Files
yggmail/internal/smtpserver/backend.go
2021-07-09 00:08:26 +01:00

89 lines
2.5 KiB
Go

package smtpserver
import (
"encoding/hex"
"fmt"
"log"
"github.com/emersion/go-smtp"
"github.com/jxskiss/base62"
"github.com/neilalexander/yggmail/internal/config"
"github.com/neilalexander/yggmail/internal/smtpsender"
"github.com/neilalexander/yggmail/internal/storage"
"github.com/neilalexander/yggmail/internal/utils"
)
type BackendMode int
const (
BackendModeInternal BackendMode = iota
BackendModeExternal
)
type Backend struct {
Mode BackendMode
Log *log.Logger
Config *config.Config
Queues *smtpsender.Queues
Storage storage.Storage
}
func (b *Backend) Login(state *smtp.ConnectionState, username, password string) (smtp.Session, error) {
switch b.Mode {
case BackendModeInternal:
// If our username is email-like, then take just the localpart
if pk, err := utils.ParseAddress(username); err == nil {
if !pk.Equal(b.Config.PublicKey) {
return nil, fmt.Errorf("failed to authenticate: wrong domain in username")
}
}
username = base62.EncodeToString(b.Config.PublicKey)
// The connection came from our local listener
if authed, err := b.Storage.ConfigTryPassword(password); err != nil {
b.Log.Printf("Failed to authenticate SMTP user %q due to error: %s", username, err)
return nil, fmt.Errorf("failed to authenticate: %w", err)
} else if !authed {
b.Log.Printf("Failed to authenticate SMTP user %q\n", username)
return nil, smtp.ErrAuthRequired
}
defer b.Log.Printf("Authenticated SMTP user %q\n", username)
return &SessionLocal{
backend: b,
state: state,
}, nil
case BackendModeExternal:
return nil, fmt.Errorf("Not expecting authenticated connection on external backend")
}
return nil, fmt.Errorf("Authenticated login failed")
}
func (b *Backend) AnonymousLogin(state *smtp.ConnectionState) (smtp.Session, error) {
switch b.Mode {
case BackendModeInternal:
return nil, fmt.Errorf("Not expecting anonymous connection on internal backend")
case BackendModeExternal:
// The connection came from our overlay listener, so we should check
// that they are who they claim to be
pks, err := hex.DecodeString(state.RemoteAddr.String())
if err != nil {
return nil, fmt.Errorf("hex.DecodeString: %w", err)
}
remote := base62.EncodeToString(pks)
if state.Hostname != remote {
return nil, fmt.Errorf("You are not who you claim to be")
}
b.Log.Println("Incoming SMTP session from", remote)
return &SessionRemote{
backend: b,
state: state,
public: pks[:],
}, nil
}
return nil, fmt.Errorf("Anonymous login failed")
}