Add 'build_output' endpoint to owner api (#641)

* add 'build_output' endpoint to owner api

* merge fix

libwallet/src/api_impl/owner.rs

@@ -17,7 +17,8 @@
 use uuid::Uuid;
 
 use crate::grin_core::core::hash::Hashed;
-use crate::grin_core::core::Transaction;
+use crate::grin_core::core::{Output, OutputFeatures, Transaction};
+use crate::grin_core::libtx::proof;
 use crate::grin_keychain::ViewKey;
 use crate::grin_util::secp::key::SecretKey;
 use crate::grin_util::Mutex;
@@ -25,14 +26,14 @@ use crate::grin_util::ToHex;
 use crate::util::{OnionV3Address, OnionV3AddressError};
 
 use crate::api_impl::owner_updater::StatusMessage;
-use crate::grin_keychain::{Identifier, Keychain};
+use crate::grin_keychain::{BlindingFactor, Identifier, Keychain, SwitchCommitmentType};
 use crate::internal::{keys, scan, selection, tx, updater};
 use crate::slate::{PaymentInfo, Slate, SlateState};
 use crate::types::{AcctPathMapping, NodeClient, TxLogEntry, WalletBackend, WalletInfo};
 use crate::{
-	address, wallet_lock, InitTxArgs, IssueInvoiceTxArgs, NodeHeightResult, OutputCommitMapping,
-	PaymentProof, ScannedBlockInfo, Slatepack, SlatepackAddress, Slatepacker, SlatepackerArgs,
-	TxLogEntryType, ViewWallet, WalletInitStatus, WalletInst, WalletLCProvider,
+	address, wallet_lock, BuiltOutput, InitTxArgs, IssueInvoiceTxArgs, NodeHeightResult,
+	OutputCommitMapping, PaymentProof, ScannedBlockInfo, Slatepack, SlatepackAddress, Slatepacker,
+	SlatepackerArgs, TxLogEntryType, ViewWallet, WalletInitStatus, WalletInst, WalletLCProvider,
 };
 use crate::{Error, ErrorKind};
 use ed25519_dalek::PublicKey as DalekPublicKey;
@@ -1376,3 +1377,42 @@ where
 	}
 	Ok(true)
 }
+
+/// Builds an output for the wallet's next available key
+pub fn build_output<'a, T: ?Sized, C, K>(
+	w: &mut T,
+	keychain_mask: Option<&SecretKey>,
+	features: OutputFeatures,
+	amount: u64,
+) -> Result<BuiltOutput, Error>
+where
+	T: WalletBackend<'a, C, K>,
+	C: NodeClient + 'a,
+	K: Keychain + 'a,
+{
+	let k = w.keychain(keychain_mask)?;
+
+	let key_id = keys::next_available_key(&mut *w, keychain_mask)?;
+
+	let blind = k.derive_key(amount, &key_id, SwitchCommitmentType::Regular)?;
+	let commit = k.secp().commit(amount, blind.clone())?;
+
+	let proof_builder = proof::ProofBuilder::new(&k);
+	let proof = proof::create(
+		&k,
+		&proof_builder,
+		amount,
+		&key_id,
+		SwitchCommitmentType::Regular,
+		commit,
+		None,
+	)?;
+
+	let output = Output::new(features, commit, proof);
+
+	Ok(BuiltOutput {
+		blind: BlindingFactor::from_secret_key(blind),
+		key_id: key_id,
+		output: output,
+	})
+}

libwallet/src/api_impl/types.rs

@@ -14,8 +14,9 @@
 
 //! Types specific to the wallet api, mostly argument serialization
 
+use crate::grin_core::core::Output;
 use crate::grin_core::libtx::secp_ser;
-use crate::grin_keychain::Identifier;
+use crate::grin_keychain::{BlindingFactor, Identifier};
 use crate::grin_util::secp::pedersen;
 use crate::slate_versions::ser as dalek_ser;
 use crate::slate_versions::SlateVersion;
@@ -24,6 +25,11 @@ use crate::SlatepackAddress;
 
 use ed25519_dalek::Signature as DalekSignature;
 
+/// Type for storing amounts (in nanogrins).
+/// Serializes as a string but can deserialize from a string or u64.
+#[derive(Serialize, Deserialize)]
+pub struct Amount(#[serde(with = "secp_ser::string_or_u64")] pub u64);
+
 /// V2 Init / Send TX API Args
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct InitTxArgs {
@@ -216,3 +222,18 @@ pub struct PaymentProof {
 	#[serde(with = "dalek_ser::dalek_sig_serde")]
 	pub sender_sig: DalekSignature,
 }
+
+/// Build output result
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct BuiltOutput {
+	/// Blinding Factor
+	#[serde(
+		serialize_with = "secp_ser::as_hex",
+		deserialize_with = "secp_ser::blind_from_hex"
+	)]
+	pub blind: BlindingFactor,
+	/// Key Identifier
+	pub key_id: Identifier,
+	/// Output
+	pub output: Output,
+}

libwallet/src/lib.rs

@@ -67,8 +67,8 @@ pub use crate::slatepack::{
 };
 pub use api_impl::owner_updater::StatusMessage;
 pub use api_impl::types::{
-	BlockFees, InitTxArgs, InitTxSendArgs, IssueInvoiceTxArgs, NodeHeightResult,
-	OutputCommitMapping, PaymentProof, VersionInfo,
+	Amount, BlockFees, BuiltOutput, InitTxArgs, InitTxSendArgs, IssueInvoiceTxArgs,
+	NodeHeightResult, OutputCommitMapping, PaymentProof, VersionInfo,
 };
 pub use internal::scan::scan;
 pub use slate_versions::ser as dalek_ser;