Change in osmo-tetra[master]: allow dumping GSMTAP to PCAP file

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Jan Hrach gerrit-no-reply at lists.osmocom.org
Mon Jul 30 20:57:31 UTC 2018


Jan Hrach has uploaded this change for review. ( https://gerrit.osmocom.org/10265


Change subject: allow dumping GSMTAP to PCAP file
......................................................................

allow dumping GSMTAP to PCAP file

When lots of packets are streamed to loopback, some of them get mixed up and
lost.

Add an option to write GSMTAP frames to a file (or a pipe for realtime
processing). Also add an option to disable streaming them via network.

Change-Id: I955589a1d576f180fc4b80dba8ed8dc364e43d8b
---
A src/pcap.h
M src/tetra-rx-tests.sh
M src/tetra-rx.c
M src/tetra_common.h
M src/tetra_gsmtap.c
M src/tetra_gsmtap.h
6 files changed, 132 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-tetra refs/changes/65/10265/1

diff --git a/src/pcap.h b/src/pcap.h
new file mode 100644
index 0000000..f3efe07
--- /dev/null
+++ b/src/pcap.h
@@ -0,0 +1,51 @@
+#ifndef PCAP_H
+#define PCAP_H
+#include <inttypes.h>
+
+typedef uint32_t guint32;
+typedef uint16_t guint16;
+typedef int32_t gint32;
+
+typedef struct __attribute__ ((__packed__)) pcap_hdr_s {
+	guint32 magic_number;   /* magic number */
+	guint16 version_major;  /* major version number */
+	guint16 version_minor;  /* minor version number */
+	gint32  thiszone;       /* GMT to local correction */
+	guint32 sigfigs;	/* accuracy of timestamps */
+	guint32 snaplen;	/* max length of captured packets, in octets */
+	guint32 network;	/* data link type */
+} pcap_hdr_t;
+
+typedef struct __attribute__ ((__packed__)) pcaprec_hdr_s {
+	guint32 ts_sec;	 /* timestamp seconds */
+	guint32 ts_usec;	/* timestamp microseconds */
+	guint32 incl_len;       /* number of octets of packet saved in file */
+	guint32 orig_len;       /* actual length of packet */
+} pcaprec_hdr_t;
+
+#define	PCAP_MAGIC	0xa1b2c3d4
+#define	PCAP_MAJOR	2
+#define	PCAP_MINOR	4
+#define	PCAP_SNAPLEN	65535
+#define	PCAP_ETHERNET	1
+
+unsigned char fake_frame_header[] = {
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Ethernet frame, dst and src MAC
+	0x08, 0x00,		// EtherType 0800 = IPv4
+	0x45,			// IPv4 (0x4_), 20B header (0x_5)
+	0x00,			// no diffserv
+	0x00, 0xff,		// length
+	0xc6, 0xd1,		// some random frag
+	0x40, 0x00,		// don't frag
+	0x3f,			// TTL
+	0x11,			// IP proto = UDP
+	0x00, 0x00,		// checksum
+	0x7f, 0x00, 0x00, 0x01,	// src = 127.0.0.1
+	0x7f, 0x00, 0x00, 0x01, // dst = 127.0.0.1
+	0xbb, 0x13,		// source port
+	0x12, 0x79,		// dst port = 4729
+	0x00, 0xeb,		// length = iplen-20
+	0x00, 0x00		// checksum
+};
+#endif
+
diff --git a/src/tetra-rx-tests.sh b/src/tetra-rx-tests.sh
index f84a1ad..d841f0c 100755
--- a/src/tetra-rx-tests.sh
+++ b/src/tetra-rx-tests.sh
@@ -53,7 +53,7 @@
 tmpdir=`mktemp -d /tmp/tetraXXX`
 
 for f in $@; do
-	corrects=`"time" -o "$tmpdir/time" ./tetra-rx "$f" $t 2>/dev/null | grep -E "^CRC COMP: 0x.+ OK" | wc -l`
+	corrects=`"time" -o "$tmpdir/time" ./tetra-rx -n "$f" $t 2>/dev/null | grep -E "^CRC COMP: 0x.+ OK" | wc -l`
 	tt=`grep user "$tmpdir/time" | head -n 1 | cut -d u -f 1`
 	echo "$f: $corrects frames, $tt s"
 	hash=`sha256sum "$f" | cut -c 1-20`
diff --git a/src/tetra-rx.c b/src/tetra-rx.c
index ed4d252..8498f8c 100644
--- a/src/tetra-rx.c
+++ b/src/tetra-rx.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <stdbool.h>
 
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -43,24 +44,42 @@
 	struct tetra_rx_state *trs;
 	struct tetra_mac_state *tms;
 
+	char *pcap_file_path = NULL;
+	bool no_udp_tap = false;
+	bool err = false;
+
 	tms = talloc_zero(tetra_tall_ctx, struct tetra_mac_state);
 	tetra_mac_state_init(tms);
 
 	trs = talloc_zero(tetra_tall_ctx, struct tetra_rx_state);
 	trs->burst_cb_priv = tms;
 
-	while ((opt = getopt(argc, argv, "d:")) != -1) {
+	while ((opt = getopt(argc, argv, "a:t:d:n")) != -1) {
 		switch (opt) {
+		case 'a':
+			tms->arfcn = atoi(optarg);
+			break;
+		case 't':
+			pcap_file_path = strdup(optarg);
+			break;
 		case 'd':
 			tms->dumpdir = strdup(optarg);
 			break;
+		case 'n':
+			no_udp_tap = 1;
+			break;
 		default:
 			fprintf(stderr, "Unknown option %c\n", opt);
+			err = true;
 		}
 	}
 
