Add Inner Ring code

pkg/util/rand/rand.go

@@ -0,0 +1,46 @@
+package rand
+
+import (
+	crand "crypto/rand"
+	"encoding/binary"
+	mrand "math/rand"
+)
+
+type cryptoSource struct{}
+
+// Read is alias for crypto/rand.Read.
+var Read = crand.Read
+
+// New constructs the source of random numbers.
+func New() *mrand.Rand {
+	return mrand.New(&cryptoSource{})
+}
+
+func (s *cryptoSource) Seed(int64) {}
+
+func (s *cryptoSource) Int63() int64 {
+	return int64(s.Uint63())
+}
+
+func (s *cryptoSource) Uint63() uint64 {
+	buf := make([]byte, 8)
+	if _, err := crand.Read(buf); err != nil {
+		return 0
+	}
+
+	return binary.BigEndian.Uint64(buf)
+}
+
+// Uint64 returns a random uint64 value.
+func Uint64(r *mrand.Rand, max int64) uint64 {
+	if max <= 0 {
+		return 0
+	}
+
+	var i int64 = -1
+	for i < 0 {
+		i = r.Int63n(max)
+	}
+
+	return uint64(i)
+}