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package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"log"
"os"
"sync"
"text/template"
"time"
"github.com/emersion/go-imap"
"github.com/emersion/go-imap/client"
"github.com/emersion/go-sasl"
"github.com/emersion/go-smtp"
)
type Config struct {
FromEmail string `json:"from-email"`
FromName string `json:"from-name"`
Subject string `json:"subject"`
IMAPServer string `json:"imap-server"`
IMAPEmail string `json:"imap-email"`
IMAPPass string `json:"imap-pass"`
SMTPServer string `json:"smtp-server"`
SMTPEmail string `json:"smtp-email"`
SMTPPass string `json:"smtp-pass"`
Message string `json:"message"`
Cooldown string `json:"cooldown"`
IgnoreAlias bool `json:"ignore-alias"`
}
type Email struct {
ToEmail string
FromName string
FromEmail string
Subject string
Date string
Message string
}
type worker struct {
config Config
sender sasl.Client
client *client.Client
idler *idler
mbox *imap.MailboxStatus
seen seen
emlPath string
}
type seen struct {
sync.Mutex
emails map[string]time.Time
cooldown time.Duration
}
type idler struct {
sync.Mutex
client *client.Client
stop chan struct{}
done chan error
waiting bool
idleing bool
}
var (
errIdleTimeout = fmt.Errorf("idle timeout")
errIdleModeHangs = fmt.Errorf("idle mode hangs; waiting to reconnect")
)
func newIdler(c *client.Client) *idler {
return &idler{client: c, done: make(chan error)}
}
func (i *idler) setWaiting(wait bool) {
i.Lock()
i.waiting = wait
i.Unlock()
}
func (i *idler) isWaiting() bool {
i.Lock()
defer i.Unlock()
return i.waiting
}
func (i *idler) isReady() bool {
i.Lock()
defer i.Unlock()
return (!i.waiting && i.client != nil &&
i.client.State() == imap.SelectedState)
}
func (i *idler) setIdleing(v bool) {
i.Lock()
defer i.Unlock()
i.idleing = v
}
func (i *idler) Start() {
switch {
case i.isReady():
i.stop = make(chan struct{})
go func() {
select {
case <-i.stop:
log.Println("Idle debounced...")
i.done <- nil
case <-time.After(10 * time.Millisecond):
i.setIdleing(true)
log.Println("Entered idle mode...")
now := time.Now()
err := i.client.Idle(i.stop,
&client.IdleOptions{
LogoutTimeout: 0,
PollInterval: 0,
})
i.setIdleing(false)
i.done <- err
log.Printf("Elapsed idle time: %v", time.Since(now))
}
}()
case i.isWaiting():
log.Println("Not started: wait for idle to exit...")
default:
log.Println("Not started: client not ready...")
}
}
func (i *idler) Stop() error {
var reterr error
switch {
case i.isReady():
close(i.stop)
select {
case err := <-i.done:
if err == nil {
log.Println("Idle done...")
} else {
log.Printf("Idle done with err: %v", err)
}
reterr = nil
case <-time.After(10 * time.Second):
log.Println("Idle err (timeout); waiting in background...")
i.waitOnIdle()
reterr = errIdleTimeout
}
case i.isWaiting():
log.Println("Not stopped: still idleing/hanging...")
reterr = errIdleModeHangs
default:
log.Println("Not stopped: client not ready...")
reterr = nil
}
return reterr
}
func (i *idler) waitOnIdle() {
i.setWaiting(true)
log.Println("Waiting for idle in background...")
go func() {
err := <-i.done
if err == nil {
log.Println("Idle waited...")
