Fix - Http3FrameCodec decode fail during unknown settings #15998
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unknown identifiers should be ignored, but if we return value , then http3codec considers it as duplicate header and throws error, we can return null but not set inside the setting map to ignore
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normanmaurer
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Dec 9, 2025
normanmaurer
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Dec 9, 2025
codec-http3/src/main/java/io/netty/handler/codec/http3/Http3SettingIdentifier.java
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…ttingIdentifier.java Fix check style
chrisvest
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**Motivation:** The change in [https://github.com/netty/netty/pull/15909](https://github.com/netty/netty/pull/15909) is merged but not yet released. While working on HTTP/3 connections I noticed a logical issue: when an unknown settings key is received, the current implementation returns a value, which causes Http3FrameCodec to treat it as an error (because settings.put(key, value) returns the previous value for known keys and null for new ones). For unknown keys we should ignore them, so we now always return null to achieve the expected behavior. **Modification:** * [x] settings.put(key, value) now returns null for unknown keys (non null triggers an error in Http3FrameCodec decoding). * [x] Added unit tests to verify this. > Note: Http3CodecTest didn’t catch the issue previously because it used frames produced by the same put logic, so both encoding and decoding behaved consistently and the issue was hidden. --------- Co-authored-by: Norman Maurer <[email protected]>
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…16002) **Motivation:** The change in [https://github.com/netty/netty/pull/15909](https://github.com/netty/netty/pull/15909) is merged but not yet released. While working on HTTP/3 connections I noticed a logical issue: when an unknown settings key is received, the current implementation returns a value, which causes Http3FrameCodec to treat it as an error (because settings.put(key, value) returns the previous value for known keys and null for new ones). For unknown keys we should ignore them, so we now always return null to achieve the expected behavior. **Modification:** * [x] settings.put(key, value) now returns null for unknown keys (non null triggers an error in Http3FrameCodec decoding). * [x] Added unit tests to verify this. > Note: Http3CodecTest didn’t catch the issue previously because it used frames produced by the same put logic, so both encoding and decoding behaved consistently and the issue was hidden. Co-authored-by: sanjomo <[email protected]>
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Motivation:
The change in #15909 is merged but not yet released. While working on HTTP/3 connections I noticed a logical issue: when an unknown settings key is received, the current implementation returns a value, which causes Http3FrameCodec to treat it as an error (because settings.put(key, value) returns the previous value for known keys and null for new ones). For unknown keys we should ignore them, so we now always return null to achieve the expected behavior.
Modification:
settings.put(key, value) now returns null for unknown keys (non null triggers an error in Http3FrameCodec decoding).
Added unit tests to verify this.