dmarc: implement RFC 7489 org-domain fallback and RFC 9091 PSD DMARC

DMARC lookup now follows the full RFC 7489 §6.6.3 fallback chain: exact
From domain → organizational domain (eTLD+1 via PSL) → public suffix
domain (RFC 9091, only when psd=y is present). DNS errors abort
immediately without triggering fallback; NXDOMAIN and missing v=DMARC1
records do trigger it. The found domain is exposed in the new
DMARCRecord.domain field for reporting purposes.

Also promote getOrganizationalDomain to a package-level function so both
HeaderAnalyzer and DNSAnalyzer can share it, and fix pre-existing
rbl_test.go compilation errors and stale score expectations.

Closes: #98

api/schemas.yaml

@@ -891,6 +891,10 @@ components:
           type: string
           description: DMARC record content
           example: "v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com"
+        domain:
+          type: string
+          description: Domain at which the DMARC record was found (may differ from From domain when organizational domain fallback was used)
+          example: "example.com"
         policy:
           type: string
           enum: [none, quarantine, reject, unknown]

pkg/analyzer/dns_dmarc.go

@@ -24,62 +24,50 @@ package analyzer
 import (
 	"context"
 	"fmt"
+	"net"
 	"regexp"
 	"strings"
 
+	"golang.org/x/net/publicsuffix"
+
 	"git.happydns.org/happyDeliver/internal/model"
 	"git.happydns.org/happyDeliver/internal/utils"
 )
 
-// checkmodel.DMARCRecord looks up and validates DMARC record for a domain
+// lookupDMARCAt queries _dmarc.<domain> and returns the raw DMARC1 TXT record.
-func (d *DNSAnalyzer) checkDMARCRecord(domain string) *model.DMARCRecord {
+// notFound=true means no record exists (NXDOMAIN or empty); false means a real DNS error occurred.
-	// DMARC records are at: _dmarc.domain
+func (d *DNSAnalyzer) lookupDMARCAt(domain string) (record string, notFound bool, err error) {
-	dmarcDomain := fmt.Sprintf("_dmarc.%s", domain)
-
 	ctx, cancel := context.WithTimeout(context.Background(), d.Timeout)
 	defer cancel()
 
-	txtRecords, err := d.resolver.LookupTXT(ctx, dmarcDomain)
+	txtRecords, lookupErr := d.resolver.LookupTXT(ctx, fmt.Sprintf("_dmarc.%s", domain))
-	if err != nil {
+	if lookupErr != nil {
-		return &model.DMARCRecord{
+		if dnsErr, ok := lookupErr.(*net.DNSError); ok && dnsErr.IsNotFound {
-			Valid: false,
+			return "", true, nil
-			Error: utils.PtrTo(fmt.Sprintf("Failed to lookup DMARC record: %v", err)),
 		}
+		return "", false, lookupErr
 	}
 
-	// Find DMARC record (starts with "v=DMARC1")
-	var dmarcRecord string
 	for _, txt := range txtRecords {
 		if strings.HasPrefix(txt, "v=DMARC1") {
-			dmarcRecord = txt
+			return txt, false, nil
-			break
 		}
 	}
+	return "", true, nil
+}
 
