The shadow route algorithm is extending the route randomly using channels
adjacent to the current destination, in the hope to create a plausible route
extension. However, instead of only retrieving the channels adjacent to the
destination it was retrieving all channels in the entire topology, and
selecting a random channel from there. This resulted in a very large request
for all channels being processed, and then mostly not being used, but also in
shadow extensions to the path which were not plausible (they didn't extend the
real path, just random edges). This is fixed by restricting the call to
`listchannels` to the channels with the current destination as source.
On my laptop retrieving all channels in the current mainnet takes
approximately 1.2 seconds, and given the geometric series expansion of the 50%
extension probability this indeed would result in an overhead of 1.2 seconds
to the `pay` command. In contrast specifying a source results in an overhead
of ~30ms.
So good news everyone, your pay commands just shaved 1.17 seconds off their
runtime.
Changelog-Changed: pay: Improved the performance of the `pay`-plugin by limiting the `listchannels` when computing the shadow route.
Changelog-Fixed: pay: The `pay`-plugin was generating non-contiguous shadow routes
Turns out that unnecessary: all callers can access the feature_set,
so make it much more like a normal primitive.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is a common thing to do, so create a macro.
Unfortunately, it still needs the type arg, because the paramter may
be const, and the return cannot be, and C doesn't have a general
"(-const)" cast.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Before this patch we used to send `double`s over the wire by just
copying them. This is not portable because the internal represenation
of a `double` is implementation specific.
Instead of this, multiply any floating-point numbers that come from
the outside (e.g. JSONs) by 1 million and round them to integers when
handling them.
* Introduce a new param_millionths() that expects a floating-point
number and returns it multipled by 1000000 as an integer.
* Replace param_double() and param_percent() with param_millionths()
* Previously the riskfactor would be allowed to be negative, which must
have been unintentional. This patch changes that to require a
non-negative number.
Changelog-None
This adds helpers to start and send a jsonrpc request using json_stream
in order to benefit from the helpers.
This then simplifies existing plugins RPC requests by using json_stream
helpers.
Before this patch we used `int` for error codes. The problem with
`int` is that we try to pass it to/from wire and the size of `int` is
not defined by the standard. So a sender with 4-byte `int` would write
4 bytes to the wire and a receiver with 2-byte `int` (for example) would
read just 2 bytes from the wire.
To resolve this:
* Introduce an error code type with a known size:
`typedef s32 errcode_t`.
* Change all error code macros to constants of type `errcode_t`.
Constants also play better with gdb - it would visualize the name of
the constant instead of the numeric value.
* Change all functions that take error codes to take the new type
`errcode_t` instead of `int`.
* Introduce towire / fromwire functions to send / receive the newly added
type `errcode_t` and use it instead of `towire_int()`.
In addition:
* Remove the now unneeded `towire_int()`.
* Replace a hardcoded error code `-2` with a new constant
`INVOICE_EXPIRED_DURING_WAIT` (903).
Changelog-Changed: The waitinvoice command would now return error code 903 to designate that the invoice expired during wait, instead of the previous -2
Changelog-Fixed: Detect a previously non-permanent error (`final_cltv_too_soon`) that has been merged into a permanent error (`incorrect_or_unknown_payment_details`), and retry that failure case in `pay`.
This won't usually be visible to the end-user, since the pay plugin doesn't
do multi-part yet (and mpp requires EXPERIMENTAL_FEATURES), but we're ready
once it does.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The pay plugin has been supplying the bolt11 string since 0.7.0, so only
ancient "pay" commands would be omitted by this change.
You can create a no-bolt11 "sendpay" manually, but then you'll find it
in 'listsendpays'.
Changelog-Removed: JSON: `listpays` won't shown payments made via sendpay without a bolt11 string, or before 0.7.0.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When doing the random walk through the channel, we now add the fees
(both the base and the proportional one) for that channel in addition to
the cltv delta.
Changelog-Added: Payment amount fuzzing is restored, but through shadow routing.
