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imap.go
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imap.go
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package main
import (
"errors"
"fmt"
"io"
"log"
"os"
"path/filepath"
imap "github.com/emersion/go-imap"
"github.com/emersion/go-imap/client"
"github.com/emersion/go-message/mail"
)
func fetchIMAPAttachments(cfg *config) error {
log.Printf("[INFO] imap: connecting to server %v", cfg.Input.IMAP.Server)
// connect to server
var c *client.Client
var err error
if cfg.Input.IMAP.Security == "plaintext" {
log.Printf("[WARN] Without encryption your credentials may be stolen. Be careful!")
c, err = client.Dial(cfg.Input.IMAP.Server)
} else if cfg.Input.IMAP.Security == "starttls" {
// go-imap v2 will replace all the following lines with
// c, err = client.DialStartTLS(cfg.Input.IMAP.Server, nil)
// and there will be no need to import "errors"
c, err = client.Dial(cfg.Input.IMAP.Server)
if err == nil {
sstRet, sstErr := c.SupportStartTLS()
if sstErr != nil {
err = sstErr
} else if !sstRet {
err = errors.New("server doesn't support starttls")
} else {
err = c.StartTLS(nil)
}
}
if err != nil {
c.Logout()
}
} else {
c, err = client.DialTLS(cfg.Input.IMAP.Server, nil)
}
if err != nil {
return err
}
log.Printf("[DEBUG] imap: connected")
defer func() {
log.Printf("[DEBUG] imap: logout")
if err := c.Logout(); err != nil {
log.Printf("[ERROR] imap: logout error %v", err)
}
}()
if cfg.Input.IMAP.Debug {
log.Printf("[DEBUG] imap: enable debug")
c.SetDebug(os.Stdout)
}
// login
err = c.Login(cfg.Input.IMAP.Username, cfg.Input.IMAP.Password)
if err != nil {
return err
}
log.Printf("[DEBUG] imap: logged in")
// select mailbox
mbox, err := c.Select(cfg.Input.IMAP.Mailbox, false)
if err != nil {
return err
}
// get all messages
if mbox.Messages == 0 {
return fmt.Errorf("no messages found in mailbox")
}
from := uint32(1)
to := mbox.Messages
log.Printf("[INFO] imap: found %v messages, %v unseen", mbox.Messages, mbox.Unseen)
// set for all messages
seqSet := new(imap.SeqSet)
seqSet.AddRange(from, to)
// set for delete messages
deleteSet := new(imap.SeqSet)
// get the whole message body
section := &imap.BodySectionName{}
items := []imap.FetchItem{section.FetchItem()}
messages := make(chan *imap.Message, 1)
done := make(chan error, 1)
go func() {
done <- c.Fetch(seqSet, items, messages)
}()
downloadCount := 0
deleteCount := 0
for msg := range messages {
if msg == nil {
return fmt.Errorf("server didn't return message")
}
br := msg.GetBody(section)
if br == nil {
return fmt.Errorf("server didn't return message body")
}
isSuccess, err := extractAttachment(br, cfg.Input.Dir)
if err != nil {
log.Printf("[ERROR] imap: %v, skip", err)
continue
}
if isSuccess && cfg.Input.IMAP.Delete {
log.Printf("[DEBUG] imap: add SeqNum %v to delete set", msg.SeqNum)
deleteSet.AddNum(msg.SeqNum)
deleteCount++
}
downloadCount++
}
log.Printf("[DEBUG] imap: %v attachments downloaded", downloadCount)
if err := <-done; err != nil {
return err
}
if cfg.Input.IMAP.Delete && deleteCount > 0 {
log.Printf("[DEBUG] imap: delete emails after fetch")
// first, mark the messages as deleted
delItems := imap.FormatFlagsOp(imap.AddFlags, false)
delFlags := []interface{}{imap.DeletedFlag}
err := c.Store(deleteSet, delItems, delFlags, nil)
if err != nil {
return err
}
// then delete it
if err := c.Expunge(nil); err != nil {
return err
}
}
return nil
}
func extractAttachment(r io.Reader, inputDir string) (bool, error) {
// Create a new mail reader
mr, err := mail.CreateReader(r)
if err != nil {
return false, err
}
// process each message's part
isSuccess := false
for {
p, err := mr.NextPart()
if err == io.EOF {
break
} else if err != nil {
log.Printf("[ERROR] imap: can't read next part: %v, skip", err)
break
}
switch h := p.Header.(type) {
case *mail.AttachmentHeader:
// this is an attachment
filename, err := h.Filename()
if err != nil {
log.Printf("[ERROR] extractAttachment: %v, skip", err)
continue
}
if filename == "" {
log.Printf("[WARN] extractAttachment: found attachment with empty filename, skip")
continue
}
log.Printf("[INFO] extractAttachment: found attachment: %v", filename)
outFile := filepath.Join(inputDir, filename)
log.Printf("[INFO] extractAttachment: save attachment to: %v", outFile)
f, err := os.Create(outFile)
if err != nil {
log.Printf("[ERROR] extractAttachment: %v, skip", err)
continue
}
_, err = io.Copy(f, p.Body)
if err != nil {
log.Printf("[ERROR] extractAttachment: %v, skip", err)
continue
}
err = f.Close()
if err != nil {
log.Printf("[ERROR] extractAttachment: %v, skip", err)
continue
}
isSuccess = true
}
}
return isSuccess, err
}