keysend: enforce BOLT11 description length limit #8535
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The keysend plugin previously used `> 1023` as the cutoff for description length when inserting an invoice. This was inconsistent with invoice.c, which enforces the BOLT11 description field limit defined in `common/bolt11.h`. This patch switches to using `BOLT11_FIELD_BYTE_LIMIT` directly. As a result, keysend no longer fails on descriptions between 641–1023 bytes, which previously caused unexpected failures. A new regression test (`test_keysend_description_size_limit`) exercises boundary cases just below, at, and above the limit. Changelog-None Signed-off-by: Wes Payne <noblepayne@noblepayne.com>
noblepayne
commented
Sep 5, 2025
| @@ -563,7 +564,7 @@ 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) > 1023) | |||
| if (strlen(desc) >= BOLT11_FIELD_BYTE_LIMIT) | |||
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Should this be > or >=? lightningd/invoice.c uses >, however the BOLT11 spec says:
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.
In common/bolt11.c BOLT11_FIELD_BYTE_LIMIT has a value of 640.
Far from an expert here and appreciate any insight. Happy to update as needed.
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The keysend plugin uses
> 1023as the cutoff for description length when inserting an invoice. This was inconsistent withlightnind/invoice.c, which enforces the BOLT11 description field limit defined incommon/bolt11.h.This patch switches to using
BOLT11_FIELD_BYTE_LIMITdirectly. As a result, keysend no longer fails on descriptions between 641–1023 bytes, which previously caused unexpected failures.A new regression test (
test_keysend_description_size_limit) exercises boundary cases just below, at, and above the limit.Changelog-None
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