git.delta.rocks / unique-network / refs/commits / bebe624eff63

difftreelog

feat prevent ouroboros creation during nest

Yaroslav Bolyukin2022-04-19parent: #07a6969.patch.diff
in: master

11 files changed

modifiedclient/rpc/src/lib.rsdiffbeforeafterboth
--- a/client/rpc/src/lib.rs
+++ b/client/rpc/src/lib.rs
@@ -77,11 +77,7 @@
 	) -> Result<Vec<u8>>;
 
 	#[rpc(name = "unique_totalSupply")]
-	fn total_supply(
-		&self,
-		collection: CollectionId,
-		at: Option<BlockHash>,
-	) -> Result<u32>;
+	fn total_supply(&self, collection: CollectionId, at: Option<BlockHash>) -> Result<u32>;
 	#[rpc(name = "unique_accountBalance")]
 	fn account_balance(
 		&self,
modifiedpallets/common/src/lib.rsdiffbeforeafterboth
--- a/pallets/common/src/lib.rs
+++ b/pallets/common/src/lib.rs
@@ -918,7 +918,7 @@
 	fn check_nesting(
 		&self,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		budget: &dyn Budget,
 	) -> DispatchResult;
modifiedpallets/fungible/src/common.rsdiffbeforeafterboth
--- a/pallets/fungible/src/common.rs
+++ b/pallets/fungible/src/common.rs
@@ -237,7 +237,7 @@
 	fn check_nesting(
 		&self,
 		_sender: <T>::CrossAccountId,
-		_from: CollectionId,
+		_from: (CollectionId, TokenId),
 		_under: TokenId,
 		_budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/fungible/src/lib.rsdiffbeforeafterboth
--- a/pallets/fungible/src/lib.rs
+++ b/pallets/fungible/src/lib.rs
@@ -224,7 +224,12 @@
 			let dispatch = T::CollectionDispatch::dispatch(handle);
 			let dispatch = dispatch.as_dyn();
 
-			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;
+			dispatch.check_nesting(
+				from.clone(),
+				(collection.id, TokenId::default()),
+				target.1,
+				nesting_budget,
+			)?;
 		}
 
 		// =========
@@ -293,7 +298,12 @@
 				let dispatch = T::CollectionDispatch::dispatch(handle);
 				let dispatch = dispatch.as_dyn();
 
-				dispatch.check_nesting(sender.clone(), collection.id, target.1, nesting_budget)?;
+				dispatch.check_nesting(
+					sender.clone(),
+					(collection.id, TokenId::default()),
+					target.1,
+					nesting_budget,
+				)?;
 			}
 		}
 
@@ -386,10 +396,11 @@
 		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {
 			// TODO: should collection owner be allowed to perform this transfer?
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(
+				<PalletStructure<T>>::check_indirectly_owned(
 					spender.clone(),
 					source.0,
 					source.1,
+					None,
 					nesting_budget
 				)?,
 				<CommonError<T>>::ApprovedValueTooLow,
modifiedpallets/nonfungible/src/common.rsdiffbeforeafterboth
--- a/pallets/nonfungible/src/common.rs
+++ b/pallets/nonfungible/src/common.rs
@@ -251,7 +251,7 @@
 	fn check_nesting(
 		&self,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/nonfungible/src/lib.rsdiffbeforeafterboth
--- a/pallets/nonfungible/src/lib.rs
+++ b/pallets/nonfungible/src/lib.rs
@@ -296,7 +296,12 @@
 			let dispatch = T::CollectionDispatch::dispatch(handle);
 			let dispatch = dispatch.as_dyn();
 
-			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;
+			dispatch.check_nesting(
+				from.clone(),
+				(collection.id, token),
+				target.1,
+				nesting_budget,
+			)?;
 		}
 
 		// =========
@@ -381,13 +386,18 @@
 			);
 		}
 
-		for (to, _) in balances.iter() {
-			if let Some(target) = T::CrossTokenAddressMapping::address_to_token(to) {
+		for (i, data) in data.iter().enumerate() {
+			let token = TokenId(first_token + i as u32 + 1);
+			if let Some(target) = T::CrossTokenAddressMapping::address_to_token(&data.owner) {
 				let handle = <CollectionHandle<T>>::try_get(target.0)?;
 				let dispatch = T::CollectionDispatch::dispatch(handle);
 				let dispatch = dispatch.as_dyn();
-
-				dispatch.check_nesting(sender.clone(), collection.id, target.1, nesting_budget)?;
+				dispatch.check_nesting(
+					sender.clone(),
+					(collection.id, token),
+					target.1,
+					nesting_budget,
+				)?;
 			}
 		}
 
