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Fix occasional SSL protocol error in XTLS Vision direct copy mode #5520

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Fix occasional SSL protocol error in XTLS Vision direct copy mode #5520

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e9774fc
Initial plan
Copilot Jan 11, 2026
bdfd1d2
Fix occasional SSL protocol error in XTLS Vision by deferring direct …
Copilot Jan 11, 2026
8ca03fa
Clarify comment about switchToDirectCopy flag remaining true
Copilot Jan 11, 2026
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2 changes: 1 addition & 1 deletion go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ require (
golang.org/x/net v0.48.0
golang.org/x/sync v0.19.0
golang.org/x/sys v0.39.0
golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2
golang.zx2c4.com/wireguard v0.0.0-20231211153847-12269c276173
google.golang.org/grpc v1.78.0
google.golang.org/protobuf v1.36.11
Expand All @@ -50,7 +51,6 @@ require (
golang.org/x/text v0.32.0 // indirect
golang.org/x/time v0.12.0 // indirect
golang.org/x/tools v0.39.0 // indirect
golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
google.golang.org/genproto/googleapis/rpc v0.0.0-20251029180050-ab9386a59fda // indirect
gopkg.in/yaml.v2 v2.4.0 // indirect
gopkg.in/yaml.v3 v3.0.1 // indirect
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14 changes: 11 additions & 3 deletions proxy/proxy.go
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Original file line number Diff line number Diff line change
Expand Up @@ -224,7 +224,8 @@ func (w *VisionReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
switchToDirectCopy = &w.trafficState.Outbound.DownlinkReaderDirectCopy
}

if *switchToDirectCopy {
if *switchToDirectCopy && w.input == nil {
// Already switched to direct copy mode
if w.directReadCounter != nil {
w.directReadCounter.Add(int64(buffer.Len()))
}
Expand Down Expand Up @@ -257,11 +258,18 @@ func (w *VisionReader) ReadMultiBuffer() (buf.MultiBuffer, error) {

if *switchToDirectCopy {
// XTLS Vision processes TLS-like conn's input and rawInput
// input contains decrypted application data - safe to merge
if inputBuffer, err := buf.ReadFrom(w.input); err == nil && !inputBuffer.IsEmpty() {
buffer, _ = buf.MergeMulti(buffer, inputBuffer)
}
if rawInputBuffer, err := buf.ReadFrom(w.rawInput); err == nil && !rawInputBuffer.IsEmpty() {
buffer, _ = buf.MergeMulti(buffer, rawInputBuffer)
// rawInput may contain encrypted bytes for the next TLS record
// If rawInput is not empty, we should NOT switch to direct mode yet
// because those bytes need to be processed by the TLS layer first
if w.rawInput != nil && w.rawInput.Len() > 0 {
// rawInput has pending data - defer direct copy to next read
// *switchToDirectCopy remains true (unchanged), so we will retry on the next ReadMultiBuffer call
// This ensures we don't mix encrypted bytes with application data
return buffer, err
}
*w.input = bytes.Reader{} // release memory
w.input = nil
Expand Down