mirror of
https://github.com/wneessen/go-mail.git
synced 2024-11-25 07:00:49 +01:00
Winni Neessen
8fbd94a675
Ensure that the connection is not nil before setting the deadline in the UpdateDeadline method. This prevents a potential runtime panic when attempting to set a deadline on a nil connection.
667 lines
18 KiB
Go
667 lines
18 KiB
Go
// SPDX-FileCopyrightText: Copyright 2010 The Go Authors. All rights reserved.
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// SPDX-FileCopyrightText: Copyright (c) 2022-2023 The go-mail Authors
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//
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// Original net/smtp code from the Go stdlib by the Go Authors.
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// Use of this source code is governed by a BSD-style
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// LICENSE file that can be found in this directory.
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//
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// go-mail specific modifications by the go-mail Authors.
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// Licensed under the MIT License.
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// See [PROJECT ROOT]/LICENSES directory for more information.
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//
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// SPDX-License-Identifier: BSD-3-Clause AND MIT
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// Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321.
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// It also implements the following extensions:
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//
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// 8BITMIME RFC 1652
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// AUTH RFC 2554
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// STARTTLS RFC 3207
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// DSN RFC 1891
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package smtp
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import (
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"crypto/tls"
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"encoding/base64"
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"errors"
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"fmt"
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"io"
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"net"
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"net/textproto"
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"os"
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"strings"
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"sync"
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"time"
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"github.com/wneessen/go-mail/log"
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)
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var (
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// ErrNonTLSConnection is returned when an attempt is made to retrieve TLS state on a non-TLS connection.
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ErrNonTLSConnection = errors.New("connection is not using TLS")
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// ErrNoConnection is returned when attempting to perform an operation that requires an established
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// connection but none exists.
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ErrNoConnection = errors.New("connection is not established")
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)
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// A Client represents a client connection to an SMTP server.
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type Client struct {
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// Text is the textproto.Conn used by the Client. It is exported to allow for clients to add extensions.
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Text *textproto.Conn
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// auth supported auth mechanisms
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auth []string
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// authIsActive indicates that the Client is currently during SMTP authentication
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authIsActive bool
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// keep a reference to the connection so it can be used to create a TLS connection later
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conn net.Conn
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// debug logging is enabled
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debug bool
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// didHello indicates whether we've said HELO/EHLO
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didHello bool
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// dsnmrtype defines the mail return option in case DSN is enabled
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dsnmrtype string
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// dsnrntype defines the recipient notify option in case DSN is enabled
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dsnrntype string
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// ext is a map of supported extensions
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ext map[string]string
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// helloError is the error from the hello
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helloError error
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// isConnected indicates if the Client has an active connection
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isConnected bool
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// logAuthData indicates if the Client should include SMTP authentication data in the logs
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logAuthData bool
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// localName is the name to use in HELO/EHLO
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localName string // the name to use in HELO/EHLO
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// logger will be used for debug logging
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logger log.Logger
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// mutex is used to synchronize access to shared resources, ensuring that only one goroutine can access
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// the resource at a time.
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mutex sync.RWMutex
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// tls indicates whether the Client is using TLS
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tls bool
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// serverName denotes the name of the server to which the application will connect. Used for
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// identification and routing.
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serverName string
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}
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// Dial returns a new [Client] connected to an SMTP server at addr.
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// The addr must include a port, as in "mail.example.com:smtp".
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func Dial(addr string) (*Client, error) {
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conn, err := net.Dial("tcp", addr)
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if err != nil {
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return nil, err
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}
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host, _, _ := net.SplitHostPort(addr)
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return NewClient(conn, host)
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}
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// NewClient returns a new [Client] using an existing connection and host as a
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// server name to be used when authenticating.
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func NewClient(conn net.Conn, host string) (*Client, error) {
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text := textproto.NewConn(conn)
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_, _, err := text.ReadResponse(220)
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if err != nil {
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if cerr := text.Close(); cerr != nil {
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// Since we are being Go <1.20 compatible, we can't combine errorrs and
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// duplicate %w vers are not suppored. Therefore let's ignore this linting
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// error for now
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// nolint:errorlint
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return nil, fmt.Errorf("%w, %s", err, cerr)
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}
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return nil, err
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}
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c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"}
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_, c.tls = conn.(*tls.Conn)
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c.isConnected = true
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return c, nil
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}
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// Close closes the connection.
