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fq/format/inet/ether8023_frame.go
Mattias Wadman 2fc0a71a47 decode: Refactor scalar usage
Move scalar into own package.
Split scalar code into decode related scalar code (that reads etc) and
scalar code that just transform the scalar value.
Use a scalar.Mapper interface instead of just a function.
Make mappers, assert and validat impement the interface.
2021-12-02 17:39:26 +01:00

52 lines
1.3 KiB
Go

package inet
// TODO: move to own package?
import (
"encoding/binary"
"fmt"
"github.com/wader/fq/format"
"github.com/wader/fq/format/registry"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/scalar"
)
var ether8023FrameIPv4Format decode.Group
func init() {
registry.MustRegister(decode.Format{
Name: format.ETHER8023_FRAME,
Description: "Ethernet 802.3 frame",
Dependencies: []decode.Dependency{
{Names: []string{format.IPV4_PACKET}, Group: &ether8023FrameIPv4Format},
},
DecodeFn: decodeEthernet,
})
}
var ether8023FrameTypeFormat = map[uint64]*decode.Group{
format.EtherTypeIPv4: &ether8023FrameIPv4Format,
}
// TODO: move to shared?
var mapUToEtherSym = scalar.Fn(func(s scalar.S) (scalar.S, error) {
var b [8]byte
binary.BigEndian.PutUint64(b[:], s.ActualU())
s.Sym = fmt.Sprintf("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x", b[2], b[3], b[4], b[5], b[6], b[7])
return s, nil
})
func decodeEthernet(d *decode.D, in interface{}) interface{} {
d.FieldU("destination", 48, mapUToEtherSym, scalar.Hex)
d.FieldU("source", 48, mapUToEtherSym, scalar.Hex)
etherType := d.FieldU16("ether_type", format.EtherTypeMap, scalar.Hex)
if g, ok := ether8023FrameTypeFormat[etherType]; ok {
d.FieldFormatLen("packet", d.BitsLeft(), *g, nil)
} else {
d.FieldRawLen("data", d.BitsLeft())
}
return nil
}