1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
package gomail
import (
"crypto/tls"
"fmt"
"io"
"net"
"net/smtp"
"strings"
"time"
)
// 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
// Username is the username to use to authenticate to the SMTP server.
Username string
// Password is the password to use to authenticate to the SMTP server.
Password string
// 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
// LocalName is the hostname sent to the SMTP server with the HELO command.
// By default, "localhost" is sent.
LocalName string
}
// NewDialer returns a new SMTP Dialer. The given parameters are used to connect
// to the SMTP server.
func NewDialer(host string, port int, username, password string) *Dialer {
return &Dialer{
Host: host,
Port: port,
Username: username,
Password: password,
SSL: port == 465,
}
}
// NewPlainDialer returns a new SMTP Dialer. The given parameters are used to
// connect to the SMTP server.
//
// Deprecated: Use NewDialer instead.
func NewPlainDialer(host string, port int, username, password string) *Dialer {
return NewDialer(host, port, username, password)
}
// Dial dials and authenticates to an SMTP server. The returned SendCloser
// should be closed when done using it.
func (d *Dialer) Dial() (SendCloser, error) {
conn, err := netDialTimeout("tcp", addr(d.Host, d.Port), 10*time.Second)
if err != nil {
return nil, err
}
if d.SSL {
conn = tlsClient(conn, d.tlsConfig())
}
c, err := smtpNewClient(conn, d.Host)
if err != nil {
return nil, err
}
if d.LocalName != "" {
if err := c.Hello(d.LocalName); err != nil {
return nil, err
}
}
if !d.SSL {
if ok, _ := c.Extension("STARTTLS"); ok {
if err := c.StartTLS(d.tlsConfig()); err != nil {
c.Close()
return nil, err
}
}
}
if d.Auth == nil && d.Username != "" {
if ok, auths := c.Extension("AUTH"); ok {
if strings.Contains(auths, "CRAM-MD5") {
d.Auth = smtp.CRAMMD5Auth(d.Username, d.Password)
} else if strings.Contains(auths, "LOGIN") &&
!strings.Contains(auths, "PLAIN") {
d.Auth = &loginAuth{
username: d.Username,
password: d.Password,
host: d.Host,
}
} else {
d.Auth = smtp.PlainAuth("", d.Username, d.Password, d.Host)
}
}
}
if d.Auth != nil {
if err = c.Auth(d.Auth); err != nil {
c.Close()
return nil, err
}
}
return &smtpSender{c, d}, nil
}
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
d *Dialer
}
func (c *smtpSender) Send(from string, to []string, msg io.WriterTo) error {
if err := c.Mail(from); err != nil {
if err == io.EOF {
// This is probably due to a timeout, so reconnect and try again.
sc, derr := c.d.Dial()
if derr == nil {
if s, ok := sc.(*smtpSender); ok {
*c = *s
return c.Send(from, to, msg)
}
}
}
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 (
netDialTimeout = net.DialTimeout
tlsClient = tls.Client
smtpNewClient = func(conn net.Conn, host string) (smtpClient, error) {
return smtp.NewClient(conn, host)
}
)
type smtpClient interface {
Hello(string) error
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
}
|
