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|
package gomail
import (
"crypto/tls"
"fmt"
"io"
"net"
"net/smtp"
)
// A Dialer is a dialer to an SMTP server.
type Dialer struct {
// Host represents the host of the SMTP server.
Host string
// Port represents the port of the SMTP server.
Port int
// Auth represents the authentication mechanism used to authenticate to the
// SMTP server.
Auth smtp.Auth
// SSL defines whether an SSL connection is used. It should be false in
// most cases since the authentication mechanism should use the STARTTLS
// extension instead.
SSL bool
// TSLConfig represents the TLS configuration used for the TLS (when the
// STARTTLS extension is used) or SSL connection.
TLSConfig *tls.Config
}
// NewPlainDialer returns a Dialer. The given parameters are used to connect to
// the SMTP server via a PLAIN authentication mechanism.
//
// It fallbacks to the LOGIN mechanism if it is the only mechanism advertised by
// the server.
func NewPlainDialer(host string, port int, username, password string) *Dialer {
return &Dialer{
Host: host,
Port: port,
Auth: &plainAuth{
username: username,
password: password,
host: host,
},
SSL: port == 465,
}
}
// Dial dials and authenticates to an SMTP server. The returned SendCloser
// should be closed when done using it.
func (d *Dialer) Dial() (SendCloser, error) {
c, err := d.dial()
if err != nil {
return nil, err
}
if d.Auth != nil {
if ok, _ := c.Extension("AUTH"); ok {
if err = c.Auth(d.Auth); err != nil {
c.Close()
return nil, err
}
}
}
return &smtpSender{c}, nil
}
func (d *Dialer) dial() (smtpClient, error) {
if d.SSL {
return d.sslDial()
}
return d.starttlsDial()
}
func (d *Dialer) starttlsDial() (smtpClient, error) {
c, err := smtpDial(addr(d.Host, d.Port))
if err != nil {
return nil, err
}
if ok, _ := c.Extension("STARTTLS"); ok {
if err := c.StartTLS(d.tlsConfig()); err != nil {
c.Close()
return nil, err
}
}
return c, nil
}
func (d *Dialer) sslDial() (smtpClient, error) {
conn, err := tlsDial("tcp", addr(d.Host, d.Port), d.tlsConfig())
if err != nil {
return nil, err
}
return newClient(conn, d.Host)
}
func (d *Dialer) tlsConfig() *tls.Config {
if d.TLSConfig == nil {
return &tls.Config{ServerName: d.Host}
}
return d.TLSConfig
}
func addr(host string, port int) string {
return fmt.Sprintf("%s:%d", host, port)
}
// DialAndSend opens a connection to the SMTP server, sends the given emails and
// closes the connection.
func (d *Dialer) DialAndSend(m ...*Message) error {
s, err := d.Dial()
if err != nil {
return err
}
defer s.Close()
return Send(s, m...)
}
type smtpSender struct {
smtpClient
}
func (c *smtpSender) Send(from string, to []string, msg io.WriterTo) error {
if err := c.Mail(from); err != nil {
return err
}
for _, addr := range to {
if err := c.Rcpt(addr); err != nil {
return err
}
}
w, err := c.Data()
if err != nil {
return err
}
if _, err = msg.WriteTo(w); err != nil {
w.Close()
return err
}
return w.Close()
}
func (c *smtpSender) Close() error {
return c.Quit()
}
// Stubbed out for tests.
var (
smtpDial = func(addr string) (smtpClient, error) {
return smtp.Dial(addr)
}
tlsDial = tls.Dial
newClient = func(conn net.Conn, host string) (smtpClient, error) {
return smtp.NewClient(conn, host)
}
)
type smtpClient interface {
Extension(string) (bool, string)
StartTLS(*tls.Config) error
Auth(smtp.Auth) error
Mail(string) error
Rcpt(string) error
Data() (io.WriteCloser, error)
Quit() error
Close() error
}
|
