71 lines
2.3 KiB
Go
71 lines
2.3 KiB
Go
package extension
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import (
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"encoding/binary"
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"github.com/pion/dtls/v2/pkg/crypto/hash"
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"github.com/pion/dtls/v2/pkg/crypto/signature"
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"github.com/pion/dtls/v2/pkg/crypto/signaturehash"
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)
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const (
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supportedSignatureAlgorithmsHeaderSize = 6
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)
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// SupportedSignatureAlgorithms allows a Client/Server to
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// negotiate what SignatureHash Algorithms they both support
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//
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// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
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type SupportedSignatureAlgorithms struct {
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SignatureHashAlgorithms []signaturehash.Algorithm
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}
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// TypeValue returns the extension TypeValue
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func (s SupportedSignatureAlgorithms) TypeValue() TypeValue {
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return SupportedSignatureAlgorithmsTypeValue
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}
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// Marshal encodes the extension
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func (s *SupportedSignatureAlgorithms) Marshal() ([]byte, error) {
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out := make([]byte, supportedSignatureAlgorithmsHeaderSize)
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binary.BigEndian.PutUint16(out, uint16(s.TypeValue()))
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binary.BigEndian.PutUint16(out[2:], uint16(2+(len(s.SignatureHashAlgorithms)*2)))
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binary.BigEndian.PutUint16(out[4:], uint16(len(s.SignatureHashAlgorithms)*2))
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for _, v := range s.SignatureHashAlgorithms {
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out = append(out, []byte{0x00, 0x00}...)
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out[len(out)-2] = byte(v.Hash)
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out[len(out)-1] = byte(v.Signature)
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}
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return out, nil
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}
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// Unmarshal populates the extension from encoded data
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func (s *SupportedSignatureAlgorithms) Unmarshal(data []byte) error {
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if len(data) <= supportedSignatureAlgorithmsHeaderSize {
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return errBufferTooSmall
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} else if TypeValue(binary.BigEndian.Uint16(data)) != s.TypeValue() {
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return errInvalidExtensionType
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}
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algorithmCount := int(binary.BigEndian.Uint16(data[4:]) / 2)
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if supportedSignatureAlgorithmsHeaderSize+(algorithmCount*2) > len(data) {
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return errLengthMismatch
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}
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for i := 0; i < algorithmCount; i++ {
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supportedHashAlgorithm := hash.Algorithm(data[supportedSignatureAlgorithmsHeaderSize+(i*2)])
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supportedSignatureAlgorithm := signature.Algorithm(data[supportedSignatureAlgorithmsHeaderSize+(i*2)+1])
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if _, ok := hash.Algorithms()[supportedHashAlgorithm]; ok {
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if _, ok := signature.Algorithms()[supportedSignatureAlgorithm]; ok {
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s.SignatureHashAlgorithms = append(s.SignatureHashAlgorithms, signaturehash.Algorithm{
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Hash: supportedHashAlgorithm,
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Signature: supportedSignatureAlgorithm,
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})
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}
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}
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}
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return nil
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}
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