discovery/gossiper: reliably send channel update msg to remote peer #1595

wpaulino · 2018-07-20T19:38:19Z

In this commit, we address an issue where it's possible that we failed
to send the channel update message for a channel to the remote peer due
to them being offline. This would cause issues with private channels, as
a channel update message is needed for the remote peer to be aware of
the channel's forwarding policy. Due to the latest changes to
NotifyWhenOnline, we can now attempt to send the message every time we
detect the remote peer is online until success.

Depends on #1505.
Fixes #1347.

discovery/gossiper.go

robtex · 2018-10-09T06:37:04Z

Any updates on this? I experience this a lot since i tend to leave the house without waiting for X confirmations for my mobile wallet to establish a channel.
Workaround would be to permanently disable wifi or leave phone at home when i walk the dogs, but it feels a bit wrong.

wpaulino · 2018-10-09T09:28:06Z

@robtex hoping to get this addressed within the next week or two.

Roasbeef · 2019-01-04T22:43:26Z

Bump on this PR.

halseth · 2019-02-04T12:45:41Z

Looks more or less LGTM, just a few suggestions 😁

joostjager · 2019-02-05T10:33:06Z

When we merge this, the downgrade path to 0.5.2 will be closed because of the db migration in this PR.

wpaulino · 2019-02-06T02:04:43Z

Broke up the reliable send logic into its own file. PTAL @cfromknecht @halseth.

discovery/message_store_test.go

discovery/reliable_sender.go

discovery/gossiper.go

wpaulino · 2019-02-14T23:37:41Z

PTAL @halseth @cfromknecht.

discovery/reliable_sender.go

discovery/gossiper.go

discovery/reliable_sender.go

discovery/gossiper.go

In this commit, we add a new store within the database that'll be responsible for storing gossip messages which we need to reliably send to peers. This aims to replace the current messageStore that exists within the gossiper, so much of this logic is borrowed from there. One of the main differences between the two is that we now index messages with a new key format in which we take into account the message's type. This allows us to store different messages for a specific channel with a peer. The old key format is still supported in order to prevent a database migration.

In this commit, we introduce a migration for the message store sub-bucket that will migrate all keys within it to a new key format. This new key format is composed of the peer's public key, followed by the short channel ID, followed by the message type. This migration is needed in order to provide backwards-compatibility with messages that were previously stored before the introduction of the new key format.

Now that we've replaced the built-in messageStore with the channeldb.GossipMessageStore, the reference to channeldb.DB is no longer needed.

In this commit, we implement a new subsystem for the gossiper that uses some of the existing logic for resending channel announcement signatures and implements it in a way to make it message-agnostic, meaning that any type of message can be resent. Along the way we also modify the way this works to prevent multiple goroutines per peer _and_ message. A peerHandler will be spawned for each peer for which we attempt to send a message reliably to. This handler is responsible for managing requests to reliably send messages to a peer while also taking the peer's connection lifecycle into account by requesting notifications for when the peer connects/disconnects. A peer connection notification is first requested to determine when we should attempt to send any pending messages. After the messages are sent, a peer disconnection notification is requested to ensure we don't continue to request connection notifications while the peer remains connected. Once there are no more pending messages left to be sent for a given peer, the peerHandler can be torn down.

In this commit, we also allow channel updates for our channels to be sent reliably to our channel counterparty. This is especially crucial for private channels, since they're not announced, in order to ensure each party can receive funds from the other side.

cfromknecht · 2019-02-15T23:50:21Z

Tested the migration via dryrun on my mainnet node, no issues to report. Very clean and structured PR, LGTM 🔥

Roasbeef · 2019-02-19T01:55:53Z

So do we want to add the --no-db-migrations option before we merge this in? I'm not sure how widely advertised it'll be since it won't be in any release notes, but I have no strong arguments against it. In a similar vein, we should also add a --no-commit-updates mode that allows lnd to come up, but ensure that it won't sign any commitment updates (maybe just disables all the channels), nor will it allow any sort of force close at all. This would make restoring from a "dirty" back up a little bit more save.

halseth

This PR LGTM now ⚡️

halseth · 2019-02-19T13:55:55Z

discovery/gossiper.go

+			// to assemble the full proof yet (maybe because of a crash),
+			// we will send them the full proof if we notice that they
+			// retry sending their half proof.
+			if chanInfo.AuthProof != nil {


Check can be removed indeed. Not that it matters though...

halseth · 2019-02-19T13:57:21Z

discovery/reliable_sender.go

+	}
+
+	// Otherwise, we'll attempt to stream the message to the handler.
+	// There's a subtle race condition where the handler can be torn down


This is still a bit strange, but I guess it is okay 🙃 Current solution should work.

I don't think there are any other ways around it. Do you have any suggestions?

wpaulino changed the title ~~Send channel update reliably~~ discovery/gossiper: reliably send channel update msg to remote peer Jul 20, 2018

wpaulino assigned wpaulino and unassigned wpaulino Jul 20, 2018

wpaulino added discovery Peer and route discovery / whisper protocol related issues/PRs P3 might get fixed, nice to have needs review PR needs review by regular contributors needs testing PR hasn't yet been actively tested on testnet/mainnet labels Jul 20, 2018

wpaulino force-pushed the send-channel-update-reliably branch 2 times, most recently from b3f3aa9 to 23d81bd Compare July 21, 2018 00:51

halseth reviewed Jul 24, 2018

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Roasbeef added this to the 0.5 milestone Aug 1, 2018

wpaulino force-pushed the send-channel-update-reliably branch from 23d81bd to e64662d Compare August 14, 2018 19:20

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wpaulino force-pushed the send-channel-update-reliably branch from e64662d to 9749e00 Compare September 7, 2018 06:00

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Roasbeef mentioned this pull request Oct 9, 2018

No channel_update is sent to non-public channels #1347

Closed

wpaulino mentioned this pull request Oct 22, 2018

rpc+server: ensure we don't leak unadvertised nodes within invoice routing hints #1981

Merged

Perlover mentioned this pull request Nov 16, 2018

The changing of the feerate in config doesn't affect to new channels #2184

Closed

Roasbeef added reviewee-respond and removed needs review PR needs review by regular contributors labels Jan 4, 2019

wpaulino dismissed cfromknecht’s stale review via 1e2a0cb February 6, 2019 01:49

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wpaulino added 8 commits February 14, 2019 18:29

server+discovery: replace gossiper message store with MessageStore

2277535

server+discovery: remove channeldb.DB reference within the gossiper

73b4bc4

Now that we've replaced the built-in messageStore with the channeldb.GossipMessageStore, the reference to channeldb.DB is no longer needed.

discovery/gossiper_test: prevent race conditions within mockGraphSource

6e556aa

server+discovery: use reliableSender to replace existing resend logic

4996d49

wpaulino force-pushed the send-channel-update-reliably branch from e3e0ec5 to 12168f0 Compare February 15, 2019 02:33

cfromknecht approved these changes Feb 15, 2019

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halseth approved these changes Feb 19, 2019

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Roasbeef merged commit 2bf2261 into lightningnetwork:master Feb 20, 2019

wpaulino deleted the send-channel-update-reliably branch February 20, 2019 07:44

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discovery/gossiper: reliably send channel update msg to remote peer #1595

discovery/gossiper: reliably send channel update msg to remote peer #1595

wpaulino commented Jul 20, 2018

robtex commented Oct 9, 2018

wpaulino commented Oct 9, 2018

Roasbeef commented Jan 4, 2019

halseth commented Feb 4, 2019

joostjager commented Feb 5, 2019

wpaulino commented Feb 6, 2019

wpaulino commented Feb 14, 2019

cfromknecht commented Feb 15, 2019

Roasbeef commented Feb 19, 2019 •

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wpaulino Feb 19, 2019

discovery/gossiper: reliably send channel update msg to remote peer #1595

discovery/gossiper: reliably send channel update msg to remote peer #1595

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wpaulino commented Jul 20, 2018

robtex commented Oct 9, 2018

wpaulino commented Oct 9, 2018

Roasbeef commented Jan 4, 2019

halseth commented Feb 4, 2019

joostjager commented Feb 5, 2019

wpaulino commented Feb 6, 2019

wpaulino commented Feb 14, 2019

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