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func (c *Client) Close() error {
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c.mutex.Lock()
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err := c.Text.Close()
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c.isConnected = false
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c.mutex.Unlock()
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return err
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}
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// hello runs a hello exchange if needed.
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func (c *Client) hello() error {
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if !c.didHello {
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c.didHello = true
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err := c.ehlo()
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if err != nil {
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c.helloError = c.helo()
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}
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}
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return c.helloError
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}
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// Hello sends a HELO or EHLO to the server as the given host name.
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// Calling this method is only necessary if the client needs control
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// over the host name used. The client will introduce itself as "localhost"
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// automatically otherwise. If Hello is called, it must be called before
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// any of the other methods.
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func (c *Client) Hello(localName string) error {
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if err := validateLine(localName); err != nil {
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return err
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}
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if c.didHello {
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return errors.New("smtp: Hello called after other methods")
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}
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c.mutex.Lock()
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c.localName = localName
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c.mutex.Unlock()
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return c.hello()
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}
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// cmd is a convenience function that sends a command and returns the response
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func (c *Client) cmd(expectCode int, format string, args ...interface{}) (int, string, error) {
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c.mutex.Lock()
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var logMsg []interface{}
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logMsg = args
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logFmt := format
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if c.authIsActive {
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logMsg = []interface{}{"<SMTP auth data redacted>"}
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logFmt = "%s"
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}
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c.debugLog(log.DirClientToServer, logFmt, logMsg...)
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id, err := c.Text.Cmd(format, args...)
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if err != nil {
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c.mutex.Unlock()
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return 0, "", err
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}
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c.Text.StartResponse(id)
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code, msg, err := c.Text.ReadResponse(expectCode)
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logMsg = []interface{}{code, msg}
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if c.authIsActive && code >= 300 && code <= 400 {
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logMsg = []interface{}{code, "<SMTP auth data redacted>"}
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}
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c.debugLog(log.DirServerToClient, "%d %s", logMsg...)
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c.Text.EndResponse(id)
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c.mutex.Unlock()
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return code, msg, err
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}
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// helo sends the HELO greeting to the server. It should be used only when the
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// server does not support ehlo.
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func (c *Client) helo() error {
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c.mutex.Lock()
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c.ext = nil
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c.mutex.Unlock()
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_, _, err := c.cmd(250, "HELO %s", c.localName)
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return err
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}
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// StartTLS sends the STARTTLS command and encrypts all further communication.
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// Only servers that advertise the STARTTLS extension support this function.
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func (c *Client) StartTLS(config *tls.Config) error {
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if err := c.hello(); err != nil {
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return err
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}
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_, _, err := c.cmd(220, "STARTTLS")
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if err != nil {
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return err
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}
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c.mutex.Lock()
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c.conn = tls.Client(c.conn, config)
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c.Text = textproto.NewConn(c.conn)
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c.tls = true
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c.mutex.Unlock()
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return c.ehlo()
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}
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// TLSConnectionState returns the client's TLS connection state.
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// The return values are their zero values if [Client.StartTLS] did
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// not succeed.
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func (c *Client) TLSConnectionState() (state tls.ConnectionState, ok bool) {
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c.mutex.RLock()
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defer c.mutex.RUnlock()
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tc, ok := c.conn.(*tls.Conn)
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if !ok {
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return
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}
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state, ok = tc.ConnectionState(), true
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return
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}
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// Verify checks the validity of an email address on the server.
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// If Verify returns nil, the address is valid. A non-nil return
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// does not necessarily indicate an invalid address. Many servers
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// will not verify addresses for security reasons.
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func (c *Client) Verify(addr string) error {
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if err := validateLine(addr); err != nil {
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return err
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}
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if err := c.hello(); err != nil {
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return err
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}
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_, _, err := c.cmd(250, "VRFY %s", addr)
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return err
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}
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// Auth authenticates a client using the provided authentication mechanism.
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// A failed authentication closes the connection.
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// Only servers that advertise the AUTH extension support this function.