@@ -535,10 +545,11 @@
 		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {
 			// TODO: should collection owner be allowed to perform this transfer?
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(
+				<PalletStructure<T>>::check_indirectly_owned(
 					spender.clone(),
 					source.0,
 					source.1,
+					None,
 					nesting_budget
 				)?,
 				<CommonError<T>>::ApprovedValueTooLow,
@@ -610,31 +621,40 @@
 	pub fn check_nesting(
 		handle: &NonfungibleHandle<T>,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		nesting_budget: &dyn Budget,
 	) -> DispatchResult {
 		fn ensure_sender_allowed<T: Config>(
 			collection: CollectionId,
 			token: TokenId,
+			for_nest: (CollectionId, TokenId),
 			sender: T::CrossAccountId,
 			budget: &dyn Budget,
 		) -> DispatchResult {
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(sender, collection, token, budget)?,
+				<PalletStructure<T>>::check_indirectly_owned(
+					sender,
+					collection,
+					token,
+					Some(for_nest),
+					budget
+				)?,
 				<CommonError<T>>::OnlyOwnerAllowedToNest,
 			);
 			Ok(())
 		}
 		match handle.limits.nesting_rule() {
 			NestingRule::Disabled => fail!(<CommonError<T>>::NestingIsDisabled),
-			NestingRule::Owner => ensure_sender_allowed::<T>(handle.id, under, sender, nesting_budget)?,
+			NestingRule::Owner => {
+				ensure_sender_allowed::<T>(handle.id, under, from, sender, nesting_budget)?
+			}
 			NestingRule::OwnerRestricted(whitelist) => {
 				ensure!(
-					whitelist.contains(&from),
+					whitelist.contains(&from.0),
 					<CommonError<T>>::SourceCollectionIsNotAllowedToNest
 				);
-				ensure_sender_allowed::<T>(handle.id, under, sender, nesting_budget)?
+				ensure_sender_allowed::<T>(handle.id, under, from, sender, nesting_budget)?
 			}
 		}
 		Ok(())
modifiedpallets/refungible/src/common.rsdiffbeforeafterboth
--- a/pallets/refungible/src/common.rs
+++ b/pallets/refungible/src/common.rs
@@ -260,7 +260,7 @@
 	fn check_nesting(
 		&self,
 		_sender: <T>::CrossAccountId,
-		_from: CollectionId,
+		_from: (CollectionId, TokenId),
 		_under: TokenId,
 		_budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/refungible/src/lib.rsdiffbeforeafterboth
before · pallets/refungible/src/lib.rs
1// Copyright 2019-2022 Unique Network (Gibraltar) Ltd.2// This file is part of Unique Network.34// Unique Network is free software: you can redistribute it and/or modify5// it under the terms of the GNU General Public License as published by6// the Free Software Foundation, either version 3 of the License, or7// (at your option) any later version.89// Unique Network is distributed in the hope that it will be useful,10// but WITHOUT ANY WARRANTY; without even the implied warranty of11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the12// GNU General Public License for more details.1314// You should have received a copy of the GNU General Public License15// along with Unique Network. If not, see <http://www.gnu.org/licenses/>.1617#![cfg_attr(not(feature = "std"), no_std)]1819use frame_support::{ensure, BoundedVec};20use up_data_structs::{21	AccessMode, CollectionId, CustomDataLimit, MAX_REFUNGIBLE_PIECES, TokenId,22	CreateCollectionData, CreateRefungibleExData, mapping::TokenAddressMapping, budget::Budget,23};24use pallet_evm::account::CrossAccountId;25use pallet_common::{26	Error as CommonError, Event as CommonEvent, Pallet as PalletCommon, CollectionHandle,27	dispatch::CollectionDispatch,28};29use pallet_structure::Pallet as PalletStructure;30use sp_runtime::{ArithmeticError, DispatchError, DispatchResult};31use sp_std::{vec::Vec, vec, collections::btree_map::BTreeMap};32use core::ops::Deref;33use codec::{Encode, Decode, MaxEncodedLen};34use scale_info::TypeInfo;3536pub use pallet::*;37#[cfg(feature = "runtime-benchmarks")]38pub mod benchmarking;39pub mod common;40pub mod erc;41pub mod weights;42pub(crate) type SelfWeightOf<T> = <T as Config>::WeightInfo;4344#[derive(Encode, Decode, Default, TypeInfo, MaxEncodedLen)]45pub struct ItemData {46	pub const_data: BoundedVec<u8, CustomDataLimit>,47	pub variable_data: BoundedVec<u8, CustomDataLimit>,48}4950#[frame_support::pallet]51pub mod pallet {52	use super::*;53	use frame_support::{Blake2_128, Blake2_128Concat, Twox64Concat, pallet_prelude::*, storage::Key};54	use up_data_structs::{CollectionId, TokenId};55	use super::weights::WeightInfo;5657	#[pallet::error]58	pub enum Error<T> {59		/// Not Refungible item data used to mint in Refungible collection.60		NotRefungibleDataUsedToMintFungibleCollectionToken,61		/// Maximum refungibility exceeded62		WrongRefungiblePieces,63		/// Refungible token can't nest