The \fBpay\fR RPC command attempts to find a route to the given destination, and send the funds it asks for\&. If the \fIbolt11\fR does not contain an amount, \fImsatoshi\fR is required, otherwise if it is specified it must be \fInull\fR\&. If \fIbolt11\fR contains a description hash (\fIh\fR field) \fIdescription\fR is required, otherwise it is unused\&. The \fIriskfactor\fR is described in detail in lightning\-getroute(7), and defaults to 1\&.0\&. The \fImaxfeepercent\fR limits the money paid in fees, and defaults to 0\&.5\&. The maxfeepercent\*(Aq 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)\&.
The \fBpay\fR RPC command attempts to find a route to the given destination, and send the funds it asks for\&. If the \fIbolt11\fR does not contain an amount, \fImsatoshi\fR is required, otherwise if it is specified it must be \fInull\fR\&. If \fIbolt11\fR contains a description hash (\fIh\fR field) \fIdescription\fR is required, otherwise it is unused\&. The \fIriskfactor\fR is described in detail in lightning\-getroute(7), and defaults to 1\&.0\&. The \fImaxfeepercent\fR limits the money paid in fees, and defaults to 0\&.5\&. The maxfeepercent\*(Aq 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)\&.
.sp
.sp
The \fBpay\fR RPC command will randomize routes slightly, as long as the route achieves the targeted \fImaxfeepercent\fR and \fImaxdelay\fR\&.
.sp
The response will occur when the payment fails or succeeds\&. Once a payment has succeeded, calls to \fBpay\fR with the same \fIbolt11\fR will succeed immediately\&.
The response will occur when the payment fails or succeeds\&. Once a payment has succeeded, calls to \fBpay\fR with the same \fIbolt11\fR will succeed immediately\&.
.sp
.sp
The command will keep finding routes and retrying the payment until it succeeds, or the given \fIretry_for\fR seconds passes\&. Note that the command may stop retrying while a pending payment is ongoing, which you need to monitor with \fBlistpayments\fR or \fBwaitsendpay\fR\&. \fIretry_for\fR defaults to 60 seconds and can only be an integer\&.
The command will keep finding routes and retrying the payment until it succeeds, or the given \fIretry_for\fR seconds passes\&. Note that the command may stop retrying while a pending payment is ongoing, which you need to monitor with \fBlistpayments\fR or \fBwaitsendpay\fR\&. \fIretry_for\fR defaults to 60 seconds and can only be an integer\&.
.sp
.sp
When using \fIlightning\-cli\fR, you may skip optional parameters by using \fInull\fR\&. Alternatively, use \fB\-k\fR option to provide parameters by name\&.
When using \fIlightning\-cli\fR, you may skip optional parameters by using \fInull\fR\&. Alternatively, use \fB\-k\fR option to provide parameters by name\&.
.SH"RANDOMIZATION"
.sp
To protect user privacy, the payment algorithm performs some randomization\&.
.sp
.RS4
.ien\{\
\h'-04' 1.\h'+01'\c
.\}
.el\{\
.sp-1
.IP" 1."4.2
.\}
Route Randomization
.RE
.sp
.RS4
.ien\{\
\h'-04' 2.\h'+01'\c
.\}
.el\{\
.sp-1
.IP" 2."4.2
.\}
Value Randomization
.RE
.sp
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\&.
.sp
Value randomization means the payment algorithm will add a small random amount to the actual value paid to the destination\&. This prevents intervening nodes from identifying exactly how much is being transacted\&.
.sp
Both randomizations respect \fImaxfeepercent\fR\&. Route randomization plus the random value in value randomization will never exceed \fImaxfeepercent\fR of the payment\&. Route randomization will not take routes that would exceed \fImaxdelay\fR\&.
.SH"RETURN VALUE"
.SH"RETURN VALUE"
.sp
.sp
On success, this returns the payment \fIpreimage\fR which hashes to the \fIpayment_hash\fR to prove that the payment was successful\&. It will also return, a \fIgetroute_tries\fR and a \fIsendpay_tries\fR statistics for the number of times it internally called \fBgetroute\fR and \fBsendpay\fR\&.
On success, this returns the payment \fIpreimage\fR which hashes to the \fIpayment_hash\fR to prove that the payment was successful\&. It will also return, a \fIgetroute_tries\fR and a \fIsendpay_tries\fR statistics for the number of times it internally called \fBgetroute\fR and \fBsendpay\fR\&.
ZmnSCPxj
6 years ago
Rusty Russell