baderror: Treat HTTP/2 NO_ERROR as closed

[LarryWang142]

baderror: Treat HTTP/2 NO_ERROR as closed

Problem

sing-box logs spurious error/warning messages when HTTP/2 connections are closed gracefully. The log contains noisy entries like:

WARN [...] baderror [...]

This is a false positive — the connection closed normally, but the error wrapper misclassifies it.

Root Cause

In common/baderror/baderror.go, the WrapH2() function converts various HTTP/2 error messages into harmless sentinel errors (e.g., net.ErrClosed). This prevents normal connection teardown from being logged as errors upstream.

HTTP/2 uses a NO_ERROR code (0x0) in GOAWAY and RST_STREAM frames to indicate graceful shutdown. When the peer sends NO_ERROR, Go's HTTP/2 implementation may return an error string containing "; NO_ERROR". This pattern was not in the recognized list, so it was treated as a genuine error.

Fix

Added "; NO_ERROR" to the recognized patterns in WrapH2():

if Contains(
    err,
    "client disconnected",
    "body closed by handler",
    "response body closed",
    "; CANCEL",
    "; NO_ERROR",       // added
) {
    return net.ErrClosed
}

This ensures HTTP/2 graceful shutdown (NO_ERROR) is treated the same as other normal close signals — returning net.ErrClosed instead of the raw error, which the caller handles silently.

Changes

• common/baderror/baderror.go: Added "; NO_ERROR" to the close detection list

Testing

• HTTP/2 connections closing with NO_ERROR no longer produce baderror warnings in logs
• Other error types (actual connection errors) continue to be reported correctly