install go2rtc on bob

installs_on_host/go2rtc/pkg/hap/hds/hds.go

@@ -0,0 +1,176 @@
+// Package hds - HomeKit Data Stream
+package hds
+
+import (
+	"bufio"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"io"
+	"net"
+	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/hap"
+	"github.com/AlexxIT/go2rtc/pkg/hap/chacha20poly1305"
+	"github.com/AlexxIT/go2rtc/pkg/hap/hkdf"
+)
+
+func NewConn(conn net.Conn, key []byte, salt string, controller bool) (*Conn, error) {
+	writeKey, err := hkdf.Sha512(key, salt, "HDS-Write-Encryption-Key")
+	if err != nil {
+		return nil, err
+	}
+
+	readKey, err := hkdf.Sha512(key, salt, "HDS-Read-Encryption-Key")
+	if err != nil {
+		return nil, err
+	}
+
+	c := &Conn{
+		conn: conn,
+		rd:   bufio.NewReaderSize(conn, 32*1024),
+		wr:   bufio.NewWriterSize(conn, 32*1024),
+	}
+
+	if controller {
+		c.decryptKey, c.encryptKey = readKey, writeKey
+	} else {
+		c.decryptKey, c.encryptKey = writeKey, readKey
+	}
+
+	return c, nil
+}
+
+type Conn struct {
+	conn net.Conn
+
+	rd *bufio.Reader
+	wr *bufio.Writer
+
+	decryptKey []byte
+	encryptKey []byte
+	decryptCnt uint64
+	encryptCnt uint64
+
+	recv int
+	send int
+}
+
+func (c *Conn) MarshalJSON() ([]byte, error) {
+	conn := core.Connection{
+		ID:         core.ID(c),
+		FormatName: "homekit",
+		Protocol:   "hds",
+		RemoteAddr: c.conn.RemoteAddr().String(),
+		Recv:       c.recv,
+		Send:       c.send,
+	}
+	return json.Marshal(conn)
+}
+
+func (c *Conn) read() (b []byte, err error) {
+	verify := make([]byte, 4)
+	if _, err = io.ReadFull(c.rd, verify); err != nil {
+		return
+	}
+
+	n := int(binary.BigEndian.Uint32(verify) & 0xFFFFFF)
+
+	ciphertext := make([]byte, n+hap.Overhead)
+	if _, err = io.ReadFull(c.rd, ciphertext); err != nil {
+		return
+	}
+
+	nonce := make([]byte, hap.NonceSize)
+	binary.LittleEndian.PutUint64(nonce, c.decryptCnt)
+	c.decryptCnt++
+
+	c.recv += n
+
+	return chacha20poly1305.DecryptAndVerify(c.decryptKey, ciphertext[:0], nonce, ciphertext, verify)
+}
+
+func (c *Conn) Read(p []byte) (n int, err error) {
+	b, err := c.read()
+	if err != nil {
+		return 0, err
+	}
+	n = copy(p, b)
+	if len(b) > n {
+		err = errors.New("hds: read buffer too small")
+	}
+	return
+}
+
+func (c *Conn) WriteTo(w io.Writer) (int64, error) {
+	var total int64
+	for {
+		b, err := c.read()
+		if err != nil {
+			return total, err
+		}
+
+		n, err := w.Write(b)
+		total += int64(n)
+		if err != nil {
+			return total, err
+		}
+	}
+}
+
+func (c *Conn) Write(b []byte) (n int, err error) {
+	n = len(b)
+
+	if n > 0xFFFFFF {
+		return 0, errors.New("hds: write buffer too big")
+	}
+
+	verify := make([]byte, 4)
+	binary.BigEndian.PutUint32(verify, 0x01000000|uint32(n))
+	if _, err = c.wr.Write(verify); err != nil {
+		return
+	}
+
+	nonce := make([]byte, hap.NonceSize)
+	binary.LittleEndian.PutUint64(nonce, c.encryptCnt)
+	c.encryptCnt++
+
+	buf := make([]byte, n+hap.Overhead)
+	if _, err = chacha20poly1305.EncryptAndSeal(c.encryptKey, buf[:0], nonce, b, verify); err != nil {
+		return
+	}
+
+	if _, err = c.wr.Write(buf); err != nil {
+		return
+	}
+
+	err = c.wr.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)
+}