public void ChainHasOneCheckPointAndAssumeValid_TwoAlternativeChainsArePresented_BothChainsAreMarkedForDownload()
{
// Chain header tree setup with disabled checkpoints.
// Initial chain has 2 headers.
// Example: h1=h2.
const int initialChainSize = 2;
const int extensionChainSize = 2;
TestContext ctx = new TestContextBuilder().WithInitialChain(initialChainSize).UseCheckpoints().Build();
ChainedHeaderTree cht = ctx.ChainedHeaderTree;
ChainedHeader initialChainTip = ctx.InitialChainTip;
// Extend chain with 2 more headers.
initialChainTip = ctx.ExtendAChain(extensionChainSize, initialChainTip); // i.e. h1=h2=h3=h4
List <BlockHeader> listOfCurrentChainHeaders = ctx.ChainedHeaderToList(initialChainTip, initialChainSize + extensionChainSize);
// Setup a known checkpoint at header 4.
// Example: h1=h2=h3=(h4).
const int checkpointHeight = 4;
var checkpoint = new CheckpointFixture(checkpointHeight, listOfCurrentChainHeaders.Last());
ctx.SetupCheckpoints(checkpoint);
// Extend chain and add "Assume valid" at block 6.
// Example: h1=h2=h3=(h4)=h5=[h6].
const int chainExtension = 2;
ChainedHeader extendedChainTip = ctx.ExtendAChain(chainExtension, initialChainTip);
ctx.ConsensusSettings.BlockAssumedValid = extendedChainTip.HashBlock;
// Setup two alternative chains A and B. Chain A covers the last checkpoint (4) and "assume valid" (6).
// Chain B only covers the last checkpoint (4).
const int chainAExtensionSize = 2;
const int chainBExtensionSize = 6;
ChainedHeader chainATip = ctx.ExtendAChain(chainAExtensionSize, extendedChainTip); // i.e. h1=h2=h3=(h4)=h5=[h6]=a7=a8
ChainedHeader chainBTip = ctx.ExtendAChain(chainBExtensionSize, initialChainTip); // i.e. h1=h2=h3=(h4)=b5=b6=b7=b8=b9=b10
List <BlockHeader> listOfChainABlockHeaders = ctx.ChainedHeaderToList(chainATip, initialChainSize + extensionChainSize + chainExtension + chainAExtensionSize);
List <BlockHeader> listOfChainBBlockHeaders = ctx.ChainedHeaderToList(chainBTip, initialChainSize + extensionChainSize + chainBExtensionSize);
// Chain A is presented by peer 1.
// DownloadFrom should be set to header 3.
// DownloadTo should be set to header 8.
ConnectNewHeadersResult result = cht.ConnectNewHeaders(1, listOfChainABlockHeaders);
result.DownloadFrom.HashBlock.Should().Be(listOfChainABlockHeaders.Skip(2).First().GetHash());
result.DownloadTo.HashBlock.Should().Be(listOfChainABlockHeaders.Last().GetHash());
// Chain B is presented by peer 2.
// DownloadFrom should be set to header 5.
// DownloadTo should be set to header 10.
result = cht.ConnectNewHeaders(2, listOfChainBBlockHeaders);
result.DownloadFrom.HashBlock.Should().Be(listOfChainBBlockHeaders[checkpointHeight].GetHash());
result.DownloadTo.HashBlock.Should().Be(listOfChainBBlockHeaders.Last().GetHash());
}
public void ChainHasTwoCheckPoints_ChainCoveringOnlyFirstCheckPointIsPresented_ChainIsDiscardedUpUntilFirstCheckpoint()
{
// Chain header tree setup.
// Initial chain has 2 headers.
// Example: h1=h2.
const int initialChainSize = 2;
const int currentChainExtension = 6;
TestContext ctx = new TestContextBuilder().WithInitialChain(initialChainSize).UseCheckpoints().Build();
ChainedHeaderTree cht = ctx.ChainedHeaderTree;
ChainedHeader initialChainTip = ctx.InitialChainTip;
ChainedHeader extendedChainTip = ctx.ExtendAChain(currentChainExtension, initialChainTip); // i.e. h1=h2=h3=h4=h5=h6=h7=h8
List <BlockHeader> listOfCurrentChainHeaders = ctx.ChainedHeaderToList(extendedChainTip, initialChainSize + currentChainExtension);
// Setup two known checkpoints at header 4 and 7.
