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285 lines
8.5 KiB
285 lines
8.5 KiB
#!/usr/bin/env python
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# @lint-avoid-python-3-compatibility-imports
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#
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# tcpaccept Trace TCP accept()s.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: tcpaccept [-h] [-t] [-p PID]
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#
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# This uses dynamic tracing of the kernel inet_csk_accept() socket function
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# (from tcp_prot.accept), and will need to be modified to match kernel changes.
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#
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# Copyright (c) 2015 Brendan Gregg.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 13-Oct-2015 Brendan Gregg Created this.
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# 14-Feb-2016 " " Switch to bpf_perf_output.
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from __future__ import print_function
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from bcc import BPF
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from socket import inet_ntop, AF_INET, AF_INET6
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from struct import pack
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import argparse
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import ctypes as ct
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from bcc.utils import printb
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# arguments
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examples = """examples:
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./tcpaccept # trace all TCP accept()s
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./tcpaccept -t # include timestamps
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./tcpaccept -p 181 # only trace PID 181
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"""
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parser = argparse.ArgumentParser(
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description="Trace TCP accepts",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog=examples)
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parser.add_argument("-t", "--timestamp", action="store_true",
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help="include timestamp on output")
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parser.add_argument("-p", "--pid",
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help="trace this PID only")
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parser.add_argument("--ebpf", action="store_true",
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help=argparse.SUPPRESS)
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args = parser.parse_args()
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debug = 0
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# define BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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#include <net/sock.h>
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#include <bcc/proto.h>
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// separate data structs for ipv4 and ipv6
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struct ipv4_data_t {
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u64 ts_us;
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u32 pid;
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u32 saddr;
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u32 daddr;
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u64 ip;
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u16 lport;
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char task[TASK_COMM_LEN];
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};
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BPF_PERF_OUTPUT(ipv4_events);
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struct ipv6_data_t {
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u64 ts_us;
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u32 pid;
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unsigned __int128 saddr;
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unsigned __int128 daddr;
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u64 ip;
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u16 lport;
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char task[TASK_COMM_LEN];
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};
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BPF_PERF_OUTPUT(ipv6_events);
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"""
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#
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# The following is the code for older kernels(Linux pre-4.16).
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# It uses kprobes to instrument inet_csk_accept(). On Linux 4.16 and
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# later, the sock:inet_sock_set_state tracepoint should be used instead, as
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# is done by the code that follows this.
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#
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bpf_text_kprobe = """
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int kretprobe__inet_csk_accept(struct pt_regs *ctx)
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{
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struct sock *newsk = (struct sock *)PT_REGS_RC(ctx);
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u32 pid = bpf_get_current_pid_tgid();
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##FILTER_PID##
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if (newsk == NULL)
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return 0;
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// check this is TCP
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u8 protocol = 0;
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// workaround for reading the sk_protocol bitfield:
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// Following comments add by Joe Yin:
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// Unfortunately,it can not work since Linux 4.10,
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// because the sk_wmem_queued is not following the bitfield of sk_protocol.
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// And the following member is sk_gso_max_segs.
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// So, we can use this:
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// bpf_probe_read(&protocol, 1, (void *)((u64)&newsk->sk_gso_max_segs) - 3);
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// In order to diff the pre-4.10 and 4.10+ ,introduce the variables gso_max_segs_offset,sk_lingertime,
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// sk_lingertime is closed to the gso_max_segs_offset,and
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// the offset between the two members is 4
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int gso_max_segs_offset = offsetof(struct sock, sk_gso_max_segs);
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int sk_lingertime_offset = offsetof(struct sock, sk_lingertime);
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if (sk_lingertime_offset - gso_max_segs_offset == 4)
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// 4.10+ with little endian
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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protocol = *(u8 *)((u64)&newsk->sk_gso_max_segs - 3);
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else
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// pre-4.10 with little endian
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protocol = *(u8 *)((u64)&newsk->sk_wmem_queued - 3);
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#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
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// 4.10+ with big endian
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protocol = *(u8 *)((u64)&newsk->sk_gso_max_segs - 1);
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else
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// pre-4.10 with big endian
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protocol = *(u8 *)((u64)&newsk->sk_wmem_queued - 1);
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#else
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# error "Fix your compiler's __BYTE_ORDER__?!"
