lnrpc: structured SendToRoute failure reporting by joostjager · Pull Request #1662 · lightningnetwork/lnd

joostjager · 2018-07-31T10:19:40Z

Background

Many ideas float around to build functions/algorithms on top of lnd. For example: rebalancing, probing, routing service, etc. The current way for that kind of scripts to operate is to make calls to SendToRoute.
Unfortunately limited error information is returned to the caller. router will keep trying the supplied routes and if none of them works, return a routes exhausted error without the real cause. Even if only one route is supplied. This makes it harder for scripts to guess what happened.

Implementation details

In order to keep it simple, the option to pass in multiple routes is removed. Only a single route per payment is allowed. If multiple routes need to be tried (with or without waiting for the result), they can still be passed in one by one. Otherwise, to get a proper error result for every route in a list of routes, the result object should also need to become a list. In the streaming version of the SendToRoute call, it would become a list (of routes) in a list (of payments).
Structured error information is represented as a (flat) list of properties. The alternative would be to use protobuf oneof. This would for example result in the following json:

{
    "payment_error": "UnknownPaymentHash",
    "StructuredResult": {
        "FailUnknownPaymentHash": {}
    }
}

Maybe not the most intuitive representation in json and I am not sure how this is supported in the proto generators for various languages. It also seems that the oneof key cannot be assigned a json_name.

Usage

A new SendToRoute rpc has been implemented in the router sub server. In order to use it, lnd needs to be compiled with tags="routerrpc".

The command has not been added to lncli and is only available on the rpc interface. See router.proto for more information.

joostjager · 2018-08-09T16:05:17Z

PR is ready for a first pass review

cmd/lncli/commands.go

Roasbeef · 2018-09-18T05:14:25Z

lnd_test.go

IMO should be carried out before this is merged in.

As the router rpc is still in experimental state and its interface may change, we could also wait until we actually deprecate the main SendToRoute rpc.

Changing it now also moves coverage away from the main rpc and it may be safer to not yet do that.

Roasbeef · 2018-09-18T05:16:54Z

lnrpc/rpc.proto

What are the flags here? Aren't they already contained in the channel update?

I actually don't know. Can you tell me what the flags field in the onion failure message channel_disabled is for?

Roasbeef · 2018-09-18T05:17:13Z

lnrpc/rpc.proto

Is this the outgoing or incoming CLTV expiry for that hop?

See comment above

This is the field as defined in the lightning spec.

Roasbeef · 2018-09-18T05:17:24Z

lnrpc/rpc.proto

Similar q here: outgoing or incoming?

This field and other fields in this message contain the raw onion error. I chose not to make it one giant oneof construct, but instead created a union of all failure message fields. The meaning of htlc_msat and also cltv_expiry depends on the actual error.

Roasbeef · 2018-09-18T05:17:56Z

lnrpc/rpc.proto

Could add a suffix like _pubkey_bytes, just to clarify what the opaque bytes represent.

Added _pubkey. Also adding bytes is maybe too much and also not what we do in other places in the proto.

Roasbeef · 2018-09-18T05:18:31Z

lnrpc/rpc.proto

Do we really need to expose the sig on the RPC level? As could say the client already fully trusts the server itself.

I'd like the signatures, for data portability

routing/pathfind.go

cmd/lncli/commands.go

lnrpc/rpc.proto

routing/router.go

lnrpc/rpc.proto

rpcserver.go

esneider · 2019-05-01T15:12:41Z

What's the status of this PR? Is it on its way to be merged, or has it been replaced/deprioritized?

I'm asking mainly due to the fact that good error reporting is needed in order to take full advantage of the new interface of QueryRoutes.

joostjager · 2019-05-02T08:30:09Z

@esneider The plan is to move ahead with this after the release of 0.6.1, as it contains a breaking change.

joostjager · 2019-05-06T19:37:34Z

@Roasbeef @halseth ptal

routing/router.go

lnrpc/routerrpc/router.proto

lnrpc/routerrpc/router_server.go

cmd/lncli/commands.go

joostjager · 2019-05-13T09:06:20Z

@Roasbeef ptal

halseth

Looks more or less good to me, just a few comments.

cmd/lncli/commands.go

halseth · 2019-05-13T10:24:46Z

routing/router.go

This will need to be shuffled around a little bit after reliable payments are in.

Yes, but as we already merged the main refactoring of router.go some time ago, it indeed won't be much.

Reverted to using sendPayment for SendToRoute also, to connect better with #2761.

lnrpc/routerrpc/router.proto

halseth · 2019-05-13T10:29:47Z

lnrpc/routerrpc/router.proto

It is uint32 in the wire protocol.

lnrpc/routerrpc/router_server.go

halseth · 2019-05-13T10:33:48Z

lnrpc/routerrpc/router_server.go

error case?

