fix: evaluate regex in the subject of an association triple

triples/extract.go

@@ -236,6 +236,28 @@ func findFirstSubject(db repository.Repository, subject *Node) (*dbt.Entity, err
 		return nil, errors.New("subject cannot be nil")
 	}
 
+	// A regular expression key cannot be expressed as an exact content filter, so
+	// fetch the entities of the subject's type and match them in Go, the same way
+	// regex matching is already handled for the object of a triple.
+	if subject.Regexp != nil {
+		since := subject.Since
+		if since.IsZero() {
+			since = time.Unix(0, 0)
+		}
+
+		ents, err := db.FindEntitiesByType(context.Background(), subject.Type, since, 0)
+		if err != nil {
+			return nil, fmt.Errorf("failed to find the subject in the database: %v", err)
+		}
+
+		for _, ent := range ents {
+			if valueMatch(ent.Asset.Key(), subject.Key, subject.Regexp) {
+				return ent, nil
+			}
+		}
+		return nil, errors.New("failed to find a subject matching the regular expression")
+	}
+
 	filter, err := subjectToAsset(subject)
 	if err != nil {
 		return nil, fmt.Errorf("failed to convert subject to asset: %v", err)

triples/extract_test.go

@@ -10,6 +10,7 @@ import (
 	"net/netip"
 	"os"
 	"path/filepath"
+	"regexp"
 	"testing"
 	"time"
 
@@ -406,3 +407,32 @@ func teardownTempSQLite(repo *sqlite3.SqliteRepository, dir string) {
 	}
 	_ = os.RemoveAll(dir)
 }
+
+func TestFindFirstSubjectRegex(t *testing.T) {
+	db, dir, err := setupTempSQLite()
+	assert.NoError(t, err, "Failed to create the sqlite database")
+	assert.NotNil(t, db, "Asset database should not be nil")
+	defer teardownTempSQLite(db, dir)
+
+	ctx := context.Background()
+	match := "192.168.1.2"
+	other := "10.0.0.5"
+
+	_, err = db.CreateAsset(ctx, &oamnet.IPAddress{Address: netip.MustParseAddr(match), Type: "IPv4"})
+	assert.NoError(t, err, "Failed to create the matching IP address asset")
+	_, err = db.CreateAsset(ctx, &oamnet.IPAddress{Address: netip.MustParseAddr(other), Type: "IPv4"})
+	assert.NoError(t, err, "Failed to create the non-matching IP address asset")
+
+	// A regex in the subject position must be evaluated against stored entities,
+	// not passed through as a literal key.
+	entity, err := findFirstSubject(db, &Node{
+		Type:   oam.IPAddress,
+		Key:    `#/^192\./#`,
+		Regexp: regexp.MustCompile(`^192\.`),
+	})
+	assert.NoError(t, err, "A regex subject should match a stored entity")
+	assert.NotNil(t, entity, "Entity should not be nil for a matching regex subject")
+	if entity != nil {
+		assert.Equal(t, match, entity.Asset.Key(), "Should return the entity matching the regex")
+	}
+}