util/rand: replace all non crypto rand stuff with own rand package

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

broker/memory.go

@@ -3,14 +3,13 @@ package broker
 import (
 	"context"
 	"errors"
-	"math/rand"
 	"sync"
-	"time"
 
 	"github.com/google/uuid"
 	"github.com/unistack-org/micro/v3/logger"
 	maddr "github.com/unistack-org/micro/v3/util/addr"
 	mnet "github.com/unistack-org/micro/v3/util/net"
+	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 type memoryBroker struct {
@@ -59,7 +58,8 @@ func (m *memoryBroker) Connect(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
-	i := rand.Intn(20000)
+	var rng rand.Rand
+	i := rng.Intn(20000)
 	// set addr with port
 	addr = mnet.HostPort(addr, 10000+i)
 
@@ -237,8 +237,6 @@ func (m *memorySubscriber) Unsubscribe(ctx context.Context) error {
 
 // NewBroker return new memory broker
 func NewBroker(opts ...Option) Broker {
-	rand.Seed(time.Now().UnixNano())
-
 	return &memoryBroker{
 		opts:        NewOptions(opts...),
 		Subscribers: make(map[string][]*memorySubscriber),

network/transport/memory.go

@@ -4,13 +4,13 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"math/rand"
 	"net"
 	"sync"
 	"time"
 
 	maddr "github.com/unistack-org/micro/v3/util/addr"
 	mnet "github.com/unistack-org/micro/v3/util/net"
+	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 type memorySocket struct {
@@ -207,7 +207,8 @@ func (m *memoryTransport) Listen(ctx context.Context, addr string, opts ...Liste
 
 	// if zero port then randomly assign one
 	if len(port) > 0 && port == "0" {
-		i := rand.Intn(20000)
+		var rng rand.Rand
+		i := rng.Intn(20000)
 		port = fmt.Sprintf("%d", 10000+i)
 	}
 
@@ -255,8 +256,6 @@ func (m *memoryTransport) Name() string {
 func NewTransport(opts ...Option) Transport {
 	options := NewOptions(opts...)
 
-	rand.Seed(time.Now().UnixNano())
-
 	return &memoryTransport{
 		opts:      options,
 		listeners: make(map[string]*memoryListener),

selector/random/random.go

@@ -1,9 +1,8 @@
 package random
 
 import (
-	"math/rand"
-
 	"github.com/unistack-org/micro/v3/selector"
+	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 type random struct{}
@@ -20,10 +19,9 @@ func (r *random) Select(routes []string, opts ...selector.SelectOption) (selecto
 		if len(routes) == 1 {
 			return routes[0]
 		}
-
+		var rng rand.Rand
 		// select a random route from the slice
-		//nolint:gosec
-		return routes[rand.Intn(len(routes))]
+		return routes[rng.Intn(len(routes))]
 	}, nil
 }
 

selector/roundrobin/roundrobin.go

@@ -1,9 +1,8 @@
 package roundrobin
 
 import (
-	"math/rand"
-
 	"github.com/unistack-org/micro/v3/selector"
+	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 // NewSelector returns an initialised round robin selector
@@ -18,8 +17,8 @@ func (r *roundrobin) Select(routes []string, opts ...selector.SelectOption) (sel
 	if len(routes) == 0 {
 		return nil, selector.ErrNoneAvailable
 	}
-
-	i := rand.Intn(len(routes))
+	var rng rand.Rand
+	i := rng.Intn(len(routes))
 
 	return func() string {
 		route := routes[i%len(routes)]

util/jitter/jitter.go

@@ -2,16 +2,14 @@
 package jitter
 
 import (
-	"math/rand"
 	"time"
-)
 
-var (
-	r = rand.New(rand.NewSource(time.Now().UnixNano()))
+	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 // Do returns a random time to jitter with max cap specified
 func Do(d time.Duration) time.Duration {
-	v := r.Float64() * float64(d.Nanoseconds())
+	var rng rand.Rand
+	v := rng.Float64() * float64(d.Nanoseconds())
 	return time.Duration(v)
 }

util/rand/rand.go

@@ -0,0 +1,84 @@
+package rand
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+)
+
+// Rand is a wrapper around crypto/rand that adds some convenience functions known from math/rand.
+type Rand struct {
+	buf [8]byte
+}
+
+func (r *Rand) Int31() int32 {
+	rand.Read(r.buf[:4])
+	return int32(binary.BigEndian.Uint32(r.buf[:4]) & ^uint32(1<<31))
+}
+
+func (r *Rand) Int() int {
+	u := uint(r.Int63())
+	return int(u << 1 >> 1) // clear sign bit if int == int32
+}
+
+func (r *Rand) Float64() float64 {
+again:
+	f := float64(r.Int63()) / (1 << 63)
+	if f == 1 {
+		goto again // resample; this branch is taken O(never)
+	}
+	return f
+}
+
+func (r *Rand) Float32() float32 {
+again:
+	f := float32(r.Float64())
+	if f == 1 {
+		goto again // resample; this branch is taken O(very rarely)
+	}
+	return f
+}
+
+func (r *Rand) Uint32() uint32 {
+	return uint32(r.Int63() >> 31)
+}
+
+func (r *Rand) Uint64() uint64 {
+	return uint64(r.Int63())>>31 | uint64(r.Int63())<<32
+}
+
+func (r *Rand) Intn(n int) int {
+	if n <= 1<<31-1 {
+		return int(r.Int31n(int32(n)))
+	}
+	return int(r.Int63n(int64(n)))
+}
+
+func (r *Rand) Int63() int64 {
+	rand.Read(r.buf[:])
+	return int64(binary.BigEndian.Uint64(r.buf[:]) & ^uint64(1<<63))
+}
+
+// copied from the standard library math/rand implementation of Int63n
+func (r *Rand) Int31n(n int32) int32 {
+	if n&(n-1) == 0 { // n is power of two, can mask
+		return r.Int31() & (n - 1)
+	}
+	max := int32((1 << 31) - 1 - (1<<31)%uint32(n))
+	v := r.Int31()
+	for v > max {
+		v = r.Int31()
+	}
+	return v % n
+}
+
+func (r *Rand) Int63n(n int64) int64 {
+	if n&(n-1) == 0 { // n is power of two, can mask
+		return r.Int63() & (n - 1)
+	}
+	max := int64((1 << 63) - 1 - (1<<63)%uint64(n))
+	v := r.Int63()
+	for v > max {
+		v = r.Int63()
+	}
+	return v % n
+}