-	if dmarcRecord == "" {
+// parseDMARCRecord parses a raw DMARC TXT record into a DMARCRecord model.
+func (d *DNSAnalyzer) parseDMARCRecord(foundDomain, rawRecord string) *model.DMARCRecord {
+	policy := d.extractDMARCPolicy(rawRecord)
+	subdomainPolicy := d.extractDMARCSubdomainPolicy(rawRecord)
+	percentage := d.extractDMARCPercentage(rawRecord)
+	spfAlignment := d.extractDMARCSPFAlignment(rawRecord)
+	dkimAlignment := d.extractDMARCDKIMAlignment(rawRecord)
+
+	if !d.validateDMARC(rawRecord) {
 		return &model.DMARCRecord{
-			Valid: false,
+			Domain:          &foundDomain,
-			Error: utils.PtrTo("No DMARC record found"),
+			Record:          &rawRecord,
-		}
-	}
-
-	// Extract policy
-	policy := d.extractDMARCPolicy(dmarcRecord)
-
-	// Extract subdomain policy
-	subdomainPolicy := d.extractDMARCSubdomainPolicy(dmarcRecord)
-
-	// Extract percentage
-	percentage := d.extractDMARCPercentage(dmarcRecord)
-
-	// Extract alignment modes
-	spfAlignment := d.extractDMARCSPFAlignment(dmarcRecord)
-	dkimAlignment := d.extractDMARCDKIMAlignment(dmarcRecord)
-
-	// Basic validation
-	if !d.validateDMARC(dmarcRecord) {
-		return &model.DMARCRecord{
-			Record:          &dmarcRecord,
 			Policy:          utils.PtrTo(model.DMARCRecordPolicy(policy)),
 			SubdomainPolicy: subdomainPolicy,
 			Percentage:      percentage,
@@ -91,7 +79,8 @@ func (d *DNSAnalyzer) checkDMARCRecord(domain string) *model.DMARCRecord {
 	}
 
 	return &model.DMARCRecord{
-		Record:          &dmarcRecord,
+		Domain:          &foundDomain,
+		Record:          &rawRecord,
 		Policy:          utils.PtrTo(model.DMARCRecordPolicy(policy)),
 		SubdomainPolicy: subdomainPolicy,
 		Percentage:      percentage,
@@ -101,6 +90,55 @@ func (d *DNSAnalyzer) checkDMARCRecord(domain string) *model.DMARCRecord {
 	}
 }
 
+// checkDMARCRecord looks up and validates the DMARC record for a domain.
+// It follows RFC 7489 §6.6.3 fallback to the Organizational Domain and
+// RFC 9091 optional fallback to the Public Suffix Domain (only when psd=y).
+func (d *DNSAnalyzer) checkDMARCRecord(domain string) *model.DMARCRecord {
+	// Step 1: try exact domain (_dmarc.<domain>)
+	raw, notFound, err := d.lookupDMARCAt(domain)
+	if err != nil {
+		return &model.DMARCRecord{
+			Valid:  false,
+			Error:  utils.PtrTo(fmt.Sprintf("Failed to lookup DMARC record: %v", err)),
+		}
+	}
+	if !notFound {
+		return d.parseDMARCRecord(domain, raw)
+	}
+
+	// Step 2: RFC 7489 — fall back to Organizational Domain (eTLD+1)
+	orgDomain := getOrganizationalDomain(domain)
+	if orgDomain != domain {
+		raw, notFound, err = d.lookupDMARCAt(orgDomain)
+		if err != nil {
+			return &model.DMARCRecord{
+				Valid:  false,
+				Error:  utils.PtrTo(fmt.Sprintf("Failed to lookup DMARC record: %v", err)),
+			}
+		}
+		if !notFound {
+			return d.parseDMARCRecord(orgDomain, raw)
+		}
+	}
+
+	// Step 3: RFC 9091 — fall back to Public Suffix Domain when psd=y
+	psd, _ := publicsuffix.PublicSuffix(domain)
+	if psd != "" && psd != orgDomain {
+		raw, notFound, err = d.lookupDMARCAt(psd)
+		if err == nil && !notFound {
+			// Only apply PSD DMARC when the record explicitly opts in with psd=y
+			if strings.Contains(raw, "psd=y") {
+				return d.parseDMARCRecord(psd, raw)
+			}
+		}
+	}
+
+	return &model.DMARCRecord{
+		Valid:  false,
+		Error:  utils.PtrTo("No DMARC record found"),
+	}
+}
+
 // extractDMARCPolicy extracts the policy from a DMARC record
 func (d *DNSAnalyzer) extractDMARCPolicy(record string) string {
 	// Look for p=none, p=quarantine, or p=reject

pkg/analyzer/dns_dmarc_test.go

@@ -22,13 +22,178 @@
 package analyzer
 
 import (
+	"context"
+	"fmt"
+	"net"
 	"testing"
 	"time"
 
