Remove `math/rand` and only use `crypto/rand`

main.go

@@ -1,16 +1,13 @@
 package main
 
 import (
-	"math/rand"
 	"runtime"
-	"time"
 
 	"github.com/navidrome/navidrome/cmd"
 	_ "github.com/navidrome/navidrome/model/criteria"
 )
 
 func main() {
-	rand.Seed(time.Now().UTC().UnixNano())
 	runtime.MemProfileRate = 0
 	cmd.Execute()
 }

server/backgrounds/handler.go

@@ -2,9 +2,11 @@ package backgrounds
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/base64"
+	"errors"
 	"io"
-	"math/rand"
+	"math/big"
 	"net/http"
 	"net/url"
 	"path"
@@ -48,7 +50,11 @@ func (h *Handler) getRandomImage(ctx context.Context) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return list[rand.Intn(len(list))], nil
+	if len(list) == 0 {
+		return "", errors.New("no images available")
+	}
+	rnd, _ := rand.Int(rand.Reader, big.NewInt(int64(len(list))))
+	return list[rnd.Int64()], nil
 }
 
 func (h *Handler) getImageList(ctx context.Context) ([]string, error) {

utils/weighted_random_chooser.go

@@ -1,24 +1,19 @@
 package utils
 
 import (
+	"crypto/rand"
 	"errors"
-	"math/rand"
-	"time"
+	"math/big"
 )
 
 type WeightedChooser struct {
 	entries     []interface{}
 	weights     []int
 	totalWeight int
-	rng         *rand.Rand
 }
 
 func NewWeightedRandomChooser() *WeightedChooser {
-	src := rand.NewSource(time.Now().UTC().UnixNano())
-
-	return &WeightedChooser{
-		rng: rand.New(src), // nolint:gosec
-	}
+	return &WeightedChooser{}
 }
 
 func (w *WeightedChooser) Put(value interface{}, weight int) {
@@ -43,9 +38,14 @@ func (w *WeightedChooser) GetAndRemove() (interface{}, error) {
 
 // Based on https://eli.thegreenplace.net/2010/01/22/weighted-random-generation-in-python/
 func (w *WeightedChooser) weightedChoice() (int, error) {
-	rnd := w.rng.Intn(w.totalWeight)
+	if w.totalWeight == 0 {
+		return 0, errors.New("no choices available")
+	}
+	rndBig, _ := rand.Int(rand.Reader, big.NewInt(int64(w.totalWeight)))
+
+	rnd := rndBig.Int64()
 	for i, weight := range w.weights {
-		rnd -= weight
+		rnd -= int64(weight)
 		if rnd < 0 {
 			return i, nil
 		}