package hcdns import ( "database/sql" "fmt" "git.hatecomputers.club/hatecomputers/hatecomputers.club/args" "git.hatecomputers.club/hatecomputers/hatecomputers.club/database" "github.com/miekg/dns" "log" ) const MAX_RECURSION = 15 func resolveInternalCNAMEs(dbConn *sql.DB, domain string, qtype uint16, maxDepth int) ([]dns.RR, error) { internalCnames, err := database.FindDNSRecords(dbConn, domain, "CNAME") if err != nil { return nil, err } var answers []dns.RR for _, record := range internalCnames { cname, err := dns.NewRR(fmt.Sprintf("%s %d IN CNAME %s", record.Name, record.TTL, record.Content)) if err != nil { log.Println(err) return nil, err } answers = append(answers, cname) cnameRecursive, err := resolveDNS(dbConn, record.Content, qtype, maxDepth-1) if err != nil { log.Println(err) return nil, err } answers = append(answers, cnameRecursive...) } qtypeName := dns.TypeToString[qtype] if qtypeName == "" { return nil, fmt.Errorf("invalid query type %d", qtype) } typeDnsRecords, err := database.FindDNSRecords(dbConn, domain, qtypeName) if err != nil { return nil, err } for _, record := range typeDnsRecords { answer, err := dns.NewRR(fmt.Sprintf("%s %d IN %s %s", record.Name, record.TTL, qtypeName, record.Content)) if err != nil { return nil, err } answers = append(answers, answer) } return answers, nil } func resolveDNS(dbConn *sql.DB, domain string, qtype uint16, maxDepth int) ([]dns.RR, error) { if maxDepth == 0 { return nil, fmt.Errorf("too much recursion") } answers, err := resolveInternalCNAMEs(dbConn, domain, qtype, maxDepth) if err != nil { return nil, err } return answers, nil } type DnsHandler struct { DnsResolvers []string DbConn *sql.DB } func (h *DnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) { msg := new(dns.Msg) msg.SetReply(r) msg.Authoritative = true for _, question := range r.Question { answers, err := resolveDNS(h.DbConn, question.Name, question.Qtype, MAX_RECURSION) if err != nil { fmt.Println(err) msg.SetRcode(r, dns.RcodeServerFailure) w.WriteMsg(msg) return } msg.Answer = append(msg.Answer, answers...) } if len(msg.Answer) == 0 { msg.SetRcode(r, dns.RcodeNameError) } log.Println(msg.Answer) w.WriteMsg(msg) } func MakeServer(argv *args.Arguments, dbConn *sql.DB) *dns.Server { handler := &DnsHandler{ DbConn: dbConn, } addr := fmt.Sprintf(":%d", argv.DnsPort) return &dns.Server{ Addr: addr, Net: "udp", Handler: handler, UDPSize: 65535, ReusePort: true, } }