simplify random string generator

utils.go

@@ -2,18 +2,15 @@ package main
 
 import (
 	"crypto/rand"
+	"encoding/base64"
 )
 
-const (
-	alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
-)
-
-// RandomString ...
+// RandomString generates random bytes and then encodes them using base64
+// which guarantees they are URL-safe. The resultant output is not necessarily
+// a valid base-64 string.
 func RandomString(length int) string {
-	bytes := make([]byte, length)
+	bytes := make([]byte, length*2)
 	rand.Read(bytes)
-	for i, b := range bytes {
-		bytes[i] = alphabet[b%byte(len(alphabet))]
-	}
-	return string(bytes)
+	se := base64.StdEncoding.EncodeToString(bytes)
+	return se[0:length]
 }