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lightningd: don't allow invoices with 640 byte descriptions.

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They are invalid!  This is because our BOLT11_FIELD_BYTE_LIMIT is not the limit,
it's one greater than the limit.

Reported-by: https://github.com/noblepayne
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Fixed: JSON-RPC: `invoice` no longer accepts 640-byte descriptions (it would produce malformed invoices).
This commit is contained in:
Rusty Russell
2025-10-02 09:24:14 +09:30
parent 89270024e8
commit b05dbeff4e
4 changed files with 28 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
common/bolt11.h
View File

@@ -9,7 +9,7 @@
#include <secp256k1_recovery.h>
/* We only have 10 bits for the field length, meaning < 640 bytes */
#define BOLT11_FIELD_BYTE_LIMIT ((1 << 10) * 5 / 8)
#define BOLT11_FIELD_BYTE_LIMIT (((1 << 10) * 5 / 8) - 1)
/* BOLT #11:
* * `c` (24): `data_length` variable.

4
lightningd/invoice.c
View File

@@ -1134,8 +1134,8 @@ static struct command_result *json_invoice(struct command *cmd,
if (strlen(desc_val) > BOLT11_FIELD_BYTE_LIMIT && !*hashonly) {
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"Descriptions greater than %d bytes "
"not yet supported "
"Description greater than %d bytes "
"invalid "
"(description length %zu)",
BOLT11_FIELD_BYTE_LIMIT,
strlen(desc_val));

2
plugins/keysend.c
View File

@@ -561,7 +561,7 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
(const char *)desc_field->value);
json_add_string(req->js, "description", desc);
/* Don't exceed max possible desc length! */
if (strlen(desc) >= BOLT11_FIELD_BYTE_LIMIT)
if (strlen(desc) > BOLT11_FIELD_BYTE_LIMIT)
json_add_bool(req->js, "deschashonly", true);
} else {
json_add_string(req->js, "description", "keysend");

24
tests/test_invoices.py
View File

@@ -937,3 +937,27 @@ def test_invoice_botched_migration(node_factory, chainparams):
assert ([(i['created_index'], i['label']) for i in l1.rpc.listinvoices()["invoices"]]
== [(1, "made_after_bad_migration"), (2, "label1")])
assert l1.rpc.invoice(100, "test", "test")["created_index"] == 3
def test_invoice_maxdesc(node_factory, chainparams):
l1, l2 = node_factory.line_graph(2)
# BOLT #11:
#
# Note that the maximum length of a Tagged Field's `data` is constricted
# by the maximum value of `data_length`. This is 1023 x 5 bits, or 639
# bytes.
maxdesc = "x" * 639
# This should fail!
with pytest.raises(RpcError, match=r'Description greater than 639 bytes invalid \(description length 641\)'):
l1.rpc.invoice(123000, 'test_invoice_maxdesc', maxdesc + 'xx')
# This should also fail, but used to produce
# lnbcrt1230n1p5dm097sp545trjl795r3mm86mk4ln5jpjvnh04x8aryl3qadjt99vspu646zspp52hf43ln8vg0564ljwccs8d84xc70ls8n7wdmp75ygp7ll8rprqzsdqq0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rc0pu8s7rcxqyjw5qcqp99qxpqysgqr6l8swzm6jc42ehy4v7s83jrggtwa9ua39cvy46c46tmqwn97mn43ycww7e9cf4w5ws8lxnef2k3m5nfa5c34nz54jaxhzc5e72q0ccq26n9fx
with pytest.raises(RpcError, match=r'Description greater than 639 bytes invalid \(description length 640\)'):
l1.rpc.invoice(123000, 'test_invoice_maxdesc2', maxdesc + 'x')
# This should succeed.
inv = l1.rpc.invoice(123000, 'test_invoice_maxdesc3', maxdesc)
assert l1.rpc.decode(inv['bolt11'])['description'] == maxdesc