feat(gateway): repair native Apollo provider path

gateway/apollo_control.go

@@ -0,0 +1,106 @@
+package gateway
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+	"errors"
+)
+
+const (
+	apolloControlOuterType    = 0x0001
+	apolloControlHeaderSize   = 8
+	apolloControlTagSize      = 16
+	apolloControlInnerSize    = 4
+	apolloControlMaximumPlain = 2048
+
+	apolloControlTypeStart  = 0x0307
+	apolloControlTypeIDR    = 0x0302
+	apolloControlTypePing   = 0x0200
+	apolloControlTypeInput  = 0x0206
+	apolloControlTypeFEC    = 0x5502
+	apolloControlTypeRumble = 0x010b
+	apolloControlTypeHDR    = 0x010e
+	apolloControlTypeTerm   = 0x0109
+)
+
+var errApolloControl = errors.New("apollo control malformed")
+
+type apolloControlMessage struct {
+	typeID  uint16
+	payload []byte
+}
+
+type apolloControlCodec struct {
+	aead       cipher.AEAD
+	nextClient uint32
+	lastHost   uint32
+	hostSeen   bool
+}
+
+func newApolloControlCodec(key []byte) (*apolloControlCodec, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	aead, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	return &apolloControlCodec{aead: aead}, nil
+}
+
+func (c *apolloControlCodec) SealClient(typeID uint16, payload []byte) ([]byte, error) {
+	if c == nil || c.aead == nil || typeID == 0 || len(payload) > apolloControlMaximumPlain || c.nextClient == ^uint32(0) {
+		return nil, errApolloControl
+	}
+	sequence := c.nextClient
+	c.nextClient++
+	inner := make([]byte, apolloControlInnerSize+len(payload))
+	binary.LittleEndian.PutUint16(inner[:2], typeID)
+	binary.LittleEndian.PutUint16(inner[2:4], uint16(len(payload)))
+	copy(inner[4:], payload)
+	nonce := apolloControlNonce(sequence, 'C')
+	sealed := c.aead.Seal(nil, nonce[:], inner, nil)
+	packet := make([]byte, apolloControlHeaderSize+len(sealed))
+	binary.LittleEndian.PutUint16(packet[:2], apolloControlOuterType)
+	binary.LittleEndian.PutUint16(packet[2:4], uint16(4+len(sealed)))
+	binary.LittleEndian.PutUint32(packet[4:8], sequence)
+	copy(packet[8:24], sealed[len(inner):])
+	copy(packet[24:], sealed[:len(inner)])
+	return packet, nil
+}
+
+func (c *apolloControlCodec) OpenHost(packet []byte) (apolloControlMessage, error) {
+	if c == nil || c.aead == nil || len(packet) < apolloControlHeaderSize+apolloControlTagSize+apolloControlInnerSize || len(packet) > apolloControlHeaderSize+apolloControlTagSize+apolloControlMaximumPlain {
+		return apolloControlMessage{}, errApolloControl
+	}
+	if binary.LittleEndian.Uint16(packet[:2]) != apolloControlOuterType || int(binary.LittleEndian.Uint16(packet[2:4])) != len(packet)-4 {
+		return apolloControlMessage{}, errApolloControl
+	}
+	sequence := binary.LittleEndian.Uint32(packet[4:8])
+	if c.hostSeen && sequence <= c.lastHost {
+		return apolloControlMessage{}, errApolloControl
+	}
+	nonce := apolloControlNonce(sequence, 'H')
+	sealed := make([]byte, len(packet)-apolloControlHeaderSize)
+	copy(sealed, packet[24:])
+	copy(sealed[len(packet)-24:], packet[8:24])
+	plaintext, err := c.aead.Open(nil, nonce[:], sealed, nil)
+	if err != nil || len(plaintext) < apolloControlInnerSize {
+		return apolloControlMessage{}, errApolloControl
+	}
+	length := int(binary.LittleEndian.Uint16(plaintext[2:4]))
+	if length != len(plaintext)-apolloControlInnerSize || length > apolloControlMaximumPlain {
+		return apolloControlMessage{}, errApolloControl
+	}
+	c.lastHost, c.hostSeen = sequence, true
+	return apolloControlMessage{typeID: binary.LittleEndian.Uint16(plaintext[:2]), payload: append([]byte(nil), plaintext[4:]...)}, nil
+}
+
+func apolloControlNonce(sequence uint32, origin byte) [12]byte {
+	var nonce [12]byte
+	binary.LittleEndian.PutUint32(nonce[:4], sequence)
+	nonce[10], nonce[11] = origin, 'C'
+	return nonce
+}