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email-collector/checkmail/checkmail.go

85 lines
1.7 KiB
Go

package checkmail
import (
"errors"
"fmt"
"net"
"net/smtp"
"regexp"
"strings"
"time"
)
type SmtpError struct {
Err error
}
func (e SmtpError) Error() string {
return e.Err.Error()
}
func (e SmtpError) Code() string {
return e.Err.Error()[0:3]
}
func NewSmtpError(err error) SmtpError {
return SmtpError{
Err: err,
}
}
const forceDisconnectAfter = time.Second * 10
var (
ErrBadFormat = errors.New("invalid format")
ErrUnresolvableHost = errors.New("unresolvable host")
//emailRegexp = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
emailRegexp = regexp.MustCompile("^.+?@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
)
func ValidateFormat(email string) error {
if !emailRegexp.MatchString(email) {
return ErrBadFormat
}
return nil
}
func ValidateHost(email string) error {
_, host := split(email)
mx, err := net.LookupMX(host)
if err != nil {
return ErrUnresolvableHost
}
client, err := smtp.Dial(fmt.Sprintf("%s:%d", mx[0].Host, 25))
if err != nil {
return NewSmtpError(err)
}
defer client.Close()
t := time.AfterFunc(forceDisconnectAfter, func() { client.Close() })
defer t.Stop()
err = client.Hello("checkmail.me")
if err != nil {
return NewSmtpError(err)
}
err = client.Mail("lansome-cowboy@gmail.com")
if err != nil {
return NewSmtpError(err)
}
err = client.Rcpt(email)
if err != nil {
return NewSmtpError(err)
}
return nil
}
func split(email string) (account, host string) {
i := strings.LastIndexByte(email, '@')
account = email[:i]
host = email[i+1:]
return
}