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package main
import (
"bytes"
"crypto/tls"
"encoding/json"
"errors"
"fmt"
"io"
"log"
"net"
"net/http"
"net/mail"
"net/smtp"
"net/url"
"os"
"path/filepath"
"strings"
"time"
)
type Mailer struct {
Host string `json:"host"`
Port int `json:"port"`
User string `json:"user"`
Password string `json:"password"`
From string `json:"from"`
StartTLS bool `json:"starttls"`
Insecure bool `json:"insecure"`
API string `json:"api"`
Key string `json:"key"`
Account string `json:"account"`
Token string `json:"token"`
}
var cloudflareAPI = "https://api.cloudflare.com/client/v4"
var mailSlots = make(chan struct{}, 4)
func loadMailer(root string) *Mailer {
b, err := os.ReadFile(filepath.Join(root, "smtp.json"))
if err != nil {
return nil
}
var m Mailer
if json.Unmarshal(b, &m) != nil || (m.Host == "" && m.API == "" && m.Account == "") || m.From == "" {
return nil
}
if m.Port == 0 {
m.Port = 465
}
return &m
}
func (m *Mailer) Send(to, subject, body string) error {
if m == nil {
return errors.New("mail is not configured")
}
if m.Account != "" {
return m.cloudflare(to, subject, body)
}
if m.API != "" {
return m.post(to, subject, body)
}
addr := net.JoinHostPort(m.Host, fmt.Sprint(m.Port))
tlsConfig := &tls.Config{ServerName: m.Host, InsecureSkipVerify: m.Insecure}
var client *smtp.Client
var err error
if m.StartTLS {
client, err = smtp.Dial(addr)
if err == nil {
err = client.StartTLS(tlsConfig)
}
} else if m.Insecure && m.Port != 465 {
client, err = smtp.Dial(addr)
} else {
var conn net.Conn
conn, err = tls.DialWithDialer(&net.Dialer{Timeout: 15 * time.Second}, "tcp", addr, tlsConfig)
if err == nil {
client, err = smtp.NewClient(conn, m.Host)
}
}
if err != nil {
return err
}
defer client.Close()
if m.User != "" {
if err := client.Auth(smtp.PlainAuth("", m.User, m.Password, m.Host)); err != nil {
return err
}
}
if err := client.Mail(m.From); err != nil {
return err
}
if err := client.Rcpt(to); err != nil {
return err
}
w, err := client.Data()
if err != nil {
return err
}
msg := fmt.Sprintf("From: %s\r\nTo: %s\r\nSubject: %s\r\nDate: %s\r\nMessage-ID: <%d.%s>\r\nMIME-Version: 1.0\r\nContent-Type: text/plain; charset=utf-8\r\n\r\n%s\r\n",
m.From, to, headerText(subject), time.Now().Format(time.RFC1123Z), time.Now().UnixNano(), m.domain(), body)
if _, err := w.Write([]byte(msg)); err != nil {
return err
}
if err := w.Close(); err != nil {
return err
}
return client.Quit()
}
func (s *Server) notify(to, subject, body string) {
if to == "" || s.mailer == nil {
return
}
go func() {
mailSlots <- struct{}{}
defer func() { <-mailSlots }()
if err := s.mailer.Send(to, subject, body); err != nil {
log.Printf("mail to %s: %v", to, err)
}
}()
}
func (m *Mailer) domain() string {
from := m.From
if i := strings.LastIndex(from, "<"); i >= 0 {
from = strings.TrimSuffix(from[i+1:], ">")
}
_, d, _ := strings.Cut(from, "@")
return d
}
func (m *Mailer) post(to, subject, body string) error {
payload, _ := json.Marshal(map[string]any{"from": m.From, "to": []string{to}, "subject": headerText(subject), "text": body})
req, err := http.NewRequest("POST", m.API, bytes.NewReader(payload))
if err != nil {
return err
}
req.Header.Set("Authorization", "Bearer "+m.Key)
req.Header.Set("Content-Type", "application/json")
resp, err := (&http.Client{Timeout: 20 * time.Second}).Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode/100 != 2 {
msg, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
return fmt.Errorf("mail api: %s: %s", resp.Status, strings.TrimSpace(string(msg)))
}
return nil
}
func headerText(s string) string {
return strings.Map(func(r rune) rune {
if r < 0x20 || r == 0x7f {
return ' '
}
return r
}, s)
}
func (m *Mailer) cloudflare(to, subject, body string) error {
from := m.From
if addr, err := mail.ParseAddress(from); err == nil {
from = addr.Address
}
payload, _ := json.Marshal(map[string]any{"from": from, "to": to, "subject": headerText(subject), "text": body})
req, err := http.NewRequest("POST", cloudflareAPI+"/accounts/"+url.PathEscape(m.Account)+"/email/sending/send", bytes.NewReader(payload))
if err != nil {
return err
}
req.Header.Set("Authorization", "Bearer "+m.Token)
req.Header.Set("Content-Type", "application/json")
resp, err := (&http.Client{Timeout: 20 * time.Second}).Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
var out struct {
Success bool `json:"success"`
Errors []struct {
Code int `json:"code"`
Message string `json:"message"`
} `json:"errors"`
Result *struct {
Delivered []string `json:"delivered"`
Queued []string `json:"queued"`
Bounced []string `json:"permanent_bounces"`
} `json:"result"`
}
if err := json.NewDecoder(io.LimitReader(resp.Body, 64<<10)).Decode(&out); err != nil {
return fmt.Errorf("cloudflare mail: %s", resp.Status)
}
if !out.Success || out.Result == nil {
var reasons []string
for _, e := range out.Errors {
reasons = append(reasons, fmt.Sprintf("%d %s", e.Code, e.Message))
}
return fmt.Errorf("cloudflare mail: %s: %s", resp.Status, strings.Join(reasons, ", "))
}
for _, list := range [][]string{out.Result.Delivered, out.Result.Queued} {
for _, addr := range list {
if strings.EqualFold(addr, to) {
return nil
}
}
}
return fmt.Errorf("cloudflare mail: %s bounced", to)
}
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