other tokens64		RefungibleDisallowsNesting,65	}6667	#[pallet::config]68	pub trait Config:69		frame_system::Config + pallet_common::Config + pallet_structure::Config70	{71		type WeightInfo: WeightInfo;72	}7374	#[pallet::pallet]75	#[pallet::generate_store(pub(super) trait Store)]76	pub struct Pallet<T>(_);7778	#[pallet::storage]79	pub type TokensMinted<T: Config> =80		StorageMap<Hasher = Twox64Concat, Key = CollectionId, Value = u32, QueryKind = ValueQuery>;81	#[pallet::storage]82	pub type TokensBurnt<T: Config> =83		StorageMap<Hasher = Twox64Concat, Key = CollectionId, Value = u32, QueryKind = ValueQuery>;8485	#[pallet::storage]86	pub type TokenData<T: Config> = StorageNMap<87		Key = (Key<Twox64Concat, CollectionId>, Key<Twox64Concat, TokenId>),88		Value = ItemData,89		QueryKind = ValueQuery,90	>;9192	#[pallet::storage]93	pub type TotalSupply<T: Config> = StorageNMap<94		Key = (Key<Twox64Concat, CollectionId>, Key<Twox64Concat, TokenId>),95		Value = u128,96		QueryKind = ValueQuery,97	>;9899	/// Used to enumerate tokens owned by account100	#[pallet::storage]101	pub type Owned<T: Config> = StorageNMap<102		Key = (103			Key<Twox64Concat, CollectionId>,104			Key<Blake2_128Concat, T::CrossAccountId>,105			Key<Twox64Concat, TokenId>,106		),107		Value = bool,108		QueryKind = ValueQuery,109	>;110111	#[pallet::storage]112	pub type AccountBalance<T: Config> = StorageNMap<113		Key = (114			Key<Twox64Concat, CollectionId>,115			// Owner116			Key<Blake2_128Concat, T::CrossAccountId>,117		),118		Value = u32,119		QueryKind = ValueQuery,120	>;121122	#[pallet::storage]123	pub type Balance<T: Config> = StorageNMap<124		Key = (125			Key<Twox64Concat, CollectionId>,126			Key<Twox64Concat, TokenId>,127			// Owner128			Key<Blake2_128Concat, T::CrossAccountId>,129		),130		Value = u128,131		QueryKind = ValueQuery,132	>;133134	#[pallet::storage]135	pub type Allowance<T: Config> = StorageNMap<136		Key = (137			Key<Twox64Concat, CollectionId>,138			Key<Twox64Concat, TokenId>,139			// Owner140			Key<Blake2_128, T::CrossAccountId>,141			// Spender142			Key<Blake2_128Concat, T::CrossAccountId>,143		),144		Value = u128,145		QueryKind = ValueQuery,146	>;147}148149pub struct RefungibleHandle<T: Config>(pallet_common::CollectionHandle<T>);150impl<T: Config> RefungibleHandle<T> {151	pub fn cast(inner: pallet_common::CollectionHandle<T>) -> Self {152		Self(inner)153	}154	pub fn into_inner(self) -> pallet_common::CollectionHandle<T> {155		self.0156	}157}158impl<T: Config> Deref for RefungibleHandle<T> {159	type Target = pallet_common::CollectionHandle<T>;160161	fn deref(&self) -> &Self::Target {162		&self.0163	}164}165166impl<T: Config> Pallet<T> {167	pub fn total_supply(collection: &RefungibleHandle<T>) -> u32 {168		<TokensMinted<T>>::get(collection.id) - <TokensBurnt<T>>::get(collection.id)169	}170	pub fn token_exists(collection: &RefungibleHandle<T>, token: TokenId) -> bool {171		<TotalSupply<T>>::contains_key((collection.id, token))172	}173}174175// unchecked calls skips any permission checks176impl<T: Config> Pallet<T> {177	pub fn init_collection(178		owner: T::AccountId,179		data: CreateCollectionData<T::AccountId>,180	) -> Result<CollectionId, DispatchError> {181		<PalletCommon<T>>::init_collection(owner, data)182	}183	pub fn destroy_collection(184		collection: RefungibleHandle<T>,185		sender: &T::CrossAccountId,186	) -> DispatchResult {187		let id = collection.id;188189		// =========190191		PalletCommon::destroy_collection(collection.0, sender)?;192193		<TokensMinted<T>>::remove(id);194		<TokensBurnt<T>>::remove(id);195		<TokenData<T>>::remove_prefix((id,), None);196		<TotalSupply<T>>::remove_prefix((id,), None);197		<Balance<T>>::remove_prefix((id,), None);198		<Allowance<T>>::remove_prefix((id,), None);199		<Owned<T>>::remove_prefix((id,), None);200		<AccountBalance<T>>::remove_prefix((id,), None);201		Ok(())202	}203204	pub fn burn_token(collection: &RefungibleHandle<T>, token_id: TokenId) -> DispatchResult {205		let burnt = <TokensBurnt<T>>::get(collection.id)206			.checked_add(1)207			.ok_or(ArithmeticError::Overflow)?;208209		<TokensBurnt<T>>::insert(collection.id, burnt);210		<TokenData<T>>::remove((collection.id, token_id));211		<TotalSupply<T>>::remove((collection.id, token_id));212		<Balance<T>>::remove_prefix((collection.id, token_id), None);213		<Allowance<T>>::remove_prefix((collection.id, token_id), None);214		// TODO: ERC721 transfer event215		Ok(())216	}217218	pub fn burn(219		collection: &RefungibleHandle<T>,220		owner: &T::CrossAccountId,221		token: TokenId,222		amount: u128,223	) -> DispatchResult {224		let total_supply = <TotalSupply<T>>::get((collection.id, token))225			.checked_sub(amount)226			.ok_or(<CommonError<T>>::TokenValueTooLow)?;227228		// This was probally last owner of this token?229		if total_supply == 0 {230			// Ensure user actually owns this amount231			ensure!(232				<Balance<T>>::get((collection.id, token, owner)) == amount,233				<CommonError<T>>::TokenValueTooLow234			);235			let account_balance = <AccountBalance<T>>::get((collection.id, owner))236				.checked_sub(1)237				// Should not occur238				.ok_or(ArithmeticError::Underflow)?;239240			// =========241242			<Owned<T>>::remove((collection.id, owner, token));243			<AccountBalance<T>>::insert((collection.id, owner), account_balance);244			Self::burn_token(collection, token)?;245			<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(246				collection.id,247				token,248				owner.clone(),249				amount,250			));251			return Ok(());252		}253254		let balance = <Balance<T>>::get((collection.id, token, owner))255			.checked_sub(amount)256			.ok_or(<CommonError<T>>::TokenValueTooLow)?;257		let account_balance = if balance == 0 {258			<AccountBalance<T>>::get((collection.id, owner))259				.checked_sub(1)260				// Should not occur261				.ok_or(ArithmeticError::Underflow)?262		} else {263			0264		};265266		// =========267268		if balance == 0 {269			<Owned<T>>::remove((collection.id, owner, token));270			<Balance<T>>::remove((collection.id, token, owner));271			<AccountBalance<T>>::insert((collection.id, owner), account_balance);272		} else {273			<Balance<T>>::insert((collection.id, token, owner), balance);274		}275		<TotalSupply<T>>::insert((collection.id, token), total_supply);276		// TODO: ERC20 transfer event277		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(278			collection.id,279			token,280			owner.clone(),281			amount,282		));283		Ok(())284	}285286	pub fn transfer(287		collection: &RefungibleHandle<T>,288		from: &T::CrossAccountId,289		to: &T::CrossAccountId,290		token: TokenId,291		amount: u128,292		nesting_budget: &dyn Budget,293	) -> DispatchResult {294		ensure!(295			collection.limits.transfers_enabled(),296			<CommonError<T>>::TransferNotAllowed297		);298299		if collection.access == AccessMode::AllowList {300			collection.check_allowlist(from)?;301			collection.check_allowlist(to)?;302		}303		<PalletCommon<T>>::ensure_correct_receiver(to)?;304305		let balance_from = <Balance<T>>::get((collection.id, token, from))306			.checked_sub(amount)307			.ok_or(<CommonError<T>>::TokenValueTooLow)?;308		let mut create_target = false;309		let from_to_differ = from != to;310		let balance_to = if from != to {311			let old_balance = <Balance<T>>::get((collection.id, token, to));312			if old_balance == 0 {313				create_target = true;314			}315			Some(316				old_balance317					.checked_add(amount)318					.ok_or(ArithmeticError::Overflow)?,319			)320		} else {321			None322		};323324		let account_balance_from = if balance_from == 0 {325			Some(326				<AccountBalance<T>>::get((collection.id, from))327					.checked_sub(1)328					// Should not occur329					.ok_or(ArithmeticError::Underflow)?,330			)331		} else {332			None333		};334		// Account data is created in token, AccountBalance should be increased335		// But only if from != to as we shouldn't check overflow in this case336		let account_balance_to = if create_target && from_to_differ {337			let account_balance_to = <AccountBalance<T>>::get((collection.id, to))338				.checked_add(1)339				.ok_or(ArithmeticError::Overflow)?;340			ensure!(341				account_balance_to < collection.limits.account_token_ownership_limit(),342				<CommonError<T>>::AccountTokenLimitExceeded,343			);344345			Some(account_balance_to)346		} else {347			None348		};349350		if let Some(target) = T::CrossTokenAddressMapping::address_to_token(to) {351			let handle = <CollectionHandle<T>>::try_get(target.0)?;352			let dispatch = T::CollectionDispatch::dispatch(handle);353			let dispatch = dispatch.as_dyn();354355			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;356		}357358		// =========359360		if let Some(balance_to) = balance_to {361			// from != to362			if balance_from == 0 {363				<Balance<T>>::remove((collection.id, token, from));364			} else {365				<Balance<T>>::insert((collection.id, token, from), balance_from);366			}367			<Balance<T>>::insert((collection.id, token, to), balance_to);368			if let Some(account_balance_from) = account_balance_from {369				<AccountBalance<T>>::insert((collection.id, from), account_balance_from);370				<Owned<T>>::remove((collection.id, from, token));371			}372			if let Some(account_balance_to) = account_balance_to {373				<AccountBalance<T>>::insert((collection.id, to), account_balance_to);374				<Owned<T>>::insert((collection.id, to, token), true);375			}376		}377378		// TODO: ERC20 transfer event379		<PalletCommon<T>>::deposit_event(CommonEvent::Transfer(380			collection.id,381			token,382			from.clone(),383			to.clone(),384			amount,385		));386		Ok(())387	}388389	pub fn create_multiple_items(390		collection: &RefungibleHandle<T>,391		sender: &T::CrossAccountId,392		data: Vec<CreateRefungibleExData<T::CrossAccountId>>,393		nesting_budget: &dyn Budget,394	) -> DispatchResult {395		if !collection.is_owner_or_admin(sender) {396			ensure!(397				collection.mint_mode,398				<CommonError<T>>::PublicMintingNotAllowed399			);400			collection.check_allowlist(sender)?;401402			for item in data.iter() {403				for user in item.users.keys() {404					collection.check_allowlist(user)?;405				}406			}407		}408409		for item in data.iter() {410			for (owner, _) in item.users.iter() {411				<PalletCommon<T>>::ensure_correct_receiver(owner)?;412			}413		}414415		// Total pieces per tokens416		let totals = data417			.iter()418			.map(|data| {419				Ok(data420					.users421					.iter()422					.map(|u| u.1)423					.try_fold(0u128, |acc, v| acc.checked_add(*v))424					.ok_or(ArithmeticError::Overflow)?)425			})426			.collect::<Result<Vec<_>, DispatchError>>()?;427		for total in &totals {428			ensure!(429				*total <= MAX_REFUNGIBLE_PIECES,430				<Error<T>>::WrongRefungiblePieces431			);432		}433434		let first_token_id = <TokensMinted<T>>::get(collection.id);435		let tokens_minted = first_token_id436			.checked_add(data.len() as u32)437			.ok_or(ArithmeticError::Overflow)?;438		ensure!(439			tokens_minted < collection.limits.token_limit(),440			<CommonError<T>>::CollectionTokenLimitExceeded441		);442443		let mut balances = BTreeMap::new();444		for data in &data {445			for owner in data.users.keys() {446				let balance = balances447					.entry(owner)448					.or_insert_with(|| <AccountBalance<T>>::get((collection.id, owner)));449				*balance = balance.checked_add(1).ok_or(ArithmeticError::Overflow)?;450451				ensure!(452					*balance <= collection.limits.account_token_ownership_limit(),453					<CommonError<T>>::AccountTokenLimitExceeded,454				);455			}456		}457458		for token in data.iter() {459			for (to, _) in token.users.iter() {460				if let Some(target) = T::CrossTokenAddressMapping::address_to_token(to) {461					let handle = <CollectionHandle<T>>::try_get(target.0)?;462					let dispatch = T::CollectionDispatch::dispatch(handle);463					let dispatch = dispatch.as_dyn();464465					dispatch.check_nesting(466						sender.clone(),467						collection.id,468						target.1,469						nesting_budget,470					)?;471				}472			}473		}474475		// =========476477		<TokensMinted<T>>::insert(collection.id, tokens_minted);478		for (account, balance) in balances {479			<AccountBalance<T>>::insert((collection.id, account), balance);480		}481		for (i, token) in data.into_iter().enumerate() {482			let token_id = first_token_id + i as u32 + 1;483			<TotalSupply<T>>::insert((collection.id, token_id), totals[i]);484485			<TokenData<T>>::insert(486				(collection.id, token_id),487				ItemData {488					const_data: token.const_data,489					variable_data: token.variable_data,490				},491			);492			for (user, amount) in token.users.into_iter() {493				if amount == 0 {494					continue;495				}496				<Balance<T>>::insert((collection.id, token_id, &user), amount);497				<Owned<T>>::insert((collection.id, &user, TokenId(token_id)), true);498				// TODO: ERC20 transfer event499				<PalletCommon<T>>::deposit_event(CommonEvent::ItemCreated(500					collection.id,501					TokenId(token_id),502					user,503					amount,504				));505			}506		}507		Ok(())508	}509510	pub fn set_allowance_unchecked(511		collection: &RefungibleHandle<T>,512		sender: &T::CrossAccountId,513		spender: &T::CrossAccountId,514		token: TokenId,515		amount: u128,516	) {517		if amount == 0 {518			<Allowance<T>>::remove((collection.id, token, sender, spender));519		} else {520			<Allowance<T>>::insert((collection.id, token, sender, spender), amount);521		}522		// TODO: ERC20 approval event523		<PalletCommon<T>>::deposit_event(CommonEvent::Approved(524			collection.id,525			token,526			sender.clone(),527			spender.clone(),528			amount,529		))530	}531532	pub fn set_allowance(533		collection: &RefungibleHandle<T>,534		sender: &T::CrossAccountId,535		spender: &T::CrossAccountId,536		token: TokenId,537		amount: u128,538	) -> DispatchResult {539		if collection.access == AccessMode::AllowList {540			collection.check_allowlist(sender)?;541			collection.check_allowlist(spender)?;542		}543544		<PalletCommon<T>>::ensure_correct_receiver(spender)?;545546		if <Balance<T>>::get((collection.id, token, sender)) < amount {547			ensure!(548				collection.ignores_owned_amount(sender) && Self::token_exists(collection, token),549				<CommonError<T>>::CantApproveMoreThanOwned550			);551		}552553		// =========554555		Self::set_allowance_unchecked(collection, sender, spender, token, amount);556		Ok(())557	}558559	/// Returns allowance, which should be set after transaction560	fn check_allowed(561		collection: &RefungibleHandle<T>,562		spender: &T::CrossAccountId,563		from: &T::CrossAccountId,564		token: TokenId,565		amount: u128,566		nesting_budget: &dyn Budget,567	) -> Result<Option<u128>, DispatchError> {568		if spender.conv_eq(from) {569			return Ok(None);570		}571		if collection.access == AccessMode::AllowList {572			// `from`, `to` checked in [`transfer`]573			collection.check_allowlist(spender)?;574		}575		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {576			// TODO: should collection owner be allowed to perform this transfer?577			ensure!(578				<PalletStructure<T>>::indirectly_owned(579					spender.clone(),580					source.0,581					source.1,582					nesting_budget583				)?,584				<CommonError<T>>::ApprovedValueTooLow,585			);586			return Ok(None);587		}588		let allowance =589			<Allowance<T>>::get((collection.id, token, from, &spender)).checked_sub(amount);590		if allowance.is_none() {591			ensure!(592				collection.ignores_allowance(spender),593				<CommonError<T>>::ApprovedValueTooLow594			);595		}596		Ok(allowance)597	}598599	pub fn transfer_from(600		collection: &RefungibleHandle<T>,601		spender: &T::CrossAccountId,602		from: &T::CrossAccountId,603		to: &T::CrossAccountId,604		token: TokenId,605		amount: u128,606		nesting_budget: &dyn Budget,607	) -> DispatchResult {608		let allowance =609			Self::check_allowed(collection, spender, from, token, amount, nesting_budget)?;610611		// =========612613		Self::transfer(collection, from, to, token, amount, nesting_budget)?;614		if let Some(allowance) = allowance {615			Self::set_allowance_unchecked(collection, from, spender, token, allowance);616		}617		Ok(())618	}619620	pub fn burn_from(621		collection: &RefungibleHandle<T>,622		spender: &T::CrossAccountId,623		from: &T::CrossAccountId,624		token: TokenId,625		amount: u128,626		nesting_budget: &dyn Budget,627	) -> DispatchResult {628		let allowance =629			Self::check_allowed(collection, spender, from, token, amount, nesting_budget)?;630631		// =========632633		Self::burn(collection, from, token, amount)?;634		if let Some(allowance) = allowance {635			Self::set_allowance_unchecked(collection, from, spender, token, allowance);636		}637		Ok(())638	}639640	pub fn set_variable_metadata(641		collection: &RefungibleHandle<T>,642		sender: &T::CrossAccountId,643		token: TokenId,644		data: BoundedVec<u8, CustomDataLimit>,645	) -> DispatchResult {646		collection.check_can_update_meta(647			sender,648			&T::CrossAccountId::from_sub(collection.owner.clone()),649		)?;650651		let token_data = <TokenData<T>>::get((collection.id, token));652653		// =========654655		<TokenData<T>>::insert(656			(collection.id, token),657			ItemData {658				variable_data: data,659				..token_data660			},661		);662		Ok(())663	}664665	/// Delegated to `create_multiple_items`666	pub fn create_item(667		collection: &RefungibleHandle<T>,668		sender: &T::CrossAccountId,669		data: CreateRefungibleExData<T::CrossAccountId>,670		nesting_budget: &dyn Budget,671	) -> DispatchResult {672		Self::create_multiple_items(collection, sender, vec![data], nesting_budget)673	}674}
modifiedpallets/structure/src/lib.rsdiffbeforeafterboth
--- a/pallets/structure/src/lib.rs
+++ b/pallets/structure/src/lib.rs
@@ -71,7 +71,7 @@
 #[derive(PartialEq)]
 pub enum Parent<CrossAccountId> {
 	/// Token owned by normal account
-	Normal(CrossAccountId),
+	User(CrossAccountId),
 	/// Passed token not found
 	TokenNotFound,
 	/// Token owner is another token (target token still may not exist)
@@ -94,7 +94,7 @@
 		Ok(match handle.token_owner(token) {
 			Some(owner) => match T::CrossTokenAddressMapping::address_to_token(&owner) {
 				Some((collection, token)) => Parent::Token(collection, token),
-				None => Parent::Normal(owner),
+				None => Parent::User(owner),
 			},
 			None => Parent::TokenNotFound,
 		})
@@ -137,29 +137,46 @@
 	) -> Result<T::CrossAccountId, DispatchError> {
 		let owner = Self::parent_chain(collection, token)
 			.take_while(|_| budget.consume())
-			.find(|p| matches!(p, Ok(Parent::Normal(_) | Parent::TokenNotFound)))
+			.find(|p| matches!(p, Ok(Parent::User(_) | Parent::TokenNotFound)))
 			.ok_or(<Error<T>>::DepthLimit)??;
 
