/
packet.go
executable file
·135 lines (112 loc) · 2.74 KB
/
packet.go
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package packet
import (
"encoding/binary"
"hash/fnv"
"log"
"net/netip"
"github.com/gookit/color"
"github.com/pouriyajamshidi/flat/internal/flowtable"
)
var (
colorLightYellow = color.LightYellow.Printf
colorCyan = color.Cyan.Printf
)
// Packet represents a TCP or UDP packet
type Packet struct {
SrcIP netip.Addr
DstIP netip.Addr
SrcPort uint16
DstPort uint16
Protocol uint8
TTL uint8
Syn bool
Ack bool
TimeStamp uint64
}
func hash(value []byte) uint64 {
hash := fnv.New64a()
hash.Write(value)
return hash.Sum64()
}
// Hash hashes the packets based on their 5-tuple hash
func (pkt *Packet) Hash() uint64 {
tmp := make([]byte, 2)
var src []byte
var dst []byte
var proto []byte
binary.BigEndian.PutUint16(tmp, pkt.SrcPort)
src = append(pkt.SrcIP.AsSlice(), tmp...)
binary.BigEndian.PutUint16(tmp, pkt.DstPort)
dst = append(pkt.DstIP.AsSlice(), tmp...)
binary.BigEndian.PutUint16(tmp, uint16(pkt.Protocol))
proto = append(proto, tmp...)
return hash(src) + hash(dst) + hash(proto)
}
// UnmarshalBinary builds and fills up the Packet struct coming from eBPF map
func UnmarshalBinary(in []byte) (Packet, bool) {
srcIP, ok := netip.AddrFromSlice(in[0:16])
if !ok {
return Packet{}, ok
}
dstIP, ok := netip.AddrFromSlice(in[16:32])
if !ok {
return Packet{}, ok
}
return Packet{
SrcIP: srcIP,
SrcPort: binary.BigEndian.Uint16(in[32:34]),
DstIP: dstIP,
DstPort: binary.BigEndian.Uint16(in[34:36]),
Protocol: in[36],
TTL: in[37],
Syn: in[38] == 1,
Ack: in[39] == 1,
TimeStamp: binary.LittleEndian.Uint64(in[40:48]),
}, true
}
var ipProtoNums = map[uint8]string{
6: "TCP",
17: "UDP",
}
// CalcLatency calculates and displays flow latencies
func CalcLatency(pkt Packet, table *flowtable.FlowTable) {
proto, ok := ipProtoNums[pkt.Protocol]
if !ok {
log.Print("Failed fetching protocol number: ", pkt.Protocol)
return
}
pktHash := pkt.Hash()
ts, ok := table.Get(pktHash)
if !ok && pkt.Syn {
table.Insert(pktHash, pkt.TimeStamp)
return
} else if !ok && proto == "UDP" {
table.Insert(pktHash, pkt.TimeStamp)
return
} else if !ok {
return
}
if pkt.Ack {
colorCyan("(%v) | src: %v:%-7v\tdst: %v:%-9v\tTTL: %-4v\tlatency: %.3f ms\n",
proto,
pkt.DstIP.Unmap().String(),
pkt.DstPort,
pkt.SrcIP.Unmap().String(),
pkt.SrcPort,
pkt.TTL,
(float64(pkt.TimeStamp)-float64(ts))/1_000_000,
)
table.Remove(pktHash)
} else if proto == "UDP" {
colorLightYellow("(%v) | src: %v:%-7v\tdst: %v:%-9v\tTTL: %-4v\tlatency: %.3f ms\n",
proto,
pkt.DstIP.Unmap().String(),
pkt.DstPort,
pkt.SrcIP.Unmap().String(),
pkt.SrcPort,
pkt.TTL,
(float64(pkt.TimeStamp)-float64(ts))/1_000_000,
)
table.Remove(pktHash)
}
}