problem: doesn't respond to eth_chainId method

fix: #22

src/main/kotlin/io/emeraldpay/dshackle/upstream/calls/AggregatedCallMethods.kt

@@ -41,7 +41,7 @@ class AggregatedCallMethods(
     override fun getQuorumFor(method: String): CallQuorum {
         return delegates.find {
             it.isAllowed(method) || it.isHardcoded(method)
-        }?.getQuorumFor(method) ?: throw IllegalStateException("No quorum for $method")
+        }?.getQuorumFor(method) ?: throw IllegalStateException("No executor delegate for $method")
     }
 
     /**

src/main/kotlin/io/emeraldpay/dshackle/upstream/calls/DefaultEthereumMethods.kt

@@ -76,7 +76,8 @@ class DefaultEthereumMethods(
             "eth_coinbase",
             "eth_mining",
             "eth_hashrate",
-            "eth_accounts"
+            "eth_accounts",
+            "eth_chainId"
     )
 
     override fun getQuorumFor(method: String): CallQuorum {
@@ -125,6 +126,23 @@ class DefaultEthereumMethods(
                     else -> throw RpcException(-32602, "Invalid chain")
                 }
             }
+            "eth_chainId" -> {
+                when {
+                    Chain.ETHEREUM == chain -> {
+                        "0x0"
+                    }
+                    Chain.ETHEREUM_CLASSIC == chain -> {
+                        "0x3d"
+                    }
+                    Chain.TESTNET_MORDEN == chain -> {
+                        "0x3c"
+                    }
+                    Chain.TESTNET_KOVAN == chain -> {
+                        "0x2a"
+                    }
+                    else -> throw RpcException(-32602, "Invalid chain")
+                }
+            }
             "net_peerCount" -> {
                 "\"0x2a\""
             }

src/test/groovy/io/emeraldpay/dshackle/upstream/calls/DefaultEthereumMethodsSpec.groovy

@@ -0,0 +1,26 @@
+package io.emeraldpay.dshackle.upstream.calls
+
+import io.emeraldpay.grpc.Chain
+import spock.lang.Specification
+
+class DefaultEthereumMethodsSpec extends Specification {
+
+    def "eth_chainId is hardcoded"() {
+        setup:
+        def methods = new DefaultEthereumMethods(Chain.ETHEREUM)
+        when:
+        def act = methods.isHardcoded("eth_chainId")
+        then:
+        act
+    }
+
+    def "Provides hardcoded correct chainId"() {
+        expect:
+        new String(new DefaultEthereumMethods(chain).executeHardcoded("eth_chainId")) == id
+        where:
+        chain                  | id
+        Chain.ETHEREUM         | "0x0"
+        Chain.ETHEREUM_CLASSIC | "0x3d"
+        Chain.TESTNET_KOVAN    | "0x2a"
+    }
+}