cleanup util::from_hex() (#3265)

* cleanup our from_hex()

* fix keychain tests

* add test coverage for empty hex string

api/src/foreign_rpc.rs

@@ -747,7 +747,7 @@ impl ForeignRpc for Foreign {
 	) -> Result<BlockHeaderPrintable, ErrorKind> {
 		let mut parsed_hash: Option<Hash> = None;
 		if let Some(hash) = hash {
-			let vec = util::from_hex(hash)
+			let vec = util::from_hex(&hash)
 				.map_err(|e| ErrorKind::Argument(format!("invalid block hash: {}", e)))?;
 			parsed_hash = Some(Hash::from_vec(&vec));
 		}
@@ -761,7 +761,7 @@ impl ForeignRpc for Foreign {
 	) -> Result<BlockPrintable, ErrorKind> {
 		let mut parsed_hash: Option<Hash> = None;
 		if let Some(hash) = hash {
-			let vec = util::from_hex(hash)
+			let vec = util::from_hex(&hash)
 				.map_err(|e| ErrorKind::Argument(format!("invalid block hash: {}", e)))?;
 			parsed_hash = Some(Hash::from_vec(&vec));
 		}

api/src/handlers/blocks_api.rs

@@ -47,7 +47,7 @@ impl HeaderHandler {
 			}
 		}
 		check_block_param(&input)?;
-		let vec = util::from_hex(input)
+		let vec = util::from_hex(&input)
 			.map_err(|e| ErrorKind::Argument(format!("invalid input: {}", e)))?;
 		let h = Hash::from_vec(&vec);
 		let header = w(&self.chain)?
@@ -153,7 +153,7 @@ impl BlockHandler {
 			}
 		}
 		check_block_param(&input)?;
-		let vec = util::from_hex(input)
+		let vec = util::from_hex(&input)
 			.map_err(|e| ErrorKind::Argument(format!("invalid input: {}", e)))?;
 		Ok(Hash::from_vec(&vec))
 	}

api/src/handlers/chain_api.rs

@@ -308,7 +308,7 @@ impl OutputHandler {
 		let query = must_get_query!(req);
 		let params = QueryParams::from(query);
 		params.process_multival_param("id", |id| {
-			if let Ok(x) = util::from_hex(String::from(id)) {
+			if let Ok(x) = util::from_hex(id) {
 				commitments.push(Commitment::from_vec(x));
 			}
 		});
@@ -392,7 +392,7 @@ impl KernelHandler {
 			.rsplit('/')
 			.next()
 			.ok_or_else(|| ErrorKind::RequestError("missing excess".into()))?;
-		let excess = util::from_hex(excess.to_owned())
+		let excess = util::from_hex(excess)
 			.map_err(|_| ErrorKind::RequestError("invalid excess hex".into()))?;
 		if excess.len() != 33 {
 			return Err(ErrorKind::RequestError("invalid excess length".into()).into());
@@ -444,7 +444,7 @@ impl KernelHandler {
 		min_height: Option<u64>,
 		max_height: Option<u64>,
 	) -> Result<LocatedTxKernel, Error> {
-		let excess = util::from_hex(excess)
+		let excess = util::from_hex(&excess)
 			.map_err(|_| ErrorKind::RequestError("invalid excess hex".into()))?;
 		if excess.len() != 33 {
 			return Err(ErrorKind::RequestError("invalid excess length".into()).into());

api/src/handlers/pool_api.rs

@@ -109,7 +109,7 @@ async fn update_pool(
 	let fluff = params.get("fluff").is_some();
 
 	let wrapper: TxWrapper = parse_body(req).await?;
-	let tx_bin = util::from_hex(wrapper.tx_hex)
+	let tx_bin = util::from_hex(&wrapper.tx_hex)
 		.map_err(|e| ErrorKind::RequestError(format!("Bad request: {}", e)))?;
 
 	// All wallet api interaction explicitly uses protocol version 1 for now.

api/src/handlers/transactions_api.rs

@@ -120,10 +120,8 @@ impl TxHashSetHandler {
 	// return a dummy output with merkle proof for position filled out
 	// (to avoid having to create a new type to pass around)
 	fn get_merkle_proof_for_output(&self, id: &str) -> Result<OutputPrintable, Error> {
-		let c = util::from_hex(String::from(id)).context(ErrorKind::Argument(format!(
-			"Not a valid commitment: {}",
-			id
-		)))?;
+		let c = util::from_hex(id)
+			.map_err(|_| ErrorKind::Argument(format!("Not a valid commitment: {}", id)))?;
 		let commit = Commitment::from_vec(c);
 		let chain = w(&self.chain)?;
 		let output_pos = chain.get_output_pos(&commit).context(ErrorKind::NotFound)?;

api/src/handlers/utils.rs

@@ -19,7 +19,6 @@ use crate::rest::*;
 use crate::types::*;
 use crate::util;
 use crate::util::secp::pedersen::Commitment;
-use failure::ResultExt;
 use std::sync::{Arc, Weak};
 
 // All handlers use `Weak` references instead of `Arc` to avoid cycles that
@@ -35,10 +34,8 @@ fn get_unspent(
 	chain: &Arc<chain::Chain>,
 	id: &str,
 ) -> Result<Option<(CommitPos, OutputIdentifier)>, Error> {
-	let c = util::from_hex(String::from(id)).context(ErrorKind::Argument(format!(
-		"Not a valid commitment: {}",
-		id
-	)))?;
+	let c = util::from_hex(id)
+		.map_err(|_| ErrorKind::Argument(format!("Not a valid commitment: {}", id)))?;
 	let commit = Commitment::from_vec(c);
 
 	// We need the features here to be able to generate the necessary hash

api/src/types.rs

@@ -246,7 +246,7 @@ impl<'de> serde::de::Visitor<'de> for PrintableCommitmentVisitor {
 	{
 		Ok(PrintableCommitment {
 			commit: pedersen::Commitment::from_vec(
-				util::from_hex(String::from(v)).map_err(serde::de::Error::custom)?,
+				util::from_hex(v).map_err(serde::de::Error::custom)?,
 			),
 		})
 	}
@@ -337,7 +337,7 @@ impl OutputPrintable {
 			.clone()
 			.ok_or_else(|| ser::Error::HexError("output range_proof missing".to_string()))?;
 
-		let p_vec = util::from_hex(proof_str)
+		let p_vec = util::from_hex(&proof_str)
 			.map_err(|_| ser::Error::HexError("invalid output range_proof".to_string()))?;
 		let mut p_bytes = [0; util::secp::constants::MAX_PROOF_SIZE];
 		for i in 0..p_bytes.len() {
@@ -421,8 +421,7 @@ impl<'de> serde::de::Deserialize<'de> for OutputPrintable {
 							no_dup!(commit);
 
 							let val: String = map.next_value()?;
-							let vec =
-								util::from_hex(val.clone()).map_err(serde::de::Error::custom)?;
+							let vec = util::from_hex(&val).map_err(serde::de::Error::custom)?;
 							commit = Some(pedersen::Commitment::from_vec(vec));
 						}
 						Field::Spent => {