// Example: h1=h2=h3=(h4)=h5=h6=(h7)=h8.
const int firstCheckpointHeight = 4;
const int secondCheckpointHeight = 7;
var checkpoint1 = new CheckpointFixture(firstCheckpointHeight, listOfCurrentChainHeaders[firstCheckpointHeight - 1]);
var checkpoint2 = new CheckpointFixture(secondCheckpointHeight, listOfCurrentChainHeaders[secondCheckpointHeight - 1]);
ctx.SetupCheckpoints(checkpoint1, checkpoint2);
// Setup new chain that only covers first checkpoint but doesn't cover second checkpoint.
// Example: h1=h2=h3=(h4)=h5=h6=x7=x8=x9=x10.
const int newChainExtension = 4;
extendedChainTip = extendedChainTip.GetAncestor(6); // walk back to block 6
extendedChainTip = ctx.ExtendAChain(newChainExtension, extendedChainTip);
List <BlockHeader> listOfNewChainHeaders = ctx.ChainedHeaderToList(extendedChainTip, extendedChainTip.Height);
// First 5 blocks are presented by peer 1.
// DownloadTo should be set to a checkpoint 1.
ConnectNewHeadersResult result = cht.ConnectNewHeaders(1, listOfNewChainHeaders.Take(5).ToList());
result.DownloadTo.HashBlock.Should().Be(checkpoint1.Header.GetHash());
// Remaining 5 blocks are presented by peer 1 which do not cover checkpoint 2.
// InvalidHeaderException should be thrown.
List <BlockHeader> violatingHeaders = listOfNewChainHeaders.Skip(5).ToList();
Action connectAction = () =>
{
cht.ConnectNewHeaders(1, violatingHeaders);
};
connectAction.Should().Throw <CheckpointMismatchException>();
// Make sure headers for violating chain don't exist.
foreach (BlockHeader header in violatingHeaders)
{
Assert.False(cht.GetChainedHeadersByHash().ContainsKey(header.GetHash()));
}
}
public void ChainHasOneCheckPointAndAssumeValid_ChainsWithCheckpointButMissedAssumeValidIsPresented_BothChainsAreMarkedForDownload()
{
// Chain header tree setup with disabled checkpoints.
// Initial chain has 2 headers.
// Example: h1=h2.
const int initialChainSize = 2;
const int extensionChainSize = 2;
TestContext ctx = new TestContextBuilder().WithInitialChain(initialChainSize).UseCheckpoints().Build();
ChainedHeaderTree cht = ctx.ChainedHeaderTree;
ChainedHeader initialChainTip = ctx.InitialChainTip;
// Extend chain with 2 more headers.
initialChainTip = ctx.ExtendAChain(extensionChainSize, initialChainTip); // i.e. h1=h2=h3=h4
List <BlockHeader> listOfCurrentChainHeaders = ctx.ChainedHeaderToList(initialChainTip, initialChainSize + extensionChainSize);
// Setup a known checkpoint at header 4.
// Example: h1=h2=h3=(h4).
const int checkpointHeight = 4;
var checkpoint = new CheckpointFixture(checkpointHeight, listOfCurrentChainHeaders.Last());
ctx.SetupCheckpoints(checkpoint);
// Extend chain and add "Assume valid" at block 6.
// Example: h1=h2=h3=(h4)=h5=[h6].
const int chainExtension = 2;
ChainedHeader extendedChainTip = ctx.ExtendAChain(chainExtension, initialChainTip);
ctx.ConsensusSettings.BlockAssumedValid = extendedChainTip.HashBlock;
// Setup new chain, which covers the last checkpoint (4), but misses "assumed valid".
const int newChainExtensionSize = 6;
ChainedHeader newChainTip = ctx.ExtendAChain(newChainExtensionSize, initialChainTip); // i.e. h1=h2=h3=(h4)=b5=b6=b7=b8=b9=b10
listOfCurrentChainHeaders = ctx.ChainedHeaderToList(newChainTip, initialChainSize + extensionChainSize + newChainExtensionSize);
// Chain is presented by peer 2.
// DownloadFrom should be set to header 3.
// DownloadTo should be set to header 10.
ConnectNewHeadersResult result = cht.ConnectNewHeaders(2, listOfCurrentChainHeaders);
result.DownloadFrom.HashBlock.Should().Be(listOfCurrentChainHeaders.Skip(2).First().GetHash());
result.DownloadTo.HashBlock.Should().Be(listOfCurrentChainHeaders.Last().GetHash());
}