Improve eth_config types, fork_id, and resolver selectionupdate

Cargo.toml

@@ -16,3 +16,4 @@ license = "MIT"  # adjust if needed
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thiserror = "1"
+crc32fast = "1.3"

README.md

@@ -23,10 +23,10 @@ Implementation skeleton for exposing the `eth_config` JSON-RPC method (EIP-7910)
 - `make cli` — build the validator CLI.
 
 ## Tests
-- `tests/hoodi_prague.rs`: golden comparison versus the EIP Prague sample output (fixture pending).
-- `tests/hoodi_cancun.rs`: golden comparison versus the EIP Cancun sample output (fixture pending).
-- `tests/no_future_fork.rs`: ensures `next`/`last` are null when no future or past fork exists.
-- `tests/bpo_fork.rs`: covers blob-parameter-only fork transitions.
+- `tests/hoodi_prague.rs`: parses Prague sample and checks presence of `next` fork id.
+- `tests/hoodi_cancun.rs`: parses Cancun sample with blob schedule and no next fork.
+- `tests/no_future_fork.rs`: ensures `next`/`last` null handling.
+- `tests/bpo_fork.rs`: blob-parameter-only fork sample.
 - Tests live in the `eth-config-tests` crate (workspace member) and currently validate the example fixtures deserialize correctly. Run them via `make test` or `cargo test -p eth-config-tests`.
 
 ## EIP-7910 recap

crates/eth-config-api/Cargo.toml

@@ -9,3 +9,4 @@ authors = ["EIP-7910 contributors"]
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
+crc32fast = { workspace = true }

crates/eth-config-api/src/fork_id.rs

@@ -1,20 +1,43 @@
+use crc32fast::Hasher;
 use serde::{Deserialize, Serialize};
 
+use crate::types::HexU64;
+
 /// EIP-6122 fork identifier (hash + next fork block number).
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct ForkId {
     pub hash: String,
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub next: Option<u64>,
+    pub next: Option<HexU64>,
 }
 
 impl ForkId {
-    /// Placeholder constructor for scaffolding.
-    pub fn placeholder() -> Self {
+    /// Compute fork ID per EIP-6122 (CRC32 of genesis hash + fork block numbers, big-endian u64).
+    pub fn compute(genesis_hash: [u8; 32], fork_blocks: &[u64], next_fork: Option<u64>) -> Self {
+        let mut hasher = Hasher::new();
+        hasher.update(&genesis_hash);
+        for block in fork_blocks {
+            hasher.update(&block.to_be_bytes());
+        }
+        let hash = hasher.finalize();
         Self {
-            hash: String::from("0x00000000"),
-            next: None,
+            hash: format!("0x{hash:08x}"),
+            next: next_fork.map(HexU64),
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fork_id_deterministic() {
+        let genesis = [0u8; 32];
+        let forks = [0u64, 9, 30_000_000];
+        let a = ForkId::compute(genesis, &forks, Some(40_000_000));
+        let b = ForkId::compute(genesis, &forks, Some(40_000_000));
+        assert_eq!(a, b);
+    }
+}

crates/eth-config-api/src/lib.rs

@@ -6,4 +6,4 @@ pub mod types;
 pub use fork_id::ForkId;
 pub use precompiles::{PrecompileDescriptor, PrecompileRegistry};
 pub use system_contracts::{SystemContractDescriptor, SystemContractRegistry};
-pub use types::{BlobSchedule, EthConfigResponse, ForkConfig, ForkEntry};
+pub use types::{BlobSchedule, EthConfigResponse, ForkConfig, ForkEntry, HexU64};

crates/eth-config-api/src/types.rs

@@ -1,12 +1,41 @@
 use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+
+use crate::fork_id::ForkId;
+
+/// Hex-encoded quantity helper.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct HexU64(pub u64);
+
+impl Serialize for HexU64 {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        serializer.serialize_str(&format!("0x{:x}", self.0))
+    }
+}
+
+impl<'de> Deserialize<'de> for HexU64 {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        let s = s.strip_prefix("0x").unwrap_or(&s);
+        u64::from_str_radix(s, 16)
+            .map(HexU64)
+            .map_err(|e| serde::de::Error::custom(format!("invalid hex quantity: {e}")))
+    }
+}
 
 /// Blob gas scheduling parameters (EIP-4844 style).
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct BlobSchedule {
-    pub max_blob_gas_per_block: u64,
-    pub target_blob_gas_per_block: u64,
-    pub blob_gasprice_update_fraction: u64,
+    pub max_blob_gas_per_block: HexU64,
+    pub target_blob_gas_per_block: HexU64,
+    pub blob_gasprice_update_fraction: HexU64,
 }
 
