Merge pull request #362 from horizontalsystems/bitcoincash-abc-sync

Disconnect peer if it is fork of Bitcoin Cash

bitcoincashkit/src/main/kotlin/io/horizontalsystems/bitcoincash/BitcoinCashKit.kt

@@ -5,10 +5,12 @@ import android.database.sqlite.SQLiteDatabase
 import io.horizontalsystems.bitcoincash.blocks.BitcoinCashBlockValidatorHelper
 import io.horizontalsystems.bitcoincash.blocks.validators.DAAValidator
 import io.horizontalsystems.bitcoincash.blocks.validators.EDAValidator
+import io.horizontalsystems.bitcoincash.blocks.validators.ForkValidator
 import io.horizontalsystems.bitcoincore.AbstractKit
 import io.horizontalsystems.bitcoincore.BitcoinCore
 import io.horizontalsystems.bitcoincore.BitcoinCoreBuilder
 import io.horizontalsystems.bitcoincore.blocks.validators.LegacyDifficultyAdjustmentValidator
+import io.horizontalsystems.bitcoincore.extensions.toReversedByteArray
 import io.horizontalsystems.bitcoincore.managers.BitcoinCashAddressSelector
 import io.horizontalsystems.bitcoincore.managers.InsightApi
 import io.horizontalsystems.bitcoincore.models.TransactionInfo
@@ -81,7 +83,12 @@ class BitcoinCashKit : AbstractKit {
         if (networkType == NetworkType.MainNet) {
             val blockHelper = BitcoinCashBlockValidatorHelper(storage)
 
-            bitcoinCore.addBlockValidator(DAAValidator(targetSpacing, blockHelper))
+            val svForkHeight = 556767
+            val abcForkBlockHash = "0000000000000000004626ff6e3b936941d341c5932ece4357eeccac44e6d56c".toReversedByteArray()
+
+            val daaValidator = DAAValidator(targetSpacing, blockHelper)
+            bitcoinCore.addBlockValidator(ForkValidator(svForkHeight, abcForkBlockHash, daaValidator))
+            bitcoinCore.addBlockValidator(daaValidator)
             bitcoinCore.addBlockValidator(LegacyDifficultyAdjustmentValidator(blockHelper, heightInterval, targetTimespan, maxTargetBits))
             bitcoinCore.addBlockValidator(EDAValidator(maxTargetBits, blockHelper, network.bip44CheckpointBlock.height))
         }

bitcoincashkit/src/main/kotlin/io/horizontalsystems/bitcoincash/blocks/validators/ForkValidator.kt

@@ -0,0 +1,20 @@
+package io.horizontalsystems.bitcoincash.blocks.validators
+
+import io.horizontalsystems.bitcoincore.blocks.validators.BlockValidatorException
+import io.horizontalsystems.bitcoincore.blocks.validators.IBlockValidator
+import io.horizontalsystems.bitcoincore.models.Block
+
+class ForkValidator(private val forkHeight: Int, private val expectedBlockHash: ByteArray, private val concreteBlockValidator: IBlockValidator) : IBlockValidator {
+
+    override fun isBlockValidatable(block: Block, previousBlock: Block): Boolean {
+        return block.height == forkHeight
+    }
+
+    override fun validate(block: Block, previousBlock: Block) {
+        if (!block.headerHash.contentEquals(expectedBlockHash)) {
+            throw BlockValidatorException.WrongBlockHash(expectedBlockHash, block.headerHash)
+        }
+
+        concreteBlockValidator.validate(block, previousBlock)
+    }
+}

bitcoincashkit/src/test/kotlin/io/horizontalsystems/bitcoincash/blocks/validators/ForkValidatorTest.kt

@@ -0,0 +1,53 @@
+package io.horizontalsystems.bitcoincash.blocks.validators
+
+import com.nhaarman.mockito_kotlin.mock
+import com.nhaarman.mockito_kotlin.whenever
+import io.horizontalsystems.bitcoincore.blocks.validators.BlockValidatorException
+import io.horizontalsystems.bitcoincore.blocks.validators.IBlockValidator
+import io.horizontalsystems.bitcoincore.models.Block
+import org.junit.Assert
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.assertThrows
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.specification.describe
+
+object ForkValidatorTest : Spek({
+    val forkHeight = 100
+    val expectedBlockHash = byteArrayOf(1, 2, 3)
+    val concreteBlockValidator = mock<IBlockValidator>()
+    val validator by memoized { ForkValidator(forkHeight, expectedBlockHash, concreteBlockValidator) }
+
+    describe("#isBlockValidatable") {
+        val block = mock<Block>()
+
+        it("is true when block height is equal to fork height") {
+            whenever(block.height).thenReturn(forkHeight)
+            Assert.assertTrue(validator.isBlockValidatable(block, mock()))
+        }
+
+        it("is false when block height is not equal to fork height") {
+            whenever(block.height).thenReturn(104)
+            Assert.assertFalse(validator.isBlockValidatable(block, mock()))
+        }
+
+    }
+
+    describe("#validate") {
+        val block = mock<Block>()
+
+        it("validates without any error when block hash is equal to expected block hash") {
+            whenever(block.headerHash).thenReturn(expectedBlockHash)
+            Assertions.assertDoesNotThrow {
+                validator.validate(block, mock())
+            }
+        }
+
+        it("throws exception when block hash is not equal to expected block hash") {
+            whenever(block.headerHash).thenReturn(byteArrayOf(3, 2, 1))
+            assertThrows<BlockValidatorException.WrongBlockHash> {
+                validator.validate(block, mock())
+            }
+        }
+    }
+
+})

bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/blocks/validators/BlockValidatorException.kt

@@ -1,5 +1,7 @@
 package io.horizontalsystems.bitcoincore.blocks.validators
 
+import io.horizontalsystems.bitcoincore.extensions.toReversedHex
+
 open class BlockValidatorException(msg: String) : RuntimeException(msg) {
     class NoHeader : BlockValidatorException("No Header")
     class NoCheckpointBlock : BlockValidatorException("No Checkpoint Block")
@@ -8,4 +10,5 @@ open class BlockValidatorException(msg: String) : RuntimeException(msg) {
     class NotEqualBits : BlockValidatorException("Not Equal Bits")
     class NotDifficultyTransitionEqualBits : BlockValidatorException("Not Difficulty Transition Equal Bits")
     class InvalidProofOfWork : BlockValidatorException("Invalid Prove of Work")
+    class WrongBlockHash(expected: ByteArray, actual: ByteArray) : BlockValidatorException("Wrong Block Hash ${actual.toReversedHex()} vs expected ${expected.toReversedHex()}")
 }