Fast sync part 2 (#156)

* boilerplate

* Cargo.lock

* Stub of block validation

* Block validation (diff by @dllud)

* Cargo.lock

* Complete implementation of block validation request

* Apply suggestions from code review

Co-authored-by: Boog900 <boog900@tutanota.com>

* More suggestions

* Update consensus/fast-sync/src/fast_sync.rs

* Update consensus/fast-sync/src/fast_sync.rs

---------

Co-authored-by: Boog900 <boog900@tutanota.com>

Cargo.lock

@@ -565,11 +565,15 @@ version = "0.1.0"
 dependencies = [
  "clap",
  "cuprate-blockchain",
+ "cuprate-consensus",
+ "cuprate-consensus-rules",
  "cuprate-types",
  "hex",
  "hex-literal",
+ "monero-serai",
  "rayon",
  "sha3",
+ "thiserror",
  "tokio",
  "tokio-test",
  "tower",

consensus/fast-sync/Cargo.toml

@@ -11,11 +11,15 @@ path = "src/create.rs"
 [dependencies]
 clap = { workspace = true, features = ["derive", "std"] }
 cuprate-blockchain = { path = "../../storage/cuprate-blockchain" }
+cuprate-consensus = { path = ".." }
+cuprate-consensus-rules = { path = "../rules" }
 cuprate-types = { path = "../../types" }
 hex.workspace = true
 hex-literal.workspace = true
+monero-serai.workspace = true
 rayon.workspace = true
 sha3 = "0.10.8"
+thiserror.workspace = true
 tokio = { workspace = true, features = ["full"] }
 tower.workspace = true
 

consensus/fast-sync/src/fast_sync.rs

@@ -1,5 +1,6 @@
 use std::{
     cmp,
+    collections::HashMap,
     future::Future,
     pin::Pin,
     task::{Context, Poll},
@@ -7,9 +8,21 @@ use std::{
 
 #[allow(unused_imports)]
 use hex_literal::hex;
-use tower::Service;
+use monero_serai::{
+    block::Block,
+    transaction::{Input, Transaction},
+};
+use tower::{Service, ServiceExt};
+
+use cuprate_consensus::{
+    context::{BlockChainContextRequest, BlockChainContextResponse},
+    transactions::TransactionVerificationData,
+};
+use cuprate_consensus_rules::{miner_tx::MinerTxError, ConsensusError};
+use cuprate_types::{VerifiedBlockInformation, VerifiedTransactionInformation};
 
 use crate::{hash_of_hashes, BlockId, HashOfHashes};
+
 #[cfg(not(test))]
 static HASHES_OF_HASHES: &[HashOfHashes] = &include!("./data/hashes_of_hashes");
 
@@ -31,13 +44,6 @@ fn max_height() -> u64 {
     (HASHES_OF_HASHES.len() * BATCH_SIZE) as u64
 }
 
-pub enum FastSyncRequest {
-    ValidateHashes {
-        start_height: u64,
-        block_ids: Vec<BlockId>,
-    },
-}
-
 #[derive(Debug, PartialEq)]
 pub struct ValidBlockId(BlockId);
 
@@ -45,31 +51,79 @@ fn valid_block_ids(block_ids: &[BlockId]) -> Vec<ValidBlockId> {
     block_ids.iter().map(|b| ValidBlockId(*b)).collect()
 }
 
+#[allow(clippy::large_enum_variant)]
+pub enum FastSyncRequest {
+    ValidateHashes {
+        start_height: u64,
+        block_ids: Vec<BlockId>,
+    },
+    ValidateBlock {
+        block: Block,
+        txs: HashMap<[u8; 32], Transaction>,
+        token: ValidBlockId,
+    },
+}
+
+#[allow(clippy::large_enum_variant)]
 #[derive(Debug, PartialEq)]
 pub enum FastSyncResponse {
     ValidateHashes {
         validated_hashes: Vec<ValidBlockId>,
         unknown_hashes: Vec<BlockId>,
     },
+    ValidateBlock(VerifiedBlockInformation),
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(thiserror::Error, Debug, PartialEq)]
 pub enum FastSyncError {
-    InvalidStartHeight, // start_height not a multiple of BATCH_SIZE
+    #[error("Block does not match its expected hash")]
-    Mismatch,           // hash does not match
+    BlockHashMismatch,
-    NothingToDo,        // no complete batch to check
+
-    OutOfRange,         // start_height too high
+    #[error("Start height must be a multiple of the batch size")]
+    InvalidStartHeight,
+
+    #[error("Hash of hashes mismatch")]
+    Mismatch,
+
+    #[error("Given range too small for fast sync (less than one batch)")]
+    NothingToDo,
+
+    #[error("Start height too high for fast sync")]
+    OutOfRange,
+
+    #[error("Block does not have the expected height entry")]
+    BlockHeightMismatch,
+
+    #[error("Block does not contain the expected transaction list")]
+    TxsIncludedWithBlockIncorrect,
+
+    #[error(transparent)]
+    Consensus(#[from] ConsensusError),
+
+    #[error(transparent)]
+    MinerTx(#[from] MinerTxError),
+
+    #[error("Database error: {0}")]
+    DbErr(String),
+}
+
+impl From<tower::BoxError> for FastSyncError {
+    fn from(error: tower::BoxError) -> Self {
+        Self::DbErr(error.to_string())
+    }
 }
 