 /// Fork-level configuration object as returned by eth_config.
@@ -15,17 +44,18 @@ pub struct BlobSchedule {
 pub struct ForkConfig {
     /// Human-readable fork name (e.g. "cancun").
     pub name: String,
-    /// Block number at which the fork activates; null in EIP becomes None here.
+    /// Block number at which the fork activates.
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub block: Option<u64>,
+    pub block: Option<HexU64>,
     /// Optional blob gas schedule parameters for blob-enabled forks.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub blob_schedule: Option<BlobSchedule>,
     /// List of enabled precompiles at this fork (hex addresses as strings).
-    pub precompiles: Vec<String>,
+    #[serde(default)]
+    pub precompiles: BTreeMap<String, String>,
     /// List of system contracts active at this fork.
     #[serde(default)]
-    pub system_contracts: Vec<SystemContract>,
+    pub system_contracts: BTreeMap<String, SystemContract>,
 }
 
 /// System contract entry in eth_config response.
@@ -50,10 +80,10 @@ pub struct ForkEntry {
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct EthConfigResponse {
-    pub current: ForkEntry,
+    pub current: ForkConfig,
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub next: Option<ForkEntry>,
+    pub next: Option<ForkConfig>,
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub last: Option<ForkEntry>,
-    pub fork_id: crate::fork_id::ForkId,
+    pub last: Option<ForkConfig>,
+    pub fork_id: ForkId,
 }

crates/eth-config-reth/src/namespace.rs

@@ -4,6 +4,8 @@ use crate::{EthConfigApi, ForkConfigCache, ForkConfigResolver};
 
 /// Hook to install the `eth_config` namespace into reth's RPC builder.
 pub fn install_namespace() {
-    let _api = EthConfigApi::new(ForkConfigCache::new(), ForkConfigResolver::new());
+    let zero_genesis = [0u8; 32];
+    let resolver = ForkConfigResolver::new(zero_genesis, Vec::new());
+    let _api = EthConfigApi::new(ForkConfigCache::new(), resolver);
     // TODO: wire `_api` into reth's RpcModule when integrating with the node.
 }

crates/eth-config-reth/src/resolver.rs

@@ -1,37 +1,58 @@
-use eth_config_api::{EthConfigResponse, ForkConfig};
+use eth_config_api::{EthConfigResponse, ForkConfig, ForkId};
 
 /// Resolves fork configuration from a chain specification at runtime.
 ///
 /// Reth plumbing will populate this with access to `ChainSpec` and consensus params; the logic
 /// belongs here so it can be tested separately from RPC wiring.
-#[derive(Debug, Default)]
-pub struct ForkConfigResolver;
+#[derive(Debug, Clone)]
+pub struct ForkConfigResolver {
+    genesis_hash: [u8; 32],
+    forks: Vec<ForkConfig>,
+}
 
 impl ForkConfigResolver {
-    /// Create a new resolver (wire in reth chain spec later).
-    pub fn new() -> Self {
-        Self
+    /// Create a new resolver with a pre-resolved fork list and genesis hash.
+    pub fn new(genesis_hash: [u8; 32], mut forks: Vec<ForkConfig>) -> Self {
+        forks.sort_by_key(|f| f.block.map(|b| b.0).unwrap_or(u64::MAX));
+        Self { genesis_hash, forks }
     }
 
     /// Compute eth_config response for the provided block height.
-    pub fn resolve_at_block(&self, _block_number: u64) -> EthConfigResponse {
-        // Placeholder implementation; real logic will derive current/next/last forks,
-        // blob parameters, precompiles, system contracts, and fork id.
-        let placeholder = ForkConfig {
-            name: "placeholder".into(),
-            block: Some(_block_number),
-            blob_schedule: None,
-            precompiles: vec![],
-            system_contracts: vec![],
-        };
+    pub fn resolve_at_block(&self, block_number: u64) -> EthConfigResponse {
+        let mut current: Option<ForkConfig> = None;
+        let mut last: Option<ForkConfig> = None;
+        let mut next: Option<ForkConfig> = None;
+
+        for fork in &self.forks {
+            let fork_block = fork.block.map(|b| b.0).unwrap_or(u64::MAX);
+            if fork_block <= block_number {
+                last = current.replace(fork.clone());
+                continue;
+            }
+            next = Some(fork.clone());
+            break;
+        }
+
+        let current = current.unwrap_or_else(|| self.forks.first().cloned().unwrap_or_default());
+
+        let fork_blocks: Vec<u64> = self
+            .forks
+            .iter()
+            .filter_map(|f| f.block.map(|b| b.0))
+            .filter(|b| *b <= block_number)
+            .collect();
+
+        let fork_id = ForkId::compute(
+            self.genesis_hash,
+            &fork_blocks,
+            next.as_ref().and_then(|f| f.block.map(|b| b.0)),
+        );
 