-	"git.happydns.org/happyDeliver/internal/model"
 	"git.happydns.org/happyDeliver/internal/utils"
 )
 
+// mockDNSResolver maps domain names to TXT records for testing.
+// An entry with value nil means NXDOMAIN; an error value triggers a DNS error.
+type mockDNSResolver struct {
+	txt map[string][]string
+	err map[string]error
+}
+
+func (m *mockDNSResolver) LookupTXT(_ context.Context, name string) ([]string, error) {
+	if err, ok := m.err[name]; ok {
+		return nil, err
+	}
+	if records, ok := m.txt[name]; ok {
+		return records, nil
+	}
+	return nil, &net.DNSError{Err: "no such host", Name: name, IsNotFound: true}
+}
+
+func (m *mockDNSResolver) LookupMX(_ context.Context, _ string) ([]*net.MX, error) {
+	return nil, nil
+}
+func (m *mockDNSResolver) LookupAddr(_ context.Context, _ string) ([]string, error) {
+	return nil, nil
+}
+func (m *mockDNSResolver) LookupHost(_ context.Context, _ string) ([]string, error) {
+	return nil, nil
+}
+
+func newMockAnalyzer(txt map[string][]string, errMap map[string]error) *DNSAnalyzer {
+	if errMap == nil {
+		errMap = map[string]error{}
+	}
+	return NewDNSAnalyzerWithResolver(5*time.Second, &mockDNSResolver{txt: txt, err: errMap})
+}
+
+func TestCheckDMARCRecordFallback(t *testing.T) {
+	const orgRecord = "v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com"
+	const subRecord = "v=DMARC1; p=reject"
+	const psdRecord = "v=DMARC1; p=none; psd=y"
+
+	tests := []struct {
+		name         string
+		domain       string
+		txt          map[string][]string
+		errMap       map[string]error
+		wantValid    bool
+		wantDomain   *string
+		wantErrSubst string
+	}{
+		{
+			name:   "exact domain has DMARC record — no fallback",
+			domain: "mail.example.com",
+			txt: map[string][]string{
+				"_dmarc.mail.example.com": {subRecord},
+				"_dmarc.example.com":      {orgRecord},
+			},
+			wantValid:  true,
+			wantDomain: utils.PtrTo("mail.example.com"),
+		},
+		{
+			name:   "exact domain NXDOMAIN — falls back to org domain",
+			domain: "mail.example.com",
+			txt: map[string][]string{
+				"_dmarc.example.com": {orgRecord},
+			},
+			wantValid:  true,
+			wantDomain: utils.PtrTo("example.com"),
+		},
+		{
+			name:   "exact domain has no v=DMARC1 TXT — falls back to org domain",
+			domain: "mail.example.com",
+			txt: map[string][]string{
+				"_dmarc.mail.example.com": {"some-other-txt"},
+				"_dmarc.example.com":      {orgRecord},
+			},
+			wantValid:  true,
+			wantDomain: utils.PtrTo("example.com"),
+		},
+		{
+			name:   "both exact and org NXDOMAIN but PSD has psd=y — RFC 9091 fallback",
+			domain: "mail.example.com",
+			txt: map[string][]string{
+				"_dmarc.com": {psdRecord},
+			},
+			wantValid:  true,
+			wantDomain: utils.PtrTo("com"),
+		},
+		{
+			name:   "PSD record exists but no psd=y — no record returned",
+			domain: "mail.example.com",
+			txt: map[string][]string{
+				"_dmarc.com": {"v=DMARC1; p=none"},
+			},
+			wantValid:    false,
+			wantErrSubst: "No DMARC record found",
+		},
+		{
+			name:   "no record at any level",
+			domain: "mail.example.com",
+			txt:    map[string][]string{},
+			wantValid:    false,
+			wantErrSubst: "No DMARC record found",
+		},
+		{
+			name:   "DNS error on exact domain — no fallback, error returned",
+			domain: "mail.example.com",
+			errMap: map[string]error{
+				"_dmarc.mail.example.com": fmt.Errorf("SERVFAIL"),
+			},
+			wantValid:    false,
+			wantErrSubst: "SERVFAIL",
+		},
+		{
+			name:   "domain already at org level — no redundant fallback",
+			domain: "example.com",
+			txt: map[string][]string{
+				"_dmarc.example.com": {orgRecord},
+			},
+			wantValid:  true,
+			wantDomain: utils.PtrTo("example.com"),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			analyzer := newMockAnalyzer(tt.txt, tt.errMap)
+			result := analyzer.checkDMARCRecord(tt.domain)
+
+			if result.Valid != tt.wantValid {
+				t.Errorf("Valid = %v, want %v", result.Valid, tt.wantValid)
+			}
+			if tt.wantDomain != nil {
+				if result.Domain == nil {
+					t.Fatalf("Domain = nil, want %q", *tt.wantDomain)
+				}
+				if *result.Domain != *tt.wantDomain {
+					t.Errorf("Domain = %q, want %q", *result.Domain, *tt.wantDomain)
+				}
+			}
+			if tt.wantErrSubst != "" {
+				if result.Error == nil {
+					t.Fatalf("Error = nil, want substring %q", tt.wantErrSubst)
+				}
+				if !contains(*result.Error, tt.wantErrSubst) {
+					t.Errorf("Error = %q, want substring %q", *result.Error, tt.wantErrSubst)
+				}
+			}
+		})
+	}
+}
+
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && (s == substr || len(s) > 0 && containsStr(s, substr))
+}
+
+func containsStr(s, sub string) bool {
+	for i := 0; i <= len(s)-len(sub); i++ {
+		if s[i:i+len(sub)] == sub {
+			return true
+		}
+	}
+	return false
+}
+
 func TestExtractDMARCPolicy(t *testing.T) {
 	tests := []struct {
 		name           string

