func (dns *Dns) GapInStream(tcpTuple *common.TcpTuple, dir uint8, nbytes int, private protos.ProtocolData) (priv protos.ProtocolData, drop bool) {
if private == nil {
return private, true
}
conn, ok := private.(*dnsConnectionData)
if !ok {
return private, false
}
stream := conn.Data[dir]
if stream == nil || stream.message == nil {
return private, false
}
decodedData, err := stream.handleTcpRawData()
if err == nil {
dns.messageComplete(conn, tcpTuple, dir, decodedData)
return private, true
}
if dir == tcp.TcpDirectionReverse {
dns.publishResponseError(conn, err)
}
logp.Debug("dns", "%s addresses %s, length %d", err.Error(),
tcpTuple.String(), len(stream.rawData))
logp.Debug("dns", "Dropping the stream %s", tcpTuple.String())
// drop the stream because it is binary Data and it would be unexpected to have a decodable message later
return private, true
}
func (dns *Dns) ReceivedFin(tcpTuple *common.TcpTuple, dir uint8, private protos.ProtocolData) protos.ProtocolData {
if private == nil {
return nil
}
conn, ok := private.(*dnsConnectionData)
if !ok {
return private
}
stream := conn.Data[dir]
if stream == nil || stream.message == nil {
return conn
}
decodedData, err := stream.handleTcpRawData()
if err == nil {
dns.messageComplete(conn, tcpTuple, dir, decodedData)
return conn
}
if dir == tcp.TcpDirectionReverse {
dns.publishResponseError(conn, err)
}
logp.Debug("dns", "%s addresses %s, length %d", err.Error(),
tcpTuple.String(), len(stream.rawData))
return conn
}
func (dns *Dns) GapInStream(tcpTuple *common.TcpTuple, dir uint8, nbytes int, private protos.ProtocolData) (priv protos.ProtocolData, drop bool) {
dnsData, ok := private.(dnsPrivateData)
if !ok {
return private, false
}
stream := dnsData.Data[dir]
if stream == nil || stream.message == nil {
return private, false
}
decodedData, err := decodeDnsData(TransportTcp, stream.data)
// Add Notes if the failed stream is the response
if err != nil {
if dir == tcp.TcpDirectionReverse {
dns.publishDecodeFailureNotes(dnsData)
}
// drop the stream because it is binary and it would be rare to have a decodable message later
logp.Debug("dns", NonDnsCompleteMsg+" addresses %s, length %d",
tcpTuple.String(), len(stream.data))
return private, true
}
// publish and ignore the gap. No case should reach this code though ...
dns.messageComplete(tcpTuple, dir, stream, decodedData)
return private, false
}
func (dns *Dns) ReceivedFin(tcpTuple *common.TcpTuple, dir uint8, private protos.ProtocolData) protos.ProtocolData {
if private == nil {
return private
}
dnsData, ok := private.(dnsPrivateData)
if !ok {
return private
}
if dnsData.Data[dir] == nil {
return dnsData
}
stream := dnsData.Data[dir]
if stream.message != nil {
decodedData, err := decodeDnsData(TransportTcp, stream.data)
if err == nil {
dns.messageComplete(tcpTuple, dir, stream, decodedData)
} else /*Failed decode */ {
if dir == tcp.TcpDirectionReverse {
dns.publishDecodeFailureNotes(dnsData)
stream.PrepareForNewMessage()
}
logp.Debug("dns", NonDnsCompleteMsg+" addresses %s, length %d",
tcpTuple.String(), len(stream.data))
}
}
return dnsData
}
func (dns *Dns) doParse(conn *dnsConnectionData, pkt *protos.Packet, tcpTuple *common.TcpTuple, dir uint8) *dnsConnectionData {
stream := conn.Data[dir]
payload := pkt.Payload
if stream == nil {
stream = newStream(pkt, tcpTuple)
conn.Data[dir] = stream
} else {
if stream.message == nil { // nth message of the same stream
stream.message = &DnsMessage{Ts: pkt.Ts, Tuple: pkt.Tuple}
}
stream.rawData = append(stream.rawData, payload...)
if len(stream.rawData) > tcp.TCP_MAX_DATA_IN_STREAM {
logp.Debug("dns", "Stream data too large, dropping DNS stream")
conn.Data[dir] = nil
return conn
}
}
decodedData, err := stream.handleTcpRawData()
if err != nil {
if err == IncompleteMsg {
logp.Debug("dns", "Waiting for more raw data")
return conn
}
if dir == tcp.TcpDirectionReverse {
dns.publishResponseError(conn, err)
}
logp.Debug("dns", "%s addresses %s, length %d", err.Error(),
tcpTuple.String(), len(stream.rawData))
// This means that malformed requests or responses are being sent...
// TODO: publish the situation also if Request
conn.Data[dir] = nil
return conn
}
dns.messageComplete(conn, tcpTuple, dir, decodedData)
stream.PrepareForNewMessage()
return conn
}
func (dns *Dns) Parse(pkt *protos.Packet, tcpTuple *common.TcpTuple, dir uint8, private protos.ProtocolData) protos.ProtocolData {
defer logp.Recover("DNS ParseTcp")
logp.Debug("dns", "Parsing packet addressed with %s of length %d.",
pkt.Tuple.String(), len(pkt.Payload))
priv := dnsPrivateData{}
if private != nil {
var ok bool
priv, ok = private.(dnsPrivateData)
if !ok {
priv = dnsPrivateData{}
}
}
payload := pkt.Payload
stream := &priv.Data[dir]
if *stream == nil {
*stream = &DnsStream{
tcpTuple: tcpTuple,
data: payload,
message: &DnsMessage{Ts: pkt.Ts, Tuple: pkt.Tuple},
}
if len(payload) <= DecodeOffset {
logp.Debug("dns", EmptyMsg+" addresses %s",
tcpTuple.String())
return priv
}
} else {
(*stream).data = append((*stream).data, payload...)
dataLength := len((*stream).data)
if dataLength > tcp.TCP_MAX_DATA_IN_STREAM {
logp.Debug("dns", "Stream data too large, dropping DNS stream")
return priv
}
if dataLength <= DecodeOffset {
logp.Debug("dns", EmptyMsg+" addresses %s",
tcpTuple.String())
return priv
}
}
data, err := decodeDnsData(TransportTcp, (*stream).data)
if err != nil {
logp.Debug("dns", NonDnsCompleteMsg+" addresses %s, length %d",
tcpTuple.String(), len((*stream).data))
// wait for decoding with the next segment
return priv
}
dns.messageComplete(tcpTuple, dir, *stream, data)
return priv
}
