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sender.go
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sender.go
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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information
package post
import (
"context"
"crypto/tls"
"io"
"net"
"net/mail"
"net/smtp"
"github.com/spacemonkeygo/monkit/v3"
"github.com/zeebo/errs"
)
// Address is alias of net/mail.Address.
type Address = mail.Address
var mon = monkit.Package()
// SMTPSender is smtp sender.
type SMTPSender struct {
ServerAddress string
From Address
Auth smtp.Auth
}
// FromAddress implements satellite/mail.SMTPSender.
func (sender *SMTPSender) FromAddress() Address {
return sender.From
}
// SendEmail sends email message to the given recipient.
func (sender *SMTPSender) SendEmail(ctx context.Context, msg *Message) (err error) {
defer mon.Task()(&ctx)(&err)
client, err := smtp.Dial(sender.ServerAddress)
if err != nil {
return err
}
if err = sender.communicate(ctx, client, msg); err != nil {
return errs.Combine(err, client.Close())
}
return nil
}
// communicate sends mail via SMTP using provided client and message.
func (sender *SMTPSender) communicate(ctx context.Context, client *smtp.Client, msg *Message) error {
// suppress error because address should be validated
// before creating SMTPSender
host, _, _ := net.SplitHostPort(sender.ServerAddress)
// send smtp hello or ehlo msg and establish connection over tls
err := client.StartTLS(&tls.Config{ServerName: host})
if err != nil {
return err
}
err = client.Auth(sender.Auth)
if err != nil {
return err
}
err = client.Mail(sender.From.Address)
if err != nil {
return err
}
// add recipients
for _, to := range msg.To {
err = client.Rcpt(to.Address)
if err != nil {
return err
}
}
mess, err := msg.Bytes()
if err != nil {
return err
}
data, err := client.Data()
if err != nil {
return err
}
err = writeData(data, mess)
if err != nil {
return err
}
// send quit msg to stop gracefully
return client.Quit()
}
// writeData ensures that writer will be closed after data is written.
func writeData(writer io.WriteCloser, data []byte) (err error) {
defer func() {
err = errs.Combine(err, writer.Close())
}()
_, err = writer.Write(data)
return
}