} else {
log.Printf("Idle waited; with err: %v", err)
}
i.setWaiting(false)
i.stop = make(chan struct{})
fmt.Println("restart")
i.Start()
}()
}
func (w *worker) handleUpdate(update *client.MailboxUpdate) {
log.Println("New update, stopping idle...")
defer func() {
w.idler.Start()
}()
if err := w.idler.Stop(); err != nil {
log.Fatal(err)
}
log.Println("Searching for messages...")
criteria := imap.NewSearchCriteria()
criteria.WithoutFlags = []string{imap.SeenFlag}
ids, err := w.client.Search(criteria)
if err != nil {
log.Fatal(err)
}
if len(ids) == 0 {
log.Println("No IDs Found")
return
}
log.Println("IDs found:", ids)
seqset := new(imap.SeqSet)
seqset.AddNum(ids...)
messages := make(chan *imap.Message, 10)
done := make(chan error, 1)
go func() {
done <- w.client.Fetch(seqset, []imap.FetchItem{imap.FetchEnvelope}, messages)
}()
tmpl, err := template.ParseFiles(w.emlPath)
if err != nil {
log.Fatal(err)
}
for msg := range messages {
log.Println("* ", msg.Envelope.From[0].Address(), msg.Envelope.Subject)
if w.config.IgnoreAlias {
foundAddress := false
for _, toEmail := range msg.Envelope.To {
if toEmail.Address() == w.config.FromEmail {
foundAddress = true
}
}
if !foundAddress {
log.Println("Our address absent from 'to' set, skipping...")
continue
}
}
eml := Email{
ToEmail: msg.Envelope.From[0].Address(),
FromEmail: w.config.FromEmail,
FromName: w.config.FromName,
Subject: w.config.Subject,
Date: time.Now().Format(time.RFC1123Z),
Message: w.config.Message,
}
if prevSend, exists := w.seen.emails[eml.ToEmail]; exists {
log.Println("Address exists, checking time...")
diff := time.Now().Sub(prevSend)
if diff < w.seen.cooldown {
log.Println("Address seen too recently, skipping...")
continue
}
}
log.Println("Sending email...")
to := []string{msg.Envelope.From[0].Address()}
buf := new(bytes.Buffer)
err := tmpl.Execute(buf, &eml)
if err != nil {
log.Fatal(err)
}
err = smtp.SendMail(w.config.SMTPServer, w.sender, w.config.SMTPEmail, to, buf)
if err != nil {
log.Fatal(err)
}
log.Println("Adding address to seen map...")
w.seen.Lock()
w.seen.emails[eml.ToEmail] = time.Now()
w.seen.Unlock()
}
log.Println("Marking messages as seen...")
item := imap.FormatFlagsOp(imap.AddFlags, true)
flags := []interface{}{imap.SeenFlag}
err = w.client.Store(seqset, item, flags, nil)
if err != nil {
log.Fatal(err)
}
if err := <-done; err != nil {
log.Fatal(err)
}
}
func main() {
var configPath string
var w worker
var err error
flag.StringVar(&configPath, "conf", "./pigeon.json", "path to JSON configuration")
flag.StringVar(&w.emlPath, "eml", "./message.eml", "path to EML message")
flag.Parse()
conf, err := os.ReadFile(configPath)
if err != nil {
log.Fatal(err)
}
err = json.Unmarshal(conf, &w.config)
if err != nil {
log.Fatal(err)
}
if cd, err := time.ParseDuration(w.config.Cooldown); err != nil {
log.Fatal(err)
} else {
w.seen.cooldown = cd
}
w.seen.emails = make(map[string]time.Time)
log.Println("Connecting to server...")
w.client, err = client.DialTLS(w.config.IMAPServer, nil)
if err != nil {
log.Fatal(err)
}
// w.client.SetDebug(os.Stdout)
defer w.client.Logout()
if err := w.client.Login(w.config.IMAPEmail, w.config.IMAPPass); err != nil {
log.Fatal(err)
}
log.Println("Logged in")
w.idler = newIdler(w.client)
w.mbox, err = w.client.Select("INBOX", false)
if err != nil {
log.Fatal(err)
}
w.sender = sasl.NewPlainClient("", w.config.SMTPEmail, w.config.SMTPPass)
updates := make(chan client.Update, 1)
w.client.Updates = updates
w.idler.Start()
for {
update := <-updates
switch update := update.(type) {
case *client.MailboxUpdate:
log.Println("Mailbox update received, processing...")
w.handleUpdate(update)
}
}
}
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