GoToSocial/internal/email/common.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package email
import (
"bytes"
"errors"
"fmt"
"net/smtp"
"os"
"path/filepath"
"strings"
"text/template"
"github.com/superseriousbusiness/gotosocial/internal/config"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
)
func (s *sender) sendTemplate(template string, subject string, data any, toAddresses ...string) error {
buf := &bytes.Buffer{}
if err := s.template.ExecuteTemplate(buf, template, data); err != nil {
return err
}
msg, err := assembleMessage(subject, buf.String(), s.from, toAddresses...)
if err != nil {
return err
}
if err := smtp.SendMail(s.hostAddress, s.auth, s.from, toAddresses, msg); err != nil {
return gtserror.SetSMTP(err)
}
return nil
}
func loadTemplates(templateBaseDir string) (*template.Template, error) {
if !filepath.IsAbs(templateBaseDir) {
cwd, err := os.Getwd()
if err != nil {
return nil, fmt.Errorf("error getting current working directory: %s", err)
}
templateBaseDir = filepath.Join(cwd, templateBaseDir)
}
// look for all templates that start with 'email_'
return template.ParseGlob(filepath.Join(templateBaseDir, "email_*"))
}
// assembleMessage assembles a valid email message following:
// - https://datatracker.ietf.org/doc/html/rfc2822
// - https://pkg.go.dev/net/smtp#SendMail
func assembleMessage(mailSubject string, mailBody string, mailFrom string, mailTo ...string) ([]byte, error) {
if strings.ContainsAny(mailSubject, "\r\n") {
return nil, errors.New("email subject must not contain newline characters")
}
if strings.ContainsAny(mailFrom, "\r\n") {
return nil, errors.New("email from address must not contain newline characters")
}
for _, to := range mailTo {
if strings.ContainsAny(to, "\r\n") {
return nil, errors.New("email to address must not contain newline characters")
}
}
// Normalize the message body to use CRLF line endings
const CRLF = "\r\n"
mailBody = strings.ReplaceAll(mailBody, CRLF, "\n")
mailBody = strings.ReplaceAll(mailBody, "\n", CRLF)
msg := bytes.Buffer{}
switch {
case len(mailTo) == 1:
// Address email directly to the one recipient.
msg.WriteString("To: " + mailTo[0] + CRLF)
case config.GetSMTPDiscloseRecipients():
// Simply address To all recipients.
msg.WriteString("To: " + strings.Join(mailTo, ", ") + CRLF)
default:
// Address To anonymous group.
//
// Email will be sent to all recipients but we shouldn't include Bcc header.
//
// From the smtp.SendMail function: 'Sending "Bcc" messages is accomplished by
// including an email address in the to parameter but not including it in the
// msg headers.'
msg.WriteString("To: Undisclosed Recipients:;" + CRLF)
}
msg.WriteString("From: " + mailFrom + CRLF)
msg.WriteString("Subject: " + mailSubject + CRLF)
msg.WriteString("MIME-Version: 1.0" + CRLF)
msg.WriteString("Content-Transfer-Encoding: 8bit" + CRLF)
msg.WriteString("Content-Type: text/plain; charset=\"UTF-8\"" + CRLF)
msg.WriteString(CRLF)
msg.WriteString(mailBody)
msg.WriteString(CRLF)
return msg.Bytes(), nil
}