Replace HaveInventory with HaveBlock.

The original thought was that chain would also house the transaction
memory pool, but that ultimately was decided against.  As a result,
it only makes sense to query chain for blocks rather than generic
inventory.

chain.go

@@ -167,38 +167,13 @@ func (b *BlockChain) DisableVerify(disable bool) {
 	b.noVerify = disable
 }
 
-// HaveInventory returns whether or not the chain instance has the inventory
-// represented by the passed inventory vector.  This includes checking all of
-// the various places inventory can be when it is in different states such as
-// part of the main chain, on a side chain, and orphans.
+// HaveBlock returns whether or not the chain instance has the block represented
+// by the passed hash.  This includes checking the various places a block can
+// be like part of the main chain, on a side chain, or in the orphan pool.
 //
-// This function is safe for concurrent access.
-func (b *BlockChain) HaveInventory(inventoryVector *btcwire.InvVect) bool {
-	switch inventoryVector.Type {
-	case btcwire.InvVect_Block:
-		// Check the main chain and side chains.
-		if b.blockExists(&inventoryVector.Hash) {
-			return true
-		}
-
-		// Check orphan blocks.
-		if b.IsKnownOrphan(&inventoryVector.Hash) {
-			return true
-		}
-
-	case btcwire.InvVect_Tx:
-		// TODO(davec): Need to ultimately maintain a transaction pool
-		// of transactions that are not already in a block and check
-		// for the existing transaction there too.
-
-		// Check if the transaction exists from the point of view of the
-		// end of the main chain.
-		return b.db.ExistsTxSha(&inventoryVector.Hash)
-	}
-
-	// The requested inventory is either not known or is an unsupported
-	// type (which also implies it is not known).
-	return false
+// This function is NOT safe for concurrent access.
+func (b *BlockChain) HaveBlock(hash *btcwire.ShaHash) bool {
+	return b.IsKnownOrphan(hash) && b.blockExists(hash)
 }
 
 // IsKnownOrphan returns whether the passed hash is currently a known orphan.