  = 8
+	Overhead   = 16 // chacha20poly1305.Overhead
+)
+
+func (c *Conn) Read(b []byte) (n int, err error) {
+	if cap(b) < packetSizeMax {
+		return 0, errors.New("hap: read buffer is too small")
+	}
+
+	verify := make([]byte, VerifySize) // verify = plain message size
+	if _, err = io.ReadFull(c.rw, verify); err != nil {
+		return
+	}
+
+	n = int(binary.LittleEndian.Uint16(verify))
+
+	ciphertext := make([]byte, n+Overhead)
+	if _, err = io.ReadFull(c.rw, ciphertext); err != nil {
+		return
+	}
+
+	nonce := make([]byte, NonceSize)
+	binary.LittleEndian.PutUint64(nonce, c.decryptCnt)
+	c.decryptCnt++
+
+	_, err = chacha20poly1305.DecryptAndVerify(c.decryptKey, b[:0], nonce, ciphertext, verify)
+
+	c.recv += n
+	return
+}
+
+func (c *Conn) Write(b []byte) (n int, err error) {
+	c.wmu.Lock()
+	defer c.wmu.Unlock()
+
+	buf := make([]byte, 0, packetSizeMax+Overhead)
+	nonce := make([]byte, NonceSize)
+	verify := make([]byte, VerifySize)
+
+	for len(b) > 0 {
+		size := len(b)
+		if size > packetSizeMax {
+			size = packetSizeMax
+		}
+
+		binary.LittleEndian.PutUint16(verify, uint16(size))
+		if _, err = c.rw.Write(verify); err != nil {
+			return
+		}
+
+		binary.LittleEndian.PutUint64(nonce, c.encryptCnt)
+		c.encryptCnt++
+
+		_, err = chacha20poly1305.EncryptAndSeal(c.encryptKey, buf, nonce, b[:size], verify)
+		if err != nil {
+			return
+		}
+
+		if _, err = c.rw.Write(buf[:size+Overhead]); err != nil {
+			return
+		}
+
+		b = b[size:]
+		n += size
+	}
+
+	err = c.rw.Flush()
+
+	c.send += n
+	return
+}
+
+func (c *Conn) Close() error {
+	return c.conn.Close()
+}
+
+func (c *Conn) LocalAddr() net.Addr {
+	return c.conn.LocalAddr()
+}
+
+func (c *Conn) RemoteAddr() net.Addr {
+	return c.conn.RemoteAddr()
+}
+
+func (c *Conn) SetDeadline(t time.Time) error {
+	return c.conn.SetDeadline(t)
+}
+
+func (c *Conn) SetReadDeadline(t time.Time) error {
+	return c.conn.SetReadDeadline(t)
+}
+
+func (c *Conn) SetWriteDeadline(t time.Time) error {
+	return c.conn.SetWriteDeadline(t)
+}