[FAB-3245] Use crypto rand in gossip

In gossip the random uses math instead of crypto,
and it is initialized with a static seed of 42 instead of something more random.
This has an implication that the randomized selection is not so random.

We should replace it with a crypto random for more security.

Change-Id: Iaa28c14410a19d076b301d76b4539769c03f4764
Signed-off-by: Yacov Manevich <[email protected]>

Author: yacovm

gossip/comm/comm_impl.go

@@ -21,7 +21,6 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
-	"math/rand"
 	"net"
 	"os"
 	"reflect"
@@ -52,10 +51,6 @@ const (
 
 var errSendOverflow = errors.New(sendOverflowErr)
 
-func init() {
-	rand.Seed(42)
-}
-
 // SetDialTimeout sets the dial timeout
 func SetDialTimeout(timeout time.Duration) {
 	viper.Set("peer.gossip.dialTimeout", timeout)
@@ -604,8 +599,8 @@ func createGRPCLayer(port int) (*grpc.Server, net.Listener, grpc.DialOption, []b
 	var serverOpts []grpc.ServerOption
 	var dialOpts grpc.DialOption
 
-	keyFileName := fmt.Sprintf("key.%d.pem", rand.Int63())
-	certFileName := fmt.Sprintf("cert.%d.pem", rand.Int63())
+	keyFileName := fmt.Sprintf("key.%d.pem", util.RandomUInt64())
+	certFileName := fmt.Sprintf("cert.%d.pem", util.RandomUInt64())
 
 	defer os.Remove(keyFileName)
 	defer os.Remove(certFileName)

gossip/comm/comm_test.go

@@ -43,7 +43,7 @@ import (
 )
 
 func init() {
-	rand.Seed(42)
+	rand.Seed(time.Now().UnixNano())
 	factory.InitFactories(nil)
 }
 

gossip/gossip/algo/pull.go

@@ -17,7 +17,6 @@ limitations under the License.
 package algo
 
 import (
-	"math/rand"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -44,10 +43,6 @@ import (
 
 */
 
-func init() {
-	rand.Seed(42)
-}
-
 const (
 	defDigestWaitTime   = time.Duration(1) * time.Second
 	defRequestWaitTime  = time.Duration(1) * time.Second
@@ -214,7 +209,7 @@ func (engine *PullEngine) processIncomingDigests() {
 	requestMapping := make(map[string][]string)
 	for n, sources := range engine.item2owners {
 		// select a random source
-		source := sources[rand.Intn(len(sources))]
+		source := sources[util.RandomInt(len(sources))]
 		if _, exists := requestMapping[source]; !exists {
 			requestMapping[source] = make([]string, 0)
 		}
@@ -341,7 +336,7 @@ func (engine *PullEngine) OnRes(items []string, nonce uint64) {
 func (engine *PullEngine) newNONCE() uint64 {
 	n := uint64(0)
 	for {
-		n = uint64(rand.Int63())
+		n = util.RandomUInt64()
 		if !engine.outgoingNONCES.Exists(n) {
 			return n
 		}

gossip/gossip/msgstore/msgs_test.go

@@ -29,7 +29,7 @@ import (
 )
 
 func init() {
-	rand.Seed(42)
+	rand.Seed(time.Now().UnixNano())
 }
 
 func alwaysNoAction(this interface{}, that interface{}) common.InvalidationResult {

gossip/state/state.go

@@ -19,7 +19,6 @@ package state
 import (
 	"bytes"
 	"errors"
-	"math/rand"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -543,7 +542,7 @@ func (s *GossipStateProviderImpl) requestBlocksInRange(start uint64, end uint64)
 // Generate state request message for given blocks in range [beginSeq...endSeq]
 func (s *GossipStateProviderImpl) stateRequestMessage(beginSeq uint64, endSeq uint64) *proto.GossipMessage {
 	return &proto.GossipMessage{
-		Nonce:   uint64(rand.Uint32())<<32 + uint64(rand.Uint32()),
+		Nonce:   util.RandomUInt64(),
 		Tag:     proto.GossipMessage_CHAN_OR_ORG,
 		Channel: []byte(s.chainID),
 		Content: &proto.GossipMessage_StateRequest{
@@ -566,7 +565,7 @@ func (s *GossipStateProviderImpl) selectPeerToRequestFrom(height uint64) (*comm.
 	}
 
