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bindsnoop.c
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bindsnoop.c
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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/*
* Copyright (c) 2021 Hengqi Chen
*
* Based on bindsnoop(8) from BCC by Pavel Dubovitsky.
* 11-May-2021 Hengqi Chen Created this.
*/
#include <argp.h>
#include <arpa/inet.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <time.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "bindsnoop.h"
#include "bindsnoop.skel.h"
#include "trace_helpers.h"
#define PERF_BUFFER_PAGES 16
#define PERF_POLL_TIMEOUT_MS 100
#define warn(...) fprintf(stderr, __VA_ARGS__)
static volatile sig_atomic_t exiting = 0;
static bool emit_timestamp = false;
static pid_t target_pid = 0;
static bool ignore_errors = true;
static char *target_ports = NULL;
const char *argp_program_version = "bindsnoop 0.1";
const char *argp_program_bug_address =
"https://github.com/iovisor/bcc/tree/master/libbpf-tools";
const char argp_program_doc[] =
"Trace bind syscalls.\n"
"\n"
"USAGE: bindsnoop [-h] [-t] [-x] [-p PID] [-P ports]\n"
"\n"
"EXAMPLES:\n"
" bindsnoop # trace all bind syscall\n"
" bindsnoop -t # include timestamps\n"
" bindsnoop -x # include errors on output\n"
" bindsnoop -p 1216 # only trace PID 1216\n"
" bindsnoop -P 80,81 # only trace port 80 and 81\n"
"\n"
"Socket options are reported as:\n"
" SOL_IP IP_FREEBIND F....\n"
" SOL_IP IP_TRANSPARENT .T...\n"
" SOL_IP IP_BIND_ADDRESS_NO_PORT ..N..\n"
" SOL_SOCKET SO_REUSEADDR ...R.\n"
" SOL_SOCKET SO_REUSEPORT ....r\n";
static const struct argp_option opts[] = {
{ "timestamp", 't', NULL, 0, "Include timestamp on output" },
{ "failed", 'x', NULL, 0, "Include errors on output." },
{ "pid", 'p', "PID", 0, "Process ID to trace" },
{ "ports", 'P', "PORTS", 0, "Comma-separated list of ports to trace." },
{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" },
{},
};
static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
long pid, port_num;
char *port;
switch (key) {
case 'p':
errno = 0;
pid = strtol(arg, NULL, 10);
if (errno || pid <= 0) {
warn("Invalid PID: %s\n", arg);
argp_usage(state);
}
target_pid = pid;
break;
case 'P':
if (!arg) {
warn("No ports specified\n");
argp_usage(state);
}
target_ports = strdup(arg);
port = strtok(arg, ",");
while (port) {
port_num = strtol(port, NULL, 10);
if (errno || port_num <= 0 || port_num > 65536) {
warn("Invalid ports: %s\n", arg);
argp_usage(state);
}
port = strtok(NULL, ",");
}
break;
case 'x':
ignore_errors = false;
break;
case 't':
emit_timestamp = true;
break;
case 'h':
argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static void sig_int(int signo)
{
exiting = 1;
}
static void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
{
struct bind_event *e = data;
time_t t;
struct tm *tm;
char ts[32], addr[48];
char opts[] = {'F', 'T', 'N', 'R', 'r', '\0'};
const char *proto;
int i = 0;
if (emit_timestamp) {
time(&t);
tm = localtime(&t);
strftime(ts, sizeof(ts), "%H:%M:%S", tm);
printf("%8s ", ts);
}
if (e->proto == IPPROTO_TCP)
proto = "TCP";
else if (e->proto == IPPROTO_UDP)
proto = "UDP";
else
proto = "UNK";
while (opts[i]) {
if (!((1 << i) & e->opts)) {
opts[i] = '.';
}
i++;
}
if (e->ver == 4) {
inet_ntop(AF_INET, &e->addr, addr, sizeof(addr));
} else {
inet_ntop(AF_INET6, &e->addr, addr, sizeof(addr));
}
printf("%-7d %-16s %-3d %-5s %-5s %-4d %-5d %-48s\n",
e->pid, e->task, e->ret, proto, opts, e->bound_dev_if, e->port, addr);
}
static void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
{
warn("lost %llu events on CPU #%d\n", lost_cnt, cpu);
}
int main(int argc, char **argv)
{
static const struct argp argp = {
.options = opts,
.parser = parse_arg,
.doc = argp_program_doc,
};
struct perf_buffer_opts pb_opts;
struct perf_buffer *pb = NULL;
struct bindsnoop_bpf *obj;
int err, port_map_fd;
char *port;
short port_num;
err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
return err;
err = bump_memlock_rlimit();
if (err) {
warn("failed to increase rlimit: %d\n", err);
return 1;
}
obj = bindsnoop_bpf__open();
if (!obj) {
warn("failed to open BPF object\n");
return 1;
}
obj->rodata->target_pid = target_pid;
obj->rodata->ignore_errors = ignore_errors;
obj->rodata->filter_by_port = target_ports != NULL;
err = bindsnoop_bpf__load(obj);
if (err) {
warn("failed to load BPF object: %d\n", err);
goto cleanup;
}
if (target_ports) {
port_map_fd = bpf_map__fd(obj->maps.ports);
port = strtok(target_ports, ",");
while (port) {
port_num = strtol(port, NULL, 10);
bpf_map_update_elem(port_map_fd, &port_num, &port_num, BPF_ANY);
port = strtok(NULL, ",");
}
}
err = bindsnoop_bpf__attach(obj);
if (err) {
warn("failed to attach BPF programs: %d\n", err);
goto cleanup;
}
pb_opts.sample_cb = handle_event;
pb_opts.lost_cb = handle_lost_events;
pb = perf_buffer__new(bpf_map__fd(obj->maps.events),
PERF_BUFFER_PAGES, &pb_opts);
err = libbpf_get_error(pb);
if (err) {
warn("failed to open perf buffer: %d\n", err);
goto cleanup;
}
if (signal(SIGINT, sig_int) == SIG_ERR) {
warn("can't set signal handler: %s\n", strerror(-errno));
goto cleanup;
}
if (emit_timestamp)
printf("%-8s ", "TIME(s)");
printf("%-7s %-16s %-3s %-5s %-5s %-4s %-5s %-48s\n",
"PID", "COMM", "RET", "PROTO", "OPTS", "IF", "PORT", "ADDR");
while (1) {
if ((err = perf_buffer__poll(pb, PERF_POLL_TIMEOUT_MS)) < 0)
break;
if (exiting)
goto cleanup;
}
warn("error polling perf buffer: %d\n", err);
cleanup:
bindsnoop_bpf__destroy(obj);
return err != 0;
}