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[3/4] Route Blinding: send MPP over multiple blinded paths

Open ellemouton opened this issue 1 year ago • 1 comments

In this PR, we remove the restriction of only being able to send to a single blinded payment path. Nodes will now be able to take advantage of the multiple blinded paths provided for a given payment to perform MPP if needed.

Depends on: https://github.com/lightningnetwork/lnd/pull/8735 Tracking Issue: https://github.com/lightningnetwork/lnd/issues/6690

ellemouton avatar May 16 '24 08:05 ellemouton

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coderabbitai[bot] avatar May 16 '24 08:05 coderabbitai[bot]

Finally, there is one more assumption we make here: if a recipient provides us with a set of paths of various lengths but one of those paths is an intro-node-only path, then we just go ahead and discard the rest of the paths since it doesnt make sense to try those since we know that the intro node is the dest node.

I wonder if this would be considered a wrong behaviour of the person providing us the invoice, so maybe we should consider this as an invalid invoice to spot wrong implementations ?

ziggie1984 avatar Jul 21 '24 17:07 ziggie1984

@ellemouton, remember to re-request review from reviewers when ready

lightninglabs-deploy avatar Jul 29 '24 12:07 lightninglabs-deploy

I went to create an invoice with a blinded path on testnet, and ran into this panic:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x143a82b]

goroutine 4084 [running]:
github.com/lightningnetwork/lnd/routing.(*ChannelRouter).FindBlindedPaths(0xc0022b6f00, {0x2, 0x70, 0x68, 0x5c, 0xa8, 0x1a, 0x8e, 0x4d, 0x4d, ...}, ...)
	github.com/lightningnetwork/[email protected]/routing/router.go:727 +0x64b
github.com/lightningnetwork/lnd.(*rpcServer).AddInvoice.func3(0x20?)
	github.com/lightningnetwork/[email protected]/rpcserver.go:5816 +0x97
github.com/lightningnetwork/lnd/lnrpc/invoicesrpc.buildBlindedPaymentPaths(0xc0070713e0)
	github.com/lightningnetwork/[email protected]/lnrpc/invoicesrpc/addinvoice.go:1054 +0x42
github.com/lightningnetwork/lnd/lnrpc/invoicesrpc.AddInvoice({0x36f9090, 0xc003fc4450}, 0xc004d95080, 0xc0070715c8)
	github.com/lightningnetwork/[email protected]/lnrpc/invoicesrpc/addinvoice.go:517 +0x108e
github.com/lightningnetwork/lnd.(*rpcServer).AddInvoice(0xc00061a600, {0x36f9090, 0xc003fc4450}, 0xc001487980)
	github.com/lightningnetwork/[email protected]/rpcserver.go:5856 +0x6a5
github.com/lightningnetwork/lnd/lnrpc._Lightning_AddInvoice_Handler.func1({0x36f9090?, 0xc003fc4450?}, {0x22965c0?, 0xc001487980?})
	github.com/lightningnetwork/[email protected]/lnrpc/lightning_grpc.pb.go:2610 +0xcb
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).CreateServerOpts.(*InterceptorChain).middlewareUnaryServerInterceptor.func7({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980}, 0xc00391a660, 0xc002205ec0)
	github.com/lightningnetwork/[email protected]/rpcperms/interceptor.go:832 +0x111
google.golang.org/grpc.getChainUnaryHandler.func1({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980})
	google.golang.org/[email protected]/server.go:1163 +0xb2
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).CreateServerOpts.(*InterceptorChain).MacaroonUnaryServerInterceptor.func5({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980}, 0xc00391a660?, 0xc003f8fec0)
	github.com/lightningnetwork/[email protected]/rpcperms/interceptor.go:689 +0x7d
google.golang.org/grpc.getChainUnaryHandler.func1({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980})
	google.golang.org/[email protected]/server.go:1163 +0xb2
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).CreateServerOpts.(*InterceptorChain).rpcStateUnaryServerInterceptor.func3({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980}, 0xc00391a660, 0xc002b80900)
	github.com/lightningnetwork/[email protected]/rpcperms/interceptor.go:781 +0xfc
google.golang.org/grpc.getChainUnaryHandler.func1({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980})
	google.golang.org/[email protected]/server.go:1163 +0xb2
github.com/lightningnetwork/lnd/rpcperms.(*InterceptorChain).CreateServerOpts.errorLogUnaryServerInterceptor.func1({0x36f9090?, 0xc003fc4450?}, {0x22965c0?, 0xc001487980?}, 0xc00391a660, 0xc002205ec0?)
	github.com/lightningnetwork/[email protected]/rpcperms/interceptor.go:605 +0x52
google.golang.org/grpc.NewServer.chainUnaryServerInterceptors.chainUnaryInterceptors.func1({0x36f9090, 0xc003fc4450}, {0x22965c0, 0xc001487980}, 0xc00391a660, 0x78?)
	google.golang.org/[email protected]/server.go:1154 +0x85
github.com/lightningnetwork/lnd/lnrpc._Lightning_AddInvoice_Handler({0x22d29c0, 0xc00061a600}, {0x36f9090, 0xc003fc4450}, 0xc004b3b280, 0xc0007747a0)
	github.com/lightningnetwork/[email protected]/lnrpc/lightning_grpc.pb.go:2612 +0x143
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0002661e0, {0x36f9090, 0xc003ed0f30}, {0x3708e60, 0xc004871a00}, 0xc002440240, 0xc000769770, 0x4a551d8, 0x0)
	google.golang.org/[email protected]/server.go:1343 +0xdd1
google.golang.org/grpc.(*Server).handleStream(0xc0002661e0, {0x3708e60, 0xc004871a00}, 0xc002440240)
	google.golang.org/[email protected]/server.go:1737 +0xc47
google.golang.org/grpc.(*Server).serveStreams.func1.1()
	google.golang.org/[email protected]/server.go:986 +0x86
created by google.golang.org/grpc.(*Server).serveStreams.func1 in goroutine 4083
	google.golang.org/[email protected]/server.go:997 +0x136

