34Pass
14Fail
11Unsupported
71%of 48 conclusive
Stack: .NET HttpClient + msquic ·
Language: C# ·
Version: 2.7.0 (7e6525d)
· Measured 2026-10-27
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By class
Rolled up by what the clause requires rather than into one number. A client that ignores unknown extensions correctly but never emits the right error codes has a specific, nameable problem, and an average is exactly what hides it.
| Class | Passing means | Pass | Fail | Inconclusive |
|---|---|---|---|---|
| correctness | Rejected something invalid, with the code the RFC names. | 8 | 14 | 0 |
| discretionary | The RFC permits either behaviour; the report says which was chosen. | 11 | 0 | 0 |
| extensibility | Ignored something unknown and carried on. | 4 | 0 | 0 |
| interoperability | Correctly decoded something valid but demanding. | 5 | 0 | 0 |
| resilience | Recovered rather than giving up. | 6 | 0 | 0 |
Every result
| Test | Clause | Verdict | What happened |
|---|---|---|---|
| Version Negotiation offering a reserved version alongside v1 | RFC 9000 §6 | Pass | Responded correctly: sent Version Negotiation for 1 datagram(s); the client did not persist with an unsupported version. |
| Retry packet for source-address validation | RFC 9000 §8.1.2 | Pass | Responded correctly: echoed the Retry token and completed the handshake. |
| Reserved transport parameter (31·N+27) | RFC 9000 §18.1 | Pass | Ignored the unrecognised element and carried on: completed a handshake carrying a reserved transport parameter. |
| Unknown frame type in a 1-RTT packet | RFC 9000 §12.4 | Pass | Responded correctly: closed with FRAME_ENCODING_ERROR, which is the code §12.4 requires for a frame of unknown type. |
| NEW_CONNECTION_ID followed by RETIRE_CONNECTION_ID | RFC 9000 §5.1 | Pass | Recovered: rotated connection IDs and retired 10 of them. |
| Stateless reset | RFC 9000 §10.3 | Pass | Responded correctly: was sent a Stateless Reset and went quiet — nothing further arrived in the 3 seconds that followed, which is the draining period §10.3.1 requires (0 datagram(s) were already in flight when the reset went out and are not counted against it). |
| Deliberately tight MAX_DATA and MAX_STREAM_DATA | RFC 9000 §4 | Pass | Handled it: respected the window without sending a BLOCKED frame, which §4.1 permits. |
| ACK Frequency extension offered | draft-ietf-quic-ack-frequency | Pass | Handled it: ignored the extension, which the specification permits. |
| Packets marked ECT(0) | RFC 9000 §13.4 | Pass | Responded correctly: echoed ECN counts back in its ACKs: 12 ECT(0), 0 ECT(1), 0 ECN-CE. |
| Path MTU black hole above a threshold | RFC 9000 §14, RFC 8899 | Pass | Recovered: detected the black hole 1 time(s) and settled on a 1293-byte path MTU (0 datagram(s) swallowed). |
| Server-initiated PATH_CHALLENGE | RFC 9000 §8.2 | Pass | Responded correctly: answered with 1 PATH_RESPONSE. |
| 0-RTT rejected after the client sends early data | RFC 9001 §4.6.2 | Unsupported | does not resume sessions, so nothing was rejected. An earlier connection to this port in the same session completed its exchange, and with it received session tickets that permit 0-RTT; this connection, opened afterwards, ran a full handshake instead of resuming, and a client that does not resume cannot offer early data. |
| A second path offered mid-connection | draft-ietf-quic-multipath | Pass | Handled it: declined the multipath offer and stayed on one path, which is conformant. |
| Spontaneous 1-RTT key update | RFC 9001 §6.2 | Pass | Decoded it and completed the request. |
| Stream limits set to the minimum a request needs | RFC 9000 §4.6 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. |
| One datagram in twelve dropped once the path is established | RFC 9000 §2.2, §13.3 | Pass | Recovered and completed the follow-up request. |
| Datagrams arriving from a second server address | RFC 9000 §9.6 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. The client process had already exited 1252ms in, before this test's reaction point at 3131ms, so the silence after that is not evidence either way. |
| Transport parameter carrying a value the specification forbids | RFC 9000 §7.4, §18.2 | Fail | rejected the out-of-range parameter with Code::crypto(00), where RFC 9000 §7.4 requires TRANSPORT_PARAMETER_ERROR. The violation was detected; the code reported is wrong. |
