From 932bc981b5b2f3ca3e68a07084d5c39213878292 Mon Sep 17 00:00:00 2001
From: Pierre-Olivier Mercier <nemunaire@nemunai.re>
Date: Fri, 24 Oct 2025 16:12:19 +0700
Subject: [PATCH] Filter Authentication-Results to keep only local ones

---
 pkg/analyzer/authentication_dkim_test.go |  2 ++
 pkg/analyzer/parser.go                   | 28 +++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/pkg/analyzer/authentication_dkim_test.go b/pkg/analyzer/authentication_dkim_test.go
index 0d00031..323e421 100644
--- a/pkg/analyzer/authentication_dkim_test.go
+++ b/pkg/analyzer/authentication_dkim_test.go
@@ -270,6 +270,8 @@ func TestParseLegacyDKIM(t *testing.T) {
 }
 
 func TestParseLegacyDKIM_Integration(t *testing.T) {
+	hostname = ""
+
 	// Test that parseLegacyDKIM is properly integrated into AnalyzeAuthentication
 	t.Run("Legacy DKIM is used when no Authentication-Results", func(t *testing.T) {
 		analyzer := NewAuthenticationAnalyzer()
diff --git a/pkg/analyzer/parser.go b/pkg/analyzer/parser.go
index 13c012c..ca3cb46 100644
--- a/pkg/analyzer/parser.go
+++ b/pkg/analyzer/parser.go
@@ -28,9 +28,16 @@ import (
 	"mime/multipart"
 	"net/mail"
 	"net/textproto"
+	"os"
 	"strings"
 )
 
+var hostname = ""
+
+func init() {
+	hostname, _ = os.Hostname()
+}
+
 // EmailMessage represents a parsed email message
 type EmailMessage struct {
 	Header     mail.Header
@@ -211,8 +218,27 @@ func buildRawHeaders(header mail.Header) string {
 }
 
 // GetAuthenticationResults extracts Authentication-Results headers
+// If hostname is provided, only returns headers that begin with that hostname
 func (e *EmailMessage) GetAuthenticationResults() []string {
-	return e.Header[textproto.CanonicalMIMEHeaderKey("Authentication-Results")]
+	allResults := e.Header[textproto.CanonicalMIMEHeaderKey("Authentication-Results")]
+
+	// If no hostname specified, return all results
+	if hostname == "" {
+		return allResults
+	}
+
+	// Filter results that begin with the specified hostname
+	var filtered []string
+	prefix := hostname + ";"
+	for _, result := range allResults {
+		// Trim whitespace and check if it starts with hostname;
+		trimmed := strings.TrimSpace(result)
+		if strings.HasPrefix(trimmed, prefix) {
+			filtered = append(filtered, result)
+		}
+	}
+
+	return filtered
 }
 
 // GetSpamAssassinHeaders extracts SpamAssassin-related headers