client creates an SMTP client capable of communicating over a plain or TLS-encrypted connection.
(ctx context.Context, host string, port string)
| 273 | |
| 274 | // client creates an SMTP client capable of communicating over a plain or TLS-encrypted connection. |
| 275 | func (s *SMTPHandler) client(ctx context.Context, host string, port string) (*smtp.Client, error) { |
| 276 | var ( |
| 277 | c *smtp.Client |
| 278 | conn net.Conn |
| 279 | d net.Dialer |
| 280 | err error |
| 281 | ) |
| 282 | |
| 283 | // Outer context has a deadline (see CODER_NOTIFICATIONS_DISPATCH_TIMEOUT). |
| 284 | deadline, ok := ctx.Deadline() |
| 285 | if !ok { |
| 286 | return nil, xerrors.Errorf("context has no deadline") |
| 287 | } |
| 288 | // Align with context deadline. |
| 289 | d.Deadline = deadline |
| 290 | |
| 291 | tlsCfg, err := s.tlsConfig() |
| 292 | if err != nil { |
| 293 | return nil, xerrors.Errorf("build TLS config: %w", err) |
| 294 | } |
| 295 | |
| 296 | smarthost := fmt.Sprintf("%s:%s", host, port) |
| 297 | useTLS := false |
| 298 | |
| 299 | // Use TLS if known TLS port(s) are used or TLS is forced. |
| 300 | if port == "465" || s.cfg.ForceTLS { |
| 301 | useTLS = true |
| 302 | |
| 303 | // STARTTLS is only used on plain connections to upgrade. |
| 304 | if s.cfg.TLS.StartTLS { |
| 305 | s.log.Warn(ctx, "STARTTLS is not allowed on TLS connections; disabling STARTTLS") |
| 306 | s.cfg.TLS.StartTLS = false |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | // Dial a TLS or plain connection to the smarthost. |
| 311 | if useTLS { |
| 312 | conn, err = tls.DialWithDialer(&d, "tcp", smarthost, tlsCfg) |
| 313 | if err != nil { |
| 314 | return nil, xerrors.Errorf("establish TLS connection to server: %w", err) |
| 315 | } |
| 316 | } else { |
| 317 | conn, err = d.DialContext(ctx, "tcp", smarthost) |
| 318 | if err != nil { |
| 319 | return nil, xerrors.Errorf("establish plain connection to server: %w", err) |
| 320 | } |
| 321 | } |
| 322 | |
| 323 | // If the connection is plain, and STARTTLS is configured, try to upgrade the connection. |
| 324 | if s.cfg.TLS.StartTLS { |
| 325 | c, err = smtp.NewClientStartTLS(conn, tlsCfg) |
| 326 | if err != nil { |
| 327 | return nil, xerrors.Errorf("upgrade connection with STARTTLS: %w", err) |
| 328 | } |
| 329 | } else { |
| 330 | c = smtp.NewClient(conn) |
| 331 | |
| 332 | // HELO is performed here and not always because smtp.NewClientStartTLS greets the server already to establish |
no test coverage detected