| 425 (Too Early) in answer to a request sent as early data | RFC 8470 §5.2 | Unsupported | does not resume sessions, so it was never answered 425. An earlier connection to this port in the same session completed its exchange, and with it received session tickets that permit 0-RTT; this connection, opened afterwards, ran a full handshake instead of resuming, and a client that does not resume cannot offer early data. |
| Path marking packets CE, not just ECT(0) | RFC 9000 §13.4 | Pass | Responded correctly: reported the congestion back: 15 ECN-CE among 0 ECT(0) and 0 ECT(1), after 31 datagram(s) were marked. |
| A second key update after the first is acknowledged | RFC 9001 §6.1, §6.5 | Pass | Decoded it and completed the request. |
| No stream credit at first, then MAX_STREAMS mid-connection | RFC 9000 §4.6 | Pass | Handled it: announced the block with 1 STREAMS_BLOCKED rather than opening a stream it had no credit for, which is what §4.6 recommends. |
| Reserved SETTINGS identifier (0x1f·N+0x21) | RFC 9114 §7.2.4.1 | Pass | Ignored the unrecognised element and completed the follow-up request. The client process had already exited 1352ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| Reserved frame type on the response stream | RFC 9114 §7.2.8 | Pass | Ignored the unrecognised element and completed the follow-up request. |
| Unidirectional stream with a reserved stream type | RFC 9114 §6.2.3 | Pass | Ignored the unrecognised element and completed the follow-up request. The client process had already exited 1303ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| SETTINGS containing the same identifier twice | RFC 9114 §7.2.4 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. The client process had already exited 1303ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| A DATA frame on the control stream | RFC 9114 §7.2.1 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Control stream whose first frame is not SETTINGS | RFC 9114 §6.2.1 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| A second control stream opened by the server | RFC 9114 §6.2.1 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Field lines referencing dynamic table insertions | RFC 9204 §4.3.3, §4.5.2 | Unsupported | the client advertised SETTINGS_QPACK_MAX_TABLE_CAPACITY of 0 and SETTINGS_QPACK_BLOCKED_STREAMS of 0, which forbid the server's encoder from using the dynamic table at all. |
| Huffman-coded field lines with maximal padding | RFC 9204 §4.1.2, RFC 7541 §5.2 | Pass | Decoded it and completed the request. |
| Field section larger than the client's advertised maximum | RFC 9114 §4.2.2 | Pass | Decoded it and completed the request. |
| Trailing field section after the body | RFC 9114 §4.1 | Pass | Decoded it and completed the request. |
| 103 Early Hints before the final response | RFC 9110 §15.2, RFC 8297 | Pass | Recovered and completed the follow-up request. |
| GOAWAY sent mid-connection | RFC 9114 §5.2 | Pass | Recovered and completed the follow-up request. The client process had already exited 1302ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| MAX_PUSH_ID sent by the server | RFC 9114 §7.2.7 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| SETTINGS frame on a request stream | RFC 9114 §7.2.4 | Pass | Rejected with the required error code 0x105. |
| DATA frame before any HEADERS on the response stream | RFC 9114 §4.1 | Fail | Rejected, but with error 0x102 where the specification requires 0x105. The violation was detected; the code reported is wrong. |
| CANCEL_PUSH for a push ID that was never promised | RFC 9114 §7.2.3 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Field section that blocks until the encoder stream catches up | RFC 9204 §2.1.2, §2.2.1 | Unsupported | the client advertised SETTINGS_QPACK_MAX_TABLE_CAPACITY of 0 and SETTINGS_QPACK_BLOCKED_STREAMS of 0, which forbid the server's encoder from using the dynamic table at all. |
| Response stream reset mid-body with H3_REQUEST_CANCELLED | RFC 9114 §8, §4.1 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. |
