lightning-pay -- Command for sending a payment to a BOLT11 invoice

SYNOPSIS

pay bolt11 [amount_msat] [label] [riskfactor]
[maxfeepercent] [retry_for] [maxdelay] [exemptfee]
[localinvreqid] [exclude] [maxfee] [description]

DESCRIPTION

The pay RPC command attempts to find a route to the given
destination, and send the funds it asks for. If the bolt11 does not
contain an amount, amount_msat is required, otherwise if it is specified
it must be null. amount_msat is in millisatoshi precision; it can be a
whole number, or a whole number with suffix msat or sat, or a three
decimal point number with suffix sat, or an 1 to 11 decimal point
number suffixed by btc.

(Note: if experimental-offers is enabled, bolt11 can actually be
a bolt12 invoice, such as one received from lightningd-fetchinvoice(7)).

The label field is used to attach a label to payments, and is returned
in lightning-listpays(7) and lightning-listsendpays(7). The riskfactor
is described in detail in lightning-getroute(7), and defaults to 10. The
maxfeepercent limits the money paid in fees, and defaults to 0.5. The
maxfeepercent is a percentage of the amount that is to be paid. The exemptfee
option can be used for tiny payments which would be dominated by the fee
leveraged by forwarding nodes. Setting exemptfee allows the
maxfeepercent check to be skipped on fees that are smaller than
exemptfee (default: 5000 millisatoshi).

localinvreqid is used by offers to link a payment attempt to a local
invoice_request offer created by lightningd-invoicerequest(7). This ensures
that we only make a single payment for an offer, and that the offer is
marked used once paid.

maxfee overrides both maxfeepercent and exemptfee defaults (and
if you specify maxfee you cannot specify either of those), and
creates an absolute limit on what fee we will pay. This allows you to
implement your own heuristics rather than the primitive ones used
here.

description is only required for bolt11 invoices which do not
contain a description themselves, but contain a description hash:
in this case description is required.
description is then checked against the hash inside the invoice
before it will be paid.

The response will occur when the payment fails or succeeds. Once a
payment has succeeded, calls to pay with the same bolt11 will
succeed immediately.

Until retry_for seconds passes (default: 60), the command will keep
finding routes and retrying the payment. However, a payment may be
delayed for up to maxdelay blocks by another node; clients should be
prepared for this worst case.

exclude is a JSON array of short-channel-id/direction (e.g. [
"564334x877x1/0", "564195x1292x0/1" ]) or node-id which should be excluded
from consideration for routing. The default is not to exclude any channels
or nodes.

When using lightning-cli, you may skip optional parameters by using
null. Alternatively, use -k option to provide parameters by name.

RANDOMIZATION

To protect user privacy, the payment algorithm performs some
randomization.

1: Route Randomization

Route randomization means the payment algorithm does not always use the
lowest-fee or shortest route. This prevents some highly-connected node
from learning all of the user payments by reducing their fees below the
network average.

2: Shadow Route

Shadow route means the payment algorithm will virtually extend the route
by adding delays and fees along it, making it appear to intermediate nodes
that the route is longer than it actually is. This prevents intermediate
nodes from reliably guessing their distance from the payee.

Route randomization will never exceed maxfeepercent of the payment.
Route randomization and shadow routing will not take routes that would
exceed maxdelay.

RETURN VALUE

On success, an object is returned, containing:

payment_preimage (secret): the proof of payment: SHA256 of this payment_hash
payment_hash (hash): the hash of the payment_preimage which will prove payment
created_at (number): the UNIX timestamp showing when this payment was initiated
parts (u32): how many attempts this took
amount_msat (msat): Amount the recipient received
amount_sent_msat (msat): Total amount we sent (including fees)
status (string): status of payment (one of "complete", "pending", "failed")
destination (pubkey, optional): the final destination of the payment

The following warnings may also be returned:

warning_partial_completion: Not all parts of a multi-part payment have completed

You can monitor the progress and retries of a payment using the
lightning-paystatus(7) command.

The following error codes may occur:

-1: Catchall nonspecific error.
201: Already paid with this hash using different amount or
destination.
203: Permanent failure at destination. The data field of the error
will be routing failure object (except for self-payment, which currently returns the error directly from lightning-sendpay(7)).
205: Unable to find a route.
206: Route too expensive. Either the fee or the needed total
locktime for the route exceeds your maxfeepercent or maxdelay
settings, respectively. The data field of the error will indicate
the actual fee as well as the feepercent percentage that the fee
has of the destination payment amount. It will also indicate the
actual delay along the route.
207: Invoice expired. Payment took too long before expiration, or
already expired at the time you initiated payment. The data field
of the error indicates now (the current time) and expiry (the
invoice expiration) as UNIX epoch time in seconds.
210: Payment timed out without a payment in progress.

Error codes 202 and 204 will only get reported at sendpay; in
pay we will keep retrying if we would have gotten those errors.

A routing failure object has the fields below:

erring_index: The index of the node along the route that reported
the error. 0 for the local node, 1 for the first hop, and so on.
erring_node: The hex string of the pubkey id of the node that
reported the error.
erring_channel: The short channel ID of the channel that has the
error, or 0:0:0 if the destination node raised the error.
failcode: The failure code, as per BOLT #4.
channel_update. The hex string of the channel_update message
received from the remote node. Only present if error is from the
remote node and the failcode has the UPDATE bit set, as per BOLT #4.

The data field of errors will include statistics getroute_tries and
sendpay_tries. It will also contain a failures field with detailed
data about routing errors.

AUTHOR

Rusty Russell <[email protected]> is mainly responsible.

RESOURCES

Main web site: https://github.com/ElementsProject/lightning