Add PAM authentication

modules/auth/pam/pam.go

@@ -0,0 +1,35 @@
+// +build !windows
+
+// Copyright 2014 The Gogs 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 pam
+
+import (
+	"errors"
+
+	"github.com/msteinert/pam"
+)
+
+func PAMAuth(serviceName, userName, passwd string) error {
+	t, err := pam.StartFunc(serviceName, userName, func(s pam.Style, msg string) (string, error) {
+		switch s {
+		case pam.PromptEchoOff:
+			return passwd, nil
+		case pam.PromptEchoOn, pam.ErrorMsg, pam.TextInfo:
+			return "", nil
+		}
+		return "", errors.New("Unrecognized PAM message style")
+	})
+
+	if err != nil {
+		return err
+	}
+
+	if err = t.Authenticate(0); err != nil {
+		return err
+	}
+
+	return nil
+}