55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
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package srtp
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const labelExtractorDtlsSrtp = "EXTRACTOR-dtls_srtp"
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// KeyingMaterialExporter allows package SRTP to extract keying material
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type KeyingMaterialExporter interface {
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ExportKeyingMaterial(label string, context []byte, length int) ([]byte, error)
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}
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// ExtractSessionKeysFromDTLS allows setting the Config SessionKeys by
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// extracting them from DTLS. This behavior is defined in RFC5764:
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// https://tools.ietf.org/html/rfc5764
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func (c *Config) ExtractSessionKeysFromDTLS(exporter KeyingMaterialExporter, isClient bool) error {
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keyLen, err := c.Profile.keyLen()
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if err != nil {
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return err
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}
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saltLen, err := c.Profile.saltLen()
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if err != nil {
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return err
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}
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keyingMaterial, err := exporter.ExportKeyingMaterial(labelExtractorDtlsSrtp, nil, (keyLen*2)+(saltLen*2))
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if err != nil {
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return err
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}
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offset := 0
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clientWriteKey := append([]byte{}, keyingMaterial[offset:offset+keyLen]...)
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offset += keyLen
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serverWriteKey := append([]byte{}, keyingMaterial[offset:offset+keyLen]...)
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offset += keyLen
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clientWriteKey = append(clientWriteKey, keyingMaterial[offset:offset+saltLen]...)
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offset += saltLen
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serverWriteKey = append(serverWriteKey, keyingMaterial[offset:offset+saltLen]...)
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if isClient {
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c.Keys.LocalMasterKey = clientWriteKey[0:keyLen]
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c.Keys.LocalMasterSalt = clientWriteKey[keyLen:]
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c.Keys.RemoteMasterKey = serverWriteKey[0:keyLen]
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c.Keys.RemoteMasterSalt = serverWriteKey[keyLen:]
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return nil
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}
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c.Keys.LocalMasterKey = serverWriteKey[0:keyLen]
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c.Keys.LocalMasterSalt = serverWriteKey[keyLen:]
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c.Keys.RemoteMasterKey = clientWriteKey[0:keyLen]
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c.Keys.RemoteMasterSalt = clientWriteKey[keyLen:]
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return nil
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}
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