 		Ok(match owner {
-			Parent::Normal(v) => v,
+			Parent::User(v) => v,
 			_ => fail!(<Error<T>>::TokenNotFound),
 		})
 	}
 
 	/// Check if token indirectly owned by specified user
-	pub fn indirectly_owned(
+	pub fn check_indirectly_owned(
 		user: T::CrossAccountId,
 		collection: CollectionId,
 		token: TokenId,
+		for_nest: Option<(CollectionId, TokenId)>,
 		budget: &dyn Budget,
 	) -> Result<bool, DispatchError> {
 		let target_parent = match T::CrossTokenAddressMapping::address_to_token(&user) {
 			Some((collection, token)) => Parent::Token(collection, token),
-			None => Parent::Normal(user),
+			None => Parent::User(user),
 		};
 
-		Ok(Self::parent_chain(collection, token)
-			.take_while(|_| budget.consume())
-			.any(|parent| Ok(&target_parent) == parent.as_ref()))
+		// Tried to nest token in itself
+		if Some((collection, token)) == for_nest {
+			return Err(<Error<T>>::OuroborosDetected.into());
+		}
+
+		for parent in Self::parent_chain(collection, token).take_while(|_| budget.consume()) {
+			match parent? {
+				// Tried to nest token in chain, which has this token as one of parents
+				Parent::Token(collection, token) if Some((collection, token)) == for_nest => {
+					return Err(<Error<T>>::OuroborosDetected.into())
+				}
+				// Found needed parent, token is indirecty owned
+				v if v == target_parent => return Ok(true),
+				Parent::TokenNotFound => return Ok(false),
+				_ => {}
+			}
+		}
+
+		Err(<Error<T>>::DepthLimit.into())
 	}
 }
modifiedtests/src/eth/util/helpers.tsdiffbeforeafterboth
--- a/tests/src/eth/util/helpers.ts
+++ b/tests/src/eth/util/helpers.ts
@@ -23,7 +23,7 @@
 import usingApi, {submitTransactionAsync} from '../../substrate/substrate-api';
 import {IKeyringPair} from '@polkadot/types/types';
 import {expect} from 'chai';
-import {getGenericResult, UNIQUE} from '../../util/helpers';
+import {CrossAccountId, getGenericResult, UNIQUE} from '../../util/helpers';
 import * as solc from 'solc';
 import config from '../../config';
 import privateKey from '../../substrate/privateKey';
@@ -80,6 +80,11 @@
   ]);
   return Web3.utils.toChecksumAddress('0x' + buf.toString('hex'));
 }
+export function tokenIdToCross(collection: number, token: number): CrossAccountId {
+  return {
+    Ethereum: tokenIdToAddress(collection, token),
+  };
+}
 
