Support arbitrary RPC providers in monero-serai

Sets a clean path for no-std premised RPCs (buffers to an external RPC impl)/
Tor-based RPCs/client-side load balancing/...

coins/monero/src/wallet/decoys.rs

@@ -13,7 +13,7 @@ use curve25519_dalek::edwards::EdwardsPoint;
 
 use crate::{
   wallet::SpendableOutput,
-  rpc::{RpcError, Rpc},
+  rpc::{RpcError, RpcConnection, Rpc},
 };
 
 const LOCK_WINDOW: usize = 10;
@@ -31,9 +31,9 @@ lazy_static! {
 }
 
 #[allow(clippy::too_many_arguments)]
-async fn select_n<'a, R: RngCore + CryptoRng>(
+async fn select_n<'a, R: RngCore + CryptoRng, RPC: RpcConnection>(
   rng: &mut R,
-  rpc: &Rpc,
+  rpc: &Rpc<RPC>,
   distribution: &MutexGuard<'a, Vec<u64>>,
   height: usize,
   high: u64,
@@ -137,9 +137,9 @@ impl Decoys {
   }
 
   /// Select decoys using the same distribution as Monero.
-  pub async fn select<R: RngCore + CryptoRng>(
+  pub async fn select<R: RngCore + CryptoRng, RPC: RpcConnection>(
     rng: &mut R,
-    rpc: &Rpc,
+    rpc: &Rpc<RPC>,
     ring_len: usize,
     height: usize,
     inputs: &[SpendableOutput],

coins/monero/src/wallet/scan.rs

@@ -10,7 +10,7 @@ use crate::{
   serialize::{read_byte, read_u32, read_u64, read_bytes, read_scalar, read_point, read_raw_vec},
   transaction::{Input, Timelock, Transaction},
   block::Block,
-  rpc::{Rpc, RpcError},
+  rpc::{RpcError, RpcConnection, Rpc},
   wallet::{
     PaymentId, Extra, address::SubaddressIndex, Scanner, uniqueness, shared_key, amount_decryption,
     commitment_mask,
@@ -195,13 +195,19 @@ pub struct SpendableOutput {
 impl SpendableOutput {
   /// Update the spendable output's global index. This is intended to be called if a
   /// re-organization occurred.
-  pub async fn refresh_global_index(&mut self, rpc: &Rpc) -> Result<(), RpcError> {
+  pub async fn refresh_global_index<RPC: RpcConnection>(
+    &mut self,
+    rpc: &Rpc<RPC>,
+  ) -> Result<(), RpcError> {
     self.global_index =
       rpc.get_o_indexes(self.output.absolute.tx).await?[usize::from(self.output.absolute.o)];
     Ok(())
   }
 
-  pub async fn from(rpc: &Rpc, output: ReceivedOutput) -> Result<SpendableOutput, RpcError> {
+  pub async fn from<RPC: RpcConnection>(
+    rpc: &Rpc<RPC>,
+    output: ReceivedOutput,
+  ) -> Result<SpendableOutput, RpcError> {
     let mut output = SpendableOutput { output, global_index: 0 };
     output.refresh_global_index(rpc).await?;
     Ok(output)
@@ -408,9 +414,9 @@ impl Scanner {
   /// transactions is a dead giveaway for which transactions you successfully scanned. This
   /// function obtains the output indexes for the miner transaction, incrementing from there
   /// instead.
-  pub async fn scan(
+  pub async fn scan<RPC: RpcConnection>(
     &mut self,
-    rpc: &Rpc,
+    rpc: &Rpc<RPC>,
     block: &Block,
   ) -> Result<Vec<Timelocked<SpendableOutput>>, RpcError> {
     let mut index = rpc.get_o_indexes(block.miner_tx.hash()).await?[0];

coins/monero/src/wallet/send/mod.rs

@@ -33,7 +33,7 @@ use crate::{
     RctBase, RctPrunable, RctSignatures,
   },
   transaction::{Input, Output, Timelock, TransactionPrefix, Transaction},
-  rpc::{Rpc, RpcError},
+  rpc::{RpcError, RpcConnection, Rpc},
   wallet::{
     address::{Network, AddressSpec, MoneroAddress},
     ViewPair, SpendableOutput, Decoys, PaymentId, ExtraField, Extra, key_image_sort, uniqueness,
@@ -147,9 +147,9 @@ pub enum TransactionError {
   FrostError(FrostError),
 }
 
-async fn prepare_inputs<R: RngCore + CryptoRng>(
+async fn prepare_inputs<R: RngCore + CryptoRng, RPC: RpcConnection>(
   rng: &mut R,
-  rpc: &Rpc,
+  rpc: &Rpc<RPC>,
   ring_len: usize,
   inputs: &[SpendableOutput],
   spend: &Zeroizing<Scalar>,
@@ -663,10 +663,10 @@ impl SignableTransaction {
   }
 
   /// Sign this transaction.
-  pub async fn sign<R: RngCore + CryptoRng>(
+  pub async fn sign<R: RngCore + CryptoRng, RPC: RpcConnection>(
     mut self,
     rng: &mut R,
-    rpc: &Rpc,
+    rpc: &Rpc<RPC>,
     spend: &Zeroizing<Scalar>,
   ) -> Result<Transaction, TransactionError> {
     let mut images = Vec::with_capacity(self.inputs.len());

coins/monero/src/wallet/send/multisig.rs

@@ -30,7 +30,7 @@ use crate::{
     RctPrunable,
   },
   transaction::{Input, Transaction},
-  rpc::Rpc,
+  rpc::{RpcConnection, Rpc},
   wallet::{
     TransactionError, InternalPayment, SignableTransaction, Decoys, key_image_sort, uniqueness,
   },
@@ -74,9 +74,9 @@ pub struct TransactionSignatureMachine {
 impl SignableTransaction {
   /// Create a FROST signing machine out of this signable transaction.
   /// The height is the Monero blockchain height to synchronize around.
-  pub async fn multisig(
+  pub async fn multisig<RPC: RpcConnection>(
     self,
-    rpc: &Rpc,
+    rpc: &Rpc<RPC>,
     keys: ThresholdKeys<Ed25519>,
     mut transcript: RecommendedTranscript,
     height: usize,