tcpconnect

#!/usr/bin/python
#
# tcpconnect	Trace TCP connect()s.
#		For Linux, uses BCC, eBPF. Embedded C.
#
# USAGE: tcpconnect [-h] [-t] [-p PID]
#
# All connection attempts are traced, even if they ultimately fail.
#
# Copyright (c) 2015 Brendan Gregg.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 25-Sep-2015	Brendan Gregg	Created this.

from __future__ import print_function
from bcc import BPF
import argparse

# arguments
examples = """examples:
    ./tcpconnect           # trace all TCP connect()s
    ./tcpconnect -t        # include timestamps
    ./tcpconnect -p 181    # only trace PID 181
"""
parser = argparse.ArgumentParser(
	description="Trace TCP connects",
	formatter_class=argparse.RawDescriptionHelpFormatter,
	epilog=examples)
parser.add_argument("-t", "--timestamp", action="store_true",
	help="include timestamp on output")
parser.add_argument("-p", "--pid",
	help="trace this PID only")
args = parser.parse_args()
debug = 0

# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#include <net/sock.h>
#include <bcc/proto.h>

BPF_HASH(currsock, u32, struct sock *);

int trace_connect_entry(struct pt_regs *ctx, struct sock *sk)
{
	u32 pid = bpf_get_current_pid_tgid();
	FILTER

	// stash the sock ptr for lookup on return
	currsock.update(&pid, &sk);

	return 0;
};

static int trace_connect_return(struct pt_regs *ctx, short ipver)
{
	int ret = ctx->ax;
	u32 pid = bpf_get_current_pid_tgid();

	struct sock **skpp;
	skpp = currsock.lookup(&pid);
	if (skpp == 0) {
		return 0;	// missed entry
	}

	if (ret != 0) {
		// failed to send SYNC packet, may not have populated
		// socket __sk_common.{skc_rcv_saddr, ...}
		currsock.delete(&pid);
		return 0;
	}

	// pull in details
	struct sock *skp = *skpp;
	u32 saddr = 0, daddr = 0;
	u16 dport = 0;
	bpf_probe_read(&dport, sizeof(dport), &skp->__sk_common.skc_dport);
	if (ipver == 4) {
		bpf_probe_read(&saddr, sizeof(saddr),
		    &skp->__sk_common.skc_rcv_saddr);
		bpf_probe_read(&daddr, sizeof(daddr),
		    &skp->__sk_common.skc_daddr);

		// output
		bpf_trace_printk("4 %x %x %d\\n", saddr, daddr, ntohs(dport));
	} else /* 6 */ {
		// just grab the last 4 bytes for now
		bpf_probe_read(&saddr, sizeof(saddr),
		    &skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32[3]);
		bpf_probe_read(&daddr, sizeof(daddr),
		    &skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32[3]);

		// output and flip byte order of addresses
		bpf_trace_printk("6 %x %x %d\\n", bpf_ntohl(saddr),
		    bpf_ntohl(daddr), ntohs(dport));
	}

	currsock.delete(&pid);

	return 0;
}

int trace_connect_v4_return(struct pt_regs *ctx)
{
	return trace_connect_return(ctx, 4);
}

int trace_connect_v6_return(struct pt_regs *ctx)
{
	return trace_connect_return(ctx, 6);
}
"""

# code substitutions
if args.pid:
	bpf_text = bpf_text.replace('FILTER',
	    'if (pid != %s) { return 0; }' % args.pid)
else:
	bpf_text = bpf_text.replace('FILTER', '')
if debug:
	print(bpf_text)

# initialize BPF
b = BPF(text=bpf_text)
b.attach_kprobe(event="tcp_v4_connect", fn_name="trace_connect_entry")
b.attach_kprobe(event="tcp_v6_connect", fn_name="trace_connect_entry")
b.attach_kretprobe(event="tcp_v4_connect", fn_name="trace_connect_v4_return")
b.attach_kretprobe(event="tcp_v6_connect", fn_name="trace_connect_v6_return")

# header
if args.timestamp:
	print("%-9s" % ("TIME(s)"), end="")
print("%-6s %-12s %-2s %-16s %-16s %-4s" % ("PID", "COMM", "IP", "SADDR",
    "DADDR", "DPORT"))

start_ts = 0

def inet_ntoa(addr):
	dq = ''
	for i in range(0, 4):
		dq = dq + str(addr & 0xff)
		if (i != 3):
			dq = dq + '.'
		addr = addr >> 8
	return dq

# format output
while 1:
	(task, pid, cpu, flags, ts, msg) = b.trace_fields()
	(ip_s, saddr_hs, daddr_hs, dport_s) = msg.split(" ")

	if args.timestamp:
		if start_ts == 0:
			start_ts = ts
		print("%-9.3f" % (ts - start_ts), end="")
	print("%-6d %-12.12s %-2s %-16s %-16s %-4s" % (pid, task, ip_s,
	    inet_ntoa(int(saddr_hs, 16)) if ip_s == "4" else "..." + saddr_hs,
	    inet_ntoa(int(daddr_hs, 16)) if ip_s == "4" else "..." + daddr_hs,
	    dport_s))