Newsletters: add bitcoinops#30 (2019-01-22)

Author: harding

_posts/en/newsletters/2019-01-22-newsletter.md

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+---
+title: 'Bitcoin Optech Newsletter #30'
+permalink: /en/newsletters/2019/01/22/
+name: 2019-01-22-newsletter
+type: newsletter
+layout: newsletter
+lang: en
+---
+This week's newsletter describes a proposed LN feature to allow making
+spontaneous payments and provides our longest-ever list of notable code
+changes to popular Bitcoin infrastructure projects.
+
+## News
+
+- **PR opened for spontaneous LN payments:** LN protocol developer
+  Olaoluwa Osuntokun opened a [pull request][spontaneous payments] to
+  allow an LN node to send a payment to another node without first
+  receiving an invoice.  This takes advantage of LN's Tor-like onion
+  routing by allowing a spender to choose a preimage, encrypt it so
+  that only the receiver's node can decrypt it, and then route a payment
+  along LN like normal using the hash of the preimage.  When the
+  payment reaches the receiver, they decrypt the preimage and disclose
+  it to the routing nodes in order to claim the payment.
+
+    Spontaneous payments
+    help in cases where users just want to do ad hoc payment
+    tracking, for example you initiate a 10 mBTC withdrawal from an
+    exchange and either 10 mBTC shows up in your balance within a few
+    moments or you contact support.  Or you just publish your node's
+    information and users can send you donations without having to get
+    an invoice first.  For tracking specific payments, users
+    should still continue to generate invoices which can be uniquely
+    associated with particular orders or other expected payments.
+
+    Osuntokun's pull request for LND is still marked as a work in
+    progress as of this writing, so we don't know yet when the feature
+    will become generally available to LND users or whether other LN
+    implementations will also provide the same feature in a compatible
+    way.
+
+## Optech recommends
+
+If you prefer listening to audio rather than reading the weekly Optech
+newsletter, Max Hillebrand of World Crypto Network has recorded readings
+of every newsletter to date---providing a total of more than 6 hours of
+technical news about Bitcoin so far.  Audio and video is available on
+[YouTube][wcn optech playlist], and audio only is also available as a
+podcast via [iTunes][wcn itunes] and [acast][wcn acast].  Optech thanks
+Max for volunteering to perform the readings and for doing them so well.
+We encourage everyone who would prefer to receive the newsletter in
+video or audio form to follow Max for future readings.
+
+## Notable code changes
+
+*Notable code changes this week in [Bitcoin Core][bitcoin core repo],
+[LND][lnd repo], [C-Lightning][c-lightning repo], [Eclair][eclair repo],
+and [libsecp256k1][libsecp256k1 repo].*
+
+- [Bitcoin Core #14941][] makes the `unloadwallet` RPC synchronous.
+  It won't return now until the specified wallet has finished being
+  unloaded.
+
+- [Bitcoin Core #14982][] adds a new `getrpcinfo` RPC that provides
+  information about the RPC interface.  Right now it returns an
+  `active_commands` array listing all RPCs that haven't returned yet.
+
+- [LND #2448][] adds a standalone watchtower, allowing it to "negotiate
+  sessions with clients, accept state updates for active sessions,
+  monitor the chain for breaches matching known breach hints, [and] publish
+  reconstructed justice transactions on behalf of tower clients."
+  This is one of the last pieces of an initial watchtower implementation
+  than can help protect LN nodes that are offline from having their
+  funds stolen---a feature that's an important part of making LN mature
+  enough for general use.
+
+- [LND #2439][] adds the default policy for the watchtower, such as
+  allowing the tower to handle a maximum of 1,024 updates from a client
+  in a single session, allowing the watchtower to receive a reward of 1%
+  of the channel capacity if the tower ends up defending the channel,
+  and setting the default onchain feerate for justice transactions
+  (breach remedy transactions).
+
+- [LND #2198][] gives the `sendcoins` RPC a new `sweepall` parameter
+  that will spend all of the wallet's bitcoins to the specified address
+  without the user having to manually specify the amount.
+
+- [C-Lightning #2232][] extends the `listpeers` command with a new
+  `funding_allocation_msat` field that returns the amounts initially
+  placed into a channel by each peer.
+
+- [C-Lightning #2234][] extends the `listchannels` RPC to take a
+  `source` parameter for filtering by node id.  The same pull request also
+  causes the `invoice` RPC to include route hints for private channels
+  if you have no public channels unless you also set the new
+  `exposeprivatechannels` parameter to false.  Route hints suggest part
+  of a routing path to the spender so they can send payments through
+  nodes they previously didn't know about.
+
+- [C-Lightning #2249][] enables plugins by default on C-Lightning again,
+  but a note is added to their documentation indicating that the API is
+  still "under active development".
+
+- [C-Lightning #2215][] adds a libplugin library that provides a
+  C-language API for plugins.
+
+- [C-Lightning #2237][] gives plugins the ability to register hooks for
+  certain events that can change how the main process handles those
+  events.  An example given in the code is a plugin that prevents the LN
+  node from committing to a payment until a backup of important
+  information about the payment has been completed.
+
+- [Eclair #762][] adds limited probing.  Probing in LN is sending an
+  invalid payment to a node and waiting for it to return an error.  If
+  the node doesn't return an error, it likely means that it or some
+  other node along a payment path to it is offline and unable to process
+  payments.  Because the probe was an invalid payment that can never be
+  redeemed, the sending node can immediately treat it as a timed out
+  payment with no risk of loss.  This update to Eclair only allows
+  probing a node's direct peers---the nodes with which Eclair has an
+  open channel.
+
+{% include references.md %}
+{% include linkers/issues.md issues="14941,14982,2448,2439,2198,2232,2234,2249,2215,2237,762" %}
+[spontaneous payments]: https://github.com/lightningnetwork/lnd/pull/2455
+[wcn optech playlist]: https://www.youtube.com/playlist?list=PLPj3KCksGbSY9pV6EI5zkHcut5UTCs1cp
+[wcn itunes]: https://itunes.apple.com/us/podcast/the-world-crypto-network-podcast/id825708806
+[wcn acast]: https://play.acast.com/s/world-crypto-network