Review at https://gerrit.osmocom.org/6516
utils: add osmo-gsmtap-sink, simplistic UDP receiver Yes, I know, but this is even simpler than a netcat. Change-Id: I85499af06bc5a0d757f6071779075e57bb435930 --- M utils/Makefile.am A utils/osmo-gsmtap-sink.c 2 files changed, 121 insertions(+), 1 deletion(-) git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/16/6516/1 diff --git a/utils/Makefile.am b/utils/Makefile.am index d4999bd..6b80b3e 100644 --- a/utils/Makefile.am +++ b/utils/Makefile.am @@ -5,12 +5,14 @@ EXTRA_DIST = conv_gen.py conv_codes_gsm.py -bin_PROGRAMS = osmo-arfcn osmo-auc-gen +bin_PROGRAMS = osmo-arfcn osmo-auc-gen osmo-gsmtap-sink osmo_arfcn_SOURCES = osmo-arfcn.c osmo_auc_gen_SOURCES = osmo-auc-gen.c +osmo_gsmtap_sink_SOURCES = osmo-gsmtap-sink.c + if ENABLE_PCSC noinst_PROGRAMS = osmo-sim-test osmo_sim_test_SOURCES = osmo-sim-test.c diff --git a/utils/osmo-gsmtap-sink.c b/utils/osmo-gsmtap-sink.c new file mode 100644 index 0000000..3f4bf51 --- /dev/null +++ b/utils/osmo-gsmtap-sink.c @@ -0,0 +1,118 @@ +/*! \file osmo-gsmtap-sink.c + * Receive GSMTAP without causing ICMP reject messages */ +/* + * (C) 2018 by sysmocom - s.f.m.c. GmbH <i...@sysmocom.de> + * + * All Rights Reserved + * + * Author: Neels Hofmeyr <nhofm...@sysmocom.de> + * + * This program 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, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + */ + +#include <stdlib.h> +#include <stdio.h> +#include <stdint.h> +#include <getopt.h> +#include <netinet/in.h> +#include <stdbool.h> + +#include <osmocom/core/socket.h> +#include <osmocom/core/gsmtap.h> +#include <osmocom/core/select.h> + +static void help(const char *progname) +{ + printf("Usage: %s [-hv] [<local-ip> [<local-port>]]\n" + "\n" + "Bind to UDP local-ip:local-port, read and discard everything received.\n" + "Default is to listen on 'any' interface at the GSMTAP port %u\n" + "(hence invoking this is a no-brainer compared to e.g. a netcat).\n" + "\n" + "Rationale: sending GSMTAP has the sole purpose of being picked up by a\n" + "network trace like tcpdump. However, sending GSMTAP to an unbound port\n" + "will trigger ICMP packets to indicate rejection, and this may even\n" + "cause GSMTAP packets to go missing from the trace. Simply launch this\n" + "program, a black hole to receive GSMTAP, to resolve these problems.\n" + "\n" + " -h show help\n" + " -v verbose: print a dot for each received packet\n", + progname, GSMTAP_UDP_PORT); +} + +bool verbose = false; + +int receive_cb(struct osmo_fd *ofd, unsigned int what) +{ + static uint8_t buf[4096]; + + if (!(what & BSC_FD_READ)) + return 0; + + recv(ofd->fd, buf, sizeof(buf), 0); + if (verbose) { + printf("."); + fflush(stdout); + } + return 0; +} + +int main(int argc, char **argv) +{ + int opt; + char *local_ip = NULL; + uint16_t local_port = GSMTAP_UDP_PORT; + struct osmo_fd ofd; + + while ((opt = getopt(argc, argv, "hv")) != -1) { + switch (opt) { + case 'v': + verbose = true; + break; + case 'h': + help(argv[0]); + exit(0); + break; + default: + break; + } + } + + if (argc - optind > 0) { + local_ip = argv[optind++]; + } + + if (argc - optind > 0) { + local_port = atoi(argv[optind++]); + } + + if (argc - optind > 0) { + help(argv[0]); + exit(0); + } + + ofd.cb = receive_cb; + osmo_sock_init_ofd(&ofd, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, + local_ip, local_port, OSMO_SOCK_F_BIND); + + while (1) { + int rc; + rc = osmo_select_main(0); + if (rc < 0) + exit(1); + } + exit(0); +} -- To view, visit https://gerrit.osmocom.org/6516 To unsubscribe, visit https://gerrit.osmocom.org/settings Gerrit-MessageType: newchange Gerrit-Change-Id: I85499af06bc5a0d757f6071779075e57bb435930 Gerrit-PatchSet: 1 Gerrit-Project: libosmocore Gerrit-Branch: master Gerrit-Owner: Neels Hofmeyr <nhofm...@sysmocom.de>