Function bolt11_encode_

common/bolt11.c:1275–1428

Encodes, even if it's nonsense. */

/* Encodes, even if it's nonsense. */
char *bolt11_encode_(const tal_t *ctx,
		     const struct bolt11 *b11, bool n_field,
		     bool (*sign)(const u5 *u5bytes,
				  const u8 *hrpu8,
				  secp256k1_ecdsa_recoverable_signature *rsig,
				  void *arg),
		     void *arg)
{
	u5 *data = tal_arr(tmpctx, u5, 0);
	char *hrp, *output;
	u64 amount;
	struct bolt11_field *extra;
	secp256k1_ecdsa_recoverable_signature rsig;
	u8 sig_and_recid[65];
	u8 *hrpu8;
	int recid;

	/* BOLT #11:
	 *
	 * A writer:
	 * - MUST encode `prefix` using the currency required for successful payment.
	 * - if a specific minimum `amount` is required for successful payment:
	 *   - MUST include that `amount`.
	 * - MUST encode `amount` as a positive decimal integer with no leading 0s.
	 * - If the `p` multiplier is used the last decimal of `amount` MUST be `0`.
	 * - SHOULD use the shortest representation possible, by using the largest multiplier or omitting the multiplier.
	 */
	if (b11->msat) {
		char postfix;
		u64 msat = b11->msat->millisatoshis; /* Raw: best-multiplier calc */
		if (msat % MSAT_PER_BTC == 0) {
			postfix = '\0';
			amount = msat / MSAT_PER_BTC;
		} else {
			size_t i;
			for (i = 0; i < ARRAY_SIZE(multipliers)-1; i++) {
				if (!(msat * 10 % multipliers[i].m10))
					break;
			}
			postfix = multipliers[i].letter;
			amount = msat * 10 / multipliers[i].m10;
		}
		hrp = tal_fmt(tmpctx, "ln%s%"PRIu64"%c",
			      b11->chain->lightning_hrp, amount, postfix);
	} else
		hrp = tal_fmt(tmpctx, "ln%s", b11->chain->lightning_hrp);

	/* BOLT #11:
	 *
	 * 1. `timestamp`: seconds-since-1970 (35 bits, big-endian)
	 * 1. zero or more tagged parts
	 * 1. `signature`: compact ECDSA/secp256k1 signature of the above
	 *    (520 bits: 64-byte R||S + 1-byte recovery id)
	 */
	push_varlen_uint(&data, b11->timestamp, 35);

	/* This is a hack to match the test vectors, *some* of which
	 * order differently! */