offers: add final node's CLTV delta in when creating blinded path pay…

…info. It should probably be renamed "minimum_cltv_delta" or something. Fixes: #7179 Reported-by: @carlaKC Signed-off-by: Rusty Russell <[email protected]>
ElementsProject · May 15, 2024 · 121403b · 121403b
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commit 121403b
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/plugins/offers_invreq_hook.c b/plugins/offers_invreq_hook.c
@@ -439,7 +439,7 @@ static struct command_result *listincoming_done(struct command *cmd,
 		ir->inv->invoice_blindedpay[0] = tal(ir->inv->invoice_blindedpay, struct blinded_payinfo);
 		ir->inv->invoice_blindedpay[0]->fee_base_msat = best->feebase;
 		ir->inv->invoice_blindedpay[0]->fee_proportional_millionths = best->feeppm;
-		ir->inv->invoice_blindedpay[0]->cltv_expiry_delta = best->cltv;
+		ir->inv->invoice_blindedpay[0]->cltv_expiry_delta = best->cltv + cltv_final;
 		ir->inv->invoice_blindedpay[0]->htlc_minimum_msat = best->htlc_min;
 		ir->inv->invoice_blindedpay[0]->htlc_maximum_msat = best->htlc_max;
 		ir->inv->invoice_blindedpay[0]->features = NULL;

diff --git a/tests/test_pay.py b/tests/test_pay.py
@@ -5608,8 +5608,10 @@ def test_pay_partial_msat(node_factory, executor):
 
 
 def test_blindedpath_privchan(node_factory, bitcoind):
-    l1, l2 = node_factory.line_graph(2, wait_for_announce=True, opts={'experimental-offers': None})
-    l3 = node_factory.get_node(options={'experimental-offers': None})
+    l1, l2 = node_factory.line_graph(2, wait_for_announce=True,
+                                     opts={'experimental-offers': None})
+    l3 = node_factory.get_node(options={'experimental-offers': None,
+                                        'cltv-final': 120})
 
     # Private channel.
     node_factory.join_nodes([l2, l3], announce_channels=False)
@@ -5624,6 +5626,10 @@ def test_blindedpath_privchan(node_factory, bitcoind):
     assert len(decode['invoice_paths']) == 1
     assert decode['invoice_paths'][0]['first_node_id'] == l2.info['id']
 
+    # Carla points out that the path's cltv_expiry_delta *includes*
+    # the final node's final value.
+    assert decode['invoice_paths'][0]['payinfo']['cltv_expiry_delta'] == l3.config('cltv-final') + l2.config('cltv-delta')
+
     l1.rpc.pay(inv['invoice'])