57 lines
1.6 KiB
Go
57 lines
1.6 KiB
Go
package handshake
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import (
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"encoding/binary"
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)
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// MessageClientKeyExchange is a DTLS Handshake Message
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// With this message, the premaster secret is set, either by direct
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// transmission of the RSA-encrypted secret or by the transmission of
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// Diffie-Hellman parameters that will allow each side to agree upon
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// the same premaster secret.
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//
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// https://tools.ietf.org/html/rfc5246#section-7.4.7
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type MessageClientKeyExchange struct {
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IdentityHint []byte
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PublicKey []byte
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}
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// Type returns the Handshake Type
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func (m MessageClientKeyExchange) Type() Type {
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return TypeClientKeyExchange
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}
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// Marshal encodes the Handshake
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func (m *MessageClientKeyExchange) Marshal() ([]byte, error) {
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switch {
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case (m.IdentityHint != nil && m.PublicKey != nil) || (m.IdentityHint == nil && m.PublicKey == nil):
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return nil, errInvalidClientKeyExchange
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case m.PublicKey != nil:
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return append([]byte{byte(len(m.PublicKey))}, m.PublicKey...), nil
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default:
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out := append([]byte{0x00, 0x00}, m.IdentityHint...)
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binary.BigEndian.PutUint16(out, uint16(len(out)-2))
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return out, nil
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}
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}
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// Unmarshal populates the message from encoded data
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func (m *MessageClientKeyExchange) Unmarshal(data []byte) error {
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if len(data) < 2 {
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return errBufferTooSmall
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}
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// If parsed as PSK return early and only populate PSK Identity Hint
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if pskLength := binary.BigEndian.Uint16(data); len(data) == int(pskLength+2) {
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m.IdentityHint = append([]byte{}, data[2:]...)
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return nil
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}
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if publicKeyLength := int(data[0]); len(data) != publicKeyLength+1 {
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return errBufferTooSmall
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}
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m.PublicKey = append([]byte{}, data[1:]...)
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return nil
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}
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