The string cut & paste hack was nasty; make ->failure a json_out
object so we can splice it in properly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We now hand around struct json_out members, rather than using formatted
strings, so plugins need to construct them properly.
There's no automatic conversion between ' and " any more, so those
are eliminated too. pay still uses some manual construction of elements.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I tried to just do gossipd, but it was uncontainable, so this ended up being
a complete sweep.
We didn't get much space saving in gossipd, even though we should save
24 bytes per node.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
*best is checked for null before the comparison against the uninitialized
variable ever happens, so this isn't a real issue.
Initialize it to zero so that we don't fail to compile on certain gcc versions.
plugins/pay.c: In function ‘add_shadow_route’:
plugins/pay.c:644:18: error: ‘sample’ may be used uninitialized in this function
if (!best || v > sample) {
~~^~~~~~~~
Signed-off-by: William Casarin <jb55@jb55.com>
New name is less confusing, and most people should be transitioning to
listpays rather than this anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is to future-proof against multi-part-payments: the low-level commands
will start returning multiple results once we have that, so prepare
transition plan now.
Closes: #2372
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is the same deprecation, but one level up. For the moment, we
still support invoices with a `h` field (where description will be
necessary) but that will be removed once this option is removed.
Note that I just changed pylightning without backwards compatibility,
since the field was unlikely to be used, but we could do something
more complex here?
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We need to do it in various places, but we shouldn't do it lightly:
the primitives are there to help us get overflow handling correct.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is particularly interesting because we handle overflow during route
calculation now; this could happen in theory once we wumbo.
It fixes a thinko when we print out routehints, too: we want to print
them out literally, not print out the effect they have on fees (which
is in the route, which we also print).
This ABI change doesn't need a CHANGELOG, since paystatus is new since
release.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We need to still accept it when parsing the database, but this flag
should allow upgrade testing for devs building on top
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Up until now, riskfactor was useless due to implementation bugs, and
also the default setting is wrong (too low to have an effect on
reasonable payment scenarios).
Let's simplify the definition (by assuming that P(failure) of a node
is 1), to make it a simple percentage. I examined the current network
fees to see what would work, and under this definition, a default of
10 seems reasonable (equivalent to 1000 under the old definition).
It is *this* change which finally fixes our test case! The riskfactor
is now 40msat (1500000 * 14 * 10 / 5259600 = 39.9), comparable with
worst-case fuzz is 50msat (1001 * 0.05 = 50).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is the direct cause of the failure of the original
test_pay_direct test and it makes sense: invoice routehints may not be
necessary, so try without them *first* rather than last.
We didn't mention the use of routehints in CHANGELOG at all yet, so
do that now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Christian points out that we can iterate by ->size rather than calling
json_next() to find the end (which traverses the entire object!).
Now ->size is reliable (since previous patch), this is OK.
Reported-by: @cdecker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Avoid the unnecessary extra var, and don't use "capacity" since
that usually refers to static capacity.
Reported-by: @cdecker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
So add a new 'strategy' field. This makes it clearer what is going
on, currently one of:
* "Initial attempt"
* "Excluded channel <scid>"
* "Removed route hint"
* "Excluded expensive channel <scid>"
* "Excluded delaying channel <scid>"
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We sanitize the routes: firstly, we assume appending so eliminate the
first hop if the route points straight to us. Secondly, eliminate empty
hints. Thirdly, trim overlong hints.
Then we just use the first route hint.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We use the 'exclude' option to getroute for successive attempts. This
is more robust than having gossipd disable for some limited time.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I wrote this sync first, then rewrote async, then developed libplugin.
But committing all that just wastes reviewer time, so I present it as
if it was always asnc and using the library helper.
Currently the command it registers is 'pay2', but when it's complete
we'll remove the internal 'pay' and rename it. This does a single
'getroute/sendpay' call. No retries, no options.
Shockingly, this by itself is almost sufficient to pass our current test
suite with `pay`->`pay2`.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
