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Somehow this got lost in merging; pre-approved at meeting 2017-11-27. Reported-by: Pierre-Marie Padiou Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
39 lines
2.4 KiB
Markdown
39 lines
2.4 KiB
Markdown
# BOLT #9: Assigned Feature Flags
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This document tracks the assignment of `localfeatures` and `globalfeatures` flags in the `init` message ([BOLT #1](01-messaging.md)), as well as the `features` field in the `channel_announcement` message and `node_announcement` message ([BOLT #7](07-routing-gossip.md)).
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They are tracked separately since new flags will likely be added over time.
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The `features` flags in the routing messages are a subset of the `globalfeatures` flags, since the `localfeatures` are by definition only of interest to direct peers.
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Flags are numbered from the least-significant bit at bit 0 (ie. 0x1,
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an even bit). They are generally assigned in pairs, so that features
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can be introduced as optional (odd bits), and later upgraded to refuse
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old nodes (even bits). See [BOLT #1: The `init` message](01-messaging.md#the-init-message).
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## Assigned `localfeatures` flags
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These flags may only be used in the `init` message:
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| Bits | Name |Description | Link |
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|------|------------------|------------------------------------------------|---------------------------------------------------------------------|
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| 0/1 | `option-data-loss-protect` | Requires/supports extra `channel_reestablish` fields | [BOLT #2](02-peer-protocol.md#message-retransmission) |
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| 3 | `initial_routing_sync` | The sending node needs a complete routing information dump | [BOLT #7](07-routing-gossip.md#initial-sync) |
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| 4/5 | `option_upfront_shutdown_script` | Commit to a shutdown scriptpubkey when opening | [BOLT #2](02-peer-protocol.md#the-open_channel-message) |
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## Assigned `globalfeatures` flags
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## Requirements
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(Note that the requirements for feature bits which are not defined
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above, can be found in [BOLT #1: The `init` message](01-messaging.md#the-init-message)). The requirements when receiving set bits are defined in the linked section in the table above).
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## Rationale
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There's little point insisting on an `initial_routing_sync` (you can't
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tell if the remote node complies, and it has to know what it means as
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it's defined in the initial spec) so there's no even bit for that.
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<br>
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This work is licensed under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/).
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