Module lightning::chain::channelmonitor

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Expand description

The logic to monitor for on-chain transactions and create the relevant claim responses lives here.

ChannelMonitor objects are generated by ChannelManager in response to relevant messages/actions, and MUST be persisted to disk (and, preferably, remotely) before progress can be made in responding to certain messages, see chain::Watch for more.

Note that ChannelMonitors are an important part of the lightning trust model and a copy of the latest ChannelMonitor must always be actively monitoring for chain updates (and no out-of-date ChannelMonitors should do so). Thus, if you’re building rust-lightning into an HSM or other security-domain-separated system design, you should consider having multiple paths for ChannelMonitors to get out of the HSM and onto monitoring devices.

Structs

  • ChannelMonitor
    A ChannelMonitor handles chain events (blocks connected and disconnected) and generates on-chain transactions to ensure no loss of funds occurs.
  • ChannelMonitorUpdate
    An update generated by the underlying channel itself which contains some new information the ChannelMonitor should be made aware of.
  • HTLCUpdate
    Simple structure sent back by chain::Watch when an HTLC from a forward channel is detected on chain. Used to update the corresponding HTLC in the backward channel. Failing to pass the preimage claim backward will lead to loss of funds.

Enums

  • Balance
    Details about the balance(s) available for spending once the channel appears on chain.
  • MonitorEvent
    An event to be processed by the ChannelManager.

Constants

  • ANTI_REORG_DELAY
    Number of blocks we wait on seeing a HTLC output being solved before we fail corresponding inbound HTLCs. This prevents us from failing backwards and then getting a reorg resulting in us losing money.
  • CLOSED_CHANNEL_UPDATE_ID
    If: (1) a channel has been force closed and (2) we receive a preimage from a forward link that allows us to spend an HTLC output on this channel’s (the backward link’s) broadcasted commitment transaction then we allow the ChannelManager to send a ChannelMonitorUpdate with this update ID, with the update providing said payment preimage. No other update types are allowed after force-close.

Type Definitions