Function check_payer_sig

plugins/offers_invreq_hook.c:641–651

BOLT #12: * - MUST reject the invoice request if `signature` is not correct as detailed in * [Signature Calculation](#signature-calculation) using the * `invreq_payer_id`. *... * - MUST reject the invoice if `signature` is not a valid signature using * `invoice_node_id` as described in [Signature Calculation](#signature-calculation). */

 *   `invoice_node_id` as described in [Signature Calculation](#signature-calculation).
 */
static bool check_payer_sig(struct command *cmd,
			    const struct tlv_invoice_request *invreq,
			    const struct pubkey *payer_key,
			    const struct bip340sig *sig)
{
	struct sha256 merkle, sighash;
	merkle_tlv(invreq->fields, &merkle);
	sighash_from_merkle("invoice_request", "signature", &merkle, &sighash);

	return check_schnorr_sig(&sighash, &payer_key->pubkey, sig);
}

static struct command_result *invreq_amount_by_quantity(struct command *cmd,
							const struct invreq *ir,