Aias00 opened a new pull request, #3549:
URL: https://github.com/apache/dubbo-go/pull/3549
## What
`BuildInvokerChain` discarded the `bool` from `extension.GetFilter`, so an
unregistered filter name (typo / unimported) produced a `FilterInvoker` with a
nil `filter` that nil-derefs on the first `Invoke`.
## Why
```go
// protocol/protocolwrapper/protocol_filter_wrapper.go BuildInvokerChain
(before)
for _, filterName := range slices.Backward(filterNames) {
flt, _ := extension.GetFilter(strings.TrimSpace(filterName)) // bool
discarded
fi := &FilterInvoker{next: next, invoker: invoker, filter: flt} // flt
== nil if name unknown
next = fi
}
func (fi *FilterInvoker) Invoke(ctx, invocation) result.Result {
result := fi.filter.Invoke(ctx, fi.next, invocation) // nil interface
deref -> panic
return fi.filter.OnResponse(ctx, result, fi.invoker, invocation)
}
```
`extension.GetFilter` returns `(nil, false)` for an unknown name; the `bool`
is the intended signal and was thrown away. Setup succeeds; the first request
panics instead of failing at boot.
## Fix
Check the `bool` from `GetFilter`; on `!ok`, log an error and `continue`
(skip that filter, wrap the rest):
```go
flt, ok := extension.GetFilter(name)
if !ok {
logger.Errorf("[Protocol][Wrapper] filter %q is not registered, skip
it", name)
continue
}
```
## Tests
Added `TestBuildInvokerChainSkipsUnknownFilter`: a chain with
`mockEcho,unknownFilterName`; a non-echo invocation forces `mockEcho` to call
`next.Invoke` (which on the old code reached the nil-filter `FilterInvoker` and
panicked). Verified to **fail (panic)** on the old code and **pass** on the
fixed code. `protocol/protocolwrapper` passes under `-race`.
Fixes #3548
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