         EthConfigResponse {
-            current: eth_config_api::types::ForkEntry {
-                config: placeholder,
-            },
-            next: None,
-            last: None,
-            fork_id: eth_config_api::ForkId::placeholder(),
+            current,
+            next,
+            last,
+            fork_id,
         }
     }
 }

examples/blob_parameter_only.json

@@ -1,38 +1,34 @@
 {
   "current": {
-    "config": {
-      "name": "bpo",
-      "block": 25000000,
-      "blobSchedule": {
-        "maxBlobGasPerBlock": 800000,
-        "targetBlobGasPerBlock": 400000,
-        "blobGaspriceUpdateFraction": 3338477
-      },
-      "precompiles": [
-        "0x0000000000000000000000000000000000000001",
-        "0x0000000000000000000000000000000000000002",
-        "0x0000000000000000000000000000000000000003"
-      ],
-      "systemContracts": []
-    }
+    "name": "bpo",
+    "block": "0x17d7840",
+    "blobSchedule": {
+      "maxBlobGasPerBlock": "0xc3500",
+      "targetBlobGasPerBlock": "0x61a80",
+      "blobGaspriceUpdateFraction": "0x32f29d"
+    },
+    "precompiles": {
+      "ecrecover": "0x0000000000000000000000000000000000000001",
+      "sha256": "0x0000000000000000000000000000000000000002",
+      "ripemd": "0x0000000000000000000000000000000000000003"
+    },
+    "systemContracts": {}
   },
   "next": null,
   "last": {
-    "config": {
-      "name": "cancun",
-      "block": 19426545,
-      "blobSchedule": {
-        "maxBlobGasPerBlock": 786432,
-        "targetBlobGasPerBlock": 393216,
-        "blobGaspriceUpdateFraction": 3338477
-      },
-      "precompiles": [
-        "0x0000000000000000000000000000000000000001",
-        "0x0000000000000000000000000000000000000002",
-        "0x0000000000000000000000000000000000000003"
-      ],
-      "systemContracts": []
-    }
+    "name": "cancun",
+    "block": "0x128b7f1",
+    "blobSchedule": {
+      "maxBlobGasPerBlock": "0xc0000",
+      "targetBlobGasPerBlock": "0x60000",
+      "blobGaspriceUpdateFraction": "0x32f29d"
+    },
+    "precompiles": {
+      "ecrecover": "0x0000000000000000000000000000000000000001",
+      "sha256": "0x0000000000000000000000000000000000000002",
+      "ripemd": "0x0000000000000000000000000000000000000003"
+    },
+    "systemContracts": {}
   },
   "forkId": {
     "hash": "0x9abc0011",

examples/cancun_sample.json

@@ -1,33 +1,29 @@
 {
   "current": {
-    "config": {
-      "name": "cancun",
-      "block": 19426545,
-      "blobSchedule": {
-        "maxBlobGasPerBlock": 786432,
-        "targetBlobGasPerBlock": 393216,
-        "blobGaspriceUpdateFraction": 3338477
-      },
-      "precompiles": [
-        "0x0000000000000000000000000000000000000001",
-        "0x0000000000000000000000000000000000000002",
-        "0x0000000000000000000000000000000000000003"
-      ],
-      "systemContracts": []
-    }
+    "name": "cancun",
+    "block": "0x128b7f1",
+    "blobSchedule": {
+      "maxBlobGasPerBlock": "0xc0000",
+      "targetBlobGasPerBlock": "0x60000",
+      "blobGaspriceUpdateFraction": "0x32f29d"
+    },
+    "precompiles": {
+      "ecrecover": "0x0000000000000000000000000000000000000001",
+      "sha256": "0x0000000000000000000000000000000000000002",
+      "ripemd": "0x0000000000000000000000000000000000000003"
+    },
+    "systemContracts": {}
   },
   "next": null,
   "last": {
-    "config": {
-      "name": "shanghai",
-      "block": 17034870,
-      "precompiles": [
-        "0x0000000000000000000000000000000000000001",
-        "0x0000000000000000000000000000000000000002",
-        "0x0000000000000000000000000000000000000003"
-      ],
-      "systemContracts": []
-    }
+    "name": "shanghai",
+    "block": "0x104c533",
+    "precompiles": {
+      "ecrecover": "0x0000000000000000000000000000000000000001",
+      "sha256": "0x0000000000000000000000000000000000000002",
+      "ripemd": "0x0000000000000000000000000000000000000003"
+    },
+    "systemContracts": {}
   },
   "forkId": {
     "hash": "0xf0afd0c7",