Add support HomeKit server

2023-09-02 06:35:04 +03:00
parent a101387b26
commit f00e646612
18 changed files with 1988 additions and 53 deletions
@@ -0,0 +1,237 @@
+package hap
+
+import (
+	"bufio"
+	"crypto/sha512"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+
+	"github.com/AlexxIT/go2rtc/pkg/hap/chacha20poly1305"
+	"github.com/AlexxIT/go2rtc/pkg/hap/ed25519"
+	"github.com/AlexxIT/go2rtc/pkg/hap/hkdf"
+	"github.com/AlexxIT/go2rtc/pkg/hap/tlv8"
+	"github.com/tadglines/go-pkgs/crypto/srp"
+)
+
+const (
+	PairMethodSetup = iota
+	PairMethodSetupWithAuth
+	PairMethodVerify
+	PairMethodAdd
+	PairMethodRemove
+	PairMethodList
+)
+
+func (s *Server) PairSetup(req *http.Request, rw *bufio.ReadWriter, conn net.Conn) error {
+	if req.Header.Get("Content-Type") != MimeTLV8 {
+		return errors.New("hap: wrong content type")
+	}
+
+	// STEP 1. Request from iPhone
+	var plainM1 struct {
+		Method byte   `tlv8:"0"`
+		State  byte   `tlv8:"6"`
+		Flags  uint32 `tlv8:"19"`
+	}
+	if err := tlv8.UnmarshalReader(io.LimitReader(rw, req.ContentLength), &plainM1); err != nil {
+		return err
+	}
+	if plainM1.State != StateM1 {
+		return newRequestError(plainM1)
+	}
+
+	username := []byte("Pair-Setup")
+
+	// Stanford Secure Remote Password (SRP) / Password Authenticated Key Exchange (PAKE)
+	pake, err := srp.NewSRP(
+		"rfc5054.3072", sha512.New, keyDerivativeFuncRFC2945(username),
+	)
+	if err != nil {
+		return err
+	}
+
+	pake.SaltLength = 16
+
+	salt, verifier, err := pake.ComputeVerifier([]byte(s.Pin))
+
+	session := pake.NewServerSession(username, salt, verifier)
+
+	// STEP 2. Response to iPhone
+	plainM2 := struct {
+		Salt      string `tlv8:"2"`
+		PublicKey string `tlv8:"3"`
+		State     byte   `tlv8:"6"`
+	}{
+		State:     StateM2,
+		PublicKey: string(session.GetB()),
+		Salt:      string(salt),
+	}
+	body, err := tlv8.Marshal(plainM2)
+	if err != nil {
+		return err
+	}
+	if err = WriteResponse(rw.Writer, http.StatusOK, MimeTLV8, body); err != nil {
+		return err
+	}
+
+	// STEP 3. Request from iPhone
+	if req, err = http.ReadRequest(rw.Reader); err != nil {
+		return err
+	}
+
+	var plainM3 struct {
+		SessionKey string `tlv8:"3"`
+		Proof      string `tlv8:"4"`
+		State      byte   `tlv8:"6"`
+	}
+	if err = tlv8.UnmarshalReader(req.Body, &plainM3); err != nil {
+		return err
+	}
+	if plainM3.State != StateM3 {
+		return newRequestError(plainM3)
+	}
+
+	// important to compute key before verify client
+	sessionShared, err := session.ComputeKey([]byte(plainM3.SessionKey))
+	if err != nil {
+		return err
+	}
+
+	if !session.VerifyClientAuthenticator([]byte(plainM3.Proof)) {
+		return errors.New("hap: VerifyClientAuthenticator")
+	}
+
+	proof := session.ComputeAuthenticator([]byte(plainM3.Proof)) // server proof
+
+	// STEP 4. Response to iPhone
+	payloadM4 := struct {
+		Proof string `tlv8:"4"`
+		State byte   `tlv8:"6"`
+	}{
+		Proof: string(proof),
+		State: StateM4,
+	}
+	if body, err = tlv8.Marshal(payloadM4); err != nil {
+		return err
+	}
+	if err = WriteResponse(rw.Writer, http.StatusOK, MimeTLV8, body); err != nil {
