add better function/method comments

clsact/clsact.go

@@ -2,18 +2,22 @@ package clsact
 
 import "github.com/vishvananda/netlink"
 
+// ClsAct represents a CLSAct netlink qdisc
 type ClsAct struct {
 	attrs *netlink.QdiscAttrs
 }
 
+// NewClsAct creates a new ClsAct struct
 func NewClsAct(attrs *netlink.QdiscAttrs) *ClsAct {
 	return &ClsAct{attrs: attrs}
 }
 
+// Attrs returns netlink.QdiscAttrs. Satisfies the Qdisc interface
 func (qdisc *ClsAct) Attrs() *netlink.QdiscAttrs {
 	return qdisc.attrs
 }
 
+// Type returns the qdisc type. Satisfies the Qdisc interface
 func (qdisc *ClsAct) Type() string {
 	return "clsact"
 }

internal/flowtable/flowtable.go

@@ -8,6 +8,7 @@ import (
 	"github.com/pouriyajamshidi/flat/internal/timer"
 )
 
+// FlowTable stores all TCP and UDP flows
 type FlowTable struct {
 	Ticker *time.Ticker
 	sync.Map
@@ -18,12 +19,12 @@ func NewFlowTable() *FlowTable {
 	return &FlowTable{Ticker: time.NewTicker(time.Second * 10)}
 }
 
-// add adds packet hash and its timestamp to the FlowTable
+// Insert adds packet hash and its timestamp to the FlowTable
 func (table *FlowTable) Insert(hash, timestamp uint64) {
 	table.Store(hash, timestamp)
 }
 
-// load loads packet hash and its timestamp from the FlowTable
+// Get loads packet hash and its timestamp from the FlowTable
 func (table *FlowTable) Get(hash uint64) (uint64, bool) {
 	value, ok := table.Load(hash)
 
@@ -33,7 +34,7 @@ func (table *FlowTable) Get(hash uint64) (uint64, bool) {
 	return value.(uint64), true
 }
 
-// delete deletes packet hash and its timestamp from the FlowTable
+// Remove deletes packet hash and its timestamp from the FlowTable
 func (table *FlowTable) Remove(hash uint64) {
 	_, found := table.Load(hash)
 

internal/packet/packet.go

@@ -28,13 +28,14 @@ const (
 	tcp = "TCP"
 )
 
+// Packet represents a TCP or UDP packet
 type Packet struct {
 	SrcIP     netip.Addr
 	DstIP     netip.Addr
 	SrcPort   uint16
 	DstPort   uint16
 	Protocol  uint8
-	Ttl       uint8
+	TTL       uint8
 	Syn       bool
 	Ack       bool
 	TimeStamp uint64
@@ -46,6 +47,7 @@ func hash(value []byte) uint64 {
 	return hash.Sum64()
 }
 
+// Hash hashes the packets based on their 5-tuple hash
 func (pkt *Packet) Hash() uint64 {
 	tmp := make([]byte, 2)
 
@@ -65,6 +67,7 @@ func (pkt *Packet) Hash() uint64 {
 	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])
 
@@ -84,7 +87,7 @@ func UnmarshalBinary(in []byte) (Packet, bool) {
 		DstIP:     dstIP,
 		DstPort:   binary.BigEndian.Uint16(in[34:36]),
 		Protocol:  in[36],
-		Ttl:       in[37],
+		TTL:       in[37],
 		Syn:       in[38] == 1,
 		Ack:       in[39] == 1,
 		TimeStamp: binary.LittleEndian.Uint64(in[40:48]),
@@ -96,6 +99,7 @@ var ipProtoNums = map[uint8]string{
 	17: "UDP",
 }
 
+// CalcLatency calculates and displays flow latencies
 func CalcLatency(pkt Packet, table *flowtable.FlowTable) {
 	proto, ok := ipProtoNums[pkt.Protocol]
 
@@ -128,7 +132,7 @@ func CalcLatency(pkt Packet, table *flowtable.FlowTable) {
 			pkt.DstPort,
 			convertIPToString(pkt.SrcIP),
 			pkt.SrcPort,
-			pkt.Ttl,
+			pkt.TTL,
 			(float64(pkt.TimeStamp)-float64(ts))/1000000,
 		)
 

internal/packets/packets.go

@@ -8,6 +8,7 @@ import (
 	"github.com/google/gopacket/layers"
 )
 
+// EthernetHeader creates an arbitrary Ethernet header
 func EthernetHeader(proto layers.EthernetType) []byte {
 	buf := gopacket.NewSerializeBuffer()
 
@@ -24,6 +25,7 @@ func EthernetHeader(proto layers.EthernetType) []byte {
 	return buf.Bytes()[0:14] // Override the gopacket padding. If not done like this, it will pad it to make a 60 byte ethernet frame
 }
 
+// IPv4Header creates an arbitrary IPv4 header
 func IPv4Header(proto layers.IPProtocol) []byte {
 	buf := gopacket.NewSerializeBuffer()
 
@@ -40,6 +42,7 @@ func IPv4Header(proto layers.IPProtocol) []byte {
 	return buf.Bytes()
 }
 
+// TCPv4SYN creates an arbitrary TCP SYN header
 func TCPv4SYN() []byte {
 	var packet []byte
 	packet = append(packet, EthernetHeader(layers.EthernetTypeIPv4)...)
@@ -62,6 +65,7 @@ func TCPv4SYN() []byte {
 	return append(packet, buf.Bytes()...)
 }
 
+// TCPv4ACK creates an arbitrary TCP ACK header
 func TCPv4ACK() []byte {
 	var packet []byte
 	packet = append(packet, EthernetHeader(layers.EthernetTypeIPv4)...)
@@ -84,6 +88,7 @@ func TCPv4ACK() []byte {
 	return append(packet, buf.Bytes()...)
 }
 
+// TCPv4SYNACK creates an arbitrary TCP SYN/ACK header
 func TCPv4SYNACK() []byte {
 	var packet []byte
 	packet = append(packet, EthernetHeader(layers.EthernetTypeIPv4)...)

internal/probe/probe.go

@@ -181,6 +181,7 @@ func (p *probe) Close() error {
 	return nil
 }
 
+// Run starts the program
 func Run(ctx context.Context, iface netlink.Link) error {
 	log.Println("Starting up the probe")
 

internal/timer/timer.go

@@ -13,6 +13,7 @@ static unsigned long long get_nsecs(void) {
 */
 import "C"
 
+// GetNanosecSinceBoot returns the nanoseconds since system boot time
 func GetNanosecSinceBoot() uint64 {
 	return uint64(C.get_nsecs())
 }