[MM-33794] Improve password generation during bulk import (#17147)

Automatic Merge

app/import_utils.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"crypto/rand"
+	"math/big"
+)
+
+const (
+	passwordSpecialChars     = "!$%^&*(),."
+	passwordNumbers          = "0123456789"
+	passwordUpperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	passwordLowerCaseLetters = "abcdefghijklmnopqrstuvwxyz"
+	passwordAllChars         = passwordSpecialChars + passwordNumbers + passwordUpperCaseLetters + passwordLowerCaseLetters
+)
+
+func randInt(max int) (int, error) {
+	val, err := rand.Int(rand.Reader, big.NewInt(int64(max)))
+	if err != nil {
+		return 0, err
+	}
+	return int(val.Int64()), nil
+}
+
+func generatePassword(minimumLength int) (string, error) {
+	upperIdx, err := randInt(len(passwordUpperCaseLetters))
+	if err != nil {
+		return "", err
+	}
+	numberIdx, err := randInt(len(passwordNumbers))
+	if err != nil {
+		return "", err
+	}
+	lowerIdx, err := randInt(len(passwordLowerCaseLetters))
+	if err != nil {
+		return "", err
+	}
+	specialIdx, err := randInt(len(passwordSpecialChars))
+	if err != nil {
+		return "", err
+	}
+
+	// Make sure we are guaranteed at least one of each type to meet any possible password complexity requirements.
+	password := string([]rune(passwordUpperCaseLetters)[upperIdx]) +
+		string([]rune(passwordNumbers)[numberIdx]) +
+		string([]rune(passwordLowerCaseLetters)[lowerIdx]) +
+		string([]rune(passwordSpecialChars)[specialIdx])
+
+	for len(password) < minimumLength {
+		i, err := randInt(len(passwordAllChars))
+		if err != nil {
+			return "", err
+		}
+		password = password + string([]rune(passwordAllChars)[i])
+	}
+
+	return password, nil
+}