1 files changed, 157 insertions, 0 deletions
diff --git a/database/dns.go b/database/dns.go
new file mode 100644
index 0000000..8372936
--- /dev/null
+++ b/database/dns.go
@@ -0,0 +1,157 @@
+package database
+
+import (
+	"database/sql"
+	"strings"
+	"time"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// DNSRecord is a user-owned record in the LAN zone. Names are stored fully
+// qualified with a trailing dot (e.g. "tux.penguins.lan.") to match the form
+// the resolver queries with.
+type DNSRecord struct {
+	ID        string
+	UserID    string
+	Name      string
+	Type      string
+	Content   string
+	TTL       int
+	CreatedAt time.Time
+}
+
+const dnsColumns = "id, user_id, name, type, content, ttl, created_at"
+
+func scanDNSRecord(s interface{ Scan(...any) error }) (*DNSRecord, error) {
+	var r DNSRecord
+	if err := s.Scan(&r.ID, &r.UserID, &r.Name, &r.Type, &r.Content, &r.TTL, &r.CreatedAt); err != nil {
+		return nil, err
+	}
+	return &r, nil
+}
+
+func CountUserDNSRecords(db *sql.DB, userID string) (int, error) {
+	var count int
+	err := db.QueryRow("SELECT COUNT(*) FROM dns_records WHERE user_id = ?", userID).Scan(&count)
+	return count, err
+}
+
+func GetUserDNSRecords(db *sql.DB, userID string) ([]DNSRecord, error) {
+	rows, err := db.Query("SELECT "+dnsColumns+" FROM dns_records WHERE user_id = ? ORDER BY name, type", userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	records := []DNSRecord{}
+	for rows.Next() {
+		r, err := scanDNSRecord(rows)
+		if err != nil {
+			return nil, err
+		}
+		records = append(records, *r)
+	}
+	return records, rows.Err()
+}
+
+// SaveDNSRecord upserts a record. The unique (name, type, content) index means
+// re-saving the same record is a no-op rather than a duplicate.
+func SaveDNSRecord(db *sql.DB, record *DNSRecord) (*DNSRecord, error) {
+	if record.CreatedAt.IsZero() {
+		record.CreatedAt = time.Now()
+	}
+	_, err := db.Exec(
+		"INSERT OR REPLACE INTO dns_records ("+dnsColumns+") VALUES (?, ?, ?, ?, ?, ?, ?)",
+		record.ID, record.UserID, record.Name, record.Type, record.Content, record.TTL, record.CreatedAt,
+	)
+	if err != nil {
+		return nil, err
+	}
+	return record, nil
+}
+
+func GetDNSRecord(db *sql.DB, recordID string) (*DNSRecord, error) {
+	r, err := scanDNSRecord(db.QueryRow("SELECT "+dnsColumns+" FROM dns_records WHERE id = ?", recordID))
+	if err == sql.ErrNoRows {
+		return nil, ErrNotFound
+	}
+	return r, err
+}
+
+func DeleteDNSRecord(db *sql.DB, recordID string) error {
+	_, err := db.Exec("DELETE FROM dns_records WHERE id = ?", recordID)
+	return err
+}
+
+// DeleteUserRecordsByNameType removes a user's records at a name of a given
+// type. Used to keep a single CNAME per name (so re-running the wizard or
+// repointing the primary replaces rather than duplicates).
+func DeleteUserRecordsByNameType(db *sql.DB, userID, name, qtype string) error {
+	_, err := db.Exec("DELETE FROM dns_records WHERE user_id = ? AND name = ? AND type = ?", userID, name, qtype)
+	return err
+}
+
+// RenameUserDNSDomain moves a user's records from oldDomain to newDomain (both
+// of the form "<username>.<zone>", no trailing dot) when their handle changes,
+// rewriting the suffix in both record names and contents so their setup keeps
+// working under the new name. Records that don't reference the domain are left
+// alone.
+func RenameUserDNSDomain(db *sql.DB, userID, oldDomain, newDomain string) error {
+	records, err := GetUserDNSRecords(db, userID)
+	if err != nil {
+		return err
+	}
+	for _, rec := range records {
+		newName := rewriteDomainSuffix(rec.Name, oldDomain, newDomain)
+		newContent := rewriteDomainSuffix(rec.Content, oldDomain, newDomain)
+		if newName == rec.Name && newContent == rec.Content {
+			continue
+		}
+		rec.Name, rec.Content = newName, newContent
+		if _, err := SaveDNSRecord(db, &rec); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// rewriteDomainSuffix replaces a trailing oldDomain (the whole string or a
+// dot-separated suffix) with newDomain, preserving any trailing dot. A value
+// that merely contains oldDomain mid-string is left untouched.
+func rewriteDomainSuffix(s, oldDomain, newDomain string) string {
+	hadDot := strings.HasSuffix(s, ".")
+	bare := strings.TrimSuffix(s, ".")
+	switch {
+	case bare == oldDomain:
+		bare = newDomain
+	case strings.HasSuffix(bare, "."+oldDomain):
+		bare = strings.TrimSuffix(bare, "."+oldDomain) + "." + newDomain
+	default:
+		return s
+	}
+	if hadDot {
+		return bare + "."
+	}
+	return bare
+}
+
+// FindDNSRecords returns every record matching a fully-qualified name and type.
+// This is the resolver's lookup path.
+func FindDNSRecords(db *sql.DB, name, qtype string) ([]DNSRecord, error) {
+	rows, err := db.Query("SELECT "+dnsColumns+" FROM dns_records WHERE name = ? AND type = ?", name, qtype)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	records := []DNSRecord{}
+	for rows.Next() {
+		r, err := scanDNSRecord(rows)
+		if err != nil {
+			return nil, err
+		}
+		records = append(records, *r)
+	}
+	return records, rows.Err()
+}