Function onion_decode

common/onion_decode.c:188–464

}

struct onion_payload *onion_decode(const tal_t *ctx,
				   const struct route_step *rs,
				   const struct pubkey *path_key,
				   const u64 *accepted_extra_tlvs,
				   struct amount_msat amount_in,
				   u32 cltv_expiry,
				   u64 *failtlvtype,
				   size_t *failtlvpos,
				   const char **explanation)
{
	struct onion_payload *p = tal(ctx, struct onion_payload);
	const u8 *cursor = rs->raw_payload;
	size_t max = tal_bytelen(cursor), len;

	p->final = (rs->nextcase == ONION_END);

	/* BOLT #4:
	 * 1. type: `hop_payloads`
	 * 2. data:
	 *    * [`bigsize`:`length`]
	 *    * [`length*byte`:`payload`]
	 */
	len = fromwire_bigsize(&cursor, &max);
	if (!cursor || len > max) {
		*failtlvtype = 0;
		*failtlvpos = tal_bytelen(rs->raw_payload);
		if (explanation)
			*explanation = tal_fmt(ctx, "Too short for initial length");
		return tal_free(p);
	}

	/* We do this manually so we can accept extra types, and get
	 * error off and type. */
	p->tlv = tlv_payload_new(p);
	if (!fromwire_tlv(&cursor, &max, tlvs_tlv_payload,
			  TLVS_ARRAY_SIZE_tlv_payload,
			  p->tlv, &p->tlv->fields, accepted_extra_tlvs,
			  failtlvpos, failtlvtype)) {
		if (explanation)
			*explanation = tal_fmt(ctx, "Unparseable TLV");
		return tal_free(p);
	}

	/* BOLT #4:
	 *
	 * The reader:
	 *
	 *   - If `encrypted_recipient_data` is present:
	 */
	if (p->tlv->encrypted_recipient_data) {
		struct tlv_encrypted_data_tlv *enc;

		/* BOLT #4:
		 *
		 *   - If `path_key` is set in the incoming `update_add_htlc`:
		 *     - MUST return an error if `current_path_key` is present.
		 *     - MUST use that `path_key` as `path_key` for decryption.
		 *   - Otherwise: