[NFTs] Offchain mint (#13158)

* Allow to mint with the pre-signed signatures

* Another try

* WIP: test encoder

* Fix the deposits

* Refactoring + tests + benchmarks

* Add sp-core/runtime-benchmarks

* Remove sp-core from dev deps

* Enable full_crypto for benchmarks

* Typo

* Fix

* Update frame/nfts/src/mock.rs

Co-authored-by: Squirrel <gilescope@gmail.com>

* ".git/.scripts/commands/bench/bench.sh" pallet dev pallet_nfts

* Add docs

* Add attributes into the pre-signed object & track the deposit owner for attributes

* Update docs

* ".git/.scripts/commands/bench/bench.sh" pallet dev pallet_nfts

* Add the number of attributes provided to weights

* Apply suggestions

* Remove dead code

* Remove Copy

* Fix docs

* Update frame/nfts/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update frame/nfts/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

---------

Co-authored-by: Squirrel <gilescope@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

bin/node/runtime/src/lib.rs

@@ -1566,6 +1566,7 @@ impl pallet_uniques::Config for Runtime {
 
 parameter_types! {
 	pub Features: PalletFeatures = PalletFeatures::all_enabled();
+	pub const MaxAttributesPerCall: u32 = 10;
 }
 
 impl pallet_nfts::Config for Runtime {
@@ -1586,7 +1587,10 @@ impl pallet_nfts::Config for Runtime {
 	type ItemAttributesApprovalsLimit = ItemAttributesApprovalsLimit;
 	type MaxTips = MaxTips;
 	type MaxDeadlineDuration = MaxDeadlineDuration;
+	type MaxAttributesPerCall = MaxAttributesPerCall;
 	type Features = Features;
+	type OffchainSignature = Signature;
+	type OffchainPublic = <Signature as traits::Verify>::Signer;
 	type WeightInfo = pallet_nfts::weights::SubstrateWeight<Runtime>;
 	#[cfg(feature = "runtime-benchmarks")]
 	type Helper = ();

frame/nfts/Cargo.toml

@@ -21,14 +21,13 @@ frame-benchmarking = { version = "4.0.0-dev", default-features = false, optional
 frame-support = { version = "4.0.0-dev", default-features = false, path = "../support" }
 frame-system = { version = "4.0.0-dev", default-features = false, path = "../system" }
 sp-core = { version = "7.0.0", default-features = false, path = "../../primitives/core" }
+sp-io = { version = "7.0.0", default-features = false, path = "../../primitives/io" }
 sp-runtime = { version = "7.0.0", default-features = false, path = "../../primitives/runtime" }
 sp-std = { version = "5.0.0", default-features = false, path = "../../primitives/std" }
 
 [dev-dependencies]
 pallet-balances = { version = "4.0.0-dev", path = "../balances" }
-sp-core = { version = "7.0.0", path = "../../primitives/core" }
-sp-io = { version = "7.0.0", path = "../../primitives/io" }
-sp-std = { version = "5.0.0", path = "../../primitives/std" }
+sp-keystore = { version = "0.13.0", path = "../../primitives/keystore" }
 
 [features]
 default = ["std"]
@@ -40,6 +39,7 @@ std = [
 	"log/std",
 	"scale-info/std",
 	"sp-core/std",
+	"sp-io/std",
 	"sp-runtime/std",
 	"sp-std/std",
 ]

frame/nfts/src/benchmarking.rs

@@ -31,7 +31,11 @@ use frame_support::{
 	BoundedVec,
 };
 use frame_system::RawOrigin as SystemOrigin;
-use sp_runtime::traits::{Bounded, One};
+use sp_io::crypto::{sr25519_generate, sr25519_sign};
+use sp_runtime::{
+	traits::{Bounded, IdentifyAccount, One},
+	AccountId32, MultiSignature, MultiSigner,
+};
 use sp_std::prelude::*;
 
 use crate::Pallet as Nfts;
@@ -148,7 +152,21 @@ fn default_item_config() -> ItemConfig {
 	ItemConfig { settings: ItemSettings::all_enabled() }
 }
 
+fn make_filled_vec(value: u16, length: usize) -> Vec<u8> {
+	let mut vec = vec![0u8; length];
+	let mut s = Vec::from(value.to_be_bytes());
+	vec.truncate(length - s.len());
+	vec.append(&mut s);
+	vec
+}
+
 benchmarks_instance_pallet! {
+	where_clause {
+		where
+			T::OffchainSignature: From<MultiSignature>,
+			T::AccountId: From<AccountId32>,
+	}
+
 	create {
 		let collection = T::Helper::collection(0);
 		let origin = T::CreateOrigin::try_successful_origin(&collection)
@@ -439,11 +457,7 @@ benchmarks_instance_pallet! {
 		T::Currency::make_free_balance_be(&target, DepositBalanceOf::<T, I>::max_value());
 		let value: BoundedVec<_, _> = vec![0u8; T::ValueLimit::get() as usize].try_into().unwrap();
 		for i in 0..n {
-			let mut key = vec![0u8; T::KeyLimit::get() as usize];
-			let mut s = Vec::from((i as u16).to_be_bytes());
-			key.truncate(s.len());
-			key.append(&mut s);
-
+			let key = make_filled_vec(i as u16, T::KeyLimit::get() as usize);
 			Nfts::<T, I>::set_attribute(
 				SystemOrigin::Signed(target.clone()).into(),
 				T::Helper::collection(0),
@@ -717,5 +731,47 @@ benchmarks_instance_pallet! {
 		}.into());
 	}
 
+	mint_pre_signed {
+		let n in 0 .. T::MaxAttributesPerCall::get() as u32;
+		let caller_public = sr25519_generate(0.into(), None);
+		let caller = MultiSigner::Sr25519(caller_public).into_account().into();
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
+		let caller_lookup = T::Lookup::unlookup(caller.clone());
+
+		let collection = T::Helper::collection(0);
+		let item = T::Helper::item(0);
+		assert_ok!(Nfts::<T, I>::force_create(
+			SystemOrigin::Root.into(),
+			caller_lookup.clone(),
+			default_collection_config::<T, I>()
+		));
+
+		let metadata = vec![0u8; T::StringLimit::get() as usize];
+		let mut attributes = vec![];
+		let attribute_value = vec![0u8; T::ValueLimit::get() as usize];
+		for i in 0..n {
+			let attribute_key = make_filled_vec(i as u16, T::KeyLimit::get() as usize);
+			attributes.push((attribute_key, attribute_value.clone()));
+		}
+		let mint_data = PreSignedMint {
+			collection,
+			item,
+			attributes,
+			metadata: metadata.clone(),
+			only_account: None,
+			deadline: One::one(),
+		};
+		let message = Encode::encode(&mint_data);
+		let signature = MultiSignature::Sr25519(sr25519_sign(0.into(), &caller_public, &message).unwrap());
+
+		let target: T::AccountId = account("target", 0, SEED);
+		T::Currency::make_free_balance_be(&target, DepositBalanceOf::<T, I>::max_value());
+		frame_system::Pallet::<T>::set_block_number(One::one());
+	}: _(SystemOrigin::Signed(target.clone()), mint_data, signature.into(), caller)
+	verify {
+		let metadata: BoundedVec<_, _> = metadata.try_into().unwrap();
+		assert_last_event::<T, I>(Event::ItemMetadataSet { collection, item, data: metadata }.into());
+	}
+
 	impl_benchmark_test_suite!(Nfts, crate::mock::new_test_ext(), crate::mock::Test);
 }

frame/nfts/src/common_functions.rs

@@ -17,7 +17,7 @@
 
 //! Various pieces of common functionality.
 
-use super::*;
+use crate::*;
 
 impl<T: Config<I>, I: 'static> Pallet<T, I> {
 	/// Get the owner of the item, if the item exists.

frame/nfts/src/features/attributes.rs

@@ -26,6 +26,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		namespace: AttributeNamespace<T::AccountId>,
 		key: BoundedVec<u8, T::KeyLimit>,
 		value: BoundedVec<u8, T::ValueLimit>,
+		depositor: T::AccountId,
 	) -> DispatchResult {
 		ensure!(
 			Self::is_pallet_feature_enabled(PalletFeature::Attributes),
@@ -66,14 +67,16 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		}
 
 		let attribute = Attribute::<T, I>::get((collection, maybe_item, &namespace, &key));
-		if attribute.is_none() {
+		let attribute_exists = attribute.is_some();
+		if !attribute_exists {
 			collection_details.attributes.saturating_inc();
 		}
 
 		let old_deposit =
 			attribute.map_or(AttributeDeposit { account: None, amount: Zero::zero() }, |m| m.1);
 
 		let mut deposit = Zero::zero();
+		// disabled DepositRequired setting only affects the CollectionOwner namespace
 		if collection_config.is_setting_enabled(CollectionSetting::DepositRequired) ||
 			namespace != AttributeNamespace::CollectionOwner
 		{
@@ -82,33 +85,50 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 				.saturating_add(T::AttributeDepositBase::get());
 		}
 
+		let is_collection_owner_namespace = namespace == AttributeNamespace::CollectionOwner;
+		let is_depositor_collection_owner =
+			is_collection_owner_namespace && collection_details.owner == depositor;
+
+		// NOTE: in the CollectionOwner namespace if the depositor is `None` that means the deposit
+		// was paid by the collection's owner.
+		let old_depositor =
+			if is_collection_owner_namespace && old_deposit.account.is_none() && attribute_exists {
+				Some(collection_details.owner.clone())
+			} else {
+				old_deposit.account
+			};
+		let depositor_has_changed = old_depositor != Some(depositor.clone());
+
 		// NOTE: when we transfer an item, we don't move attributes in the ItemOwner namespace.
 		// When the new owner updates the same attribute, we will update the depositor record
 		// and return the deposit to the previous owner.
-		if old_deposit.account.is_some() && old_deposit.account != Some(origin.clone()) {
-			T::Currency::unreserve(&old_deposit.account.unwrap(), old_deposit.amount);
-			T::Currency::reserve(&origin, deposit)?;
+		if depositor_has_changed {
+			if let Some(old_depositor) = old_depositor {
+				T::Currency::unreserve(&old_depositor, old_deposit.amount);
+			}
+			T::Currency::reserve(&depositor, deposit)?;
 		} else if deposit > old_deposit.amount {
-			T::Currency::reserve(&origin, deposit - old_deposit.amount)?;
+			T::Currency::reserve(&depositor, deposit - old_deposit.amount)?;
 		} else if deposit < old_deposit.amount {
-			T::Currency::unreserve(&origin, old_deposit.amount - deposit);
+			T::Currency::unreserve(&depositor, old_deposit.amount - deposit);
 		}
 
-		// NOTE: we don't track the depositor in the CollectionOwner namespace as it's always a
-		// collection's owner. This simplifies the collection's transfer to another owner.
-		let deposit_owner = match namespace {
-			AttributeNamespace::CollectionOwner => {
-				collection_details.owner_deposit.saturating_accrue(deposit);
+		if is_depositor_collection_owner {
+			if !depositor_has_changed {
 				collection_details.owner_deposit.saturating_reduce(old_deposit.amount);
-				None
-			},
-			_ => Some(origin),
-		};
+			}
+			collection_details.owner_deposit.saturating_accrue(deposit);
+		}
 
+		let new_deposit_owner = match is_depositor_collection_owner {
+			true => None,
+			false => Some(depositor),
+		};
 		Attribute::<T, I>::insert(
 			(&collection, maybe_item, &namespace, &key),
-			(&value, AttributeDeposit { account: deposit_owner, amount: deposit }),
+			(&value, AttributeDeposit { account: new_deposit_owner, amount: deposit }),
 		);
+
 		Collection::<T, I>::insert(collection, &collection_details);
 		Self::deposit_event(Event::AttributeSet { collection, maybe_item, key, value, namespace });
 		Ok(())
@@ -188,27 +208,38 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 						// NOTE: if the item was previously burned, the ItemConfigOf record
 						// might not exist. In that case, we allow to clear the attribute.
 						let maybe_is_locked = Self::get_item_config(&collection, &item)
-							.map_or(false, |c| {
-								c.has_disabled_setting(ItemSetting::UnlockedAttributes)
+							.map_or(None, |c| {
+								Some(c.has_disabled_setting(ItemSetting::UnlockedAttributes))
 							});
-						ensure!(!maybe_is_locked, Error::<T, I>::LockedItemAttributes);
+						match maybe_is_locked {
+							Some(is_locked) => {
+								// when item exists, then only the collection's owner can clear that
+								// attribute
+								ensure!(
+									check_owner == &collection_details.owner,
+									Error::<T, I>::NoPermission
+								);
+								ensure!(!is_locked, Error::<T, I>::LockedItemAttributes);
+							},
+							None => (),
+						}
 					},
 				},
 				_ => (),
 			};
 		}
 
 		collection_details.attributes.saturating_dec();
-		match namespace {
-			AttributeNamespace::CollectionOwner => {
+
+		match deposit.account {
+			Some(deposit_account) => {
+				T::Currency::unreserve(&deposit_account, deposit.amount);
+			},
+			None if namespace == AttributeNamespace::CollectionOwner => {
 				collection_details.owner_deposit.saturating_reduce(deposit.amount);
 				T::Currency::unreserve(&collection_details.owner, deposit.amount);
 			},
 			_ => (),
-		};
-
-		if let Some(deposit_account) = deposit.account {
-			T::Currency::unreserve(&deposit_account, deposit.amount);
 		}
 
 		Collection::<T, I>::insert(collection, &collection_details);

frame/nfts/src/features/create_delete_item.rs

@@ -85,6 +85,62 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(())
 	}
 
+	pub(crate) fn do_mint_pre_signed(
+		mint_to: T::AccountId,
+		mint_data: PreSignedMintOf<T, I>,
+		signer: T::AccountId,
+	) -> DispatchResult {
+		let PreSignedMint { collection, item, attributes, metadata, deadline, only_account } =
+			mint_data;
+		let metadata = Self::construct_metadata(metadata)?;
+
+		ensure!(
+			attributes.len() <= T::MaxAttributesPerCall::get() as usize,
+			Error::<T, I>::MaxAttributesLimitReached
+		);
+		if let Some(account) = only_account {
+			ensure!(account == mint_to, Error::<T, I>::WrongOrigin);
+		}
+
+		let now = frame_system::Pallet::<T>::block_number();
+		ensure!(deadline >= now, Error::<T, I>::DeadlineExpired);
+
+		let collection_details =
+			Collection::<T, I>::get(&collection).ok_or(Error::<T, I>::UnknownCollection)?;
+		ensure!(collection_details.owner == signer, Error::<T, I>::NoPermission);
+
+		let item_config = ItemConfig { settings: Self::get_default_item_settings(&collection)? };
+		Self::do_mint(
+			collection,
+			item,
+			Some(mint_to.clone()),
+			mint_to.clone(),
+			item_config,
+			|_, _| Ok(()),
+		)?;
+		for (key, value) in attributes {
+			Self::do_set_attribute(
+				collection_details.owner.clone(),
+				collection,
+				Some(item),
+				AttributeNamespace::CollectionOwner,
+				Self::construct_attribute_key(key)?,
+				Self::construct_attribute_value(value)?,
+				mint_to.clone(),
+			)?;
+		}
+		if !metadata.len().is_zero() {
+			Self::do_set_item_metadata(
+				Some(collection_details.owner.clone()),
+				collection,
+				item,
+				metadata,
+				Some(mint_to.clone()),
+			)?;
+		}
+		Ok(())
+	}
+
 	pub fn do_burn(
 		collection: T::CollectionId,
 		item: T::ItemId,

frame/nfts/src/features/metadata.rs

@@ -60,14 +60,16 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 					.saturating_add(T::MetadataDepositBase::get());
 			}
 
-			// the previous deposit was taken from the item's owner
-			if old_deposit.account.is_some() && maybe_depositor.is_none() {
-				T::Currency::unreserve(&old_deposit.account.unwrap(), old_deposit.amount);
-				T::Currency::reserve(&collection_details.owner, deposit)?;
+			let depositor = maybe_depositor.clone().unwrap_or(collection_details.owner.clone());
+			let old_depositor = old_deposit.account.unwrap_or(collection_details.owner.clone());
+
+			if depositor != old_depositor {
+				T::Currency::unreserve(&old_depositor, old_deposit.amount);
+				T::Currency::reserve(&depositor, deposit)?;
 			} else if deposit > old_deposit.amount {
-				T::Currency::reserve(&collection_details.owner, deposit - old_deposit.amount)?;
+				T::Currency::reserve(&depositor, deposit - old_deposit.amount)?;
 			} else if deposit < old_deposit.amount {
-				T::Currency::unreserve(&collection_details.owner, old_deposit.amount - deposit);
+				T::Currency::unreserve(&depositor, old_deposit.amount - deposit);
 			}
 
 			if maybe_depositor.is_none() {
@@ -191,4 +193,11 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			Ok(())
 		})
 	}
+
+	/// A helper method to construct metadata.
+	pub fn construct_metadata(
+		metadata: Vec<u8>,
+	) -> Result<BoundedVec<u8, T::StringLimit>, DispatchError> {
+		Ok(BoundedVec::try_from(metadata).map_err(|_| Error::<T, I>::IncorrectMetadata)?)
+	}
 }