143 lines
3.0 KiB
Go
143 lines
3.0 KiB
Go
package server
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import (
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"bytes"
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"errors"
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"github.com/emersion/go-smtp"
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"io"
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"net/mail"
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"strings"
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"sync"
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)
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var (
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errInvalidDomain = errors.New("invalid domain")
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errInvalidAddress = errors.New("invalid address")
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errInvalidTopic = errors.New("invalid topic")
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errTooManyRecipients = errors.New("too many recipients")
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)
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// smtpBackend implements SMTP server methods.
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type smtpBackend struct {
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config *Config
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sub subscriber
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success int64
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failure int64
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mu sync.Mutex
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}
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func newMailBackend(conf *Config, sub subscriber) *smtpBackend {
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return &smtpBackend{
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config: conf,
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sub: sub,
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}
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}
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func (b *smtpBackend) Login(state *smtp.ConnectionState, username, password string) (smtp.Session, error) {
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return &smtpSession{backend: b}, nil
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}
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func (b *smtpBackend) AnonymousLogin(state *smtp.ConnectionState) (smtp.Session, error) {
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return &smtpSession{backend: b}, nil
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}
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func (b *smtpBackend) Counts() (success int64, failure int64) {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.success, b.failure
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}
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// smtpSession is returned after EHLO.
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type smtpSession struct {
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backend *smtpBackend
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topic string
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mu sync.Mutex
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}
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func (s *smtpSession) AuthPlain(username, password string) error {
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return nil
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}
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func (s *smtpSession) Mail(from string, opts smtp.MailOptions) error {
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return nil
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}
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func (s *smtpSession) Rcpt(to string) error {
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return s.withFailCount(func() error {
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conf := s.backend.config
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addressList, err := mail.ParseAddressList(to)
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if err != nil {
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return err
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} else if len(addressList) != 1 {
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return errTooManyRecipients
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}
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to = addressList[0].Address
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if !strings.HasSuffix(to, "@"+conf.SMTPServerDomain) {
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return errInvalidDomain
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}
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to = strings.TrimSuffix(to, "@"+conf.SMTPServerDomain)
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if conf.SMTPServerAddrPrefix != "" {
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if !strings.HasPrefix(to, conf.SMTPServerAddrPrefix) {
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return errInvalidAddress
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}
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to = strings.TrimPrefix(to, conf.SMTPServerAddrPrefix)
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}
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if !topicRegex.MatchString(to) {
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return errInvalidTopic
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}
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s.mu.Lock()
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s.topic = to
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s.mu.Unlock()
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return nil
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})
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}
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func (s *smtpSession) Data(r io.Reader) error {
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return s.withFailCount(func() error {
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b, err := io.ReadAll(r) // Protected by MaxMessageBytes
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if err != nil {
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return err
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}
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msg, err := mail.ReadMessage(bytes.NewReader(b))
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if err != nil {
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return err
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}
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body, err := io.ReadAll(io.LimitReader(msg.Body, int64(s.backend.config.MessageLimit)))
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if err != nil {
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return err
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}
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m := newDefaultMessage(s.topic, string(body))
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subject := msg.Header.Get("Subject")
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if subject != "" {
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m.Title = subject
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}
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if err := s.backend.sub(m); err != nil {
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return err
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}
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s.backend.mu.Lock()
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s.backend.success++
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s.backend.mu.Unlock()
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return nil
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})
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}
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func (s *smtpSession) Reset() {
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s.mu.Lock()
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s.topic = ""
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s.mu.Unlock()
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}
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func (s *smtpSession) Logout() error {
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return nil
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}
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func (s *smtpSession) withFailCount(fn func() error) error {
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err := fn()
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s.backend.mu.Lock()
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defer s.backend.mu.Unlock()
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if err != nil {
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s.backend.failure++
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}
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return err
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}
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