move SFTPGo package to the internal folder

SFTPGo is a daemon and command line tool, not a library.

The public API are provided by the SDK

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/smtp/smtp.go

@@ -0,0 +1,214 @@
+// Copyright (C) 2019-2022  Nicola Murino
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+// Package smtp provides supports for sending emails
+package smtp
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"html/template"
+	"path/filepath"
+	"time"
+
+	mail "github.com/xhit/go-simple-mail/v2"
+
+	"github.com/drakkan/sftpgo/v2/internal/logger"
+	"github.com/drakkan/sftpgo/v2/internal/util"
+)
+
+const (
+	logSender = "smtp"
+)
+
+// EmailContentType defines the support content types for email body
+type EmailContentType int
+
+// Supported email body content type
+const (
+	EmailContentTypeTextPlain EmailContentType = iota
+	EmailContentTypeTextHTML
+)
+
+const (
+	templateEmailDir             = "email"
+	templateRetentionCheckResult = "retention-check-report.html"
+	templatePasswordReset        = "reset-password.html"
+)
+
+var (
+	smtpServer     *mail.SMTPServer
+	from           string
+	emailTemplates = make(map[string]*template.Template)
+)
+
+// IsEnabled returns true if an SMTP server is configured
+func IsEnabled() bool {
+	return smtpServer != nil
+}
+
+// Config defines the SMTP configuration to use to send emails
+type Config struct {
+	// Location of SMTP email server. Leavy empty to disable email sending capabilities
+	Host string `json:"host" mapstructure:"host"`
+	// Port of SMTP email server
+	Port int `json:"port" mapstructure:"port"`
+	// From address, for example "SFTPGo <sftpgo@example.com>".
+	// Many SMTP servers reject emails without a `From` header so, if not set,
+	// SFTPGo will try to use the username as fallback, this may or may not be appropriate
+	From string `json:"from" mapstructure:"from"`
+	// SMTP username
+	User string `json:"user" mapstructure:"user"`
+	// SMTP password. Leaving both username and password empty the SMTP authentication
+	// will be disabled
+	Password string `json:"password" mapstructure:"password"`
+	// 0 Plain
+	// 1 Login
+	// 2 CRAM-MD5
+	AuthType int `json:"auth_type" mapstructure:"auth_type"`
+	// 0 no encryption
+	// 1 TLS
+	// 2 start TLS
+	Encryption int `json:"encryption" mapstructure:"encryption"`
+	// Domain to use for HELO command, if empty localhost will be used
+	Domain string `json:"domain" mapstructure:"domain"`
+	// Path to the email templates. This can be an absolute path or a path relative to the config dir.
+	// Templates are searched within a subdirectory named "email" in the specified path
+	TemplatesPath string `json:"templates_path" mapstructure:"templates_path"`
+}
+
+// Initialize initialized and validates the SMTP configuration
+func (c *Config) Initialize(configDir string) error {
+	smtpServer = nil
+	if c.Host == "" {
+		logger.Debug(logSender, "", "configuration disabled, email capabilities will not be available")
+		return nil
+	}
+	if c.Port <= 0 || c.Port > 65535 {
+		return fmt.Errorf("smtp: invalid port %v", c.Port)
+	}
+	if c.AuthType < 0 || c.AuthType > 2 {
+		return fmt.Errorf("smtp: invalid auth type %v", c.AuthType)
+	}
+	if c.Encryption < 0 || c.Encryption > 2 {
+		return fmt.Errorf("smtp: invalid encryption %v", c.Encryption)
+	}
+	templatesPath := util.FindSharedDataPath(c.TemplatesPath, configDir)
