Fix chunked request parsing

[wtgodbe]

No description provided.

[wtgodbe]

/backport to release/10.0

[github-actions]

Started backporting to release/10.0: https://github.com/dotnet/aspnetcore/actions/runs/18509024636

[Copilot]

Pull Request Overview

This PR fixes chunked request parsing by improving validation of chunk extensions to properly reject malformed requests containing unpaired carriage return (\r) or line feed (\n) characters. The fix ensures HTTP/1.1 chunked transfer encoding follows RFC compliance while maintaining backward compatibility through a configurable switch.

Key changes:

• Enhanced chunk extension parsing to detect and reject invalid newline sequences
• Added comprehensive test coverage for both valid and invalid chunk extension scenarios
• Introduced a configurable switch for backward compatibility with existing behavior

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
ChunkedRequestTests.cs	Adds comprehensive test cases for valid/invalid chunk extensions and edge cases with partial reads
MessageBodyTests.cs	Updates existing test to use proper CRLF sequence instead of malformed input
KestrelBadHttpRequestException.cs	Adds new exception case for bad chunk extensions
RequestRejectionReason.cs	Defines new rejection reason for invalid chunk extensions
Http1ChunkedEncodingMessageBody.cs	Implements improved chunk extension parsing with RFC compliance and backward compatibility
CoreStrings.resx	Adds error message for bad chunk extension validation

[wtgodbe]

/azp run

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