-#[allow(dead_code)]
 pub struct FastSyncService<C> {
     context_svc: C,
 }
 
 impl<C> FastSyncService<C>
 where
-    C: Service<FastSyncRequest, Response = FastSyncResponse, Error = FastSyncError>
+    C: Service<
-        + Clone
+            BlockChainContextRequest,
+            Response = BlockChainContextResponse,
+            Error = tower::BoxError,
+        > + Clone
         + Send
         + 'static,
 {
@@ -81,8 +135,11 @@ where
 
 impl<C> Service<FastSyncRequest> for FastSyncService<C>
 where
-    C: Service<FastSyncRequest, Response = FastSyncResponse, Error = FastSyncError>
+    C: Service<
-        + Clone
+            BlockChainContextRequest,
+            Response = BlockChainContextResponse,
+            Error = tower::BoxError,
+        > + Clone
         + Send
         + 'static,
     C::Future: Send + 'static,
@@ -97,12 +154,17 @@ where
     }
 
     fn call(&mut self, req: FastSyncRequest) -> Self::Future {
+        let context_svc = self.context_svc.clone();
+
         Box::pin(async move {
             match req {
                 FastSyncRequest::ValidateHashes {
                     start_height,
                     block_ids,
                 } => validate_hashes(start_height, &block_ids).await,
+                FastSyncRequest::ValidateBlock { block, txs, token } => {
+                    validate_block(context_svc, block, txs, token).await
+                }
             }
         })
     }
@@ -149,6 +211,91 @@ async fn validate_hashes(
     })
 }
 
+async fn validate_block<C>(
+    mut context_svc: C,
+    block: Block,
+    mut txs: HashMap<[u8; 32], Transaction>,
+    token: ValidBlockId,
+) -> Result<FastSyncResponse, FastSyncError>
+where
+    C: Service<
+            BlockChainContextRequest,
+            Response = BlockChainContextResponse,
+            Error = tower::BoxError,
+        > + Send
+        + 'static,
+    C::Future: Send + 'static,
+{
+    let BlockChainContextResponse::Context(checked_context) = context_svc
+        .ready()
+        .await?
+        .call(BlockChainContextRequest::GetContext)
+        .await?
+    else {
+        panic!("Context service returned wrong response!");
+    };
+
+    let block_chain_ctx = checked_context.unchecked_blockchain_context().clone();
+
+    let block_hash = block.hash();
+    if block_hash != token.0 {
+        return Err(FastSyncError::BlockHashMismatch);
+    }
+
+    let block_blob = block.serialize();
+
+    let Some(Input::Gen(height)) = block.miner_tx.prefix.inputs.first() else {
+        return Err(FastSyncError::MinerTx(MinerTxError::InputNotOfTypeGen));
+    };
+    if *height != block_chain_ctx.chain_height {
+        return Err(FastSyncError::BlockHeightMismatch);
+    }
+
+    let mut verified_txs = Vec::with_capacity(txs.len());
+    for tx in &block.txs {
+        let tx = txs
+            .remove(tx)
+            .ok_or(FastSyncError::TxsIncludedWithBlockIncorrect)?;
+
+        let data = TransactionVerificationData::new(tx)?;
+        verified_txs.push(VerifiedTransactionInformation {
+            tx_blob: data.tx_blob,
+            tx_weight: data.tx_weight,
+            fee: data.fee,
+            tx_hash: data.tx_hash,
+            tx: data.tx,
+        });
+    }
+
+    let total_fees = verified_txs.iter().map(|tx| tx.fee).sum::<u64>();
+    let total_outputs = block
+        .miner_tx
+        .prefix
+        .outputs
+        .iter()
+        .map(|output| output.amount.unwrap_or(0))
+        .sum::<u64>();
+
+    let generated_coins = total_outputs - total_fees;
+
+    let weight =
+        block.miner_tx.weight() + verified_txs.iter().map(|tx| tx.tx_weight).sum::<usize>();
+
+    Ok(FastSyncResponse::ValidateBlock(VerifiedBlockInformation {
+        block_blob,
+        txs: verified_txs,
+        block_hash,
+        pow_hash: [0u8; 32],
+        height: *height,
+        generated_coins,
+        weight,
+        long_term_weight: block_chain_ctx.next_block_long_term_weight(weight),
+        cumulative_difficulty: block_chain_ctx.cumulative_difficulty
+            + block_chain_ctx.next_difficulty,
+        block,
+    }))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;