 export function createEthAccount(web3: Web3) {
   const account = web3.eth.accounts.create();
addedtests/src/nesting/graphs.test.tsdiffbeforeafterboth
--- /dev/null
+++ b/tests/src/nesting/graphs.test.ts
@@ -0,0 +1,51 @@
+import {ApiPromise} from '@polkadot/api';
+import {IKeyringPair} from '@polkadot/types/types';
+import {expect} from 'chai';
+import {tokenIdToCross} from '../eth/util/helpers';
+import privateKey from '../substrate/privateKey';
+import usingApi, {executeTransaction} from '../substrate/substrate-api';
+import {getCreateCollectionResult, transferExpectSuccess} from '../util/helpers';
+
+/**
+ * ```dot
+ * 4 -> 3 -> 2 -> 1
+ * 7 -> 6 -> 5 -> 2
+ * 8 -> 5
+ * ```
+ */
+async function buildComplexObjectGraph(api: ApiPromise, sender: IKeyringPair): Promise<number> {
+  const events = await executeTransaction(api, sender, api.tx.unique.createCollectionEx({mode: 'NFT'}));
+  const {collectionId} = getCreateCollectionResult(events);
+
+  await executeTransaction(api, sender, api.tx.unique.createMultipleItemsEx(collectionId, {NFT: Array(8).fill({owner: {Substrate: sender.address}})}));
+
+  await transferExpectSuccess(collectionId, 8, sender, tokenIdToCross(collectionId, 5));
+
+  await transferExpectSuccess(collectionId, 7, sender, tokenIdToCross(collectionId, 6));
+  await transferExpectSuccess(collectionId, 6, sender, tokenIdToCross(collectionId, 5));
+  await transferExpectSuccess(collectionId, 5, sender, tokenIdToCross(collectionId, 2));
+
+  await transferExpectSuccess(collectionId, 4, sender, tokenIdToCross(collectionId, 3));
+  await transferExpectSuccess(collectionId, 3, sender, tokenIdToCross(collectionId, 2));
+  await transferExpectSuccess(collectionId, 2, sender, tokenIdToCross(collectionId, 1));
+
+  return collectionId;
+}
+
+describe('graphs', () => {
+  it('ouroboros can\'t be created in graph', async () => {
+    await usingApi(async api => {
+      const alice = privateKey('//Alice');
+      const collection = await buildComplexObjectGraph(api, alice);
+
+      // to self
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 1), collection, 1, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+      // to nested part of graph
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 5), collection, 1, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 8), collection, 2, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+    });
+  });
+});