blockchain: Add IsAncestor method to blockNode

blockchain/blockindex.go

@@ -135,6 +135,20 @@ func newBlockNode(blockHeader *wire.BlockHeader, parent *blockNode) *blockNode {
 	return &node
 }
 
+// Equals compares all the fields of the block node except for the parent and
+// ancestor and returns true if they're equal.
+func (node *blockNode) Equals(other *blockNode) bool {
+	return node.hash == other.hash &&
+		node.workSum.Cmp(other.workSum) == 0 &&
+		node.height == other.height &&
+		node.version == other.version &&
+		node.bits == other.bits &&
+		node.nonce == other.nonce &&
+		node.timestamp == other.timestamp &&
+		node.merkleRoot == other.merkleRoot &&
+		node.status == other.status
+}
+
 // Header constructs a block header from the node and returns it.
 //
 // This function is safe for concurrent access.
@@ -260,6 +274,28 @@ func (node *blockNode) RelativeAncestorCtx(distance int32) HeaderCtx {
 	return ancestor
 }
 
+// IsAncestor returns if the other node is an ancestor of this block node.
+func (node *blockNode) IsAncestor(otherNode *blockNode) bool {
+	// Return early as false if the otherNode is nil.
+	if otherNode == nil {
+		return false
+	}
+
+	ancestor := node.Ancestor(otherNode.height)
+	if ancestor == nil {
+		return false
+	}
+
+	// If the otherNode has the same height as me, then the returned
+	// ancestor will be me.  Return false since I'm not an ancestor of me.
+	if node.height == ancestor.height {
+		return false
+	}
+
+	// Return true if the fetched ancestor is other node.
+	return ancestor.Equals(otherNode)
+}
+
 // RelativeAncestor returns the ancestor block node a relative 'distance' blocks
 // before this node.  This is equivalent to calling Ancestor with the node's
 // height minus provided distance.

blockchain/chain_test.go

@@ -1155,3 +1155,159 @@ func TestChainTips(t *testing.T) {
 		}
 	}
 }
+
+func TestIsAncestor(t *testing.T) {
+	// Construct a synthetic block chain with a block index consisting of
+	// the following structure.
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	tip := tstTip
+	chain := newFakeChain(&chaincfg.MainNetParams)
+	branch0Nodes := chainedNodes(chain.bestChain.Genesis(), 3)
+	for _, node := range branch0Nodes {
+		chain.index.SetStatusFlags(node, statusDataStored)
+		chain.index.SetStatusFlags(node, statusValid)
+		chain.index.AddNode(node)
+	}
+	chain.bestChain.SetTip(tip(branch0Nodes))
+
+	branch1Nodes := chainedNodes(chain.bestChain.Genesis(), 1)
+	for _, node := range branch1Nodes {
+		chain.index.SetStatusFlags(node, statusDataStored)
+		chain.index.SetStatusFlags(node, statusValid)
+		chain.index.AddNode(node)
+	}
+
+	branch2Nodes := chainedNodes(chain.bestChain.Genesis(), 1)
+	for _, node := range branch2Nodes {
+		chain.index.SetStatusFlags(node, statusDataStored)
+		chain.index.SetStatusFlags(node, statusValidateFailed)
+		chain.index.AddNode(node)
+	}
+
+	// Is 1 an ancestor of 3?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeTrue := branch0Nodes[2].IsAncestor(branch0Nodes[0])
+	if !shouldBeTrue {
+		t.Errorf("TestIsAncestor fail. Node %s is an ancestor of node %s but got false",
+			branch0Nodes[0].hash.String(), branch0Nodes[2].hash.String())
+	}
+
+	// Is 1 an ancestor of 2?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeTrue = branch0Nodes[1].IsAncestor(branch0Nodes[0])
+	if !shouldBeTrue {
+		t.Errorf("TestIsAncestor fail. Node %s is an ancestor of node %s but got false",
+			branch0Nodes[0].hash.String(), branch0Nodes[1].hash.String())
+	}
+
+	// Is the genesis an ancestor of 1?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeTrue = branch0Nodes[0].IsAncestor(chain.bestChain.Genesis())
+	if !shouldBeTrue {
+		t.Errorf("TestIsAncestor fail. The genesis block is an ancestor of all blocks "+
+			"but got false for node %s",
+			branch0Nodes[0].hash.String())
+	}
+
+	// Is the genesis an ancestor of 1a?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeTrue = branch1Nodes[0].IsAncestor(chain.bestChain.Genesis())
+	if !shouldBeTrue {
+		t.Errorf("TestIsAncestor fail. The genesis block is an ancestor of all blocks "+
+			"but got false for node %s",
+			branch1Nodes[0].hash.String())
+	}
+
+	// Is the genesis an ancestor of 1b?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeTrue = branch2Nodes[0].IsAncestor(chain.bestChain.Genesis())
+	if !shouldBeTrue {
+		t.Errorf("TestIsAncestor fail. The genesis block is an ancestor of all blocks "+
+			"but got false for node %s",
+			branch2Nodes[0].hash.String())
+	}
+
+	// Is 1 an ancestor of 1a?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeFalse := branch1Nodes[0].IsAncestor(branch0Nodes[0])
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node %s is in a different branch than "+
+			"node %s but got true", branch1Nodes[0].hash.String(),
+			branch0Nodes[0].hash.String())
+	}
+
+	// Is 1 an ancestor of 1b?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeFalse = branch2Nodes[0].IsAncestor(branch0Nodes[0])
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node %s is in a different branch than "+
+			"node %s but got true", branch2Nodes[0].hash.String(),
+			branch0Nodes[0].hash.String())
+	}
+
+	// Is 1a an ancestor of 1b?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeFalse = branch2Nodes[0].IsAncestor(branch1Nodes[0])
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node %s is in a different branch than "+
+			"node %s but got true", branch2Nodes[0].hash.String(),
+			branch1Nodes[0].hash.String())
+	}
+
+	// Is 1 an ancestor of 1?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeFalse = branch0Nodes[0].IsAncestor(branch0Nodes[0])
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node is not an ancestor of itself but got true for node %s",
+			branch0Nodes[0].hash.String())
+	}
+
+	// Is the geneis an ancestor of genesis?
+	//
+	// 	genesis -> 1  -> 2  -> 3 (active)
+	//            \ -> 1a (valid-fork)
+	//            \ -> 1b (invalid)
+	shouldBeFalse = chain.bestChain.Genesis().IsAncestor(chain.bestChain.Genesis())
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node is not an ancestor of itself but got true for node %s",
+			chain.bestChain.Genesis().hash.String())
+	}
+
+	// Is a block from another chain an ancestor of 1b?
+	fakeChain := newFakeChain(&chaincfg.TestNet3Params)
+	shouldBeFalse = branch2Nodes[0].IsAncestor(fakeChain.bestChain.Genesis())
+	if shouldBeFalse {
+		t.Errorf("TestIsAncestor fail. Node %s is in a different chain than "+
+			"node %s but got true", fakeChain.bestChain.Genesis().hash.String(),
+			branch2Nodes[0].hash.String())
+	}
+}