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Copy pathtcpretrans.py
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executable file
·209 lines (187 loc) · 5.83 KB
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#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
#
# tcpretrans Trace TCP retransmits and TLPs.
# For Linux, uses BCC, eBPF. Embedded C.
#
# USAGE: tcpretrans [-h] [-l]
#
# This uses dynamic tracing of kernel functions, and will need to be updated
# to match kernel changes.
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 14-Feb-2016 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF
import argparse
from time import strftime
from socket import inet_ntop, AF_INET, AF_INET6
from struct import pack
import ctypes as ct
# arguments
examples = """examples:
./tcpretrans # trace TCP retransmits
./tcpretrans -l # include TLP attempts
"""
parser = argparse.ArgumentParser(
description="Trace TCP retransmits",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-l", "--lossprobe", action="store_true",
help="include tail loss probe attempts")
args = parser.parse_args()
# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#include <net/sock.h>
#include <bcc/proto.h>
#define RETRANSMIT 1
#define TLP 2
// separate data structs for ipv4 and ipv6
struct ipv4_data_t {
// XXX: switch some to u32's when supported
u64 pid;
u64 ip;
u64 saddr;
u64 daddr;
u64 lport;
u64 dport;
u64 state;
u64 type;
};
BPF_PERF_OUTPUT(ipv4_events);
struct ipv6_data_t {
u64 pid;
u64 ip;
unsigned __int128 saddr;
unsigned __int128 daddr;
u64 lport;
u64 dport;
u64 state;
u64 type;
};
BPF_PERF_OUTPUT(ipv6_events);
static int trace_event(struct pt_regs *ctx, struct sock *sk, int type)
{
if (sk == NULL)
return 0;
u32 pid = bpf_get_current_pid_tgid();
struct sock *skp = NULL;
bpf_probe_read(&skp, sizeof(skp), &sk);
// pull in details
u16 family = 0, lport = 0, dport = 0;
char state = 0;
bpf_probe_read(&family, sizeof(family), &skp->__sk_common.skc_family);
bpf_probe_read(&lport, sizeof(lport), &skp->__sk_common.skc_num);
bpf_probe_read(&dport, sizeof(dport), &skp->__sk_common.skc_dport);
bpf_probe_read(&state, sizeof(state), (void *)&skp->__sk_common.skc_state);
if (family == AF_INET) {
struct ipv4_data_t data4 = {.pid = pid, .ip = 4, .type = type};
bpf_probe_read(&data4.saddr, sizeof(u32),
&skp->__sk_common.skc_rcv_saddr);
bpf_probe_read(&data4.daddr, sizeof(u32),
&skp->__sk_common.skc_daddr);
// lport is host order
data4.lport = lport;
data4.dport = ntohs(dport);
data4.state = state;
ipv4_events.perf_submit(ctx, &data4, sizeof(data4));
} else if (family == AF_INET6) {
struct ipv6_data_t data6 = {.pid = pid, .ip = 6, .type = type};
bpf_probe_read(&data6.saddr, sizeof(data6.saddr),
&skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
bpf_probe_read(&data6.daddr, sizeof(data6.daddr),
&skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
// lport is host order
data6.lport = lport;
data6.dport = ntohs(dport);
data6.state = state;
ipv6_events.perf_submit(ctx, &data6, sizeof(data6));
}
// else drop
return 0;
}
int trace_retransmit(struct pt_regs *ctx, struct sock *sk)
{
trace_event(ctx, sk, RETRANSMIT);
return 0;
}
int trace_tlp(struct pt_regs *ctx, struct sock *sk)
{
trace_event(ctx, sk, TLP);
return 0;
}
"""
# event data
class Data_ipv4(ct.Structure):
_fields_ = [
("pid", ct.c_ulonglong),
("ip", ct.c_ulonglong),
("saddr", ct.c_ulonglong),
("daddr", ct.c_ulonglong),
("lport", ct.c_ulonglong),
("dport", ct.c_ulonglong),
("state", ct.c_ulonglong),
("type", ct.c_ulonglong)
]
class Data_ipv6(ct.Structure):
_fields_ = [
("pid", ct.c_ulonglong),
("ip", ct.c_ulonglong),
("saddr", (ct.c_ulonglong * 2)),
("daddr", (ct.c_ulonglong * 2)),
("lport", ct.c_ulonglong),
("dport", ct.c_ulonglong),
("state", ct.c_ulonglong),
("type", ct.c_ulonglong)
]
# from bpf_text:
type = {}
type[1] = 'R'
type[2] = 'L'
# from include/net/tcp_states.h:
tcpstate = {}
tcpstate[1] = 'ESTABLISHED'
tcpstate[2] = 'SYN_SENT'
tcpstate[3] = 'SYN_RECV'
tcpstate[4] = 'FIN_WAIT1'
tcpstate[5] = 'FIN_WAIT2'
tcpstate[6] = 'TIME_WAIT'
tcpstate[7] = 'CLOSE'
tcpstate[8] = 'CLOSE_WAIT'
tcpstate[9] = 'LAST_ACK'
tcpstate[10] = 'LISTEN'
tcpstate[11] = 'CLOSING'
tcpstate[12] = 'NEW_SYN_RECV'
# process event
def print_ipv4_event(cpu, data, size):
event = ct.cast(data, ct.POINTER(Data_ipv4)).contents
print("%-8s %-6d %-2d %-20s %1s> %-20s %s" % (
strftime("%H:%M:%S"), event.pid, event.ip,
"%s:%d" % (inet_ntop(AF_INET, pack('I', event.saddr)), event.lport),
type[event.type],
"%s:%s" % (inet_ntop(AF_INET, pack('I', event.daddr)), event.dport),
tcpstate[event.state]))
def print_ipv6_event(cpu, data, size):
event = ct.cast(data, ct.POINTER(Data_ipv6)).contents
print("%-8s %-6d %-2d %-20s %1s> %-20s %s" % (
strftime("%H:%M:%S"), event.pid, event.ip,
"%s:%d" % (inet_ntop(AF_INET6, event.saddr), event.lport),
type[event.type],
"%s:%d" % (inet_ntop(AF_INET6, event.daddr), event.dport),
tcpstate[event.state]))
# initialize BPF
b = BPF(text=bpf_text)
b.attach_kprobe(event="tcp_retransmit_skb", fn_name="trace_retransmit")
if args.lossprobe:
b.attach_kprobe(event="tcp_send_loss_probe", fn_name="trace_tlp")
# header
print("%-8s %-6s %-2s %-20s %1s> %-20s %-4s" % ("TIME", "PID", "IP",
"LADDR:LPORT", "T", "RADDR:RPORT", "STATE"))
# read events
b["ipv4_events"].open_perf_buffer(print_ipv4_event)
b["ipv6_events"].open_perf_buffer(print_ipv6_event)
while 1:
b.kprobe_poll()