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mirror of https://github.com/wader/fq.git synced 2024-11-24 11:16:09 +03:00
fq/format/pcap/shared.go
Mattias Wadman 7c5215347d bitio,decode: Refactor bitio usage and make buffer slicing more correct
Remove bitio.Buffer layer. bitio.Buffer was a kitchen sink layer with helpers
now it's just a buffer and most functions have been moved to decode instead.

bitio package now only have primitive types and functions simialar to standard
library io and bytes packages.

Make nearly eveything internally use bitio.Bit* interfaces so that slicing work
correctly this will also make it possible to start experimenting with more
complicated silcing helpers, ex things like:
breplace(.header.bitrate; 123) to get a new buffer with bitrate changed.
2022-02-04 21:41:53 +01:00

87 lines
2.6 KiB
Go

package pcap
import (
"fmt"
"github.com/wader/fq/format"
"github.com/wader/fq/format/inet/flowsdecoder"
"github.com/wader/fq/pkg/bitio"
"github.com/wader/fq/pkg/decode"
)
var linkToDecodeFn = map[int]func(fd *flowsdecoder.Decoder, bs []byte) error{
format.LinkTypeNULL: (*flowsdecoder.Decoder).LoopbackFrame,
format.LinkTypeETHERNET: (*flowsdecoder.Decoder).EthernetFrame,
format.LinkTypeLINUX_SLL: (*flowsdecoder.Decoder).SLLPacket,
format.LinkTypeLINUX_SLL2: func(fd *flowsdecoder.Decoder, bs []byte) error {
if len(bs) < 20 {
// TODO: too short sll packet, error somehow?
return fmt.Errorf("packet too short %d", len(bs))
}
// TODO: gopacket does not support SLL2 atm so convert SLL to SSL2
nbs := []byte{
0, bs[10], // packet type
bs[8], bs[9], // arphdr
0, bs[11], // link layer address length
bs[12], bs[13], bs[14], bs[15], bs[16], bs[17], bs[18], bs[19], // link layer address
bs[0], bs[1], // protocol type
}
nbs = append(nbs, bs[20:]...)
return fd.SLLPacket(nbs)
},
}
func fieldFlows(d *decode.D, fd *flowsdecoder.Decoder, tcpStreamFormat decode.Group, ipv4PacketFormat decode.Group) {
d.FieldArray("ipv4_reassembled", func(d *decode.D) {
for _, p := range fd.IPV4Reassembled {
br := bitio.NewBitReader(p.Datagram, -1)
if dv, _, _ := d.TryFieldFormatBitBuf(
"ipv4_packet",
br,
ipv4PacketFormat,
nil,
); dv == nil {
d.FieldRootBitBuf("ipv4_packet", br)
}
}
})
d.FieldArray("tcp_connections", func(d *decode.D) {
for _, s := range fd.TCPConnections {
d.FieldStruct("flow", func(d *decode.D) {
d.FieldValueStr("source_ip", s.ClientEndpoint.IP.String())
d.FieldValueU("source_port", uint64(s.ClientEndpoint.Port), format.TCPPortMap)
d.FieldValueStr("destination_ip", s.ServerEndpoint.IP.String())
d.FieldValueU("destination_port", uint64(s.ServerEndpoint.Port), format.TCPPortMap)
csBR := bitio.NewBitReader(s.ClientToServer.Bytes(), -1)
if dv, _, _ := d.TryFieldFormatBitBuf(
"client_stream",
csBR,
tcpStreamFormat,
format.TCPStreamIn{
SourcePort: s.ClientEndpoint.Port,
DestinationPort: s.ServerEndpoint.Port,
},
); dv == nil {
d.FieldRootBitBuf("client_stream", csBR)
}
scBR := bitio.NewBitReader(s.ServerToClient.Bytes(), -1)
if dv, _, _ := d.TryFieldFormatBitBuf(
"server_stream",
scBR,
tcpStreamFormat,
format.TCPStreamIn{
SourcePort: s.ClientEndpoint.Port,
DestinationPort: s.ServerEndpoint.Port,
},
); dv == nil {
d.FieldRootBitBuf("server_stream", scBR)
}
})
}
})
}