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func (c *Client) Auth(a Auth) error {
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if err := c.hello(); err != nil {
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return err
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}
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c.mutex.Lock()
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if !c.logAuthData {
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c.authIsActive = true
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}
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c.mutex.Unlock()
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defer func() {
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c.mutex.Lock()
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if !c.logAuthData {
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c.authIsActive = false
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}
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c.mutex.Unlock()
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}()
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encoding := base64.StdEncoding
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mech, resp, err := a.Start(&ServerInfo{c.serverName, c.tls, c.auth})
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if err != nil {
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if qerr := c.Quit(); qerr != nil {
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// Since we are being Go <1.20 compatible, we can't combine errorrs and
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// duplicate %w vers are not suppored. Therefore let's ignore this linting
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// error for now
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// nolint:errorlint
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return fmt.Errorf("%w, %s", err, qerr)
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}
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return err
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}
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resp64 := make([]byte, encoding.EncodedLen(len(resp)))
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encoding.Encode(resp64, resp)
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code, msg64, err := c.cmd(0, "%s", strings.TrimSpace(fmt.Sprintf("AUTH %s %s", mech,
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resp64)))
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for err == nil {
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var msg []byte
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switch code {
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case 334:
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msg, err = encoding.DecodeString(msg64)
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case 235:
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// the last message isn't base64 because it isn't a challenge
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msg = []byte(msg64)
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default:
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err = &textproto.Error{Code: code, Msg: msg64}
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}
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if err == nil {
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resp, err = a.Next(msg, code == 334)
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}
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if err != nil {
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if mech != "XOAUTH2" {
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// abort the AUTH. Not required for XOAUTH2
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_, _, _ = c.cmd(501, "*")
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}
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_ = c.Quit()
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break
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}
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if resp == nil {
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break
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}
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resp64 = make([]byte, encoding.EncodedLen(len(resp)))
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encoding.Encode(resp64, resp)
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code, msg64, err = c.cmd(0, "%s", resp64)
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}
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return err
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}
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// Mail issues a MAIL command to the server using the provided email address.
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// If the server supports the 8BITMIME extension, Mail adds the BODY=8BITMIME
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// parameter. If the server supports the SMTPUTF8 extension, Mail adds the
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// SMTPUTF8 parameter.
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// This initiates a mail transaction and is followed by one or more [Client.Rcpt] calls.
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func (c *Client) Mail(from string) error {
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if err := validateLine(from); err != nil {
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return err
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}
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if err := c.hello(); err != nil {
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return err
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}
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cmdStr := "MAIL FROM:<%s>"
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c.mutex.RLock()
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if c.ext != nil {
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if _, ok := c.ext["8BITMIME"]; ok {
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cmdStr += " BODY=8BITMIME"
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}
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if _, ok := c.ext["SMTPUTF8"]; ok {
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cmdStr += " SMTPUTF8"
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}
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_, ok := c.ext["DSN"]
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if ok && c.dsnmrtype != "" {
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cmdStr += fmt.Sprintf(" RET=%s", c.dsnmrtype)
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}
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}
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c.mutex.RUnlock()
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_, _, err := c.cmd(250, cmdStr, from)
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return err
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}
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// Rcpt issues a RCPT command to the server using the provided email address.
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// A call to Rcpt must be preceded by a call to [Client.Mail] and may be followed by
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// a [Client.Data] call or another Rcpt call.
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func (c *Client) Rcpt(to string) error {
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if err := validateLine(to); err != nil {
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return err
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}
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c.mutex.RLock()
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_, ok := c.ext["DSN"]
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c.mutex.RUnlock()
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if ok && c.dsnrntype != "" {
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_, _, err := c.cmd(25, "RCPT TO:<%s> NOTIFY=%s", to, c.dsnrntype)
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return err
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}
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_, _, err := c.cmd(25, "RCPT TO:<%s>", to)
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return err
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}
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type dataCloser struct {
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c *Client
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io.WriteCloser
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}
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// Close releases the lock, closes the WriteCloser, waits for a response, and then returns any error encountered.
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func (d *dataCloser) Close() error {
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d.c.mutex.Lock()
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_ = d.WriteCloser.Close()
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_, _, err := d.c.Text.ReadResponse(250)
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d.c.mutex.Unlock()
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return err
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}
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// Write writes data to the underlying WriteCloser while ensuring thread-safety by locking and unlocking a mutex.
