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vdecapture.c
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vdecapture.c
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/*
* vdecapture: capture vde traffic in pcap format
* Copyright (C) 2023 Renzo Davoli, Virtualsquare
*
* randmac is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <libgen.h>
#include <libvdeplug.h>
#include <inttypes.h>
#include <poll.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <getopt.h>
#include <sys/time.h>
#include <pcap/pcap.h>
#define PCAP_MAGIC 0xa1b2c3d4
#define SNAPLEN 65535
#define VERSION_MAJOR 2
#define VERSION_MINOR 4
#define UNUSED 0
struct pcap_pkthdr_filefmt {
uint32_t ts_sec; /* timestamp seconds */
uint32_t ts_usec; /* timestamp microseconds */
uint32_t caplen; /* length of portion present */
uint32_t len; /* length of this packet (off wire) */
};
#define VDECAPTURE_FLAG_QUIET 0x1
#define VDECAPTURE_FLAG_APPEND 0x2
struct options {
int maxcount;
size_t maxlen;
time_t maxtime;
int flags;
};
int terminate = 0;
int reload = 0;
void sighandler(int signo) {
if (signo == SIGHUP)
reload = 1;
else
terminate = 1;
}
static FILE *open_outfile(char *path, int append) {
FILE *f;
struct pcap_file_header hdr = {
PCAP_MAGIC,
VERSION_MAJOR, VERSION_MINOR,
UNUSED, UNUSED,
SNAPLEN,
1};
if (strcmp(path, "-") == 0) {
f = stdout;
fwrite(&hdr, sizeof(hdr), 1, f);
} else if (append) {
f = fopen(path, "a+");
if (f) {
struct pcap_file_header filehdr;
size_t hdrlen = fread(&filehdr, 1, sizeof(filehdr), f);
if (hdrlen == 0)
fwrite(&hdr, sizeof(hdr), 1, f);
else if (hdrlen != sizeof(filehdr) ||
memcmp(&hdr, &filehdr, sizeof(hdr)) != 0) {
fclose(f);
return errno = EBADF, NULL;
}
}
} else {
f = fopen(path, "w+");
if (f)
fwrite(&hdr, sizeof(hdr), 1, f);
}
return f;
}
static int mainloop(char *vnl, char *outpath, struct options *options) {
int count = 0;
size_t outlen = 0;
char buf[SNAPLEN];
FILE *f;
VDECONN *conn = vde_open(vnl, "vdecapture", NULL);
if (conn == NULL) {
fprintf(stderr, "vde_open error\n");
goto err_vde;
}
f = open_outfile(outpath, !!(options->flags & VDECAPTURE_FLAG_APPEND));
if (f == NULL) {
perror(outpath);
goto err_file;
}
if (options->maxtime > 0)
alarm(options->maxtime);
struct pollfd fds[] = {{vde_datafd(conn), POLLIN, 0}, {fileno(f), POLLERR, 0}};
while(terminate == 0) {
poll(fds, 2, 1000);
if (fds[0].revents & POLLIN) {
ssize_t n = vde_recv(conn, buf, SNAPLEN, 0);
if (n <= 0) break;
struct timeval tv;
gettimeofday(&tv, NULL);
struct pcap_pkthdr_filefmt phdr = {tv.tv_sec, tv.tv_usec, n, n};
outlen += n + sizeof(phdr);
if (options->maxlen > 0 && outlen > options->maxlen)
break;
if (fwrite(&phdr, sizeof(phdr), 1, f) == 0)
break;
if (fwrite(buf, n, 1, f) == 0)
break;
count++;
if (isatty(STDERR_FILENO) && !(options->flags & VDECAPTURE_FLAG_QUIET))
fprintf(stderr, "\r%d", count);
if (options->maxcount > 0 && count >= options->maxcount)
break;
} else if (fds[1].revents & POLLERR)
break;
else
fflush(f);
if (reload) {
reload = 0;
if (strcmp(outpath, "-") != 0) {
fclose(f);
f = open_outfile(outpath, !!(options->flags & VDECAPTURE_FLAG_APPEND));
if (f == NULL) {
perror(outpath);
goto err_file;
}
}
}
}
if (isatty(STDERR_FILENO) && !(options->flags & VDECAPTURE_FLAG_QUIET))
fprintf(stderr, "\n");
fclose(f);
vde_close(conn);
return 0;
err_file:
vde_close(conn);
err_vde:
return 1;
}
static char *short_options = "c:s:t:aqh";
static struct option long_options[] = {
{"count", required_argument, 0, 'c' },
{"size", required_argument, 0, 's' },
{"time", required_argument, 0, 't' },
{"quiet", no_argument, 0, 'q' },
{"append",no_argument, 0, 'a' },
{"help", no_argument, 0, 'h' },
{0, 0, 0, 0 }
};
static void usage_exit(char *progname) {
fprintf(stderr,
"Usage: %s [OPTIONS] VNL outfile\n"
" VNL is the Virtual Network Locator (e.g. hub:///tmp/hub)\n"
" see vde_plug(1)]\n"
" outfile is the pathname of the output file (- means stdout)\n\n"
"OPTIONS:\n"
" -c, --count max number of captured packets\n"
" -s, --size max size of the output file\n"
" -t, --time max capture time\n"
" -a, --append append data if the output file exists\n"
" -q, --quiet do not print packet counter on stderr\n"
" -h, --help display this help and exit\n"
"\n", progname);
exit(1);
}
int main(int argc, char *argv[]) {
static struct options options;
char *vnl;
char *outpath;
while (1) {
int option_index = 0;
int c = getopt_long(argc, argv, short_options,
long_options, &option_index);
if (c == -1)
break;
switch (c) {
case 'c': options.maxcount = strtol(optarg, NULL, 10); break;
case 's': options.maxlen = strtoll(optarg, NULL, 10); break;
case 't': options.maxtime = strtol(optarg, NULL, 10); break;
case 'a': options.flags |= VDECAPTURE_FLAG_APPEND; break;
case 'q': options.flags |= VDECAPTURE_FLAG_QUIET; break;
case 'h':
default: usage_exit(basename(argv[0]));
}
}
if (optind + 2 != argc)
usage_exit(basename(argv[0]));
vnl = argv[optind];
outpath = argv[optind + 1];
signal(SIGINT, sighandler);
signal(SIGINT, sighandler);
signal(SIGALRM, sighandler);
signal(SIGHUP, sighandler);
return mainloop(vnl, outpath, &options);
}