Fixed kovan chain validation (#6758)

* Fixed kovan chain validation

* Fork detection

* Fixed typo

ethcore/res/ethereum/kovan.json

@@ -30,11 +30,14 @@
 	"params": {
 		"gasLimitBoundDivisor": "0x400",
 		"registrar" : "0xfAb104398BBefbd47752E7702D9fE23047E1Bca3",
-	"maximumExtraDataSize": "0x20",
+		"maximumExtraDataSize": "0x20",
 		"minGasLimit": "0x1388",
 		"networkID" : "0x2A",
+		"forkBlock": 4297256,
+		"forkCanonHash": "0x0a66d93c2f727dca618fabaf70c39b37018c73d78b939d8b11efbbd09034778f",
 		"validateReceiptsTransition" : 1000000,
-		"eip155Transition": 1000000
+		"eip155Transition": 1000000,
+		"validateChainIdTransition": 1000000
 	},
 	"genesis": {
 		"seal": {

ethcore/src/machine.rs

@@ -351,7 +351,9 @@ impl EthereumMachine {
 			None => true,
 		};
 
-		let chain_id = if header.number() >= self.params().eip155_transition {
+		let chain_id = if header.number() < self.params().validate_chain_id_transition {
+			t.chain_id()
+		} else if header.number() >= self.params().eip155_transition {
 			Some(self.params().chain_id)
 		} else {
 			None

ethcore/src/spec/spec.rs

@@ -85,6 +85,8 @@ pub struct CommonParams {
 	pub eip155_transition: BlockNumber,
 	/// Validate block receipts root.
 	pub validate_receipts_transition: BlockNumber,
+	/// Validate transaction chain id.
+	pub validate_chain_id_transition: BlockNumber,
 	/// Number of first block where EIP-86 (Metropolis) rules begin.
 	pub eip86_transition: BlockNumber,
 	/// Number of first block where EIP-140 (Metropolis: REVERT opcode) rules begin.
@@ -153,7 +155,7 @@ impl CommonParams {
 			self.validate_receipts_transition != 0 && self.eip86_transition != 0 &&
 			self.eip140_transition != 0 && self.eip210_transition != 0 &&
 			self.eip211_transition != 0 && self.eip214_transition != 0 &&
-			self.dust_protection_transition != 0
+			self.validate_chain_id_transition != 0 && self.dust_protection_transition != 0
 	}
 }
 
@@ -178,6 +180,7 @@ impl From<ethjson::spec::Params> for CommonParams {
 			eip98_transition: p.eip98_transition.map_or(0, Into::into),
 			eip155_transition: p.eip155_transition.map_or(0, Into::into),
 			validate_receipts_transition: p.validate_receipts_transition.map_or(0, Into::into),
+			validate_chain_id_transition: p.validate_chain_id_transition.map_or(0, Into::into),
 			eip86_transition: p.eip86_transition.map_or(
 				BlockNumber::max_value(),
 				Into::into,

json/src/spec/params.rs

@@ -58,6 +58,9 @@ pub struct Params {
 	#[serde(rename="eip155Transition")]
 	pub eip155_transition: Option<Uint>,
 	/// See `CommonParams` docs.
+	#[serde(rename="validateChainIdTransition")]
+	pub validate_chain_id_transition: Option<Uint>,
+	/// See `CommonParams` docs.
 	#[serde(rename="validateReceiptsTransition")]
 	pub validate_receipts_transition: Option<Uint>,
 	/// See `CommonParams` docs.