From c5345396806bf8ff724cd40a68b86cd83c0490aa Mon Sep 17 00:00:00 2001
From: ZmnSCPxj jxPCSnmZ <zmnscpxj@protonmail.com>
Date: Sun, 19 Jul 2020 23:06:52 +0800
Subject: [PATCH 1/2] tests/test_pay.py: Replicate #3855.

---
 tests/test_pay.py | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/tests/test_pay.py b/tests/test_pay.py
index c3d870dab203..90789176986c 100644
--- a/tests/test_pay.py
+++ b/tests/test_pay.py
@@ -3143,3 +3143,38 @@ def test_mpp_adaptive(node_factory, bitcoind):
     from pprint import pprint
     pprint(p)
     pprint(l1.rpc.paystatus(inv))
+
+
+@pytest.mark.xfail(strict=True)
+def test_pay_fail_unconfirmed_channel(node_factory, bitcoind):
+    '''
+    Replicate #3855.
+    `pay` crash when any direct channel is still
+    unconfirmed.
+    '''
+    l1, l2 = node_factory.get_nodes(2)
+
+    amount_sat = 10 ** 6
+
+    # create l2->l1 channel.
+    l2.fundwallet(amount_sat * 5)
+    l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
+    l2.rpc.fundchannel(l1.info['id'], amount_sat * 3)
+    # channel is still unconfirmed.
+
+    # Attempt to pay from l1 to l2.
+    # This should fail since the channel capacities are wrong.
+    invl2 = l2.rpc.invoice(Millisatoshi(amount_sat * 1000), 'i', 'i')['bolt11']
+    with pytest.raises(RpcError):
+        l1.rpc.pay(invl2)
+
+    # Let the channel confirm.
+    bitcoind.generate_block(6)
+    sync_blockheight(bitcoind, [l1, l2])
+
+    # Now give enough capacity so l1 can pay.
+    invl1 = l1.rpc.invoice(Millisatoshi(amount_sat * 2 * 1000), 'j', 'j')['bolt11']
+    l2.rpc.pay(invl1)
+
+    # Now l1 can pay to l2.
+    l1.rpc.pay(invl2)

From 1e62ac0e20496be1f8a8bdc2646ca0af5e4356df Mon Sep 17 00:00:00 2001
From: Vincent <vincenzopalazzo1996@gmail.com>
Date: Sun, 19 Jul 2020 17:09:24 +0200
Subject: [PATCH 2/2] Fixed assertion in pay plugin

This PR includes the fix discussed on PR #3855. This fix was tested with the use case described inside the issue and worked.

Fixes: #3855

Changelog-None
---
 plugins/libplugin-pay.c | 3 ++-
 tests/test_pay.py       | 1 -
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/plugins/libplugin-pay.c b/plugins/libplugin-pay.c
index aa414b2f07b8..fadae6f03eec 100644
--- a/plugins/libplugin-pay.c
+++ b/plugins/libplugin-pay.c
@@ -1428,7 +1428,8 @@ local_channel_hints_listpeers(struct command *cmd, const char *buffer,
 			spendsats = json_get_member(buffer, channel, "spendable_msat");
 			scid = json_get_member(buffer, channel, "short_channel_id");
 			dir = json_get_member(buffer, channel, "direction");
-			assert(spendsats != NULL && scid != NULL && dir != NULL);
+			if(spendsats == NULL || scid == NULL || dir == NULL)
+				continue;
 
 			json_to_bool(buffer, connected, &h.enabled);
 			json_to_short_channel_id(buffer, scid, &h.scid.scid);
diff --git a/tests/test_pay.py b/tests/test_pay.py
index 90789176986c..b5b4ad824ec5 100644
--- a/tests/test_pay.py
+++ b/tests/test_pay.py
@@ -3145,7 +3145,6 @@ def test_mpp_adaptive(node_factory, bitcoind):
     pprint(l1.rpc.paystatus(inv))
 
 
-@pytest.mark.xfail(strict=True)
 def test_pay_fail_unconfirmed_channel(node_factory, bitcoind):
     '''
     Replicate #3855.