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func (d *dataCloser) Write(p []byte) (n int, err error) {
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d.c.mutex.Lock()
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n, err = d.WriteCloser.Write(p)
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d.c.mutex.Unlock()
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return
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}
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// Data issues a DATA command to the server and returns a writer that
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// can be used to write the mail headers and body. The caller should
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// close the writer before calling any more methods on c. A call to
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// Data must be preceded by one or more calls to [Client.Rcpt].
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func (c *Client) Data() (io.WriteCloser, error) {
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_, _, err := c.cmd(354, "DATA")
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if err != nil {
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return nil, err
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}
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datacloser := &dataCloser{}
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c.mutex.Lock()
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datacloser.c = c
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datacloser.WriteCloser = c.Text.DotWriter()
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c.mutex.Unlock()
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return datacloser, nil
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}
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var testHookStartTLS func(*tls.Config) // nil, except for tests
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// SendMail connects to the server at addr, switches to TLS if
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// possible, authenticates with the optional mechanism a if possible,
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// and then sends an email from address from, to addresses to, with
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// message msg.
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// The addr must include a port, as in "mail.example.com:smtp".
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//
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// The addresses in the to parameter are the SMTP RCPT addresses.
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//
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// The msg parameter should be an RFC 822-style email with headers
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// first, a blank line, and then the message body. The lines of msg
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// should be CRLF terminated. The msg headers should usually include
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// fields such as "From", "To", "Subject", and "Cc". Sending "Bcc"
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// messages is accomplished by including an email address in the to
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// parameter but not including it in the msg headers.
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//
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// The SendMail function and the net/smtp package are low-level
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// mechanisms and provide no support for DKIM signing, MIME
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// attachments (see the mime/multipart package), or other mail
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// functionality. Higher-level packages exist outside of the standard
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// library.
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func SendMail(addr string, a Auth, from string, to []string, msg []byte) error {
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if err := validateLine(from); err != nil {
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return err
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}
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for _, recp := range to {
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if err := validateLine(recp); err != nil {
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return err
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}
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}
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c, err := Dial(addr)
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if err != nil {
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return err
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}
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defer func() {
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_ = c.Close()
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}()
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if err = c.hello(); err != nil {
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return err
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}
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if ok, _ := c.Extension("STARTTLS"); ok {
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config := &tls.Config{ServerName: c.serverName}
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if testHookStartTLS != nil {
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testHookStartTLS(config)
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}
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if err = c.StartTLS(config); err != nil {
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return err
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}
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}
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if a != nil && c.ext != nil {
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if _, ok := c.ext["AUTH"]; !ok {
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return errors.New("smtp: server doesn't support AUTH")
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}
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if err = c.Auth(a); err != nil {
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return err
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}
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}
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if err = c.Mail(from); err != nil {
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return err
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}
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for _, addr := range to {
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if err = c.Rcpt(addr); err != nil {
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return err
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}
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}
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w, err := c.Data()
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if err != nil {
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return err
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}
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_, err = w.Write(msg)
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if err != nil {
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return err
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}
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err = w.Close()
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if err != nil {
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return err
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}
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return c.Quit()
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}
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// Extension reports whether an extension is support by the server.
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// The extension name is case-insensitive. If the extension is supported,
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// Extension also returns a string that contains any parameters the
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// server specifies for the extension.
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func (c *Client) Extension(ext string) (bool, string) {
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if err := c.hello(); err != nil {
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return false, ""
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}
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if c.ext == nil {
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return false, ""
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}
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ext = strings.ToUpper(ext)
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c.mutex.RLock()
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param, ok := c.ext[ext]
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c.mutex.RUnlock()
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return ok, param
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}
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// Reset sends the RSET command to the server, aborting the current mail
|
|
// transaction.
|
|
func (c *Client) Reset() error {
|
|
if err := c.hello(); err != nil {
|
|
return err
|
|
}
|
|
_, _, err := c.cmd(250, "RSET")
|
|
return err
|
|
}
|
|
|
|
// Noop sends the NOOP command to the server. It does nothing but check
|
|
// that the connection to the server is okay.
|
|
func (c *Client) Noop() error {
|
|
if err := c.hello(); err != nil {
|
|
return err
|
|
}
|
|
_, _, err := c.cmd(250, "NOOP")
|
|
return err
|
|
}
|
|
|
|
// Quit sends the QUIT command and closes the connection to the server.
