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server/vendor/github.com/pion/srtp/v2/keying.go

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package srtp
+
+const labelExtractorDtlsSrtp = "EXTRACTOR-dtls_srtp"
+
+// KeyingMaterialExporter allows package SRTP to extract keying material
+type KeyingMaterialExporter interface {
+	ExportKeyingMaterial(label string, context []byte, length int) ([]byte, error)
+}
+
+// ExtractSessionKeysFromDTLS allows setting the Config SessionKeys by
+// extracting them from DTLS. This behavior is defined in RFC5764:
+// https://tools.ietf.org/html/rfc5764
+func (c *Config) ExtractSessionKeysFromDTLS(exporter KeyingMaterialExporter, isClient bool) error {
+	keyLen, err := c.Profile.KeyLen()
+	if err != nil {
+		return err
+	}
+
+	saltLen, err := c.Profile.SaltLen()
+	if err != nil {
+		return err
+	}
+
+	keyingMaterial, err := exporter.ExportKeyingMaterial(labelExtractorDtlsSrtp, nil, (keyLen*2)+(saltLen*2))
+	if err != nil {
+		return err
+	}
+
+	offset := 0
+	clientWriteKey := append([]byte{}, keyingMaterial[offset:offset+keyLen]...)
+	offset += keyLen
+
+	serverWriteKey := append([]byte{}, keyingMaterial[offset:offset+keyLen]...)
+	offset += keyLen
+
+	clientWriteKey = append(clientWriteKey, keyingMaterial[offset:offset+saltLen]...)
+	offset += saltLen
+
+	serverWriteKey = append(serverWriteKey, keyingMaterial[offset:offset+saltLen]...)
+
+	if isClient {
+		c.Keys.LocalMasterKey = clientWriteKey[0:keyLen]
+		c.Keys.LocalMasterSalt = clientWriteKey[keyLen:]
+		c.Keys.RemoteMasterKey = serverWriteKey[0:keyLen]
+		c.Keys.RemoteMasterSalt = serverWriteKey[keyLen:]
+		return nil
+	}
+
+	c.Keys.LocalMasterKey = serverWriteKey[0:keyLen]
+	c.Keys.LocalMasterSalt = serverWriteKey[keyLen:]
+	c.Keys.RemoteMasterKey = clientWriteKey[0:keyLen]
+	c.Keys.RemoteMasterSalt = clientWriteKey[keyLen:]
+	return nil
+}