54 lines
1.0 KiB
Go
54 lines
1.0 KiB
Go
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package main
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import (
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"errors"
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"time"
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)
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type CryptoConstruction uint16
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const (
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UndefinedConstruction CryptoConstruction = iota
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XSalsa20Poly1305
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XChacha20Poly1305
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)
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var (
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CertMagic = [4]byte{0x44, 0x4e, 0x53, 0x43}
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ServerMagic = [8]byte{0x72, 0x36, 0x66, 0x6e, 0x76, 0x57, 0x6a, 0x38}
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MinDNSPacketSize = uint(12)
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MaxDNSPacketSize = uint(4096)
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InitialMinQuestionSize = uint(128)
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TimeoutMin = 1 * time.Second
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TimeoutMax = 5 * time.Second
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)
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func HasTCFlag(packet []byte) bool {
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return packet[2]&2 == 2
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}
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func Pad(packet []byte, minSize uint) []byte {
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packet = append(packet, 0x80)
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for uint(len(packet)) < minSize {
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packet = append(packet, 0)
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}
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return packet
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}
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func Unpad(packet []byte) ([]byte, error) {
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i := len(packet)
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for {
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if i == 0 {
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return nil, errors.New("Invalid padding (short packet)")
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}
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i--
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if packet[i] == 0x80 {
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break
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}
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if packet[i] != 0x00 {
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return nil, errors.New("Invalid padding (delimiter not found)")
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}
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}
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return packet[:i], nil
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}
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