generated from ironpeakservices/iron-go-project
-
Notifications
You must be signed in to change notification settings - Fork 0
/
main.go
186 lines (155 loc) · 3.69 KB
/
main.go
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
package main
import (
"context"
"fmt"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
"net"
"net/smtp"
"os"
"path/filepath"
"strings"
"time"
)
const (
smtpPort = 25
smtpTLSPort = 465
dnsPort = 53
dnsServer = "1.1.1.1"
)
var (
defaultDialer = &net.Dialer{
Timeout: time.Second * 5,
}
dnsResolver = &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
return defaultDialer.DialContext(ctx, "udp", fmt.Sprintf("%s:%d", dnsServer, dnsPort))
},
}
)
func lookupMX(domain string) (servers []string, err error) {
mxRecords, err := dnsResolver.LookupMX(context.Background(), domain)
if err != nil {
return []string{}, err
}
for _, mx := range mxRecords {
servers = append(servers, mx.Host)
}
return servers, nil
}
func extractDomain(email string) (domain string, err error) {
parts := strings.Split(email, "@")
if len(parts) != 2 {
return "", errors.New("invalid email address")
}
return parts[1], nil
}
func checkMailbox(fromDomain, fromEmail, checkEmail string, servers []string) (err error) {
var smtpClient *smtp.Client
// try to find a valid mx server to use
for _, mx := range servers {
/*
conn, err := tls.DialWithDialer(
defaultDialer, "tcp", fmt.Sprintf("%s:%d", mx, smtpTLSPort),
&tls.Config {
InsecureSkipVerify: true,
ServerName: mx,
},
)
*/
conn, err := defaultDialer.Dial("tcp", fmt.Sprintf("%s:%d", mx, smtpPort))
if err != nil {
log.Debugf("skipping %s: %v", mx, err)
continue
}
smtpClient, err = smtp.NewClient(conn, mx)
if err != nil {
log.Warnf("could not setup smtp client for %s: %v", mx, err)
continue
}
}
// if no mx server was found, error out
if smtpClient == nil {
return errors.New("no working mail servers could be found")
}
defer func() {
_ = smtpClient.Close()
_ = smtpClient.Quit()
}()
err = smtpClient.Hello(fromDomain)
if err != nil {
return errors.Wrap(err, "could not HELO smtp server")
}
err = smtpClient.Mail(fromEmail)
if err != nil {
return errors.Wrap(err, "could not MAIL FROM smtp server")
}
// RCPT TO
id, err := smtpClient.Text.Cmd("RCPT TO:<%s>", checkEmail)
if err != nil {
return errors.Wrap(err, "could not MAIL FROM smtp server")
}
smtpClient.Text.StartResponse(id)
code, _, err := smtpClient.Text.ReadResponse(25)
smtpClient.Text.EndResponse(id)
if code == 554 {
return errors.New("appears our IP is blacklisted")
}
// seems to be invalid email
if code == 550 {
return errors.New("email does not seem to exist (or server blocks detection)")
}
// seems to be valid email
if code == 250 {
return nil
}
log.Warnf("unknown code returned: %d", code)
if err != nil {
return errors.Wrap(err, "smtp response error")
}
return nil
}
func main() {
log.SetLevel(log.DebugLevel)
emails := os.Args[1:]
if len(emails) == 0 {
log.Fatalf("usage: %s email ...", filepath.Base(os.Args[0]))
}
for _, email := range emails {
emailDomain, err := extractDomain(email)
if err != nil {
log.Errorf("could not extract domain: %v", err)
if len(emails) == 1 {
os.Exit(1)
} else {
continue
}
}
mxServers, err := lookupMX(emailDomain)
if err != nil {
log.Errorf("could not retrieve mail server: %v", err)
if len(emails) == 1 {
os.Exit(1)
} else {
continue
}
}
if len(mxServers) == 0 {
log.Infof("no mail servers found for %s", email)
if len(emails) == 1 {
os.Exit(0)
} else {
continue
}
}
if err := checkMailbox("ironpeak.be", "test@ironpeak.be", email, mxServers); err != nil {
log.Infof("seems to be invalid (%s)", err)
if len(emails) == 1 {
os.Exit(1)
}
} else {
log.Infof("seems to be valid")
}
}
}