Skip to content

Output TCP flags alongside tuple #466

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 22, 2025
Merged

Output TCP flags alongside tuple #466

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 2 additions & 1 deletion bpf/kprobe_pwru.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,7 @@ struct tuple {
u16 dport;
u16 l3_proto;
u8 l4_proto;
u8 pad;
u8 tcp_flags;
} __attribute__((packed));

enum event_type {
Expand Down Expand Up @@ -313,6 +313,7 @@ __set_tuple(struct tuple *tpl, void *data, u16 l3_off, bool is_ipv4) {
struct tcphdr *tcp = (struct tcphdr *) (data + l4_off);
tpl->sport= BPF_CORE_READ(tcp, source);
tpl->dport= BPF_CORE_READ(tcp, dest);
bpf_probe_read_kernel(&tpl->tcp_flags, sizeof(tpl->tcp_flags), (void *)tcp + offsetof(struct tcphdr, window) - 1);
} else if (tpl->l4_proto == IPPROTO_UDP) {
struct udphdr *udp = (struct udphdr *) (data + l4_off);
tpl->sport= BPF_CORE_READ(udp, source);
Expand Down
18 changes: 13 additions & 5 deletions internal/pwru/output.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ type jsonTuple struct {
Sport uint16 `json:"sport,omitempty"`
Dport uint16 `json:"dport,omitempty"`
Proto uint8 `json:"proto,omitempty"`
Flags string `json:"flags,omitempty"`
}

func centerAlignString(s string, width int) string {
Expand All @@ -101,7 +102,7 @@ func NewOutput(flags *Flags, printSkbMap, printShinfoMap, printStackMap *ebpf.Ma

reasons, err := getKFreeSKBReasons(btfSpec)
if err != nil {
log.Printf("Unable to load packet drop reaons: %v", err)
log.Printf("Unable to load packet drop reasons: %v", err)
}

var ifs map[uint64]map[uint32]string
Expand Down Expand Up @@ -204,6 +205,7 @@ func (o *output) PrintJson(event *Event) {
t.Sport = byteorder.NetworkToHost16(event.Tuple.Sport)
t.Dport = byteorder.NetworkToHost16(event.Tuple.Dport)
t.Proto = event.Tuple.L4Proto
t.Flags = event.Tuple.TCPFlag.String()
d.Tuple = t
}

Expand Down Expand Up @@ -271,11 +273,17 @@ func getAddrByArch(event *Event, o *output) (addr uint64) {
return addr
}

func getTupleData(event *Event) (tupleData string) {
func getTupleData(event *Event, outputTCPFlags bool) (tupleData string) {
var l4Info string
if event.Tuple.L4Proto == syscall.IPPROTO_TCP && event.Tuple.TCPFlag != 0 && outputTCPFlags {
l4Info = fmt.Sprintf("%s:%s", protoToStr(event.Tuple.L4Proto), event.Tuple.TCPFlag)
} else {
l4Info = protoToStr(event.Tuple.L4Proto)
}
tupleData = fmt.Sprintf("%s:%d->%s:%d(%s)",
addrToStr(event.Tuple.L3Proto, event.Tuple.Saddr), byteorder.NetworkToHost16(event.Tuple.Sport),
addrToStr(event.Tuple.L3Proto, event.Tuple.Daddr), byteorder.NetworkToHost16(event.Tuple.Dport),
protoToStr(event.Tuple.L4Proto))
l4Info)
return tupleData
}

Expand Down Expand Up @@ -432,7 +440,7 @@ func (o *output) Print(event *Event) {
}

if o.flags.OutputTuple {
fprintWithPadding(o.writer, getTupleData(event), &maxTupleLengthSeen)
fprintWithPadding(o.writer, getTupleData(event, o.flags.OutputTCPFlags), &maxTupleLengthSeen)
}

if o.flags.OutputCaller {
Expand Down Expand Up @@ -499,7 +507,7 @@ func addrToStr(proto uint16, addr [16]byte) string {
}
}

// getKFreeSKBReasons dervices SKB drop reasons from the "skb_drop_reason" enum
// getKFreeSKBReasons derives SKB drop reasons from the "skb_drop_reason" enum
// defined in /include/net/dropreason.h.
func getKFreeSKBReasons(spec *btf.Spec) (map[uint64]string, error) {
if _, err := spec.AnyTypeByName("kfree_skb_reason"); err != nil {
Expand Down
34 changes: 30 additions & 4 deletions internal/pwru/types.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ type Flags struct {
OutputSkbCB bool
OutputFile string
OutputJson bool
OutputTCPFlags bool

KMods []string
AllKMods bool
Expand Down Expand Up @@ -86,6 +87,7 @@ func (f *Flags) SetFlags() {
flag.BoolVar(&f.OutputCaller, "output-caller", false, "print caller function name")
flag.Uint64Var(&f.OutputLimitLines, "output-limit-lines", 0, "exit the program after the number of events has been received/printed")
flag.BoolVar(&f.OutputSkbCB, "output-skb-cb", false, "print skb->cb")
flag.BoolVar(&f.OutputTCPFlags, "output-tcp-flags", false, "print TCP flags")

flag.StringVar(&f.OutputFile, "output-file", "", "write traces to file")

Expand Down Expand Up @@ -117,14 +119,38 @@ func (f *Flags) Parse() {
}
}

type tcpFlag uint8

func (f tcpFlag) String() string {
tcpFlags := []string{
"FIN",
"SYN",
"RST",
"PSH",
"ACK",
"URG",
"ECE",
"CWR",
}

var flags []string
for i, flag := range tcpFlags {
if f&(1<<uint(i)) != 0 {
flags = append(flags, flag)
}
}

return strings.Join(flags, "|")
}

type Tuple struct {
Saddr [16]byte
Daddr [16]byte
Sport uint16
Dport uint16
L3Proto uint16
L4Proto uint8
Pad uint8
TCPFlag tcpFlag
}

type Meta struct {
Expand Down Expand Up @@ -176,7 +202,7 @@ func (f *markFlagValue) String() string {

func (f *markFlagValue) Set(value string) error {
parts := strings.Split(value, "/")

mark, err := parseUint32HexOrDecimal(parts[0])
if err != nil {
return fmt.Errorf("invalid mark value: %v", err)
Expand All @@ -191,7 +217,7 @@ func (f *markFlagValue) Set(value string) error {
}
*f.mask = mask
}

return nil
}

Expand All @@ -205,7 +231,7 @@ func parseUint32HexOrDecimal(s string) (uint32, error) {
s = s[2:]
base = 16
}

val, err := strconv.ParseUint(s, base, 32)
if err != nil {
return 0, err
Expand Down
Loading