diff options
Diffstat (limited to 'lib/dns/message_header.go')
| -rw-r--r-- | lib/dns/message_header.go | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/lib/dns/message_header.go b/lib/dns/message_header.go index c3c6f9cb..aa505aec 100644 --- a/lib/dns/message_header.go +++ b/lib/dns/message_header.go @@ -5,6 +5,9 @@ package dns import ( + "errors" + "fmt" + libbytes "git.sr.ht/~shulhan/pakakeh.go/lib/bytes" ) @@ -161,19 +164,31 @@ func (hdr *MessageHeader) pack() []byte { } // unpack the DNS header section. -func (hdr *MessageHeader) unpack(packet []byte) { +func (hdr *MessageHeader) unpack(packet []byte) (err error) { + if len(packet) < sectionHeaderSize { + return errors.New(`header too small`) + } + hdr.Op = OpCode((packet[2] & headerMaskOpCode) >> 3) + if hdr.Op < 0 || hdr.Op > OpCodeStatus { + return fmt.Errorf(`unknown op code=%d`, hdr.Op) + } + hdr.RCode = ResponseCode(headerMaskRCode & packet[3]) + if hdr.RCode < 0 || hdr.RCode > RCodeRefused { + return fmt.Errorf(`unknown response code=%d`, hdr.RCode) + } + hdr.ID = libbytes.ReadUint16(packet, 0) hdr.IsQuery = packet[2]&headerIsResponse != headerIsResponse - hdr.Op = OpCode((packet[2] & headerMaskOpCode) >> 3) hdr.IsAA = packet[2]&headerIsAA == headerIsAA hdr.IsTC = packet[2]&headerIsTC == headerIsTC hdr.IsRD = packet[2]&headerIsRD == headerIsRD hdr.IsRA = packet[3]&headerIsRA == headerIsRA - hdr.RCode = ResponseCode(headerMaskRCode & packet[3]) hdr.QDCount = libbytes.ReadUint16(packet, 4) hdr.ANCount = libbytes.ReadUint16(packet, 6) hdr.NSCount = libbytes.ReadUint16(packet, 8) hdr.ARCount = libbytes.ReadUint16(packet, 10) + + return nil } |