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// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package smtp
import (
"crypto/tls"
"errors"
"fmt"
"net"
"net/smtp"
"os"
"strconv"
)
// _________ __________________________
// / _____/ / \__ ___/\______ \
// \_____ \ / \ / \| | | ___/
// / \/ Y \ | | |
// /_______ /\____|__ /____| |____|
// \/ \/
type loginAuthenticator struct {
username, password string
}
func (auth *loginAuthenticator) Start(server *smtp.ServerInfo) (string, []byte, error) {
return "LOGIN", []byte(auth.username), nil
}
func (auth *loginAuthenticator) Next(fromServer []byte, more bool) ([]byte, error) {
if more {
switch string(fromServer) {
case "Username:":
return []byte(auth.username), nil
case "Password:":
return []byte(auth.password), nil
}
}
return nil, nil
}
// SMTP authentication type names.
const (
PlainAuthentication = "PLAIN"
LoginAuthentication = "LOGIN"
CRAMMD5Authentication = "CRAM-MD5"
)
// Authenticators contains available SMTP authentication type names.
var Authenticators = []string{PlainAuthentication, LoginAuthentication, CRAMMD5Authentication}
// ErrUnsupportedLoginType login source is unknown error
var ErrUnsupportedLoginType = errors.New("Login source is unknown")
// Authenticate performs an SMTP authentication.
func Authenticate(a smtp.Auth, source *Source) error {
tlsConfig := &tls.Config{
InsecureSkipVerify: source.SkipVerify,
ServerName: source.Host,
}
conn, err := net.Dial("tcp", net.JoinHostPort(source.Host, strconv.Itoa(source.Port)))
if err != nil {
return err
}
defer conn.Close()
if source.UseTLS() {
conn = tls.Client(conn, tlsConfig)
}
client, err := smtp.NewClient(conn, source.Host)
if err != nil {
return fmt.Errorf("failed to create NewClient: %w", err)
}
defer client.Close()
if !source.DisableHelo {
hostname := source.HeloHostname
if len(hostname) == 0 {
hostname, err = os.Hostname()
if err != nil {
return fmt.Errorf("failed to find Hostname: %w", err)
}
}
if err = client.Hello(hostname); err != nil {
return fmt.Errorf("failed to send Helo: %w", err)
}
}
// If not using SMTPS, always use STARTTLS if available
hasStartTLS, _ := client.Extension("STARTTLS")
if !source.UseTLS() && hasStartTLS {
if err = client.StartTLS(tlsConfig); err != nil {
return fmt.Errorf("failed to start StartTLS: %w", err)
}
}
if ok, _ := client.Extension("AUTH"); ok {
return client.Auth(a)
}
return ErrUnsupportedLoginType
}
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