Exposed a hash-based API for accessing blocks

Also corrects a few panics, which shouldn't have been present, and unnecessary
Cursor uses.

coins/monero/src/rpc.rs

@@ -249,9 +249,10 @@ impl Rpc {
       .txs
       .iter()
       .map(|res| {
-        let tx = Transaction::deserialize(&mut std::io::Cursor::new(rpc_hex(
-          if !res.as_hex.is_empty() { &res.as_hex } else { &res.pruned_as_hex },
-        )?))
+        let tx = Transaction::deserialize::<&[u8]>(
+          &mut rpc_hex(if !res.as_hex.is_empty() { &res.as_hex } else { &res.pruned_as_hex })?
+            .as_ref(),
+        )
         .map_err(|_| match hash_hex(&res.tx_hash) {
           Ok(hash) => RpcError::InvalidTransaction(hash),
           Err(err) => err,
@@ -287,27 +288,52 @@ impl Rpc {
     Ok(txs.txs[0].block_height)
   }
 
-  pub async fn get_block(&self, height: usize) -> Result<Block, RpcError> {
+  pub async fn get_block_hash(&self, number: usize) -> Result<[u8; 32], RpcError> {
+    #[derive(Deserialize, Debug)]
+    struct BlockHeaderResponse {
+      hash: String,
+    }
+    #[derive(Deserialize, Debug)]
+    struct BlockHeaderByHeightResponse {
+      block_header: BlockHeaderResponse,
+    }
+
+    let header: BlockHeaderByHeightResponse =
+      self.json_rpc_call("get_block_header_by_height", Some(json!({ "height": number }))).await?;
+    rpc_hex(&header.block_header.hash)?.try_into().map_err(|_| RpcError::InvalidNode)
+  }
+
+  pub async fn get_block(&self, hash: [u8; 32]) -> Result<Block, RpcError> {
     #[derive(Deserialize, Debug)]
     struct BlockResponse {
       blob: String,
     }
 
-    let block: BlockResponse =
-      self.json_rpc_call("get_block", Some(json!({ "height": height }))).await?;
-    Ok(
-      Block::deserialize(&mut std::io::Cursor::new(rpc_hex(&block.blob)?))
-        .expect("Monero returned a block we couldn't deserialize"),
-    )
+    let res: BlockResponse =
+      self.json_rpc_call("get_block", Some(json!({ "hash": hex::encode(hash) }))).await?;
+
+    Block::deserialize::<&[u8]>(&mut rpc_hex(&res.blob)?.as_ref())
+      .map_err(|_| RpcError::InvalidNode)
   }
 
-  pub async fn get_block_transactions(&self, height: usize) -> Result<Vec<Transaction>, RpcError> {
-    let block = self.get_block(height).await?;
+  pub async fn get_block_by_number(&self, number: usize) -> Result<Block, RpcError> {
+    self.get_block(self.get_block_hash(number).await?).await
+  }
+
+  pub async fn get_block_transactions(&self, hash: [u8; 32]) -> Result<Vec<Transaction>, RpcError> {
+    let block = self.get_block(hash).await?;
     let mut res = vec![block.miner_tx];
     res.extend(self.get_transactions(&block.txs).await?);
     Ok(res)
   }
 
+  pub async fn get_block_transactions_by_number(
+    &self,
+    number: usize,
+  ) -> Result<Vec<Transaction>, RpcError> {
+    self.get_block_transactions(self.get_block_hash(number).await?).await
+  }
+
   /// Get the output indexes of the specified transaction.
   pub async fn get_o_indexes(&self, hash: [u8; 32]) -> Result<Vec<u64>, RpcError> {
     #[derive(Serialize, Debug)]
@@ -407,13 +433,8 @@ impl Rpc {
         &outs
           .outs
           .iter()
-          .map(|out| {
-            rpc_hex(&out.txid)
-              .expect("Monero returned an invalidly encoded hash")
-              .try_into()
-              .expect("Monero returned an invalid sized hash")
-          })
-          .collect::<Vec<_>>(),
+          .map(|out| rpc_hex(&out.txid)?.try_into().map_err(|_| RpcError::InvalidNode))
+          .collect::<Result<Vec<_>, _>>()?,
       )
       .await?;
 

coins/monero/src/wallet/extra.rs

@@ -1,5 +1,5 @@
 use core::ops::BitXor;
-use std::io::{self, Read, Write, Cursor};
+use std::io::{self, Read, Write};
 
 use zeroize::Zeroize;
 
@@ -127,7 +127,7 @@ impl Extra {
   pub(crate) fn payment_id(&self) -> Option<PaymentId> {
     for field in &self.0 {
       if let ExtraField::Nonce(data) = field {
-        return PaymentId::deserialize(&mut Cursor::new(data)).ok();
+        return PaymentId::deserialize::<&[u8]>(&mut data.as_ref()).ok();
       }
     }
     None

coins/monero/src/wallet/scan.rs

@@ -1,5 +1,3 @@
-use std::io::Cursor;
-
 use zeroize::{Zeroize, ZeroizeOnDrop};
 
 use curve25519_dalek::{constants::ED25519_BASEPOINT_TABLE, scalar::Scalar, edwards::EdwardsPoint};
@@ -232,7 +230,7 @@ impl<O: Clone + Zeroize> Timelocked<O> {
 impl Scanner {
   /// Scan a transaction to discover the received outputs.
   pub fn scan_transaction(&mut self, tx: &Transaction) -> Timelocked<ReceivedOutput> {
-    let extra = Extra::deserialize(&mut Cursor::new(&tx.prefix.extra));
+    let extra = Extra::deserialize::<&[u8]>(&mut tx.prefix.extra.as_ref());
     let keys;
     let extra = if let Ok(extra) = extra {
       keys = extra.keys();

coins/monero/tests/runner.rs

@@ -43,7 +43,7 @@ pub async fn mine_until_unlocked(rpc: &Rpc, addr: &str, tx_hash: [u8; 32]) {
   let mut height = rpc.get_height().await.unwrap();
   let mut found = false;
   while !found {
-    let block = rpc.get_block(height - 1).await.unwrap();
+    let block = rpc.get_block_by_number(height - 1).await.unwrap();
     found = match block.txs.iter().find(|&&x| x == tx_hash) {
       Some(_) => true,
       None => {
@@ -69,7 +69,7 @@ pub async fn get_miner_tx_output(rpc: &Rpc, view: &ViewPair) -> SpendableOutput
     .await
     .unwrap();
 
-  let block = rpc.get_block(start).await.unwrap();
+  let block = rpc.get_block_by_number(start).await.unwrap();
   scanner.scan(rpc, &block).await.unwrap().swap_remove(0).ignore_timelock().swap_remove(0)
 }