Introduces `frame`s and all related concepts such as `FRAME_SIZE`. It also
fixes a conceptual issue where `hops_data` would be used both for the section
of the overall packet as well as the wire format for individual payloads. This
separation now lends itself better to the incremental wrapping of the onion.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
The clarifications were tacked on after the fact, but they should really be
part of the conventions. I also updated the links to use the reference style,
which results in better text flow and makes it easier to read the source.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
914ebab908 effectively deprecated this, but
left it for "reject if more than 2x expected amount" case.
Leaving it for gross overpayment still leaves an attack on the current
network in practice (all implementations I know of reject grossly excessive
payments), and removing it causes our code to nicely break when regenerating,
since that error code is now not defined anywhere.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Because the errors are separate, if an intermediate node sees a
payment hash for relay and has several guesses as to the
destination of the payment, they can check their guesses by sending
HTLCs with the same payment hashes first and seeing the error sent
back.
By adding the htlc_msat that the final node received to
unknown_or_incorrect_payment_details, origin nodes can still
identify bad value-relaying peers.
This commit documents the allowance of non-strict
forwarding, permitting forwarding nodes to select
between any available outgoing channel with the peer
that would otherwise be specified by the
short_channel_id in the onion packet.
It also includes recommendations for fee schedules
when using non-strict forwarding, either by using
a uniform fee schedule with a peer or only
considering like-policied channels, to ensure the
channel is truly equivalent in terms of fee revenue
for the forwarder.
* BOLT 4: update sphinx packet test vector
In this commit, we update the test vector for the final onion packet. In
commit 068b0bccf9, the per-hop payloads
were updated to use 8 byte amounts everywhere. However, the test vectors
were not updated. In 578573f92f the test
vectors were updated to use the proper version prefix. However, this
assumed that the state of the vectors as is was correct.
To remedy this, we've updated the test vectors to reflect the final
result using the current format for encoding the per-hop payloads. This
final test vector was generated using the original tool that we used to
confirm compatibility between the C and Go versions.
The description now suggests the use of an ephemeral private key, so
the reference code is simplified by using that concept. The reference
code is also updated to make fewer calls to undefined functions.
The new description introduces the concept of an ephemeral private key,
which I find easier to reason about and suggests a linear instead of
quadratic construction algorithm.
second pass copy edit to line 253, according to stylesheet
update node terminology to remove ambiguity; update conventions section and implement consistent usage of terms: origin node, final node, processing node, hop, sending peer, and receiving peer
Complete rewrite, including a routing example and the new
min_final_cltv expirt. I hope this makes it clear.
(Thanks to everyone who reviewed and gave feedback; you rock!)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is a partial response to #250. Reordering the HMAC and Encrypt
steps do not give us much, but we might want to hide the route
length. So we suggest that the node should continue unwrapping until
the maximum route length of 20 is reached.
