rob thijssen
84f60959d9
The console rendered nothing against Quantus and I had reported tier 3 as
working on the strength of a unit-level test. It was not working. This is the
fault.
`qp_header::Header` is not `sp_runtime::generic::Header`. `number` is a plain
u32 where Substrate writes a Compact, and a `zk_tree_root: H256` sits between
`extrinsics_root` and `digest` — deliberately, so the ZK root has a fixed offset
in the header preimage that miners cannot shift by manipulating the digest.
Reading a Quantus header as a Substrate one consumes 2 bytes where 4 were
written. Every field after shifts, and the digest vector eventually reads a byte
that is not a known DigestItem index, which surfaces three layers away as
`TypeError: innerDecoder is not a function`. papi retried the subfollow forever,
`runtime$` never emitted, and the page stayed blank.
The patched codec carries both layouts and picks by **round trip**: a layout is
right only if decoding and re-encoding reproduces the input byte for byte, which
also catches a short read, trailing bytes and a non-canonical compact. Trying
them in a fixed order and taking the first that survives is deterministic;
choosing by inspecting a byte would not be.
Pinned per version rather than by bare package name, unlike the signers-common
patch: four copies of substrate-bindings resolve in this tree and blockHeader.js
is not identical across majors — a bare-name key fails the whole install trying
to patch 0.19.0 and 0.6.0.
Two things this cost, both recorded because they are the kind that recur:
- My first attempt replaced the codec with a bare [enc, dec] pair, which
dropped scale-ts's `inner`. This console's own block.state.ts does
`blockHeader.inner.digests.inner`, so that module threw while evaluating,
`createRoot().render()` never ran, and the page was blank with nothing in
the UI — the same symptom as the bug, from the opposite cause. The patch now
copies the original codec and overrides only the decoder.
- The Poseidon block hash is NOT a second blocker, which I had claimed on #1
and #4 without checking. `getHasherFromHeader` returns a function that
throws rather than throwing, and only the extrinsic Analyzer page consumes
`hasher$`. Everything else works without it.
Verified in a browser this time, not by unit test: against mainnet the console
renders live data — Finalized 53,989, Best 54,089, block time — advancing, and
matching what the node reports. Polkadot still decodes through the same patched
codec, and garbage is refused rather than mis-read.
Residual: four "fetch header failed TypeError: e is not an object" on first load,
from the per-block detail fetch, not recurring since. Not diagnosed.
Refs #1, #4
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012uDUodEcRbBwNRi3UCmw8f
100 lines
3.6 KiB
Diff
100 lines
3.6 KiB
Diff
diff --git a/dist/codecs/blockHeader.js b/dist/codecs/blockHeader.js
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index 0675e59633a14c34148e90aa8c32bcfbc437330c..691ac4ede3c816bad444a6054860ed0bb3fcd37d 100644
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--- a/dist/codecs/blockHeader.js
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+++ b/dist/codecs/blockHeader.js
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@@ -1,4 +1,4 @@
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-import { enhanceCodec, Bytes, _void } from 'scale-ts';
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+import { enhanceCodec, Bytes, _void, u32 } from 'scale-ts';
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import '../utils/ss58-util.js';
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import './scale/Binary.js';
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import './scale/bitSequence.js';
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@@ -33,7 +33,23 @@ const diggest = Variant(
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[0, 4, 5, 6, 8]
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);
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const hex32 = Hex(32);
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-const blockHeader = Struct({
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+
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+// Quantus patch: this console serves two header layouts.
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+//
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+// `sp_runtime::generic::Header` encodes `number` with #[codec(compact)] and has
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+// no field between `extrinsics_root` and `digest`. Quantus's `qp_header::Header`
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+// does neither: `number` is a plain u32, and a `zk_tree_root: H256` sits before
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+// the digest — deliberately, so the ZK root has a fixed offset in the header
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+// preimage that miners cannot shift by manipulating the digest.
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+//
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+// Reading a Quantus header as a Substrate one consumes 2 bytes where 4 were
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+// written; every field after shifts, and the digest vector eventually reads a
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+// byte that is not a known DigestItem index. That surfaces three layers away as
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+// `TypeError: innerDecoder is not a function`, papi retries the subfollow
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+// forever, `runtime$` never emits, and the page renders nothing at all.
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+//
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+// See quantus/papi-console#4.
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+const substrateHeader = Struct({
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parentHash: hex32,
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number: compactNumber,
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stateRoot: hex32,
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@@ -41,5 +57,63 @@ const blockHeader = Struct({
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digests: Vector(diggest)
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});
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+const quantusHeader = Struct({
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+ parentHash: hex32,
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+ number: u32,
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+ stateRoot: hex32,
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+ extrinsicRoot: hex32,
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+ zkTreeRoot: hex32,
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+ digests: Vector(diggest)
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+});
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+
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+const asBytes = (input) =>
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+ typeof input === "string"
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+ ? Uint8Array.from(
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+ input
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+ .slice(2)
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+ .match(/../g)
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+ ?.map((b) => parseInt(b, 16)) ?? []
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+ )
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+ : input;
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+
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+const sameBytes = (a, b) =>
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+ a.length === b.length && a.every((x, i) => x === b[i]);
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+
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+// Decide by round trip, not by guessing. A layout is right only if decoding and
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+// re-encoding reproduces the input byte for byte — which also catches a short
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+// read, trailing bytes, and a non-canonical compact. Trying the layouts in a
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+// fixed order and taking the first that survives that check is deterministic;
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+// picking one by inspecting a byte would not be.
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+const decodeEitherLayout = (input) => {
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+ const bytes = asBytes(input);
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+ let firstError;
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+
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+ for (const codec of [substrateHeader, quantusHeader]) {
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+ try {
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+ const value = codec.dec(bytes);
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+
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+ if (sameBytes(codec.enc(value), bytes)) return value;
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+ } catch (error) {
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+ firstError ??= error;
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+ }
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+ }
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+
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+ throw firstError ?? new Error("block header matches no known layout");
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+};
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+
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+// Keep every property the original codec carried and override only the decoder.
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+// A scale-ts Struct exposes `inner` — its field codecs — and consumers reach for
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+// it: this console's own block.state.ts does `blockHeader.inner.digests.inner`.
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+// Replacing the codec with a bare [enc, dec] pair drops that, block.state.ts
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+// throws while its module is evaluating, `createRoot().render()` never runs, and
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+// the page is blank with no error on screen — the same symptom as the bug this
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+// patch exists to fix, from the opposite cause.
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+const blockHeader = Object.assign([], substrateHeader, {
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+ 0: substrateHeader.enc,
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+ 1: decodeEitherLayout,
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+ enc: substrateHeader.enc,
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+ dec: decodeEitherLayout
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+});
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+
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export { blockHeader };
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//# sourceMappingURL=blockHeader.js.map
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