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routing gossip: re-order initial sync & rebroadcast so it matches table of contents
This commit is contained in:
lisa neigut
Rusty Russell
parent
b73c77ffe9
commit
7d2c4d5542
@ -505,80 +505,6 @@ the channel when the peer reestablishes contact. Because gossip
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messages are batched and replace previous ones, the result may be a
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single seemingly-redundant update.
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## Initial Sync
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If a node requires an initial sync of gossip messages, it will be flagged
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in the `init` message, via a feature flag ([BOLT #9](09-features.md#assigned-localfeatures-flags)).
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Note that the `initial_routing_sync` feature is overridden (and should
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be considered equal to 0) by the `gossip_queries` feature if the
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latter is negotiated via `init`.
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Note that `gossip_queries` does not work with older nodes, so the
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value of `initial_routing_sync` is still important to control
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interactions with them.
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### Requirements
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An endpoint node:
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- if the `gossip_queries` feature is negotiated:
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- MUST NOT relay any gossip messages unless explicitly requested.
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- otherwise:
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- if it requires a full copy of the other endpoint's routing state:
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- SHOULD set the `initial_routing_sync` flag to 1.
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- upon receiving an `init` message with the `initial_routing_sync` flag set to
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1:
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- SHOULD send gossip messages for all known channels and nodes, as if they were just
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received.
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- if the `initial_routing_sync` flag is set to 0, OR if the initial sync was
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completed:
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- SHOULD resume normal operation, as specified in the following
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[Rebroadcasting](#rebroadcasting) section.
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## Rebroadcasting
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### Requirements
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The final node:
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- upon receiving a new `channel_announcement` or a `channel_update` or
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`node_announcement` with an updated `timestamp`:
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- SHOULD update its local view of the network's topology accordingly.
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- after applying the changes from the announcement:
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- if there are no channels associated with the corresponding origin node:
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- MAY purge the origin node from its set of known nodes.
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- otherwise:
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- SHOULD update the appropriate metadata AND store the signature
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associated with the announcement.
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- Note: this will later allow the final node to rebuild the announcement
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for its peers.
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An endpoint node:
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- if the `gossip_queries` feature is negotiated:
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- MUST not send gossip until it receives `gossip_timestamp_range`.
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- SHOULD flush outgoing gossip messages once every 60 seconds, independently of
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the arrival times of the messages.
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- Note: this results in staggered announcements that are unique (not
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duplicated).
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- MAY re-announce its channels regularly.
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- Note: this is discouraged, in order to keep the resource requirements low.
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- upon connection establishment:
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- SHOULD send all `channel_announcement` messages, followed by the latest
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`node_announcement` AND `channel_update` messages.
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### Rationale
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Once the gossip message has been processed, it's added to a list of outgoing
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messages, destined for the processing node's peers, replacing any older
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updates from the origin node. This list of gossip messages will be flushed at
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regular intervals; such a store-and-delayed-forward broadcast is called a
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_staggered broadcast_. Also, such batching forms a natural rate
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limit with low overhead.
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The sending of all gossip on reconnection is naive, but simple,
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and allows bootstrapping for new nodes as well as updating for nodes that
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have been offline for some time. The `gossip_queries` option
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allows for more refined synchronization.
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## Query Messages
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Negotiating the `gossip_queries` option enables a number of extended
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@ -764,6 +690,80 @@ implement.
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In the case where the `channel_announcement` is nonetheless missed,
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`query_short_channel_ids` can be used to retrieve it.
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## Initial Sync
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If a node requires an initial sync of gossip messages, it will be flagged
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in the `init` message, via a feature flag ([BOLT #9](09-features.md#assigned-localfeatures-flags)).
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Note that the `initial_routing_sync` feature is overridden (and should
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be considered equal to 0) by the `gossip_queries` feature if the
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latter is negotiated via `init`.
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Note that `gossip_queries` does not work with older nodes, so the
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value of `initial_routing_sync` is still important to control
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interactions with them.
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### Requirements
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An endpoint node:
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- if the `gossip_queries` feature is negotiated:
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- MUST NOT relay any gossip messages unless explicitly requested.
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- otherwise:
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- if it requires a full copy of the other endpoint's routing state:
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- SHOULD set the `initial_routing_sync` flag to 1.
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- upon receiving an `init` message with the `initial_routing_sync` flag set to
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1:
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- SHOULD send gossip messages for all known channels and nodes, as if they were just
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received.
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- if the `initial_routing_sync` flag is set to 0, OR if the initial sync was
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completed:
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- SHOULD resume normal operation, as specified in the following
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[Rebroadcasting](#rebroadcasting) section.
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## Rebroadcasting
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### Requirements
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A message receiving node:
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- upon receiving a new `channel_announcement` or a `channel_update` or
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`node_announcement` with an updated `timestamp`:
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- SHOULD update its local view of the network's topology accordingly.
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- after applying the changes from the announcement:
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- if there are no channels associated with the corresponding origin node:
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- MAY purge the origin node from its set of known nodes.
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- otherwise:
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- SHOULD update the appropriate metadata AND store the signature
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associated with the announcement.
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- Note: this will later allow the final node to rebuild the announcement
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for its peers.
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A node:
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- if the `gossip_queries` feature is negotiated:
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- MUST not send gossip until it receives `gossip_timestamp_range`.
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- SHOULD flush outgoing gossip messages once every 60 seconds, independently of
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the arrival times of the messages.
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- Note: this results in staggered announcements that are unique (not
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duplicated).
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- MAY re-announce its channels regularly.
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- Note: this is discouraged, in order to keep the resource requirements low.
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- upon connection establishment:
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- SHOULD send all `channel_announcement` messages, followed by the latest
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`node_announcement` AND `channel_update` messages.
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### Rationale
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Once the gossip message has been processed, it's added to a list of outgoing
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messages, destined for the processing node's peers, replacing any older
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updates from the origin node. This list of gossip messages will be flushed at
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regular intervals; such a store-and-delayed-forward broadcast is called a
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_staggered broadcast_. Also, such batching forms a natural rate
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limit with low overhead.
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The sending of all gossip on reconnection is naive, but simple,
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and allows bootstrapping for new nodes as well as updating for nodes that
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have been offline for some time. The `gossip_queries` option
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allows for more refined synchronization.
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## HTLC Fees
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### Requirements
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