In c986e52ce8, an `MppId` was added
to `HTLCSource` objects as a way of correlating HTLCs which belong
to the same payment when the `ChannelManager` sees an HTLC
succeed/fail. This allows it to have awareness of the state of all
HTLCs in a payment when it generates the ultimate user-facing
payment success/failure events. This was used in the same PR to
avoid generating duplicative success/failure events for a single
payment.
Because the field was only used as an internal token to correlate
HTLCs, and retries were not supported, it was generated randomly by
calling the `KeysInterface`'s 32-byte random-fetching function.
This also provided a backwards-compatibility story as the existing
HTLC randomization key was re-used for older clients.
In 28eea12bbe `MppId` was renamed to
the current `PaymentId` which was then used expose the
`retry_payment` interface, allowing users to send new HTLCs which
are considered a part of an existing payment.
At no point has the payment-sending API seriously considered
idempotency, a major drawback which leaves the API unsafe in most
deployments. Luckily, there is a simple solution - because the
`PaymentId` must be unique, and because payment information for a
given payment is held for several blocks after a payment
completes/fails, it represents an obvious idempotency token.
Here we simply require the user provide the `PaymentId` directly in
`send_payment`, allowing them to use whatever token they may
already have for a payment's idempotency token.
This repo provides data structures for BOLT 11 lightning invoices and
functions to parse and serialize these from and to bech32.
Please be sure to run the test suite since we need to check assumptions
regarding SystemTime's bounds on your platform. You can also call check_platform
on startup or in your test suite to do so.
a10223d1ff
