Fix randoms

Use seeded mathematical random where uniqueness is needed
but not required to be cryptographic.

examples/internal/signal/rand.go

@@ -2,16 +2,17 @@ package signal
 
 import (
 	"math/rand"
-	"time"
 )
 
 // RandSeq generates a random string to serve as dummy data
+//
+// It returns a deterministic sequence of values each time a program is run.
+// Use rand.Seed() function in your real applications.
 func RandSeq(n int) string {
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
 	b := make([]rune, n)
 	for i := range b {
-		b[i] = letters[r.Intn(len(letters))]
+		b[i] = letters[rand.Intn(len(letters))]
 	}
 	return string(b)
 }

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/pion/ice/v2 v2.0.0-rc.4
 	github.com/pion/logging v0.2.2
 	github.com/pion/quic v0.1.1
+	github.com/pion/randutil v0.0.0
 	github.com/pion/rtcp v1.2.3
 	github.com/pion/rtp v1.5.5
 	github.com/pion/sctp v1.7.6

go.sum

@@ -39,6 +39,8 @@ github.com/pion/mdns v0.0.4 h1:O4vvVqr4DGX63vzmO6Fw9vpy3lfztVWHGCQfyw0ZLSY=
 github.com/pion/mdns v0.0.4/go.mod h1:R1sL0p50l42S5lJs91oNdUL58nm0QHrhxnSegr++qC0=
 github.com/pion/quic v0.1.1 h1:D951FV+TOqI9A0rTF7tHx0Loooqz+nyzjEyj8o3PuMA=
 github.com/pion/quic v0.1.1/go.mod h1:zEU51v7ru8Mp4AUBJvj6psrSth5eEFNnVQK5K48oV3k=
+github.com/pion/randutil v0.0.0 h1:aLWLVhTG2jzoD25F0OlW6nXvXrjoGwiXq2Sz7j7NzL0=
+github.com/pion/randutil v0.0.0/go.mod h1:XcJrSMMbbMRhASFVOlj/5hQial/Y8oH/HVo7TBZq+j8=
 github.com/pion/rtcp v1.2.3 h1:2wrhKnqgSz91Q5nzYTO07mQXztYPtxL8a0XOss4rJqA=
 github.com/pion/rtcp v1.2.3/go.mod h1:zGhIv0RPRF0Z1Wiij22pUt5W/c9fevqSzT4jje/oK7I=
 github.com/pion/rtp v1.5.5 h1:WTqWdmBuIj+luh8Wg6XVX+w7OytZHAIgtC7uSvgEl9Y=

internal/util/util.go

@@ -2,20 +2,26 @@
 package util
 
 import (
-	"math/rand"
 	"strings"
-	"time"
+
+	"github.com/pion/randutil"
 )
 
-// RandSeq generates a random alpha numeric sequence of the requested length
+const (
-func RandSeq(n int) string {
+	runesAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+)
-	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
-	b := make([]rune, n)
+// Use global random generator to properly seed by crypto grade random.
-	for i := range b {
+var globalMathRandomGenerator = randutil.NewMathRandomGenerator() // nolint:gochecknoglobals
-		b[i] = letters[r.Intn(len(letters))]
+
-	}
+// MathRandAlpha generates a mathmatical random alphabet sequence of the requested length.
-	return string(b)
+func MathRandAlpha(n int) string {
+	return globalMathRandomGenerator.GenerateString(n, runesAlpha)
+}
+
+// RandUint32 generates a mathmatical random uint32.
+func RandUint32() uint32 {
+	return globalMathRandomGenerator.Uint32()
 }
 
 // FlattenErrs flattens multiple errors into one

internal/util/util_test.go

@@ -6,14 +6,14 @@ import (
 	"testing"
 )
 
-func TestRandSeq(t *testing.T) {
+func TestMathRandAlpha(t *testing.T) {
-	if len(RandSeq(10)) != 10 {
+	if len(MathRandAlpha(10)) != 10 {
-		t.Errorf("RandSeq return invalid length")
+		t.Errorf("MathRandAlpha return invalid length")
 	}
 
 	var isLetter = regexp.MustCompile(`^[a-zA-Z]+$`).MatchString
-	if !isLetter(RandSeq(10)) {
+	if !isLetter(MathRandAlpha(10)) {
-		t.Errorf("RandSeq should be AlphaNumeric only")
+		t.Errorf("MathRandAlpha should be AlphaNumeric only")
 	}
 }
 

peerconnection.go

@@ -8,7 +8,6 @@ import (
 	"crypto/elliptic"
 	"crypto/rand"
 	"fmt"
-	mathRand "math/rand"
 	"strconv"
 	"strings"
 	"sync"
@@ -1272,7 +1271,7 @@ func (pc *PeerConnection) AddTransceiverFromKind(kind RTPCodecType, init ...RtpT
 			return nil, fmt.Errorf("no %s codecs found", kind.String())
 		}
 
-		track, err := pc.NewTrack(codecs[0].PayloadType, mathRand.Uint32(), util.RandSeq(trackDefaultIDLength), util.RandSeq(trackDefaultLabelLength))
+		track, err := pc.NewTrack(codecs[0].PayloadType, util.RandUint32(), util.MathRandAlpha(trackDefaultIDLength), util.MathRandAlpha(trackDefaultLabelLength))
 		if err != nil {
 			return nil, err
 		}

peerconnection_go_test.go

@@ -143,9 +143,9 @@ func TestNew_Go(t *testing.T) {
 		assert.NoError(t, err)
 		assert.NotNil(t, pc)
 
-		pc.configuration.ICEServers[0].Username = util.RandSeq(15)
+		pc.configuration.ICEServers[0].Username = util.MathRandAlpha(15) // Tests doesn't need crypto random
-		pc.configuration.ICEServers[0].Credential = util.RandSeq(15)
+		pc.configuration.ICEServers[0].Credential = util.MathRandAlpha(15)
-		pc.configuration.ICEServers[0].URLs[0] = util.RandSeq(15)
+		pc.configuration.ICEServers[0].URLs[0] = util.MathRandAlpha(15)
 
 		assert.Equal(t, expectedUsername, cfg.ICEServers[0].Username)
 		assert.Equal(t, expectedPassword, cfg.ICEServers[0].Credential)

peerconnection_renegotiation_test.go

@@ -147,7 +147,7 @@ func TestPeerConnection_Renegotiation_AddTrack_Multiple(t *testing.T) {
 		return track
 	}
 
-	trackNames := []string{util.RandSeq(trackDefaultIDLength), util.RandSeq(trackDefaultIDLength), util.RandSeq(trackDefaultIDLength)}
+	trackNames := []string{util.MathRandAlpha(trackDefaultIDLength), util.MathRandAlpha(trackDefaultIDLength), util.MathRandAlpha(trackDefaultIDLength)}
 	outboundTracks := []*Track{}
 	onTrackCount := map[string]int{}
 	onTrackChan := make(chan struct{}, 1)