+	if templatesPath == "" {
+		return fmt.Errorf("smtp: invalid templates path %#v", templatesPath)
+	}
+	loadTemplates(filepath.Join(templatesPath, templateEmailDir))
+	from = c.From
+	smtpServer = mail.NewSMTPClient()
+	smtpServer.Host = c.Host
+	smtpServer.Port = c.Port
+	smtpServer.Username = c.User
+	smtpServer.Password = c.Password
+	smtpServer.Authentication = c.getAuthType()
+	smtpServer.Encryption = c.getEncryption()
+	smtpServer.KeepAlive = false
+	smtpServer.ConnectTimeout = 10 * time.Second
+	smtpServer.SendTimeout = 30 * time.Second
+	if c.Domain != "" {
+		smtpServer.Helo = c.Domain
+	}
+	logger.Debug(logSender, "", "configuration successfully initialized, host: %#v, port: %v, username: %#v, auth: %v, encryption: %v, helo: %#v",
+		smtpServer.Host, smtpServer.Port, smtpServer.Username, smtpServer.Authentication, smtpServer.Encryption, smtpServer.Helo)
+	return nil
+}
+
+func (c *Config) getEncryption() mail.Encryption {
+	switch c.Encryption {
+	case 1:
+		return mail.EncryptionSSLTLS
+	case 2:
+		return mail.EncryptionSTARTTLS
+	default:
+		return mail.EncryptionNone
+	}
+}
+
+func (c *Config) getAuthType() mail.AuthType {
+	if c.User == "" && c.Password == "" {
+		return mail.AuthNone
+	}
+	switch c.AuthType {
+	case 1:
+		return mail.AuthLogin
+	case 2:
+		return mail.AuthCRAMMD5
+	default:
+		return mail.AuthPlain
+	}
+}
+
+func loadTemplates(templatesPath string) {
+	logger.Debug(logSender, "", "loading templates from %#v", templatesPath)
+	retentionCheckPath := filepath.Join(templatesPath, templateRetentionCheckResult)
+	retentionTmpl := util.LoadTemplate(nil, retentionCheckPath)
+
+	passwordResetPath := filepath.Join(templatesPath, templatePasswordReset)
+	pwdResetTmpl := util.LoadTemplate(nil, passwordResetPath)
+
+	emailTemplates[templateRetentionCheckResult] = retentionTmpl
+	emailTemplates[templatePasswordReset] = pwdResetTmpl
+}
+
+// RenderRetentionReportTemplate executes the retention report template
+func RenderRetentionReportTemplate(buf *bytes.Buffer, data any) error {
+	if smtpServer == nil {
+		return errors.New("smtp: not configured")
+	}
+	return emailTemplates[templateRetentionCheckResult].Execute(buf, data)
+}
+
+// RenderPasswordResetTemplate executes the password reset template
+func RenderPasswordResetTemplate(buf *bytes.Buffer, data any) error {
+	if smtpServer == nil {
+		return errors.New("smtp: not configured")
+	}
+	return emailTemplates[templatePasswordReset].Execute(buf, data)
+}
+
+// SendEmail tries to send an email using the specified parameters.
+func SendEmail(to []string, subject, body string, contentType EmailContentType) error {
+	if smtpServer == nil {
+		return errors.New("smtp: not configured")
+	}
+	smtpClient, err := smtpServer.Connect()
+	if err != nil {
+		return fmt.Errorf("smtp: unable to connect: %w", err)
+	}
+
+	email := mail.NewMSG()
+	if from != "" {
+		email.SetFrom(from)
+	} else {
+		email.SetFrom(smtpServer.Username)
+	}
+	email.AddTo(to...).SetSubject(subject)
+	switch contentType {
+	case EmailContentTypeTextPlain:
+		email.SetBody(mail.TextPlain, body)
+	case EmailContentTypeTextHTML:
+		email.SetBody(mail.TextHTML, body)
+	default:
+		return fmt.Errorf("smtp: unsupported body content type %v", contentType)
+	}
+	if email.Error != nil {
+		return fmt.Errorf("smtp: email error: %w", email.Error)
+	}
+	return email.Send(smtpClient)
+}