(Feat): Initial Commit

internal/mailer/transport/smtp_login_auth.go

@@ -0,0 +1,50 @@
+package transport
+
+import (
+	"errors"
+	"fmt"
+	"net/smtp"
+)
+
+type loginAuth struct {
+	username []byte
+	password []byte
+	host     string
+}
+
+func LoginAuth(username string, password string, host ...string) smtp.Auth {
+	auth := &loginAuth{
+		username: []byte(username),
+		password: []byte(password),
+		host:     "",
+	}
+
+	if len(host) > 0 {
+		auth.host = host[0]
+	}
+
+	return auth
+}
+
+func (a *loginAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
+	if len(a.host) > 0 && server.Name != a.host {
+		return "", nil, errors.New("wrong host name")
+	}
+
+	return "LOGIN", a.username, nil
+}
+
+func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
+	if more {
+		switch string(fromServer) {
+		case "Username:":
+			return a.username, nil
+		case "Password:":
+			return a.password, nil
+		default:
+			return nil, fmt.Errorf("unknown challenge received from server: %q", fromServer)
+		}
+	}
+
+	return nil, nil
+}