82 lines
1.6 KiB
Go
82 lines
1.6 KiB
Go
package challenge
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import (
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"crypto/sha256"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"net/http"
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"time"
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)
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type Key [KeySize]byte
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const KeySize = sha256.Size
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func (k *Key) Set(flags KeyFlags) {
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(*k)[0] |= uint8(flags)
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}
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func (k *Key) Get(flags KeyFlags) KeyFlags {
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return KeyFlags((*k)[0] & uint8(flags))
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}
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func (k *Key) Unset(flags KeyFlags) {
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(*k)[0] = (*k)[0] & ^(uint8(flags))
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}
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type KeyFlags uint8
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const (
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KeyFlagIsIPv4 = KeyFlags(1 << iota)
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)
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func KeyFromString(s string) (Key, error) {
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b, err := hex.DecodeString(s)
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if err != nil {
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return Key{}, err
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}
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if len(b) != KeySize {
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return Key{}, errors.New("invalid challenge key")
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}
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return Key(b), nil
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}
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func GetChallengeKeyForRequest(state StateInterface, reg *Registration, until time.Time, r *http.Request) Key {
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data := RequestDataFromContext(r.Context())
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hasher := sha256.New()
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hasher.Write([]byte("challenge\x00"))
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hasher.Write([]byte(reg.Name))
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hasher.Write([]byte{0})
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keyAddr := data.NetworkPrefix().As16()
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hasher.Write(keyAddr[:])
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hasher.Write([]byte{0})
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// specific headers
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for _, k := range []string{
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"Accept-Language",
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// General browser information
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"User-Agent",
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// TODO: not sent in preload
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//"Sec-Ch-Ua",
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//"Sec-Ch-Ua-Platform",
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} {
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hasher.Write([]byte(r.Header.Get(k)))
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hasher.Write([]byte{0})
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}
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hasher.Write([]byte{0})
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_ = binary.Write(hasher, binary.LittleEndian, until.UTC().Unix())
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hasher.Write([]byte{0})
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hasher.Write(state.PublicKey())
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hasher.Write([]byte{0})
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sum := Key(hasher.Sum(nil))
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sum[0] = 0
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if data.RemoteAddress.Addr().Unmap().Is4() {
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// Is IPv4, mark
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sum.Set(KeyFlagIsIPv4)
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}
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return Key(sum)
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}
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