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Refactor error handling in SMTP authentication

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Centralized error definitions in `smtp/auth.go` and updated references in `auth_login.go` and `auth_plain.go`. This improves code maintainability and error consistency across the package.
This commit is contained in:
Winni Neessen 2024-10-02 18:02:23 +02:00
parent a41639ec07
commit 580981b158
Signed by: wneessen
GPG key ID: 385AC9889632126E
3 changed files with 18 additions and 13 deletions
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13
smtp/auth.go
View file

@ -13,6 +13,19 @@
package smtp
import "errors"
var (
// ErrUnencrypted is an error indicating that the connection is not encrypted.
ErrUnencrypted = errors.New("unencrypted connection")
// ErrUnexpectedServerChallange is an error indicating that the server issued an unexpected challenge.
ErrUnexpectedServerChallange = errors.New("unexpected server challenge")
// ErrUnexpectedServerResponse is an error indicating that the server issued an unexpected response.
ErrUnexpectedServerResponse = errors.New("unexpected server response")
// ErrWrongHostname is an error indicating that the provided hostname does not match the expected value.
ErrWrongHostname = errors.New("wrong host name")
)
// Auth is implemented by an SMTP authentication mechanism.
type Auth interface {
// Start begins an authentication with a server.

8
smtp/auth_login.go
View file

@ -5,13 +5,9 @@
package smtp
import (
"errors"
"fmt"
)
// ErrUnencrypted is an error indicating that the connection is not encrypted.
var ErrUnencrypted = errors.New("unencrypted connection")
// loginAuth is the type that satisfies the Auth interface for the "SMTP LOGIN" auth
type loginAuth struct {
username, password string
@ -55,7 +51,7 @@ func (a *loginAuth) Start(server *ServerInfo) (string, []byte, error) {
return "", nil, ErrUnencrypted
}
if server.Name != a.host {
return "", nil, errors.New("wrong host name")
return "", nil, ErrWrongHostname
}
a.respStep = 0
return "LOGIN", nil, nil
@ -73,7 +69,7 @@ func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
a.respStep++
return []byte(a.password), nil
default:
return nil, fmt.Errorf("unexpected server response: %s", string(fromServer))
return nil, fmt.Errorf("%w: %s", ErrUnexpectedServerResponse, string(fromServer))
}
}
return nil, nil

10
smtp/auth_plain.go
View file

@ -13,10 +13,6 @@
package smtp
import (
"errors"
)
// plainAuth is the type that satisfies the Auth interface for the "SMTP PLAIN" auth
type plainAuth struct {
identity, username, password string
@ -42,10 +38,10 @@ func (a *plainAuth) Start(server *ServerInfo) (string, []byte, error) {
// That might just be the attacker saying
// "it's ok, you can trust me with your password."
if !server.TLS && !isLocalhost(server.Name) {
return "", nil, errors.New("unencrypted connection")
return "", nil, ErrUnencrypted
}
if server.Name != a.host {
return "", nil, errors.New("wrong host name")
return "", nil, ErrWrongHostname
}
resp := []byte(a.identity + "\x00" + a.username + "\x00" + a.password)
return "PLAIN", resp, nil
@ -54,7 +50,7 @@ func (a *plainAuth) Start(server *ServerInfo) (string, []byte, error) {
func (a *plainAuth) Next(_ []byte, more bool) ([]byte, error) {
if more {
// We've already sent everything.
return nil, errors.New("unexpected server challenge")
return nil, ErrUnexpectedServerChallange
}
return nil, nil
}