Add router API for invoice routing hints #1590
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The router can return local channels, with all necessary information to build routing hints from these channels. It's not eclair-core's responsibility to choose what channels to use in routing hints: this is really a wallet strategy, so each wallet should have its own heuristics to choose what channels to include (if any).
| def getRemoteNodeId(localNodeId: PublicKey): PublicKey = channel.fold( | ||
| c => c.remoteNodeId, | ||
| c => if (localNodeId == c.ann.nodeId1) c.ann.nodeId2 else c.ann.nodeId1 | ||
| ) | ||
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| /** Get our remote peer's channel_update: this is what must be used in invoice routing hints. */ | ||
| def getRemoteUpdate(localNodeId: PublicKey): Option[ChannelUpdate] = channel.fold( | ||
| c => if (localNodeId == c.nodeId1) c.update_2_opt else c.update_1_opt, | ||
| c => if (localNodeId == c.ann.nodeId1) c.update_2_opt else c.update_1_opt | ||
| ) | ||
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| /** Create an invoice routing hint from that channel. Note that if the channel is private, the invoice will leak its existence. */ | ||
| def toExtraHop(localNodeId: PublicKey): Option[ExtraHop] = getRemoteUpdate(localNodeId).map(remoteUpdate => | ||
| ExtraHop(getRemoteNodeId(localNodeId), remoteUpdate.shortChannelId, remoteUpdate.feeBaseMsat, remoteUpdate.feeProportionalMillionths, remoteUpdate.cltvExpiryDelta) | ||
| ) | ||
| } |
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It seems to me that we could make remoteNodeId part of the constructor. It is a bit strange that we need to provide more info for a class named LocalChannel to tell which side is the local one.
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Agreed, I'll revisit that.
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Done in 273dd81, let me know what you think.
Yes it does, but only to the router :). It doesn't add it to the HTTP API as I think it's unnecessary, it's meant to be used by plugins for nodes that offer custodial wallet capabilities (for public nodes you usually don't need any routing hint, you have public channels). |
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Yes, my rationale is that some nodes may start pruning smaller public channels at some point to keep graph manageable, so adding hints for smaller public channels can be useful. |
The router can now return local channels, with all necessary information to build routing hints from these channels.
It's not eclair-core's responsibility to choose what channels to use in routing hints: this is really a wallet strategy, so each wallet should have its own heuristics to choose what channels to include (if any).
I think @btcontract was interested in these.