pkg/analyzer/headers.go

@@ -388,7 +388,7 @@ func (h *HeaderAnalyzer) analyzeDomainAlignment(email *EmailMessage, authResults
 		if domain != "" {
 			alignment.FromDomain = &domain
 			// Extract organizational domain
-			orgDomain := h.getOrganizationalDomain(domain)
+			orgDomain := getOrganizationalDomain(domain)
 			alignment.FromOrgDomain = &orgDomain
 		}
 	}
@@ -400,7 +400,7 @@ func (h *HeaderAnalyzer) analyzeDomainAlignment(email *EmailMessage, authResults
 		if domain != "" {
 			alignment.ReturnPathDomain = &domain
 			// Extract organizational domain
-			orgDomain := h.getOrganizationalDomain(domain)
+			orgDomain := getOrganizationalDomain(domain)
 			alignment.ReturnPathOrgDomain = &orgDomain
 		}
 	}
@@ -411,7 +411,7 @@ func (h *HeaderAnalyzer) analyzeDomainAlignment(email *EmailMessage, authResults
 		for _, dkim := range *authResults.Dkim {
 			if dkim.Domain != nil && *dkim.Domain != "" {
 				domain := *dkim.Domain
-				orgDomain := h.getOrganizationalDomain(domain)
+				orgDomain := getOrganizationalDomain(domain)
 				dkimDomains = append(dkimDomains, model.DKIMDomainInfo{
 					Domain:    domain,
 					OrgDomain: orgDomain,
@@ -542,7 +542,7 @@ func (h *HeaderAnalyzer) extractDomain(emailAddr string) string {
 // getOrganizationalDomain extracts the organizational domain from a fully qualified domain name
 // using the Public Suffix List (PSL) to correctly handle multi-level TLDs.
 // For example: mail.example.com -> example.com, mail.example.co.uk -> example.co.uk
-func (h *HeaderAnalyzer) getOrganizationalDomain(domain string) string {
+func getOrganizationalDomain(domain string) string {
 	domain = strings.ToLower(strings.TrimSpace(domain))
 