 	// Select peers to ask for blocks
-	return peers[rand.Intn(n)], nil
+	return peers[util.RandomInt(n)], nil
 }
 
 // filterPeers return list of peers which aligns the predicate provided

gossip/util/misc.go

@@ -17,7 +17,10 @@ limitations under the License.
 package util
 
 import (
+	cryptorand "crypto/rand"
 	"fmt"
+	"io"
+	"math/big"
 	"math/rand"
 	"reflect"
 	"runtime"
@@ -30,10 +33,6 @@ import (
 // Equals returns whether a and b are the same
 type Equals func(a interface{}, b interface{}) bool
 
-func init() {
-	rand.Seed(42)
-}
-
 // IndexInSlice returns the index of given object o in array
 func IndexInSlice(array interface{}, o interface{}, equals Equals) int {
 	arr := reflect.ValueOf(array)
@@ -65,7 +64,7 @@ func GetRandomIndices(indiceCount, highestIndex int) []int {
 	}
 
 	for len(indices) < indiceCount {
-		n := rand.Intn(highestIndex + 1)
+		n := RandomInt(highestIndex + 1)
 		if IndexInSlice(indices, n, numbericEqual) != -1 {
 			continue
 		}
@@ -159,3 +158,28 @@ func GetDurationOrDefault(key string, defVal time.Duration) time.Duration {
 
 	return defVal
 }
+
+// RandomInt returns, as an int, a non-negative pseudo-random integer in [0,n)
+// It panics if n <= 0
+func RandomInt(n int) int {
+	if n <= 0 {
+		panic(fmt.Sprintf("Got invalid (non positive) value: %d", n))
+	}
+	m := int(RandomUInt64()) % n
+	if m < 0 {
+		return n + m
+	}
+	return m
+}
+
+// RandomUInt64 returns a random uint64
+func RandomUInt64() uint64 {
+	b := make([]byte, 8)
+	_, err := io.ReadFull(cryptorand.Reader, b)
+	if err == nil {
+		n := new(big.Int)
+		return n.SetBytes(b).Uint64()
+	}
+	rand.Seed(rand.Int63())
+	return uint64(rand.Int63())
+}

gossip/util/misc_test.go

@@ -0,0 +1,80 @@
+/*
+Copyright IBM Corp. 2017 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+		 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"crypto/rand"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+)
+
+func testHappyPath(t *testing.T) {
+	n1 := RandomInt(10000)
+	n2 := RandomInt(10000)
+	assert.NotEqual(t, n1, n2)
+	n3 := RandomUInt64()
+	n4 := RandomUInt64()
+	assert.NotEqual(t, n3, n4)
+}
+
+func TestGetRandomInt(t *testing.T) {
+	testHappyPath(t)
+}
+
+func TestNonNegativeValues(t *testing.T) {
+	assert.True(t, RandomInt(1000000) >= 0)
+}
+
+func TestGetRandomIntBadInput(t *testing.T) {
+	f1 := func() {
+		RandomInt(0)
+	}
+	f2 := func() {
+		RandomInt(-500)
+	}
+	assert.Panics(t, f1)
+	assert.Panics(t, f2)
+}
+
+type reader struct {
+	mock.Mock
+}
+
+func (r *reader) Read(p []byte) (int, error) {
+	args := r.Mock.Called(p)
+	n := args.Get(0).(int)
+	err := args.Get(1)
+	if err == nil {
+		return n, nil
+	}
+	return n, err.(error)
+}
+
+func TestGetRandomIntNoEntropy(t *testing.T) {
+	rr := rand.Reader
+	defer func() {
+		rand.Reader = rr
+	}()
+	r := &reader{}
+	r.On("Read", mock.Anything).Return(0, errors.New("Not enough entropy"))
+	rand.Reader = r
+	// Make sure randomness still works even when we have no entropy
+	testHappyPath(t)
+}