fix(client, qpack): align QPACK decoder with protocol spec compliance

[0x676e67]

No description provided.

[Copilot]

🟡 Changes recommended

Insert-count increments remain unvalidated and can overflow or violate the QPACK decoder-stream protocol.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Aligns QPACK decoding, buffering, blocked-stream handling, and error behavior with HTTP/3 protocol requirements.

Changes:

• Corrects QPACK prefix, capacity, reference, and insert-count handling.
• Adds fragmented encoder-stream parsing and blocked-stream coordination.
• Improves cancellation, connection-error wakeups, settings validation, and tests.

File summaries

File	Description
http3/src/tests/http3_quinn.rs	Reorders imports.
http3/src/qpack/tests.rs	Tests blocked-stream coordination.
http3/src/qpack/stream.rs	Supports larger insert-count increments.
http3/src/qpack/parse_error.rs	Expands protocol parsing errors.
http3/src/qpack/mod.rs	Adds blocked-stream registry and events.
http3/src/qpack/encoder.rs	Handles widened insert-count increments.
http3/src/qpack/dynamic.rs	Revises limits, references, and decoder insertion.
http3/src/qpack/decoder.rs	Adds buffered parsing and capacity enforcement.
http3/src/qpack/block.rs	Corrects field-section prefix reconstruction.
http3/src/proto/frame.rs	Validates SETTINGS varints.
http3/src/error/connection_error_creators.rs	Wakes QPACK waiters after publishing errors.
http3/src/connection.rs	Integrates QPACK blocking, cancellation, and wakeups.
http3/src/client/stream.rs	Routes receive cancellation through QPACK cleanup.
http3/src/client/builder.rs	Documents QPACK setting ranges.
http3/src/buf.rs	Tracks buffered byte counts efficiently.
http3-quic/src/lib.rs	Reorders conditional exports.

Review details

• Files reviewed: 16/16 changed files
• Comments generated: 1
• Review effort level: Balanced

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

🟡 Changes recommended

The server still does not poll incoming QPACK encoder streams, preventing required processing and critical-stream error detection.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

• Files reviewed: 19/19 changed files
• Comments generated: 1
• Review effort level: Balanced

[Copilot]

🔵 Needs a closer look

Field prefixes with zero Required Insert Count can still accept a protocol-invalid nonzero Base.

Review details

Suppressed comments (2)

Previously missed (2) — in code that hasn't changed since the last review.

http3/src/qpack/block.rs:187

• RFC 9204 §4.5.1.2 requires Base to be zero whenever Required Insert Count is zero. This positive-sign branch currently accepts a peer-controlled nonzero Delta Base (for example, RIC 0 and Delta Base 1), so a malformed field-section prefix is treated as valid instead of causing QPACK decompression failure. Handle the zero-RIC case explicitly before applying Delta Base.

        let base = if !self.sign_negative {
            required
                .checked_add(self.delta_base)
                .ok_or_else(invalid_base)?

http3/src/qpack/decoder.rs:56

• n is the Required Insert Count, not the number of references that are missing. For example, with insert count 99 and required count 100 this reports “missing 100 refs,” although only one insertion is unavailable. Describe the required count directly so diagnostics are accurate.

            DecoderError::MissingRefs(n) => write!(f, "missing {} refs to decode block", n),

• Files reviewed: 21/21 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.