mirror of
https://github.com/apernet/OpenGFW.git
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3bd02ed46e
Reveal intentions by: - extracting magic numbers into constants - changing function names with >1 responsibilities - documenting non-obvious behaviors.
82 lines
2.0 KiB
Go
82 lines
2.0 KiB
Go
package udp
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import (
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"github.com/apernet/OpenGFW/analyzer"
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"github.com/apernet/OpenGFW/analyzer/internal"
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"github.com/apernet/OpenGFW/analyzer/udp/internal/quic"
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"github.com/apernet/OpenGFW/analyzer/utils"
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)
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const (
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quicInvalidCountThreshold = 4
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)
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var (
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_ analyzer.UDPAnalyzer = (*QUICAnalyzer)(nil)
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_ analyzer.UDPStream = (*quicStream)(nil)
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)
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type QUICAnalyzer struct{}
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func (a *QUICAnalyzer) Name() string {
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return "quic"
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}
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func (a *QUICAnalyzer) Limit() int {
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return 0
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}
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func (a *QUICAnalyzer) NewUDP(info analyzer.UDPInfo, logger analyzer.Logger) analyzer.UDPStream {
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return &quicStream{logger: logger}
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}
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type quicStream struct {
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logger analyzer.Logger
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invalidCount int
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}
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func (s *quicStream) Feed(rev bool, data []byte) (u *analyzer.PropUpdate, done bool) {
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// minimal data size: protocol version (2 bytes) + random (32 bytes) +
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// + session ID (1 byte) + cipher suites (4 bytes) +
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// + compression methods (2 bytes) + no extensions
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const minDataSize = 41
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if rev {
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// We don't support server direction for now
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s.invalidCount++
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return nil, s.invalidCount >= quicInvalidCountThreshold
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}
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pl, err := quic.ReadCryptoPayload(data)
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if err != nil || len(pl) < 4 { // FIXME: isn't length checked inside quic.ReadCryptoPayload? Also, what about error handling?
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s.invalidCount++
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return nil, s.invalidCount >= quicInvalidCountThreshold
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}
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if pl[0] != internal.TypeClientHello {
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s.invalidCount++
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return nil, s.invalidCount >= quicInvalidCountThreshold
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}
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chLen := int(pl[1])<<16 | int(pl[2])<<8 | int(pl[3])
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if chLen < minDataSize {
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s.invalidCount++
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return nil, s.invalidCount >= quicInvalidCountThreshold
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}
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m := internal.ParseTLSClientHelloMsgData(&utils.ByteBuffer{Buf: pl[4:]})
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if m == nil {
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s.invalidCount++
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return nil, s.invalidCount >= quicInvalidCountThreshold
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}
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return &analyzer.PropUpdate{
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Type: analyzer.PropUpdateMerge,
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M: analyzer.PropMap{"req": m},
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}, true
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}
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func (s *quicStream) Close(limited bool) *analyzer.PropUpdate {
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return nil
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}
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