+		return err
+	}
+
+	// STEP 5. Request from iPhone
+	if req, err = http.ReadRequest(rw.Reader); err != nil {
+		return err
+	}
+	var cipherM5 struct {
+		EncryptedData string `tlv8:"5"`
+		State         byte   `tlv8:"6"`
+	}
+	if err = tlv8.UnmarshalReader(req.Body, &cipherM5); err != nil {
+		return err
+	}
+	if cipherM5.State != StateM5 {
+		return newRequestError(cipherM5)
+	}
+
+	// decrypt message using session shared
+	encryptKey, err := hkdf.Sha512(sessionShared, "Pair-Setup-Encrypt-Salt", "Pair-Setup-Encrypt-Info")
+	if err != nil {
+		return err
+	}
+
+	b, err := chacha20poly1305.Decrypt(encryptKey, "PS-Msg05", []byte(cipherM5.EncryptedData))
+	if err != nil {
+		return err
+	}
+
+	// unpack message from TLV8
+	var plainM5 struct {
+		Identifier string `tlv8:"1"`
+		PublicKey  string `tlv8:"3"`
+		Signature  string `tlv8:"10"`
+	}
+	if err = tlv8.Unmarshal(b, &plainM5); err != nil {
+		return err
+	}
+
+	// 3. verify client ID and Public
+	remoteSign, err := hkdf.Sha512(
+		sessionShared, "Pair-Setup-Controller-Sign-Salt", "Pair-Setup-Controller-Sign-Info",
+	)
+	if err != nil {
+		return err
+	}
+
+	b = Append(remoteSign, plainM5.Identifier, plainM5.PublicKey)
+	if !ed25519.ValidateSignature([]byte(plainM5.PublicKey), b, []byte(plainM5.Signature)) {
+		return errors.New("hap: ValidateSignature")
+	}
+
+	// 4. generate signature to our ID and Public
+	localSign, err := hkdf.Sha512(
+		sessionShared, "Pair-Setup-Accessory-Sign-Salt", "Pair-Setup-Accessory-Sign-Info",
+	)
+	if err != nil {
+		return err
+	}
+
+	b = Append(localSign, s.DeviceID, s.ServerPublic()) // ServerPublic
+	signature, err := ed25519.Signature(s.DevicePrivate, b)
+	if err != nil {
+		return err
+	}
+
+	// 5. pack our ID and Public
+	plainM6 := struct {
+		Identifier string `tlv8:"1"`
+		PublicKey  string `tlv8:"3"`
+		Signature  string `tlv8:"10"`
+	}{
+		Identifier: s.DeviceID,
+		PublicKey:  string(s.ServerPublic()),
+		Signature:  string(signature),
+	}
+	if b, err = tlv8.Marshal(plainM6); err != nil {
+		return err
+	}
+
+	// 6. encrypt message
+	b, err = chacha20poly1305.Encrypt(encryptKey, "PS-Msg06", b)
+	if err != nil {
+		return err
+	}
+
+	// STEP 6. Response to iPhone
+	cipherM6 := struct {
+		EncryptedData string `tlv8:"5"`
+		State         byte   `tlv8:"6"`
+	}{
+		State:         StateM6,
+		EncryptedData: string(b),
+	}
+	if body, err = tlv8.Marshal(cipherM6); err != nil {
+		return err
+	}
+	if err = WriteResponse(rw.Writer, http.StatusOK, MimeTLV8, body); err != nil {
+		return err
+	}
+
+	s.AddPair(conn, plainM5.Identifier, []byte(plainM5.PublicKey), PermissionAdmin)
+
+	return nil
+}
+
+func WriteResponse(w *bufio.Writer, statusCode int, contentType string, body []byte) error {
+	header := fmt.Sprintf(
+		"HTTP/1.1 %d %s\r\nContent-Type: %s\r\nContent-Length: %d\r\n\r\n",
+		statusCode, http.StatusText(statusCode), contentType, len(body),
+	)
+	body = append([]byte(header), body...)
+	if _, err := w.Write(body); err != nil {
+		return err
+	}
+	return w.Flush()
+}