🔒 Improved random package

internal/domain/login.go

@@ -4,13 +4,16 @@ import (
 	"testing"
 	"time"
 
+	"github.com/brianvoe/gofakeit/v6"
+	"github.com/stretchr/testify/require"
+
 	"source.toby3d.me/website/oauth/internal/random"
 )
 
 type Login struct {
+	PKCE
 	CreatedAt   time.Time
 	CompletedAt time.Time
-	PKCE
 	Scopes      []string
 	ClientID    string
 	RedirectURI string
@@ -25,10 +28,11 @@ type Login struct {
 func TestLogin(tb testing.TB) *Login {
 	tb.Helper()
 
-	now := time.Now().UTC()
+	code, err := random.String(8)
+	require.NoError(tb, err)
 
 	return &Login{
-		CreatedAt:   now.Add(-1 * time.Minute),
+		CreatedAt:   gofakeit.Date(),
 		CompletedAt: time.Time{},
 		PKCE: PKCE{
 			Method:    PKCEMethodS256,
@@ -40,7 +44,7 @@ func TestLogin(tb testing.TB) *Login {
 		RedirectURI: "https://app.example.com/redirect",
 		MeEntered:   "user.example.net",
 		MeResolved:  "https://user.example.net/",
-		Code:        random.New().String(8),
+		Code:        code,
 		Provider:    "mastodon",
 		IsCompleted: false,
 	}
@@ -50,15 +54,19 @@ func TestLogin(tb testing.TB) *Login {
 func TestLoginInvalid(tb testing.TB) *Login {
 	tb.Helper()
 
-	now := time.Now().UTC()
+	challenge, err := random.String(42)
+	require.NoError(tb, err)
+
+	verifier, err := random.String(64)
+	require.NoError(tb, err)
 
 	return &Login{
-		CreatedAt:   now.Add(-1 * time.Hour),
+		CreatedAt:   time.Now().UTC().Add(-1 * time.Hour),
 		CompletedAt: time.Time{},
 		PKCE: PKCE{
 			Method:    "UNDEFINED",
-			Challenge: random.New().String(42),
+			Challenge: challenge,
-			Verifier:  random.New().String(64),
+			Verifier:  verifier,
 		},
 		Scopes:      []string{},
 		ClientID:    "whoisit",
@@ -66,7 +74,7 @@ func TestLoginInvalid(tb testing.TB) *Login {
 		MeEntered:   "whoami",
 		MeResolved:  "",
 		Code:        "",
-		Provider:    "",
+		Provider:    "undefined",
 		IsCompleted: true,
 	}
 }

internal/domain/token.go

@@ -31,6 +31,11 @@ func NewToken() *Token {
 func TestToken(tb testing.TB) *Token {
 	tb.Helper()
 
+	require := require.New(tb)
+
+	nonce, err := random.String(50)
+	require.NoError(err)
+
 	client := TestClient(tb)
 	profile := TestProfile(tb)
 	now := time.Now().UTC().Round(time.Second)
@@ -48,10 +53,10 @@ func TestToken(tb testing.TB) *Token {
 
 	// optional
 	t.Set("scope", strings.Join(scopes, " "))
-	t.Set("nonce", random.New().String(32))
+	t.Set("nonce", nonce)
 
 	accessToken, err := jwt.Sign(t, jwa.HS256, []byte("hackme"))
-	require.NoError(tb, err)
+	require.NoError(err)
 
 	return &Token{
 		AccessToken: string(accessToken),

internal/middleware/csrf.go

@@ -108,7 +108,12 @@ func CSRFWithConfig(config CSRFConfig) Interceptor {
 		if k := ctx.Request.Header.Cookie(config.CookieName); k != nil {
 			token = k
 		} else {
-			token = []byte(random.New().String(config.TokenLength))
+			var err error
+			if token, err = random.Bytes(config.TokenLength); err != nil {
+				ctx.Error(err.Error(), http.StatusInternalServerError)
+
+				return
+			}
 		}
 
 		switch string(ctx.Method()) {

internal/random/random.go

@@ -1,13 +1,11 @@
 package random
 
 import (
-	"math/rand"
+	"crypto/rand"
+	"math/big"
 	"strings"
-	"time"
 )
 
-type Random struct{}
-
 const (
 	Uppercase    = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 	Lowercase    = "abcdefghijklmnopqrstuvwxyz"
@@ -18,13 +16,17 @@ const (
 	Hex          = Numeric + "abcdef"
 )
 
-func New() *Random {
+func Bytes(length int) ([]byte, error) {
-	rand.Seed(time.Now().UnixNano())
+	b := make([]byte, length)
 
-	return new(Random)
+	if _, err := rand.Read(b); err != nil {
+		return nil, err
+	}
+
+	return b, nil
 }
 
-func (r *Random) String(length int, charsets ...string) string {
+func String(length int, charsets ...string) (string, error) {
 	charset := strings.Join(charsets, "")
 
 	if charset == "" {
@@ -34,9 +36,13 @@ func (r *Random) String(length int, charsets ...string) string {
 	b := make([]byte, length)
 
 	for i := range b {
-		//nolint: gosec
+		n, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
-		b[i] = charset[rand.Int()%len(charset)]
+		if err != nil {
+			return "", err
+		}
+
+		b[i] = charset[n.Int64()]
 	}
 
-	return string(b)
+	return string(b), nil
 }