Function handle_intermediate_failure

plugins/libplugin-pay.c:1250–1350

static struct command_result *
handle_intermediate_failure(struct command *cmd,
			    struct payment *p,
			    const struct node_id *errnode,
			    const struct route_hop *errchan,
			    enum onion_wire failcode)
{
	struct payment *root = payment_root(p);
	struct amount_msat estimated;

	paymod_log(p, LOG_DBG,
		   "Intermediate node %s reported %04x (%s) at %s on route %s",
		   type_to_string(tmpctx, struct node_id, errnode),
		   failcode, onion_wire_name(failcode),
		   type_to_string(tmpctx, struct short_channel_id,
				  &errchan->scid),
		   p->routetxt);

	/* We use an exhaustive switch statement here so you get a compile
	 * warning when new ones are added, and can think about where they go */
	switch (failcode) {
	/* BOLT #4:
	 *
	 * An _intermediate hop_ MUST NOT, but the _final node_:
	 *...
	 *     - MUST return an `incorrect_or_unknown_payment_details` error.
	 *...
	 *     - MUST return `final_incorrect_cltv_expiry` error.
	 *...
	 *     - MUST return a `final_incorrect_htlc_amount` error.
	 */
 	case WIRE_INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS:
 	case WIRE_FINAL_INCORRECT_CLTV_EXPIRY:
 	case WIRE_FINAL_INCORRECT_HTLC_AMOUNT:
	/* FIXME: Document in BOLT that intermediates must not return this! */
	case WIRE_MPP_TIMEOUT:
		goto strange_error;

	case WIRE_PERMANENT_CHANNEL_FAILURE:
	case WIRE_CHANNEL_DISABLED:
	case WIRE_UNKNOWN_NEXT_PEER:
	case WIRE_REQUIRED_CHANNEL_FEATURE_MISSING:
		/* All of these result in the channel being marked as disabled. */
		channel_hints_update(root, errchan->scid,
				     errchan->direction, false, false, NULL,
				     NULL);
		break;

	case WIRE_TEMPORARY_CHANNEL_FAILURE: {
		estimated = errchan->amount;

		/* Subtract one msat more, since we know that the amount did not
		 * work. This allows us to then allow on equality, this is for
		 * example necessary for local channels where exact matches
		 * should be allowed. */
		if (!amount_msat_sub(&estimated, estimated, AMOUNT_MSAT(1)))
			abort();