core: use block difficulty for genesis (ethereum#23793)

* core: write test showing that TD is not stored properly at genesis

The ToBlock method applies a default value for an empty
difficulty value. This default is not carried over through the Commit
method because the TotalDifficulty database write writes the
original difficulty value (nil) instead of the defaulty value
present on the genesis Block.

Date: 2021-10-22 08:25:32-07:00
Signed-off-by: meows <b5c6@protonmail.com>

* core: write TD value from Block, not original genesis value

This an issue where a default TD value was not written to
the database, resulting in a 0 value TD at genesis.

A test for this issue was provided at 90e3ffd

Date: 2021-10-22 08:28:00-07:00
Signed-off-by: meows <b5c6@protonmail.com>

* core: fix tests by adding GenesisDifficulty to expected result

See prior two commits.

Date: 2021-10-22 09:16:01-07:00
Signed-off-by: meows <b5c6@protonmail.com>

* les: fix test with genesis change

Co-authored-by: Martin Holst Swende <martin@swende.se>

core/blockchain_test.go

@@ -360,7 +360,7 @@ func TestReorgLongHeaders(t *testing.T) { testReorgLong(t, false) }
 func TestReorgLongBlocks(t *testing.T)  { testReorgLong(t, true) }
 
 func testReorgLong(t *testing.T, full bool) {
-	testReorg(t, []int64{0, 0, -9}, []int64{0, 0, 0, -9}, 393280, full)
+	testReorg(t, []int64{0, 0, -9}, []int64{0, 0, 0, -9}, 393280+params.GenesisDifficulty.Int64(), full)
 }
 
 // Tests that reorganising a short difficult chain after a long easy one
@@ -380,7 +380,7 @@ func testReorgShort(t *testing.T, full bool) {
 	for i := 0; i < len(diff); i++ {
 		diff[i] = -9
 	}
-	testReorg(t, easy, diff, 12615120, full)
+	testReorg(t, easy, diff, 12615120+params.GenesisDifficulty.Int64(), full)
 }
 
 func testReorg(t *testing.T, first, second []int64, td int64, full bool) {

core/genesis.go

@@ -326,7 +326,7 @@ func (g *Genesis) Commit(db ethdb.Database) (*types.Block, error) {
 	if config.Clique != nil && len(block.Extra()) == 0 {
 		return nil, errors.New("can't start clique chain without signers")
 	}
-	rawdb.WriteTd(db, block.Hash(), block.NumberU64(), g.Difficulty)
+	rawdb.WriteTd(db, block.Hash(), block.NumberU64(), block.Difficulty())
 	rawdb.WriteBlock(db, block)
 	rawdb.WriteReceipts(db, block.Hash(), block.NumberU64(), nil)
 	rawdb.WriteCanonicalHash(db, block.Hash(), block.NumberU64())

core/genesis_test.go

@@ -218,3 +218,33 @@ func TestGenesisHashes(t *testing.T) {
 		}
 	}
 }
+
+func TestGenesis_Commit(t *testing.T) {
+	genesis := &Genesis{
+		BaseFee: big.NewInt(params.InitialBaseFee),
+		Config:  params.TestChainConfig,
+		// difficulty is nil
+	}
+
+	db := rawdb.NewMemoryDatabase()
+	genesisBlock, err := genesis.Commit(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if genesis.Difficulty != nil {
+		t.Fatalf("assumption wrong")
+	}
+
+	// This value should have been set as default in the ToBlock method.
+	if genesisBlock.Difficulty().Cmp(params.GenesisDifficulty) != 0 {
+		t.Errorf("assumption wrong: want: %d, got: %v", params.GenesisDifficulty, genesisBlock.Difficulty())
+	}
+
+	// Expect the stored total difficulty to be the difficulty of the genesis block.
+	stored := rawdb.ReadTd(db, genesisBlock.Hash(), genesisBlock.NumberU64())
+
+	if stored.Cmp(genesisBlock.Difficulty()) != 0 {
+		t.Errorf("inequal difficulty; stored: %v, genesisBlock: %v", stored, genesisBlock.Difficulty())
+	}
+}

les/fetcher_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 // verifyImportEvent verifies that one single event arrive on an import channel.
@@ -247,7 +248,7 @@ func testInvalidAnnounces(t *testing.T, protocol int) {
 	// Prepare announcement by latest header.
 	headerOne := s.backend.Blockchain().GetHeaderByNumber(1)
 	hash, number := headerOne.Hash(), headerOne.Number.Uint64()
-	td := big.NewInt(200) // bad td
+	td := big.NewInt(params.GenesisDifficulty.Int64() + 200) // bad td
 
 	// Sign the announcement if necessary.
 	announce := announceData{hash, number, td, 0, nil}