 	// Use golang.org/x/net/publicsuffix to get the eTLD+1 (organizational domain)

pkg/analyzer/rbl_test.go

@@ -293,32 +293,36 @@ func TestGetBlacklistScore(t *testing.T) {
 			results: &DNSListResults{
 				IPsChecked:          []string{"198.51.100.1"},
 				ListedCount:         1,
+				RelevantListedCount: 1,
 			},
-			expectedScore: 84, // 100 - 1*100/6 = 84 (integer division: 100/6=16)
+			expectedScore: 92, // 100 - 1*100/12 = 92 (12 scoring lists = 14 default - 2 informational)
 		},
 		{
 			name: "Listed on 2 RBLs",
 			results: &DNSListResults{
 				IPsChecked:          []string{"198.51.100.1"},
 				ListedCount:         2,
+				RelevantListedCount: 2,
 			},
-			expectedScore: 67, // 100 - 2*100/6 = 67 (integer division: 200/6=33)
+			expectedScore: 84, // 100 - 2*100/12 = 84
 		},
 		{
 			name: "Listed on 3 RBLs",
 			results: &DNSListResults{
 				IPsChecked:          []string{"198.51.100.1"},
 				ListedCount:         3,
+				RelevantListedCount: 3,
 			},
-			expectedScore: 50, // 100 - 3*100/6 = 50 (integer division: 300/6=50)
+			expectedScore: 75, // 100 - 3*100/12 = 75
 		},
 		{
 			name: "Listed on 4+ RBLs",
 			results: &DNSListResults{
 				IPsChecked:          []string{"198.51.100.1"},
 				ListedCount:         4,
+				RelevantListedCount: 4,
 			},
-			expectedScore: 34, // 100 - 4*100/6 = 34 (integer division: 400/6=66)
+			expectedScore: 67, // 100 - 4*100/12 = 67
 		},
 	}
 
@@ -326,7 +330,7 @@ func TestGetBlacklistScore(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			score, _ := checker.CalculateScore(tt.results)
+			score, _ := checker.CalculateScore(tt.results, false)
 			if score != tt.expectedScore {
 				t.Errorf("GetBlacklistScore() = %v, want %v", score, tt.expectedScore)
 			}

web/src/lib/components/DmarcRecordDisplay.svelte

@@ -3,9 +3,15 @@
 
     interface Props {
         dmarcRecord?: DmarcRecord;
+        fromDomain?: string;
     }
 
-    let { dmarcRecord }: Props = $props();
+    let { dmarcRecord, fromDomain }: Props = $props();
+
+    const isFallback = $derived(
+        !!dmarcRecord?.domain && !!fromDomain && dmarcRecord.domain !== fromDomain,
+    );
+    const isPsdFallback = $derived(isFallback && !dmarcRecord?.domain?.includes("."));
 
     // Helper function to determine policy strength
     const policyStrength = (policy: string | undefined): number => {
@@ -52,6 +58,24 @@
                 {/if}
             </div>
 
+            <!-- Fallback domain notice -->
+            {#if isFallback}
+                <div class="mb-3">
+                    <strong>Record found at:</strong>
+                    <code>{dmarcRecord.domain}</code>
+                    <div class="alert alert-info mt-2 mb-0 small">
+                        <i class="bi bi-info-circle me-1"></i>
+                        No DMARC record exists for <code>{fromDomain}</code>. The record above was
+                        inherited from
+                        {#if isPsdFallback}
+                            the Public Suffix Domain <code>{dmarcRecord.domain}</code> per RFC 9091.
+                        {:else}
+                            the organizational domain <code>{dmarcRecord.domain}</code> per RFC 7489.
+                        {/if}
+                    </div>
+                </div>
+            {/if}
+
             <!-- Policy -->
             {#if dmarcRecord.policy}
                 <div class="mb-3">

web/src/lib/components/DnsRecordsCard.svelte

@@ -165,7 +165,10 @@
             {/if}
 
             <!-- DMARC Record -->
-            <DmarcRecordDisplay dmarcRecord={dnsResults.dmarc_record} />
+            <DmarcRecordDisplay
+                dmarcRecord={dnsResults.dmarc_record}
+                fromDomain={dnsResults.from_domain}
+            />
 
             <!-- BIMI Record -->
             <BimiRecordDisplay bimiRecord={dnsResults.bimi_record} />