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invoice::classify refuses a Lightning address whose user starts with lnbc, lntb or lnsb

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
72/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
rust
Domain
payments

Research direction

The bug is in invoice::classify in rust/src/api/invoice.rs, where the BOLT11_PREFIXES check runs before the Lightning address check. Read the classify function, the BOLT11_PREFIXES constant and is_lightning_address, then find the existing classify tests for invoices and addresses. Done when an address such as [email protected] or [email protected] classifies as LightningAddress, and the existing BOLT11 invoice classifications are unchanged.

Written by the indexing model from the issue text.

Description

area: rust-core bug priority: low

What happens

invoice::classify (rust/src/api/invoice.rs) checks the BOLT11 prefixes before it checks for a Lightning address:

let lower = bare.to_ascii_lowercase();
if BOLT11_PREFIXES.iter().any(|p| lower.starts_with(p)) {
    return match summarize(bare) {
        Some(summary) => PaymentDestination::Bolt11(summary),
        None => PaymentDestination::MalformedBolt11,
    };
}
if is_lightning_address(&lower) { ... }

So a valid LUD-16 address whose user part starts with lnbc, lntb or lnsb (for example [email protected] or [email protected]) is classified as MalformedBolt11, never as LightningAddress.

Where it shows

Every path that judges a payout destination with classify refuses such an address:

  • the buyer's add-invoice screen (check_buyer_invoice), with the "malformed invoice" error;
  • orders::send_invoice and the NWC payer (InvalidInvoice);
  • a take with TakePayout::Address (resolve_take_payout, InvalidLightningAddress);
  • the default address in Settings, since #824 judges it with the same rule.

Expected

The address is accepted as a LightningAddress. A BOLT11 invoice is bech32 and never contains @, so checking for @ (or is_lightning_address) before the BOLT11 prefixes would fix it without changing how any invoice is classified.

Found while fixing a review comment on #824.

Dominant language
Dart
Stars
11
Forks
9
Avg merge
18h 25m
Merged PRs (30d)
194

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