No, no error because the update can be optional.

joostjager · 2019-05-13T10:56:58Z

ptal @halseth

Roasbeef

LGTM 🐊

contingent removal of the last commit

joostjager · 2019-05-15T05:33:55Z

Debug commit removed

halseth

Alright, this LGTM now 🔥

joostjager mentioned this pull request Jul 31, 2018

queryroutes + paytoroute should use delta expiry instead of absolute blockheights #1518 #1638

Closed

joostjager force-pushed the raw branch 2 times, most recently from 15be4a3 to e0d8f80 Compare August 2, 2018 13:18

joostjager changed the title ~~Raw SendToRoute RPC~~ lnrpc: allow pubkey in SendToRoute and better failure reporting Aug 2, 2018

joostjager force-pushed the raw branch 2 times, most recently from 30e785a to 7602d53 Compare August 9, 2018 15:46

joostjager force-pushed the raw branch 2 times, most recently from 1bba17e to bfac456 Compare August 9, 2018 17:38

Roasbeef added enhancement Improvements to existing features / behaviour rpc Related to the RPC interface onion routing P3 might get fixed, nice to have labels Aug 14, 2018

joostjager force-pushed the raw branch from bfac456 to f9154f9 Compare August 14, 2018 08:29

Roasbeef added this to the 0.6 milestone Aug 17, 2018

joostjager force-pushed the raw branch from f9154f9 to 30806c8 Compare September 20, 2018 02:11

joostjager changed the title ~~lnrpc: allow pubkey in SendToRoute and better failure reporting~~ lnrpc: better payment failure reporting Sep 20, 2018

wpaulino mentioned this pull request Oct 12, 2018

Feature request - which hop is offline when paying #2043

Closed

Roasbeef requested review from halseth and removed request for halseth October 16, 2018 18:52

joostjager force-pushed the raw branch 2 times, most recently from f0ceaf6 to cb1dc9b Compare October 29, 2018 10:20

joostjager mentioned this pull request Nov 2, 2018

rpc+lnd: add new sub RPC server, Router service #2083

Merged

alexbosworth mentioned this pull request Nov 19, 2018

[Feature request] Structured payment errors #2201

Closed

Roasbeef requested changes Nov 20, 2018

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halseth suggested changes Nov 23, 2018

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Roasbeef removed this from the 0.6 milestone Jan 16, 2019

joostjager mentioned this pull request Feb 7, 2019

lnrpc: deprecate QueryRoutes with more than one route #2497

Merged

Roasbeef mentioned this pull request Feb 20, 2019

routing: return nicer error message when routes fail due to the fee limit #2660

Closed

3 tasks

joostjager force-pushed the raw branch from cb1dc9b to 00da13e Compare March 14, 2019 15:33

joostjager force-pushed the raw branch 2 times, most recently from 899376e to 7806475 Compare March 14, 2019 15:55

joostjager mentioned this pull request Mar 14, 2019

routerrpc: adapt to changed interfaces of routing subsystem #2781

Merged

joostjager force-pushed the raw branch from 7806475 to a09cf87 Compare March 27, 2019 16:33

joostjager force-pushed the raw branch 2 times, most recently from 4f9207c to e498f01 Compare May 6, 2019 19:28

cfromknecht added this to the 0.7 milestone May 7, 2019

Roasbeef requested changes May 11, 2019

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joostjager force-pushed the raw branch from e498f01 to 29e54ef Compare May 13, 2019 08:59

halseth reviewed May 13, 2019

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routerrpc: move UnmarshallRoute to sub server

0b66d56

joostjager force-pushed the raw branch from 29e54ef to 07964b4 Compare May 13, 2019 10:56

joostjager force-pushed the raw branch from 07964b4 to f7008ea Compare May 14, 2019 08:05

Roasbeef approved these changes May 15, 2019

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joostjager force-pushed the raw branch from f7008ea to 11adc91 Compare May 15, 2019 05:33

joostjager force-pushed the raw branch from 11adc91 to 566b924 Compare May 15, 2019 09:49

joostjager added 3 commits May 15, 2019 11:54

lnrpc+routing: Only accept a single route for SendToRoute

ba3fa94

routerrpc: connect UnmarshallRoute to existing config fields

b2eb261

routerrpc: add SendToRoute with structured failure message

c975926

joostjager force-pushed the raw branch from 566b924 to c975926 Compare May 15, 2019 09:54

halseth approved these changes May 15, 2019

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joostjager merged commit 863bf2f into lightningnetwork:master May 15, 2019

joostjager deleted the raw branch May 15, 2019 12:39

joostjager changed the title ~~lnrpc: better payment failure reporting~~ lnrpc: structured SendToRoute failure reporting May 15, 2019

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Background

Implementation details

Usage

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joostjager commented Aug 9, 2018

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esneider commented May 1, 2019

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joostjager commented May 13, 2019

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joostjager commented Jul 31, 2018 •

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