pjfanning opened a new pull request, #1267:
URL: https://github.com/apache/pekko-http/pull/1267
### Motivation
When a modelled header value fails to parse, `ModeledHeaderValueParser`
calls `onIllegalHeader` — which by default only logs — and degrades the header
to a `RawHeader`:
```scala
case HeaderParser.Failure(error) =>
onIllegalHeader(error.withSummaryPrepended(s"Illegal '$headerName'
header")...)
RawHeader(headerName, trimmedHeaderValue)
```
For `Transfer-Encoding` that is unsafe. The degraded header never reaches
the `case h: Transfer-Encoding` arm in `parseHeaderLines`, so `isChunked` stays
`false` and — with a `Content-Length` also present — the message is framed by
Content-Length. An upstream that *does* parse the value (stripping quotes,
tolerating trailing junk) frames the same message as chunked. The two then
disagree about where the message ends, which is a request-smuggling primitive.
Pekko HTTP already rejects the clear cases: `chunked` together with a
`Content-Length`, an unsupported coding, and multiple entries. Only the
*unparseable* value was silently tolerated.
### Modification
Fail the message when a `Transfer-Encoding` header arrives as a `RawHeader`.
That can only happen when the modelled parse failed: `transfer-encoding` is in
`alwaysParsedHeaders`, so it is modelled even when `modeled-header-parsing` is
off, and a well-formed value always reaches the modelled arm. The change is
therefore scoped to this one header and does not alter the general
illegal-header contract.
### Result
A message whose `Transfer-Encoding` cannot be understood is rejected, rather
than framed by a different rule than the sender used.
### Tests
- `sbt "http-core/testOnly org.apache.pekko.http.impl.engine.parsing.*"` —
pass (246 tests). A new test sends `Transfer-Encoding: "chunked"` alongside a
`Content-Length` and expects a 400. Verified it fails without the change, where
the message is accepted and framed by Content-Length.
- `sbt http-core/mimaReportBinaryIssues` — pass.
- Native `scalafmt` clean.
### References
None - rejects a message whose Transfer-Encoding value cannot be parsed
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