ntfy/server/smtp_sender.go

package server

import (
	_ "embed" // required by go:embed
	"encoding/json"
	"fmt"
	"heckel.io/ntfy/util"
	"mime"
	"net"
	"net/smtp"
	"strings"
	"time"
)

type mailer interface {
	Send(from, to string, m *message) error
}

type smtpSender struct {
	config *Config
}

func (s *smtpSender) Send(senderIP, to string, m *message) error {
	host, _, err := net.SplitHostPort(s.config.SMTPSenderAddr)
	if err != nil {
		return err
	}
	message, err := formatMail(s.config.BaseURL, senderIP, s.config.SMTPSenderFrom, to, m)
	if err != nil {
		return err
	}
	auth := smtp.PlainAuth("", s.config.SMTPSenderUser, s.config.SMTPSenderPass, host)
	return smtp.SendMail(s.config.SMTPSenderAddr, auth, s.config.SMTPSenderFrom, []string{to}, []byte(message))
}

func formatMail(baseURL, senderIP, from, to string, m *message) (string, error) {
	topicURL := baseURL + "/" + m.Topic
	subject := m.Title
	if subject == "" {
		subject = m.Message
	}
	subject = strings.ReplaceAll(strings.ReplaceAll(subject, "\r", ""), "\n", " ")
	message := m.Message
	trailer := ""
	if len(m.Tags) > 0 {
		emojis, tags, err := toEmojis(m.Tags)
		if err != nil {
			return "", err
		}
		if len(emojis) > 0 {
			subject = strings.Join(emojis, " ") + " " + subject
		}
		if len(tags) > 0 {
			trailer = "Tags: " + strings.Join(tags, ", ")
		}
	}
	if m.Priority != 0 && m.Priority != 3 {
		priority, err := util.PriorityString(m.Priority)
		if err != nil {
			return "", err
		}
		if trailer != "" {
			trailer += "\n"
		}
		trailer += fmt.Sprintf("Priority: %s", priority)
	}
	if trailer != "" {
		message += "\n\n" + trailer
	}
	subject = mime.BEncoding.Encode("utf-8", subject)
	body := `From: "{shortTopicURL}" <{from}>
To: {to}
Subject: {subject}
Content-Type: text/plain; charset="utf-8"

{message}

--
This message was sent by {ip} at {time} via {topicURL}`
	body = strings.ReplaceAll(body, "{from}", from)
	body = strings.ReplaceAll(body, "{to}", to)
	body = strings.ReplaceAll(body, "{subject}", subject)
	body = strings.ReplaceAll(body, "{message}", message)
	body = strings.ReplaceAll(body, "{topicURL}", topicURL)
	body = strings.ReplaceAll(body, "{shortTopicURL}", util.ShortTopicURL(topicURL))
	body = strings.ReplaceAll(body, "{time}", time.Unix(m.Time, 0).UTC().Format(time.RFC1123))
	body = strings.ReplaceAll(body, "{ip}", senderIP)
	return body, nil
}

var (
	//go:embed "mailer_emoji.json"
	emojisJSON string
)

type emoji struct {
	Emoji   string   `json:"emoji"`
	Aliases []string `json:"aliases"`
}

func toEmojis(tags []string) (emojisOut []string, tagsOut []string, err error) {
	var emojis []emoji
	if err = json.Unmarshal([]byte(emojisJSON), &emojis); err != nil {
		return nil, nil, err
	}
	tagsOut = make([]string, 0)
	emojisOut = make([]string, 0)
nextTag:
	for _, t := range tags { // TODO Super inefficient; we should just create a .json file with a map
		for _, e := range emojis {
			if util.InStringList(e.Aliases, t) {
				emojisOut = append(emojisOut, e.Emoji)
				continue nextTag
			}
		}
		tagsOut = append(tagsOut, t)
	}
	return
}