XCM Topics as message IDs for improved message tracing

[vgeddes]

The SetTopic([u8; 32]) instruction can be used to associate arbitrary "topic" data with an xcm message. This is useful for tracing the message as it flows from origin to destination. Some of the XCM routing pallets interpret the topic as a message id, and fallback to hashing the message if the topic is not present.

Gav describes the usage more in https://substrate.stackexchange.com/questions/1893/is-there-an-id-for-xcm-message/1906#1906.

To make full use of this feature, I have made the following changes:

• AssetHub->BridgeHub->Gateway: The XCM topic is sent over the bridge and logged in the InboundMessageDispatched event.
• Gateway->BridgeHub->AssetHub: A unique message ID is generated in the Gateway, and is also sent over the bridge and embedded in the generated XCM as SetTopic instruction.

This can be used to trace the message as follows in the Gateway->BridgeHub->AssetHub direction:

• Gateway: MessageID logged in OutboundMessageAccepted event
• BridgeHub: MessageID logged in ethereumInboundQueue::MessageReceived event
• AssetHub: MessageID logged in xcmpQueue.Success

Other changes:

• For E2E environment, Gateway is enabled by default. Made this configurable
• Using the new https://github.com/alloy-rs/core library for parsing Ethereum events in the inbound-queue pallet.

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (654f242) 82.69% compared to head (b8a5243) 82.82%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #997      +/-   ##
==========================================
+ Coverage   82.69%   82.82%   +0.12%     
==========================================
  Files          51       51              
  Lines        2069     2073       +4     
  Branches       72       72              
==========================================
+ Hits         1711     1717       +6     
+ Misses        343      341       -2     
  Partials       15       15              

Flag	Coverage Δ
rust	83.24% <94.64%> (+0.14%)	⬆️
solidity	80.87% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
contracts/src/Assets.sol	78.57% <ø> (ø)
contracts/src/Gateway.sol	86.70% <100.00%> (+0.08%)	⬆️
parachain/pallets/control/src/lib.rs	93.51% <100.00%> (ø)
...arachain/pallets/ethereum-beacon-client/src/lib.rs	96.22% <ø> (ø)
parachain/pallets/inbound-queue/src/envelope.rs	100.00% <100.00%> (+23.07%)	⬆️
parachain/pallets/inbound-queue/src/lib.rs	82.45% <100.00%> (-0.88%)	⬇️
parachain/pallets/outbound-queue/src/lib.rs	95.55% <100.00%> (+0.04%)	⬆️
...in/pallets/outbound-queue/src/send_message_impl.rs	100.00% <100.00%> (ø)
parachain/pallets/outbound-queue/src/types.rs	77.77% <100.00%> (+1.30%)	⬆️
parachain/primitives/core/src/outbound.rs	82.75% <ø> (ø)
... and 3 more

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[claravanstaden]

Nice!

[yrong]

Cool!