all: remove deprecated uses of math.rand (#26710)

This PR is a (superior) alternative to #26708, it handles deprecation, primarily two specific cases. 

`rand.Seed` is typically used in two ways
- `rand.Seed(time.Now().UnixNano())` -- we seed it, just to be sure to get some random, and not always get the same thing on every run. This is not needed, with global seeding, so those are just removed. 
- `rand.Seed(1)` this is typically done to ensure we have a stable test. If we rely on this, we need to fix up the tests to use a deterministic prng-source. A few occurrences like this has been replaced with a proper custom source. 

`rand.Read` has been replaced by `crypto/rand`.`Read` in this PR.

Author: holiman

accounts/keystore/account_cache_test.go

@@ -113,7 +113,6 @@ func TestWatchNewFile(t *testing.T) {
 func TestWatchNoDir(t *testing.T) {
 	t.Parallel()
 	// Create ks but not the directory that it watches.
-	rand.Seed(time.Now().UnixNano())
 	dir := filepath.Join(os.TempDir(), fmt.Sprintf("eth-keystore-watchnodir-test-%d-%d", os.Getpid(), rand.Int()))
 	ks := NewKeyStore(dir, LightScryptN, LightScryptP)
 	list := ks.Accounts()
@@ -322,7 +321,6 @@ func TestUpdatedKeyfileContents(t *testing.T) {
 	t.Parallel()
 
 	// Create a temporary keystore to test with
-	rand.Seed(time.Now().UnixNano())
 	dir := filepath.Join(os.TempDir(), fmt.Sprintf("eth-keystore-updatedkeyfilecontents-test-%d-%d", os.Getpid(), rand.Int()))
 	ks := NewKeyStore(dir, LightScryptN, LightScryptP)
 

common/lru/basiclru_test.go

@@ -17,6 +17,7 @@
 package lru
 
 import (
+	crand "crypto/rand"
 	"fmt"
 	"io"
 	"math/rand"
@@ -181,9 +182,9 @@ func BenchmarkLRU(b *testing.B) {
 	}
 	for i := range keys {
 		b := make([]byte, 32)
-		rand.Read(b)
+		crand.Read(b)
 		keys[i] = string(b)
-		rand.Read(b)
+		crand.Read(b)
 		values[i] = b
 	}
 

common/prque/lazyqueue_test.go

@@ -56,7 +56,6 @@ func testSetIndex(a interface{}, i int) {
 }
 
 func TestLazyQueue(t *testing.T) {
-	rand.Seed(time.Now().UnixNano())
 	clock := &mclock.Simulated{}
 	q := NewLazyQueue(testSetIndex, testPriority, testMaxPriority, clock, testQueueRefresh)
 

consensus/ethash/consensus_test.go

@@ -17,6 +17,7 @@
 package ethash
 
 import (
+	crand "crypto/rand"
 	"encoding/binary"
 	"encoding/json"
 	"math/big"
@@ -90,16 +91,15 @@ func TestCalcDifficulty(t *testing.T) {
 
 func randSlice(min, max uint32) []byte {
 	var b = make([]byte, 4)
-	rand.Read(b)
+	crand.Read(b)
 	a := binary.LittleEndian.Uint32(b)
 	size := min + a%(max-min)
 	out := make([]byte, size)
-	rand.Read(out)
+	crand.Read(out)
 	return out
 }
 
 func TestDifficultyCalculators(t *testing.T) {
-	rand.Seed(2)
 	for i := 0; i < 5000; i++ {
 		// 1 to 300 seconds diff
 		var timeDelta = uint64(1 + rand.Uint32()%3000)

core/bloombits/generator_test.go

@@ -18,6 +18,7 @@ package bloombits
 
 import (
 	"bytes"
+	crand "crypto/rand"
 	"math/rand"
 	"testing"
 
@@ -78,7 +79,7 @@ func BenchmarkGenerator(b *testing.B) {
 		}
 	})
 	for i := 0; i < types.BloomBitLength; i++ {
-		rand.Read(input[i][:])
+		crand.Read(input[i][:])
 	}
 	b.Run("random", func(b *testing.B) {
 		b.ReportAllocs()

core/rawdb/freezer_table_test.go

@@ -27,17 +27,12 @@ import (
 	"sync/atomic"
 	"testing"
 	"testing/quick"
-	"time"
 