-	if (argc <= optind) {
-		fprintf(stderr, "Usage: %s [-d DUMPDIR] <file_with_1_byte_per_bit>\n", argv[0]);
+	if (argc <= optind || err) {
+		fprintf(stderr, "Usage: %s [params] <file_with_1_byte_per_bit>\n", argv[0]);
+		fprintf(stderr, " -a arfcn     .. set ARFCN used in GSMTAP\n");
+		fprintf(stderr, " -t filename  .. output PCAP to file\n");
+		fprintf(stderr, " -d directory .. dump traffic channel to directory\n");
+		fprintf(stderr, " -n           .. disable GSMTAP over UDP\n");
 		exit(1);
 	}
 
@@ -70,7 +89,11 @@
 		exit(2);
 	}
 
-	tetra_gsmtap_init("localhost", 0);
+	if (!no_udp_tap)
+		tetra_gsmtap_init_network("localhost", 0);
+
+	if (pcap_file_path)
+		tetra_gsmtap_init_file(pcap_file_path);
 
 	while (1) {
 		uint8_t buf[64];
diff --git a/src/tetra_common.h b/src/tetra_common.h
index d141e9b..a270a26 100644
--- a/src/tetra_common.h
+++ b/src/tetra_common.h
@@ -52,6 +52,7 @@
 	char *dumpdir;	/* Where to save traffic channel dump */
 	int ssi;	/* SSI */
 	int tsn;	/* Timeslon number */
+	int arfcn;
 };
 
 void tetra_mac_state_init(struct tetra_mac_state *tms);
diff --git a/src/tetra_gsmtap.c b/src/tetra_gsmtap.c
index 79b48a7..b656ff6 100644
--- a/src/tetra_gsmtap.c
+++ b/src/tetra_gsmtap.c
@@ -4,6 +4,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
+#include <time.h>
 
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/gsmtap.h>
@@ -13,6 +14,9 @@
 
 #include "tetra_common.h"
 #include "tetra_tdma.h"
+#include "pcap.h"
+
+static FILE * pcap_file;
 
 static struct gsmtap_inst *g_gti = NULL;
 
@@ -62,15 +66,38 @@
 	return msg;
 }
 
+static void pcap_file_write(void *buf, size_t n)
+{
+	if (pcap_file) {
+		fwrite(buf, n, 1, pcap_file);
+		fflush(pcap_file);
+	}
+}
+
 int tetra_gsmtap_sendmsg(struct msgb *msg)
 {
+	pcaprec_hdr_t hdr = {0};
+
+	struct timespec now;
+
+	clock_gettime(CLOCK_REALTIME, &now);
+
+	hdr.ts_sec = now.tv_sec;
+	hdr.ts_usec = now.tv_nsec/1000;
+	hdr.incl_len = msg->len + sizeof(fake_frame_header);
+	hdr.orig_len = hdr.incl_len;
+
+	pcap_file_write(&hdr, sizeof(hdr));
+	pcap_file_write(&fake_frame_header, sizeof(fake_frame_header));
+	pcap_file_write(msg->data, msg->len);
+
 	if (g_gti)
 		return gsmtap_sendmsg(g_gti, msg);
 	else
 		return 0;
 }
 
-int tetra_gsmtap_init(const char *host, uint16_t port)
+int tetra_gsmtap_init_network(const char *host, uint16_t port)
 {
 	g_gti = gsmtap_source_init(host, port, 0);
 	if (!g_gti)
@@ -79,3 +106,25 @@
 
 	return 0;
 }
+
+int tetra_gsmtap_init_file(const char *filename)
+{
+	pcap_hdr_t hdr;
+
+	memset(&hdr, 0, sizeof(hdr));
+
+	hdr.magic_number = PCAP_MAGIC;
+	hdr.version_major = PCAP_MAJOR;
+	hdr.version_minor = PCAP_MINOR;
+	hdr.snaplen = PCAP_SNAPLEN;
+	hdr.network = PCAP_ETHERNET;
+
+	pcap_file = fopen(filename, "wb");
+	if (!pcap_file) {
+		perror("pcap file open");
+		exit(1);
+	}
+	pcap_file_write(&hdr, sizeof(pcap_hdr_t));
+
+	return 0;
+}
diff --git a/src/tetra_gsmtap.h b/src/tetra_gsmtap.h
index 34963d0..6f77240 100644
--- a/src/tetra_gsmtap.h
+++ b/src/tetra_gsmtap.h
@@ -8,6 +8,7 @@
 
 int tetra_gsmtap_sendmsg(struct msgb *msg);
 
-int tetra_gsmtap_init(const char *host, uint16_t port);
+int tetra_gsmtap_init_network(const char *host, uint16_t port);
+int tetra_gsmtap_init_file(const char *filename);
 
 #endif

-- 
To view, visit https://gerrit.osmocom.org/10265
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Gerrit-Project: osmo-tetra
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I955589a1d576f180fc4b80dba8ed8dc364e43d8b
Gerrit-Change-Number: 10265
Gerrit-PatchSet: 1
Gerrit-Owner: Jan Hrach <jenda.2vf9h at hrach.eu>
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