LIGHTNING-PAY(7)
================
:doctype: manpage

NAME
----
lightning-pay - Protocol for sending a payment to a BOLT11 invoice

SYNOPSIS
--------
*pay* 'bolt11' ['msatoshi'] ['description'] ['riskfactor'] ['maxfeepercent']

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,
'msatoshi' is required, otherwise if it is specified it must be 'null'.  If
'bolt11' contains a description hash ('h' field) 'description' is
required, otherwise it is unused.  The 'riskfactor' is described in detail
in lightning-getroute(7), and defaults to 1.0.
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 response will occur when the payment fails or succeeds.  Once a
payment has succeeded, calls to *pay* with the same 'bolt11' will
succeed immediately.

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

RETURN VALUE
------------

On success, this returns the payment 'preimage' which hashes to the
'payment_hash' to prove that the payment was successful.

On error, if the error occurred from a node other than the final
destination, the route table will be updated so that getroute(7)
should return an alternate route (if any).  An error from the final
destination implies the payment should not be retried.

The following error codes may occur:

* -1. Catchall nonspecific error.
* 200. A previous *sendpay* or *pay* is in progress.
* 201. Already paid with this 'hash' using different amount or
  destination.
* 202. Unparseable onion reply. The 'data' field of the error
  will have an 'onionreply' field, a hex string representation
  of the raw onion reply.
* 203. Permanent failure at destination. The 'data' field of
  the error will be routing failure object.
* 204. Failure along route; retry a different route. The 'data'
  field of the error will be routing failure object.
* 205. Unable to find a route.
* 206. Route too expensive. 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.
* 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.

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.


AUTHOR
------
Rusty Russell <rusty@rustcorp.com.au> is mainly responsible.

SEE ALSO
--------
lightning-listpayments(7), lightning-decodepay(7),
lightning-listinvoice(7), lightning-delinvoice(7),
lightning-getroute(7), lightning-invoice(7).

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