Perhaps it's the case of a missing edge policy: https://github.com/ellemouton/lnd/blob/53dab50d393f3acf80d846e5bdcbdad8ee4b6cb5/routing/router.go#L725-L728

Roasbeef avatar Jul 30 '24 01:07 Roasbeef

Can be rebased to point to master now!

Roasbeef avatar Jul 30 '24 02:07 Roasbeef

Hmm seems like we need to check that the inpolicy is not nil as we already do in other parts in the routing codebase ?

// If there is no edge policy for this candidate node, skip.
		// Note that we are searching backwards so this node would have
		// come prior to the pivot node in the route.
		if channel.InPolicy == nil {
			return nil
		}

ziggie1984 avatar Jul 30 '24 15:07 ziggie1984

@ziggie1984 yep was thinking the same thing, I'll add that then try again. FWIW, this is a very very very old node, which makes it great for testing!

Roasbeef avatar Jul 30 '24 18:07 Roasbeef

oops - I accidentally clicked re-request @ziggie1984 🙈 sorry about that

ellemouton avatar Jul 31 '24 08:07 ellemouton

Tried out the latest branch, and I was able to make an initial blinded paths payment!

Ran into some other issues along the way:

  • When trying to pay with default settings, I got INVALID_ONION_BLINDING each time.
  • That was with a node that may have been added within the blinded path as I had a direct channel with it.
  • I then tried to reduce max-num-paths to 1, initially thinking it woudl give me only 1 hop routes, but I understand now that means only have a single path.
  • After that I got some errors where it was unable to make a path at all: 
     tlncli addinvoice --amt=100 --blind
[lncli] rpc error: code = Unknown desc = could not collect blinded path relay info: no channel updates found from node 
022fb1230aefbd135141997f03343f5410e6f1ab11d337af6df92cb67d5a856748 for channel 2681963946846388225
 tlncli addinvoice --amt=100 --blind
[lncli] rpc error: code = Unknown desc = could not build any blinded paths
    • Perhaps we should have an inner retry loop here. I did the command a few more times until one of them finally worked.
  • I tried again with only a single blinded path ( max-num-paths=1):
    • The first time around, it was trying to find very long routes to the dest, and failing: TEMPORARY_CHANNEL_FAILURE @ 2nd hop | 34.580 | 36.342 | 100 | 2.707 | 2871717 | 3157069518315978752 | 030f375d8aecdddc8523->24hr Drive Thru->POSTECHCCBR->TuDuD->lnd-test.24h.to->SOMBERMASTER->039c25->025eac
    • I tried again, with the path succeeding with a route of similar length:
    | SUCCEEDED                           |        1.229 |        6.271 | 100          | 3.106 |  2871679 | 3157069
518315978752 | 030f375d8aecdddc8523->aranguren.org->OCEAN_TESTNET_WK1->03fef5->022060 |
+-------------------------------------+--------------+--------------+--------------+-------+----------+------------ 
---------+------------------------------------------------------------------------+
Amount + fee:   100 + 3.106 sat
Payment hash:   ab44ac84be151fde822a7dda35a7acf908d431ad719850ddfddccdb05220d38e
Payment status: SUCCEEDED, preimage: 
b6243fdf1869bae1c962c5b528b8ba563845bad51320bebd921635cbb2044ed2

Roasbeef avatar Aug 01 '24 02:08 Roasbeef

I think the instances of INVALID_ONION_BLINDING might be older nodes on testnet that aren't running the latest version of blinded paths.

Some other featrure requests after trying things out:

  • Command to unblind blinded paths as the creator. Can be useful for debugging.
  • All dynamically setting values like num paths and path length via lncli addinvoice. During testing I had to restart each time I wanted to mess with a different value.
  • Add ability to omit a node from the blinded path. Would've been useful to pinpoint if it's just certain nodes sending INVALID_ONION_BLINDING errors.

Roasbeef avatar Aug 01 '24 02:08 Roasbeef