// syncmail - transfer between maildir directories by SFTP. there are
// things to TWEAK
package main
import (
"encoding/base64"
"fmt"
"io"
"log"
"net"
"os"
"os/signal"
"path/filepath"
"syscall"
"github.com/pkg/sftp"
"golang.org/x/crypto/ssh"
"suah.dev/protect"
)
func keyString(k ssh.PublicKey) string {
return k.Type() + " " + base64.StdEncoding.EncodeToString(k.Marshal()) // e.
}
func hostkey_callback(trustedKey string) ssh.HostKeyCallback {
if trustedKey == "" {
return func(_ string, _ net.Addr, k ssh.PublicKey) error {
return fmt.Errorf("SSH no key verify: %q", keyString(k))
}
}
return func(_ string, _ net.Addr, k ssh.PublicKey) error {
ks := keyString(k)
if trustedKey != ks {
return fmt.Errorf("SSH verify: expect %q got %q", trustedKey, ks)
}
return nil
}
}
func main() {
sigc := make(chan os.Signal, 1)
signal.Notify(sigc, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT)
go func() {
<-sigc
}()
protect.Pledge("cpath inet rpath stdio wpath unveil")
// TWEAK where the remote files are copied to
home, _ := os.UserHomeDir()
tmp_path := filepath.Join(home, "mail/inbox/tmp")
new_path := filepath.Join(home, "mail/inbox/new")
herr := os.Chdir(tmp_path)
if herr != nil {
log.Fatal(herr)
}
sshkey := filepath.Join(home, ".ssh/TWEAK_your_public_key_file_here")
protect.Unveil(sshkey, "r")
protect.Unveil(tmp_path, "cw")
protect.Unveil(new_path, "cw")
protect.UnveilBlock()
key, err := os.ReadFile(sshkey)
if err != nil {
log.Fatalf("unable to read private key: %v", err)
}
signer, err := ssh.ParsePrivateKey(key)
if err != nil {
log.Fatalf("unable to parse private key: %v", err)
}
config := &ssh.ClientConfig{
User: "TWEAK_username",
Auth: []ssh.AuthMethod{
ssh.PublicKeys(signer),
},
HostKeyCallback: hostkey_callback("ssh-ed25519 TWEAK_your_host_key_here"),
}
// NOTE this requires a port, does not assume :22
ssh, err := ssh.Dial("tcp", "TWEAK_hostname_or_ip:22", config)
if err != nil {
log.Fatalf("unable to connect: %v", err)
}
defer ssh.Close()
protect.Pledge("cpath stdio wpath")
sftp, err := sftp.NewClient(ssh)
if err != nil {
log.Fatal(err)
}
defer sftp.Close()
files, err := sftp.ReadDir("mail/inbox/new")
if err != nil {
log.Fatal(err)
}
copied := 0
for _, dirent := range files {
if !dirent.Mode().IsRegular() {
// TWEAK you could log unexpected file types here
continue
}
remote_file := sftp.Join("mail/inbox/new", dirent.Name())
sfh, err := sftp.Open(remote_file)
if err != nil {
log.Fatal(err)
}
defer sfh.Close()
dfh, err := os.OpenFile(dirent.Name(), os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0755)
if err != nil {
log.Fatal(err)
}
defer dfh.Close()
_, cerr := io.Copy(dfh, sfh)
if cerr != nil {
log.Fatal(cerr)
}
derr := dfh.Sync()
if derr != nil {
log.Fatal(derr)
}
rnerr := os.Rename(dirent.Name(), filepath.Join("../new", dirent.Name()))
if rnerr != nil {
// TWEAK you may want to instead keep this file
// around, especially if the files can be large
// and network transfers expensive, but then
// you'd need something to detect the error or
// review for stale files in the "tmp"
// directory, and to manually rename the file
// or whatever
os.Remove(dirent.Name())
log.Fatal(rnerr)
}
rerr := sftp.Remove(remote_file)
if rerr != nil {
log.Fatal(rerr)
}
// TWEAK log what got copied
//log.Println(remote_file)
copied++
}
if copied > 0 {
os.Exit(0)
} else {
os.Exit(2)
}
}
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