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#endif
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if (protocol != IPPROTO_TCP)
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return 0;
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// pull in details
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u16 family = 0, lport = 0;
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family = newsk->__sk_common.skc_family;
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lport = newsk->__sk_common.skc_num;
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if (family == AF_INET) {
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struct ipv4_data_t data4 = {.pid = pid, .ip = 4};
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data4.ts_us = bpf_ktime_get_ns() / 1000;
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data4.saddr = newsk->__sk_common.skc_rcv_saddr;
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data4.daddr = newsk->__sk_common.skc_daddr;
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data4.lport = lport;
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bpf_get_current_comm(&data4.task, sizeof(data4.task));
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ipv4_events.perf_submit(ctx, &data4, sizeof(data4));
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} else if (family == AF_INET6) {
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struct ipv6_data_t data6 = {.pid = pid, .ip = 6};
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data6.ts_us = bpf_ktime_get_ns() / 1000;
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bpf_probe_read(&data6.saddr, sizeof(data6.saddr),
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&newsk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
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bpf_probe_read(&data6.daddr, sizeof(data6.daddr),
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&newsk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
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data6.lport = lport;
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bpf_get_current_comm(&data6.task, sizeof(data6.task));
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ipv6_events.perf_submit(ctx, &data6, sizeof(data6));
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}
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// else drop
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return 0;
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}
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"""
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bpf_text_tracepoint = """
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TRACEPOINT_PROBE(sock, inet_sock_set_state)
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{
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if (args->protocol != IPPROTO_TCP)
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return 0;
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u32 pid = bpf_get_current_pid_tgid();
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##FILTER_PID##
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// pull in details
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u16 family = 0, lport = 0;
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family = args->family;
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lport = args->sport;
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if (family == AF_INET) {
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struct ipv4_data_t data4 = {.pid = pid, .ip = 4};
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data4.ts_us = bpf_ktime_get_ns() / 1000;
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__builtin_memcpy(&data4.saddr, args->saddr, sizeof(data4.saddr));
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__builtin_memcpy(&data4.daddr, args->daddr, sizeof(data4.daddr));
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data4.lport = lport;
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bpf_get_current_comm(&data4.task, sizeof(data4.task));
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ipv4_events.perf_submit(args, &data4, sizeof(data4));
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} else if (family == AF_INET6) {
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struct ipv6_data_t data6 = {.pid = pid, .ip = 6};
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data6.ts_us = bpf_ktime_get_ns() / 1000;
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__builtin_memcpy(&data6.saddr, args->saddr, sizeof(data6.saddr));
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__builtin_memcpy(&data6.daddr, args->daddr, sizeof(data6.daddr));
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data6.lport = lport;
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bpf_get_current_comm(&data6.task, sizeof(data6.task));
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ipv6_events.perf_submit(args, &data6, sizeof(data6));
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}
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// else drop
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return 0;
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}
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"""
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if (BPF.tracepoint_exists("sock", "inet_sock_set_state")):
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bpf_text += bpf_text_tracepoint
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else:
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bpf_text += bpf_text_kprobe
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# code substitutions
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if args.pid:
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bpf_text = bpf_text.replace('##FILTER_PID##',
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'if (pid != %s) { return 0; }' % args.pid)
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else:
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bpf_text = bpf_text.replace('##FILTER_PID##', '')
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if debug or args.ebpf:
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print(bpf_text)
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if args.ebpf:
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exit()
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# event data
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TASK_COMM_LEN = 16 # linux/sched.h
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class Data_ipv4(ct.Structure):
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_fields_ = [
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("ts_us", ct.c_ulonglong),
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("pid", ct.c_uint),
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("saddr", ct.c_uint),
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("daddr", ct.c_uint),
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("ip", ct.c_ulonglong),
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("lport", ct.c_ushort),
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("task", ct.c_char * TASK_COMM_LEN)
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]
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class Data_ipv6(ct.Structure):
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_fields_ = [
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("ts_us", ct.c_ulonglong),
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("pid", ct.c_uint),
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("saddr", (ct.c_ulonglong * 2)),
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("daddr", (ct.c_ulonglong * 2)),
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("ip", ct.c_ulonglong),
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("lport", ct.c_ushort),
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("task", ct.c_char * TASK_COMM_LEN)
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]
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# process event
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def print_ipv4_event(cpu, data, size):
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event = ct.cast(data, ct.POINTER(Data_ipv4)).contents
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global start_ts
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if args.timestamp:
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if start_ts == 0:
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start_ts = event.ts_us
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print("%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), end="")
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printb(b"%-6d %-12.12s %-2d %-16s %-16s %-4d" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET, pack("I", event.daddr)).encode(),
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inet_ntop(AF_INET, pack("I", event.saddr)).encode(),
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event.lport))
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def print_ipv6_event(cpu, data, size):
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event = ct.cast(data, ct.POINTER(Data_ipv6)).contents
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global start_ts
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if args.timestamp:
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if start_ts == 0:
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start_ts = event.ts_us
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print("%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), end="")
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printb(b"%-6d %-12.12s %-2d %-16s %-16s %-4d" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET6, event.daddr).encode(),
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inet_ntop(AF_INET6, event.saddr).encode(),
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event.lport))
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# initialize BPF
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b = BPF(text=bpf_text)
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# header
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if args.timestamp:
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print("%-9s" % ("TIME(s)"), end="")
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print("%-6s %-12s %-2s %-16s %-16s %-4s" % ("PID", "COMM", "IP", "RADDR",
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"LADDR", "LPORT"))
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start_ts = 0
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# read events
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b["ipv4_events"].open_perf_buffer(print_ipv4_event)
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b["ipv6_events"].open_perf_buffer(print_ipv6_event)
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while 1:
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try:
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b.perf_buffer_poll()
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except KeyboardInterrupt:
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exit()
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