| PRIORITY_UPDATE sent by the server | RFC 9218 §7.2 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. The client process had already exited 1302ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| SETTINGS_ENABLE_CONNECT_PROTOCOL with a value outside 0 and 1 | RFC 9220 §3, RFC 8441 §3 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. The client process had already exited 1303ms in, before this test's reaction point at never observed, so the silence after that is not evidence either way. |
| PUSH_PROMISE for a push the client never allowed | RFC 9114 §7.2.5, §4.6 | Fail | Accepted a protocol violation and carried on. The anomaly was in the response the client read and delivered, so it was seen; this should have been rejected. |
| SETTINGS_H3_DATAGRAM with a value that is neither 0 nor 1 | RFC 9297 §2.1.1 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Encoder stream setting a dynamic table capacity above the client's limit | RFC 9204 §4.3.1, §6 | Fail | Accepted a protocol violation and carried on. The anomaly was on the QPACK encoder stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| A second GOAWAY naming a larger identifier than the first | RFC 9114 §5.2 | Fail | Accepted a protocol violation and carried on. The anomaly was on the control stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Push stream opened for a push nobody allowed | RFC 9114 §6.2.2 | Fail | Accepted a protocol violation and carried on. The anomaly was on a server-initiated push stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Field line indexing a static table entry that does not exist | RFC 9204 §3.1, §4.5.2 | Fail | Rejected, but with error 0x101 where the specification requires 0x200. The violation was detected; the code reported is wrong. |
| Datagrams delivered out of order | RFC 9000 §2.2 | Pass | Recovered and completed the follow-up request. |
| Encoder instruction naming a static index that does not exist | RFC 9204 §3.1, §4.3.2 | Fail | Accepted a protocol violation and carried on. The anomaly was on the QPACK encoder stream, and this client extended flow-control credit on it -- a receiver extends credit on a stream only once its application has consumed what was already there, so the bytes were read rather than merely delivered. This should have been rejected. |
| Server negotiates only the post-quantum hybrid X25519MLKEM768 | RFC 8446 §4.1.4, draft-ietf-tls-hybrid-design | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |
| Server negotiates only classical X25519 against a hybrid offer | RFC 8446 §4.1.1, draft-ietf-tls-hybrid-design §5 | Pass | Tolerated it and continued. The specification permits this but does not require it; a client that rejected it would also be conformant. |
| Hybrid key share large enough to split the Initial across packets | RFC 9000 §8.1, §14.1, RFC 9001 §4.4 | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |
| Server selects a key exchange group the client never offered | RFC 8446 §4.1.3, §4.2.8, RFC 9001 §4.8 | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |
| Hybrid key share with an intact X25519 half and a corrupt ML-KEM half | draft-ietf-tls-hybrid-design §3.2, RFC 8446 §4.1.3 | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |
| Hybrid key share whose length does not match the group named with it | draft-kwiatkowski-tls-ecdhe-mlkem §3.1.2, RFC 8446 §6.2, RFC 9001 §4.8 | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |
| Post-quantum certificate chain, compressed per RFC 8879 | RFC 8879 §4, RFC 8446 §4.4.2 | Unsupported | The client was refused before a handshake existed (detected an error with protocol compliance that was not covered by more specific error codes: authentication failed). The refusal is itself the measurement on this tier, but what the client lacked is not recorded in it: this endpoint constrains both the key exchange group and the certificate's signature algorithm, and the error names neither. |
| GREASE named group a client must tolerate | RFC 8701 §4, RFC 8446 §4.2.7 | Unsupported | The client offers no key exchange group this port will negotiate, so it was refused before a handshake existed (the cryptographic handshake failed: error 40: peer is incompatible: NoKxGroupsInCommon). That is a capability this client does not have, rather than something the run failed to measure. |