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authboss/defaults/smtp_mailer.go
2018-01-29 13:14:55 -08:00

125 lines
2.9 KiB
Go

package defaults
import (
"bytes"
"context"
"fmt"
"math/rand"
"net/smtp"
"strings"
"text/template"
"time"
"github.com/volatiletech/authboss"
)
// NewSMTPMailer creates an SMTP Mailer to send emails with.
func NewSMTPMailer(server string, auth smtp.Auth) *SMTPMailer {
if len(server) == 0 {
panic("SMTP Mailer must be created with a server string.")
}
random := rand.New(rand.NewSource(time.Now().UnixNano()))
return &SMTPMailer{server, auth, random}
}
// SMTPMailer uses smtp to actually send e-mails
type SMTPMailer struct {
Server string
Auth smtp.Auth
rand *rand.Rand
}
// Send an e-mail
func (s SMTPMailer) Send(ctx context.Context, mail authboss.Email) error {
buf := &bytes.Buffer{}
data := struct {
Boundary string
Mail authboss.Email
}{
Boundary: s.boundary(),
Mail: mail,
}
err := emailTmpl.Execute(buf, data)
if err != nil {
return err
}
toSend := bytes.Replace(buf.Bytes(), []byte{'\n'}, []byte{'\r', '\n'}, -1)
return smtp.SendMail(s.Server, s.Auth, mail.From, mail.To, toSend)
}
// boundary makes mime boundaries, these are largely useless strings that just
// need to be the same in the mime structure. We choose from the alphabet below
// and create a random string of length 23
// Example:
// 284fad24nao8f4na284f2n4
func (s SMTPMailer) boundary() string {
const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789"
buf := &bytes.Buffer{}
for i := 0; i < 23; i++ {
buf.WriteByte(alphabet[s.rand.Int()%len(alphabet)])
}
return buf.String()
}
func namedAddress(name, address string) string {
if len(name) == 0 {
return address
}
return fmt.Sprintf("%s <%s>", name, address)
}
func namedAddresses(names, addresses []string) string {
if len(names) == 0 {
return strings.Join(addresses, ", ")
}
buf := &bytes.Buffer{}
first := true
for i, address := range addresses {
if first {
first = false
} else {
buf.WriteString(", ")
}
buf.WriteString(namedAddress(names[i], address))
}
return buf.String()
}
var emailTmpl = template.Must(template.New("email").Funcs(template.FuncMap{
"join": strings.Join,
"namedAddress": namedAddress,
"namedAddresses": namedAddresses,
}).Parse(`To: {{namedAddresses .Mail.ToNames .Mail.To}}{{if .Mail.Cc}}
Cc: {{namedAddresses .Mail.CcNames .Mail.Cc}}{{end}}{{if .Mail.Bcc}}
Bcc: {{namedAddresses .Mail.BccNames .Mail.Bcc}}{{end}}
From: {{namedAddress .Mail.FromName .Mail.From}}
Subject: {{.Mail.Subject}}{{if .Mail.ReplyTo}}
Reply-To: {{namedAddress .Mail.ReplyToName .Mail.ReplyTo}}{{end}}
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="==============={{.Boundary}}=="
Content-Transfer-Encoding: 7bit
--==============={{.Boundary}}==
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
{{.Mail.TextBody}}
--==============={{.Boundary}}==
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 7bit
{{.Mail.HTMLBody}}
--==============={{.Boundary}}==--
`))