|
|
func (c *Client) Quit() error {
|
|
// See https://github.com/golang/go/issues/70011
|
|
_ = c.hello() // ignore error; we're quitting anyhow
|
|
|
|
_, _, err := c.cmd(221, "QUIT")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
c.mutex.Lock()
|
|
err = c.Text.Close()
|
|
c.isConnected = false
|
|
c.mutex.Unlock()
|
|
|
|
return err
|
|
}
|
|
|
|
// SetDebugLog enables the debug logging for incoming and outgoing SMTP messages
|
|
func (c *Client) SetDebugLog(v bool) {
|
|
c.debug = v
|
|
if v {
|
|
if c.logger == nil {
|
|
c.logger = log.New(os.Stderr, log.LevelDebug)
|
|
}
|
|
return
|
|
}
|
|
c.logger = nil
|
|
}
|
|
|
|
// SetLogger overrides the default log.Stdlog for the debug logging with a logger that
|
|
// satisfies the log.Logger interface
|
|
func (c *Client) SetLogger(l log.Logger) {
|
|
if l == nil {
|
|
return
|
|
}
|
|
c.mutex.Lock()
|
|
c.logger = l
|
|
c.mutex.Unlock()
|
|
}
|
|
|
|
// SetLogAuthData enables logging of authentication data in the Client.
|
|
func (c *Client) SetLogAuthData() {
|
|
c.mutex.Lock()
|
|
c.logAuthData = true
|
|
c.mutex.Unlock()
|
|
}
|
|
|
|
// SetDSNMailReturnOption sets the DSN mail return option for the Mail method
|
|
func (c *Client) SetDSNMailReturnOption(d string) {
|
|
c.dsnmrtype = d
|
|
}
|
|
|
|
// SetDSNRcptNotifyOption sets the DSN recipient notify option for the Mail method
|
|
func (c *Client) SetDSNRcptNotifyOption(d string) {
|
|
c.dsnrntype = d
|
|
}
|
|
|
|
// HasConnection checks if the client has an active connection.
|
|
// Returns true if the `conn` field is not nil, indicating an active connection.
|
|
func (c *Client) HasConnection() bool {
|
|
c.mutex.RLock()
|
|
isConn := c.isConnected
|
|
c.mutex.RUnlock()
|
|
return isConn
|
|
}
|
|
|
|
// UpdateDeadline sets a new deadline on the SMTP connection with the specified timeout duration.
|
|
func (c *Client) UpdateDeadline(timeout time.Duration) error {
|
|
c.mutex.Lock()
|
|
defer c.mutex.Unlock()
|
|
if c.conn == nil {
|
|
return errors.New("smtp: client has no connection")
|
|
}
|
|
if err := c.conn.SetDeadline(time.Now().Add(timeout)); err != nil {
|
|
return fmt.Errorf("smtp: failed to update deadline: %w", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// GetTLSConnectionState retrieves the TLS connection state of the client's current connection.
|
|
// Returns an error if the connection is not using TLS or if the connection is not established.
|
|
func (c *Client) GetTLSConnectionState() (*tls.ConnectionState, error) {
|
|
c.mutex.RLock()
|
|
defer c.mutex.RUnlock()
|
|
|
|
if !c.isConnected {
|
|
return nil, ErrNoConnection
|
|
}
|
|
if !c.tls {
|
|
return nil, ErrNonTLSConnection
|
|
}
|
|
if conn, ok := c.conn.(*tls.Conn); ok {
|
|
cstate := conn.ConnectionState()
|
|
return &cstate, nil
|
|
}
|
|
return nil, errors.New("unable to retrieve TLS connection state")
|
|
}
|
|
|
|
// debugLog checks if the debug flag is set and if so logs the provided message to
|
|
// the log.Logger interface
|
|
func (c *Client) debugLog(d log.Direction, f string, a ...interface{}) {
|
|
if c.debug {
|
|
c.logger.Debugf(log.Log{Direction: d, Format: f, Messages: a})
|
|
}
|
|
}
|
|
|
|
// validateLine checks to see if a line has CR or LF as per RFC 5321.
|
|
func validateLine(line string) error {
|
|
if strings.ContainsAny(line, "\n\r") {
|
|
return errors.New("smtp: A line must not contain CR or LF")
|
|
}
|
|
return nil
|
|
}
|