feat: fees on listpeers rpc output

doc/lightning-listpeers.7.md

@@ -100,6 +100,10 @@ The objects in the *channels* array will have at least these fields:
   a number followed by a string unit.
 * *total\_msat*: A string describing the total capacity of the channel;
   a number followed by a string unit.
+* *fee_base_msat*: The fixed routing fee we charge for forwards going out over
+  this channel, regardless of payment size.
+* *fee_proportional_millionths*: The proportional routing fees in ppm (parts-
+  per-millionths) we charge for forwards going out over this channel.
 * *features*: An array of feature names supported by this channel.
 
 These fields may exist if the channel has gotten beyond the `"OPENINGD"`
@@ -238,7 +242,8 @@ Michael Hawkins <<michael.hawkins@protonmail.com>>.
 SEE ALSO
 --------
 
-lightning-connect(7), lightning-fundchannel\_start(7)
+lightning-connect(7), lightning-fundchannel\_start(7),
+lightning-setchannelfee(7)
 
 RESOURCES
 ---------

lightningd/peer_control.c

@@ -877,6 +877,12 @@ static void json_add_channel(struct lightningd *ld,
 	json_add_amount_msat_compat(response, funding_msat,
 				    "msatoshi_total", "total_msat");
 
+	/* routing fees */
+	json_add_amount_msat_only(response, "fee_base_msat",
+				  amount_msat(channel->feerate_base));
+	json_add_u32(response, "fee_proportional_millionths",
+		     channel->feerate_ppm);
+
 	/* channel config */
 	json_add_amount_sat_compat(response,
 				   channel->our_config.dust_limit,

lightningd/test/run-invoice-select-inchan.c

@@ -224,6 +224,12 @@ void json_add_amount_msat_compat(struct json_stream *result UNNEEDED,
 				 const char *msatfieldname)
 
 { fprintf(stderr, "json_add_amount_msat_compat called!\n"); abort(); }
+/* Generated stub for json_add_amount_msat_only */
+void json_add_amount_msat_only(struct json_stream *result UNNEEDED,
+			  const char *msatfieldname UNNEEDED,
+			  struct amount_msat msat)
+
+{ fprintf(stderr, "json_add_amount_msat_only called!\n"); abort(); }
 /* Generated stub for json_add_amount_sat_compat */
 void json_add_amount_sat_compat(struct json_stream *result UNNEEDED,
 				struct amount_sat sat UNNEEDED,

tests/test_pay.py

@@ -1832,7 +1832,9 @@ def test_setchannelfee_usage(node_factory, bitcoind):
     # - check values in local nodes listchannels output
     # - json throws exception on negative values
     # - checks if peer id can be used instead of scid
+    # - checks fee_base_msat and fee_proportional_millionths in `listpeers` out
     DEF_BASE = 10
+    DEF_BASE_MSAT = Millisatoshi(DEF_BASE)
     DEF_PPM = 100
 
     l1, l2, l3 = node_factory.get_nodes(3,
@@ -1852,6 +1854,10 @@ def channel_get_fees(scid):
     db_fees = l1.db_query('SELECT feerate_base, feerate_ppm FROM channels;')
     assert(db_fees[0]['feerate_base'] == DEF_BASE)
     assert(db_fees[0]['feerate_ppm'] == DEF_PPM)
+    # this is also what listpeers should return
+    peers = l1.rpc.listpeers()['peers']
+    assert peers[0]['channels'][0]['fee_base_msat'] == DEF_BASE_MSAT
+    assert peers[0]['channels'][0]['fee_proportional_millionths'] == DEF_PPM
 
     # custom setchannelfee scid <base> <ppm>
     result = l1.rpc.setchannelfee(scid, 1337, 137)
@@ -1868,6 +1874,10 @@ def channel_get_fees(scid):
     db_fees = channel_get_fees(scid)
     assert(db_fees[0]['feerate_base'] == 1337)
     assert(db_fees[0]['feerate_ppm'] == 137)
+    # also check for updated values in `listpeers`
+    peers = l1.rpc.listpeers()['peers']
+    assert peers[0]['channels'][0]['fee_base_msat'] == Millisatoshi(1337)
+    assert peers[0]['channels'][0]['fee_proportional_millionths'] == 137
 
     # wait for gossip and check if l1 sees new fees in listchannels
     wait_for(lambda: [c['base_fee_millisatoshi'] for c in l1.rpc.listchannels(scid)['channels']] == [DEF_BASE, 1337])
@@ -1899,6 +1909,10 @@ def channel_get_fees(scid):
     db_fees = channel_get_fees(scid)
     assert(db_fees[0]['feerate_base'] == 0)
     assert(db_fees[0]['feerate_ppm'] == 0)
+    # also check for updated values in `listpeers`
+    peers = l1.rpc.listpeers()['peers']
+    assert peers[0]['channels'][0]['fee_base_msat'] == Millisatoshi(0)
+    assert peers[0]['channels'][0]['fee_proportional_millionths'] == 0
 
     # disable and check for global values to be returned
     result = l1.rpc.setchannelfee(scid)
@@ -1908,6 +1922,10 @@ def channel_get_fees(scid):
     db_fees = channel_get_fees(scid)
     assert(db_fees[0]['feerate_base'] == DEF_BASE)
     assert(db_fees[0]['feerate_ppm'] == DEF_PPM)
+    # also check for updated values in `listpeers`
+    peers = l1.rpc.listpeers()['peers']
+    assert peers[0]['channels'][0]['fee_base_msat'] == DEF_BASE_MSAT
+    assert peers[0]['channels'][0]['fee_proportional_millionths'] == DEF_PPM
 
     # check also peer id can be used
     result = l1.rpc.setchannelfee(l2.info['id'], 42, 43)