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mirror of https://github.com/wader/fq.git synced 2024-12-24 22:05:31 +03:00
fq/format/inet/ipv4_packet.go
Mattias Wadman 1ddea1ada3 interp,format: Refactor registry usage and use function helpers
Move registry to interp and add support for functions and filesystems.
This will be used later for allow formats to add own functions and fq code.

Add gojqextra function helpers to have more comfortable API to add functions.
Takes care of argument type casting and JQValue:s and some more things.

Refactor interp package to use new function helper and registry. Probably
fixes a bunch of JQValue bugs and other type errors.

Refactor out some mpeg nal things to mpeg format.

Refactor interp jq code into display.q and init.jq.

Remove undocumented aes_ctr funciton, was a test. Hopefully will add more crypto things laster.
2022-07-16 19:24:13 +02:00

116 lines
3.1 KiB
Go

package inet
import (
"encoding/binary"
"net"
"github.com/wader/fq/format"
"github.com/wader/fq/pkg/bitio"
"github.com/wader/fq/pkg/checksum"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/interp"
"github.com/wader/fq/pkg/scalar"
)
var ipv4IpPacketGroup decode.Group
func init() {
interp.RegisterFormat(decode.Format{
Name: format.IPV4_PACKET,
Description: "Internet protocol v4 packet",
Groups: []string{format.INET_PACKET},
Dependencies: []decode.Dependency{
{Names: []string{format.IP_PACKET}, Group: &ipv4IpPacketGroup},
},
DecodeFn: decodeIPv4,
})
}
const (
ipv4OptionEnd = 0
ipv4OptionNop = 1
)
var ipv4OptionsMap = scalar.UToScalar{
ipv4OptionEnd: {Sym: "end", Description: "End of options list"},
ipv4OptionNop: {Sym: "nop", Description: "No operation"},
2: {Description: "Security"},
3: {Description: "Loose Source Routing"},
9: {Description: "Strict Source Routing"},
7: {Description: "Record Route"},
8: {Description: "Stream ID"},
4: {Description: "Internet Timestamp"},
}
var mapUToIPv4Sym = scalar.Fn(func(s scalar.S) (scalar.S, error) {
var b [4]byte
binary.BigEndian.PutUint32(b[:], uint32(s.ActualU()))
s.Sym = net.IP(b[:]).String()
return s, nil
})
func decodeIPv4(d *decode.D, in any) any {
if ipi, ok := in.(format.InetPacketIn); ok && ipi.EtherType != format.EtherTypeIPv4 {
d.Fatalf("incorrect ethertype %d", ipi.EtherType)
}
d.FieldU4("version")
ihl := d.FieldU4("ihl")
d.FieldU6("dscp")
d.FieldU2("ecn")
totalLength := d.FieldU16("total_length")
d.FieldU16("identification")
d.FieldU1("reserved")
d.FieldBool("dont_fragment")
moreFragments := d.FieldBool("more_fragments")
fragmentOffset := d.FieldU13("fragment_offset")
d.FieldU8("ttl")
protocol := d.FieldU8("protocol", format.IPv4ProtocolMap)
checksumStart := d.Pos()
d.FieldU16("header_checksum", scalar.ActualHex)
checksumEnd := d.Pos()
d.FieldU32("source_ip", mapUToIPv4Sym, scalar.ActualHex)
d.FieldU32("destination_ip", mapUToIPv4Sym, scalar.ActualHex)
optionsLen := (int64(ihl) - 5) * 8 * 4
if optionsLen > 0 {
d.FramedFn(optionsLen, func(d *decode.D) {
d.FieldArray("options", func(d *decode.D) {
for !d.End() {
d.FieldStruct("option", func(d *decode.D) {
d.FieldBool("copied")
d.FieldU2("class")
kind := d.FieldU5("number", ipv4OptionsMap)
switch kind {
case ipv4OptionEnd, ipv4OptionNop:
default:
l := d.FieldU8("length")
d.FieldRawLen("data", (int64(l-2))*8)
}
})
}
})
})
}
headerEnd := d.Pos()
ipv4Checksum := &checksum.IPv4{}
d.Copy(ipv4Checksum, bitio.NewIOReader(d.BitBufRange(0, checksumStart)))
d.Copy(ipv4Checksum, bitio.NewIOReader(d.BitBufRange(checksumEnd, headerEnd-checksumEnd)))
_ = d.FieldMustGet("header_checksum").TryScalarFn(d.ValidateUBytes(ipv4Checksum.Sum(nil)), scalar.ActualHex)
dataLen := int64(totalLength-(ihl*4)) * 8
if moreFragments || fragmentOffset > 0 {
d.FieldRawLen("payload", dataLen)
} else {
d.FieldFormatOrRawLen(
"payload",
dataLen,
ipv4IpPacketGroup,
format.IPPacketIn{Protocol: int(protocol)},
)
}
return nil
}