Trace reuse TCP connection in TIME_WAIT state

tcptwreuse.py

#!/usr/bin/python

from __future__ import print_function
from bcc import BPF
from socket import inet_ntop, ntohs, AF_INET, AF_INET6
from struct import pack

b = BPF(text="""
#include <uapi/linux/ptrace.h>
#include <net/sock.h>
#include <bcc/proto.h>

BPF_HASH(currsock, u32, struct sock *);

struct data_t {
    u64 ts;
    u32 pid;
    u32 saddr;
    u32 daddr;
    u16 sport;
    u16 dport;
};
BPF_PERF_OUTPUT(events);

int trace_tcp_twsk_unique(struct pt_regs *ctx, struct sock *sk, struct sock *sktw, void *twp)
{
    u32 pid = bpf_get_current_pid_tgid();

    currsock.update(&pid, &sktw);

    return 0;
}

int trace_tcp_twsk_unique_return(struct pt_regs *ctx)
{
    int ret = PT_REGS_RC(ctx);

    struct sock **skpp;
    u32 pid = bpf_get_current_pid_tgid();
    skpp = currsock.lookup(&pid);
    if (!skpp) {
        return 0;
    }
    if (ret == 0) {
        currsock.delete(&pid);
        return 0;
    }
    struct sock *skp = *skpp;
    struct data_t data = {};
    data.ts = bpf_ktime_get_ns();
    data.pid = pid;
    data.saddr = skp->sk_rcv_saddr;
    data.daddr = skp->sk_daddr;
    data.sport = skp->sk_num;
    data.dport = skp->sk_dport;
    events.perf_submit(ctx, &data, sizeof(data));
    return 0;
}
""")

b.attach_kprobe(event="tcp_twsk_unique", fn_name="trace_tcp_twsk_unique")
b.attach_kretprobe(event="tcp_twsk_unique", fn_name="trace_tcp_twsk_unique_return")

print("%-18s %-5s %21s > %-21s" % ("TIME(s)", "PID", "SRC(addr:port)", "DST(addr:port)"))

start = 0
def print_event(cpu, data, size):
    global start
    event = b["events"].event(data)
    if start == 0:
        start = event.ts
    time_s = (float(event.ts - start)) / 1000000000
    print("%-18.9f %-5d %21s > %-21s" % (time_s, event.pid, "%15s:%-5d" % (inet_ntop(AF_INET, pack('I', event.saddr)), ntohs(event.sport)), "%s:%d" % (inet_ntop(AF_INET, pack('I', event.daddr)), ntohs(event.dport))))

b["events"].open_perf_buffer(print_event)

while 1:
    try:
        b.perf_buffer_poll()
    except KeyboardInterrupt:
        exit()

yamamoto-ma@ubuntu-server:~/LOCAL/src/tcptwreuse$ sudo ./tcptwreuse 
TIME(s)            PID          SRC(addr:port) > DST(addr:port)       
0.000000000        25007     10.15.2.166:2746  > 10.15.2.165:80       
0.000596665        25007     10.15.2.166:3258  > 10.15.2.165:80       
0.001180357        25007     10.15.2.166:3770  > 10.15.2.165:80       
0.001880267        25007     10.15.2.166:4282  > 10.15.2.165:80       
0.003179869        25007     10.15.2.166:4794  > 10.15.2.165:80       
0.003729387        25007     10.15.2.166:5306  > 10.15.2.165:80       
0.004374765        25007     10.15.2.166:5818  > 10.15.2.165:80       
0.005208688        25007     10.15.2.166:6330  > 10.15.2.165:80       
0.005603142        25007     10.15.2.166:6842  > 10.15.2.165:80       
0.006293816        25007     10.15.2.166:7354  > 10.15.2.165:80       
0.007159008        25007     10.15.2.166:7866  > 10.15.2.165:80       
0.007691763        25007     10.15.2.166:8378  > 10.15.2.165:80       
0.008147363        25007     10.15.2.166:8890  > 10.15.2.165:80       
0.008711747        25007     10.15.2.166:9402  > 10.15.2.165:80       
0.009089490        25007     10.15.2.166:9914  > 10.15.2.165:80       
0.009470028        25007     10.15.2.166:10426 > 10.15.2.165:80       
0.009773340        25007     10.15.2.166:10938 > 10.15.2.165:80       
0.010082264        25007     10.15.2.166:11450 > 10.15.2.165:80
...