1 files changed, 73 insertions, 0 deletions
diff --git a/modules/password/password.go b/modules/password/password.go
new file mode 100644
index 0000000000..54131b9641
--- /dev/null
+++ b/modules/password/password.go
@@ -0,0 +1,73 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package password
+
+import (
+	"crypto/rand"
+	"math/big"
+	"regexp"
+	"sync"
+
+	"code.gitea.io/gitea/modules/setting"
+)
+
+var matchComplexities = map[string]regexp.Regexp{}
+var matchComplexityOnce sync.Once
+var validChars string
+var validComplexities = map[string]string{
+	"lower": "abcdefghijklmnopqrstuvwxyz",
+	"upper": "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+	"digit": "0123456789",
+	"spec":  `][ !"#$%&'()*+,./:;<=>?@\^_{|}~` + "`-",
+}
+
+// NewComplexity for preparation
+func NewComplexity() {
+	matchComplexityOnce.Do(func() {
+		if len(setting.PasswordComplexity) > 0 {
+			for key, val := range setting.PasswordComplexity {
+				matchComplexity := regexp.MustCompile(val)
+				matchComplexities[key] = *matchComplexity
+				validChars += validComplexities[key]
+			}
+		} else {
+			for _, val := range validComplexities {
+				validChars += val
+			}
+		}
+	})
+}
+
+// IsComplexEnough return True if password is Complexity
+func IsComplexEnough(pwd string) bool {
+	if len(setting.PasswordComplexity) > 0 {
+		NewComplexity()
+		for _, val := range matchComplexities {
+			if !val.MatchString(pwd) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Generate  a random password
+func Generate(n int) (string, error) {
+	NewComplexity()
+	buffer := make([]byte, n)
+	max := big.NewInt(int64(len(validChars)))
+	for {
+		for j := 0; j < n; j++ {
+			rnd, err := rand.Int(rand.Reader, max)
+			if err != nil {
+				return "", err
+			}
+			buffer[j] = validChars[rnd.Int64()]
+		}
+		if IsComplexEnough(string(buffer)) && string(buffer[0]) != " " && string(buffer[n-1]) != " " {
+			return string(buffer), nil
+		}
+	}
+}