 	"github.com/davecgh/go-spew/spew"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/stretchr/testify/require"
 )
 
-func init() {
-	rand.Seed(time.Now().Unix())
-}
-
 // TestFreezerBasics test initializing a freezertable from scratch, writing to the table,
 // and reading it back.
 func TestFreezerBasics(t *testing.T) {

core/state/snapshot/difflayer_test.go

@@ -18,6 +18,7 @@ package snapshot
 
 import (
 	"bytes"
+	crand "crypto/rand"
 	"math/rand"
 	"testing"
 
@@ -73,7 +74,7 @@ func TestMergeBasics(t *testing.T) {
 		if rand.Intn(2) == 0 {
 			accStorage := make(map[common.Hash][]byte)
 			value := make([]byte, 32)
-			rand.Read(value)
+			crand.Read(value)
 			accStorage[randomHash()] = value
 			storage[h] = accStorage
 		}
@@ -294,7 +295,7 @@ func BenchmarkSearchSlot(b *testing.B) {
 		accStorage := make(map[common.Hash][]byte)
 		for i := 0; i < 5; i++ {
 			value := make([]byte, 32)
-			rand.Read(value)
+			crand.Read(value)
 			accStorage[randomHash()] = value
 			storage[accountKey] = accStorage
 		}
@@ -330,7 +331,7 @@ func BenchmarkFlatten(b *testing.B) {
 			accStorage := make(map[common.Hash][]byte)
 			for i := 0; i < 20; i++ {
 				value := make([]byte, 32)
-				rand.Read(value)
+				crand.Read(value)
 				accStorage[randomHash()] = value
 			}
 			storage[accountKey] = accStorage
@@ -379,7 +380,7 @@ func BenchmarkJournal(b *testing.B) {
 			accStorage := make(map[common.Hash][]byte)
 			for i := 0; i < 200; i++ {
 				value := make([]byte, 32)
-				rand.Read(value)
+				crand.Read(value)
 				accStorage[randomHash()] = value
 			}
 			storage[accountKey] = accStorage

core/state/snapshot/iterator_test.go

@@ -18,6 +18,7 @@ package snapshot
 
 import (
 	"bytes"
+	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
 	"math/rand"
@@ -47,7 +48,7 @@ func TestAccountIteratorBasics(t *testing.T) {
 		if rand.Intn(2) == 0 {
 			accStorage := make(map[common.Hash][]byte)
 			value := make([]byte, 32)
-			rand.Read(value)
+			crand.Read(value)
 			accStorage[randomHash()] = value
 			storage[h] = accStorage
 		}
@@ -79,7 +80,7 @@ func TestStorageIteratorBasics(t *testing.T) {
 
 		var nilstorage int
 		for i := 0; i < 100; i++ {
-			rand.Read(value)
+			crand.Read(value)
 			if rand.Intn(2) == 0 {
 				accStorage[randomHash()] = common.CopyBytes(value)
 			} else {

core/state/snapshot/snapshot_test.go

@@ -17,6 +17,7 @@
 package snapshot
 
 import (
+	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
 	"math/big"
@@ -33,7 +34,7 @@ import (
 // randomHash generates a random blob of data and returns it as a hash.
 func randomHash() common.Hash {
 	var hash common.Hash
-	if n, err := rand.Read(hash[:]); n != common.HashLength || err != nil {
+	if n, err := crand.Read(hash[:]); n != common.HashLength || err != nil {
 		panic(err)
 	}
 	return hash

core/txpool/txpool_test.go

@@ -18,6 +18,7 @@ package txpool
 
 import (
 	"crypto/ecdsa"
+	crand "crypto/rand"
 	"errors"
 	"fmt"
 	"math/big"
@@ -92,7 +93,7 @@ func pricedTransaction(nonce uint64, gaslimit uint64, gasprice *big.Int, key *ec
 
 func pricedDataTransaction(nonce uint64, gaslimit uint64, gasprice *big.Int, key *ecdsa.PrivateKey, bytes uint64) *types.Transaction {
 	data := make([]byte, bytes)
-	rand.Read(data)
+	crand.Read(data)
 
 	tx, _ := types.SignTx(types.NewTransaction(nonce, common.Address{}, big.NewInt(0), gaslimit, gasprice, data), types.HomesteadSigner{}, key)
 	return tx