Support paying 0-amount offers and invoices

diff --git a/src/cli.rs b/src/cli.rs
index 72cc484220d818e8cd2a54e4cdd9537dc6383648..a70d772769e931bed7e7bfd5312b97136ec646b6 100644 (file)
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -21,6 +21,7 @@ use lightning::util::config::{ChannelHandshakeConfig, ChannelHandshakeLimits, Us
 use lightning::util::persist::KVStore;
 use lightning::util::ser::{Writeable, Writer};
 use lightning_invoice::payment::payment_parameters_from_invoice;
+use lightning_invoice::payment::payment_parameters_from_zero_amount_invoice;
 use lightning_invoice::{utils, Bolt11Invoice, Currency};
 use lightning_persister::fs_store::FilesystemStore;
 use std::env;
@@ -162,20 +163,35 @@ pub(crate) fn poll_for_user_input(
                                                continue;
                                        }
 
+                                       let mut user_provided_amt: Option<u64> = None;
+                                       if let Some(amt_msat_str) = words.next() {
+                                               match amt_msat_str.parse() {
+                                                       Ok(amt) => user_provided_amt = Some(amt),
+                                                       Err(e) => {
+                                                               println!("ERROR: couldn't parse amount_msat: {}", e);
+                                                               continue;
+                                                       }
+                                               };
+                                       }
+
                                        if let Ok(offer) = Offer::from_str(invoice_str.unwrap()) {
                                                let offer_hash = Sha256::hash(invoice_str.unwrap().as_bytes());
                                                let payment_id = PaymentId(*offer_hash.as_ref());
 
-                                               let amt_msat =
-                                                       match offer.amount() {
-                                                               Some(offer::Amount::Bitcoin { amount_msats }) => *amount_msats,
-                                                               amt => {
-                                                                       println!("ERROR: Cannot process non-Bitcoin-denominated offer value {:?}", amt);
-                                                                       continue;
-                                                               }
-                                                       };
+                                               let amt_msat = match (offer.amount(), user_provided_amt) {
+                                                       (Some(offer::Amount::Bitcoin { amount_msats }), _) => *amount_msats,
+                                                       (_, Some(amt)) => amt,
+                                                       (amt, _) => {
+                                                               println!("ERROR: Cannot process non-Bitcoin-denominated offer value {:?}", amt);
+                                                               continue;
+                                                       }
+                                               };
+                                               if user_provided_amt.is_some() && user_provided_amt != Some(amt_msat) {
+                                                       println!("Amount didn't match offer of {}msat", amt_msat);
+                                                       continue;
+                                               }
 
-                                               loop {
+                                               while user_provided_amt.is_none() {
                                                        print!("Paying offer for {} msat. Continue (Y/N)? >", amt_msat);
                                                        io::stdout().flush().unwrap();
 
@@ -211,8 +227,9 @@ pub(crate) fn poll_for_user_input(
                                                        .unwrap();
 
                                                let retry = Retry::Timeout(Duration::from_secs(10));
+                                               let amt = Some(amt_msat);
                                                let pay = channel_manager
-                                                       .pay_for_offer(&offer, None, None, None, payment_id, retry, None);
+                                                       .pay_for_offer(&offer, None, amt, None, payment_id, retry, None);
                                                if pay.is_err() {
                                                        println!("ERROR: Failed to pay: {:?}", pay);
                                                }
@@ -221,6 +238,7 @@ pub(crate) fn poll_for_user_input(
                                                        Ok(invoice) => send_payment(
                                                                &channel_manager,
                                                                &invoice,
+                                                               user_provided_amt,
                                                                &mut outbound_payments.lock().unwrap(),
                                                                Arc::clone(&fs_store),
                                                        ),
@@ -563,7 +581,7 @@ fn help() {
        println!("      disconnectpeer <peer_pubkey>");
        println!("      listpeers");
        println!("\n  Payments:");
-       println!("      sendpayment <invoice|offer>");
+       println!("      sendpayment <invoice|offer> [<amount_msat>]");
        println!("      keysend <dest_pubkey> <amt_msats>");
        println!("      listpayments");
        println!("\n  Invoices:");
@@ -770,20 +788,41 @@ fn open_channel(
 }
 
 fn send_payment(
-       channel_manager: &ChannelManager, invoice: &Bolt11Invoice,
+       channel_manager: &ChannelManager, invoice: &Bolt11Invoice, required_amount_msat: Option<u64>,
        outbound_payments: &mut OutboundPaymentInfoStorage, fs_store: Arc<FilesystemStore>,
 ) {
        let payment_id = PaymentId((*invoice.payment_hash()).to_byte_array());
        let payment_secret = Some(*invoice.payment_secret());
-       let (payment_hash, recipient_onion, route_params) =
-               match payment_parameters_from_invoice(invoice) {
-                       Ok(res) => res,
-                       Err(e) => {
-                               println!("Failed to parse invoice");
-                               print!("> ");
-                               return;
-                       }
-               };
+       let zero_amt_invoice =
+               invoice.amount_milli_satoshis().is_none() || invoice.amount_milli_satoshis() == Some(0);
+       let pay_params_opt = if zero_amt_invoice {
+               if let Some(amt_msat) = required_amount_msat {
+                       payment_parameters_from_zero_amount_invoice(invoice, amt_msat)
+               } else {
+                       println!("Need an amount for the given 0-value invoice");
+                       print!("> ");
+                       return;
+               }
+       } else {
+               if required_amount_msat.is_some() && invoice.amount_milli_satoshis() != required_amount_msat
+               {
+                       println!(
+                               "Amount didn't match invoice value of {}msat",
+                               invoice.amount_milli_satoshis().unwrap_or(0)
+                       );
+                       print!("> ");
+                       return;
+               }
+               payment_parameters_from_invoice(invoice)
+       };
+       let (payment_hash, recipient_onion, route_params) = match pay_params_opt {
+               Ok(res) => res,
+               Err(e) => {
+                       println!("Failed to parse invoice");
+                       print!("> ");
+                       return;
+               }
+       };
        outbound_payments.payments.insert(
                payment_id,
                PaymentInfo {