Add dissector for the osmux protocol

The Osmux protocol bundles multiple AMR frames inside one UDP packet to avoid
the overhead of having one IP/UDP/RTP packet per AMR frame. It is used by the
osmocom project.

Sponsored-by: On-Waves ehf
Change-Id: I8fb21e54adec8d8bd7ac5ebd2154100a73ab71c9
Reviewed-on: https://code.wireshark.org/review/16996
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 309 insertions, 0 deletions

diff --git a/epan/dissectors/packet-gsm_osmux.c b/epan/dissectors/packet-gsm_osmux.c
new file mode 100644
index 0000000000..e452405352
--- /dev/null
+++ b/epan/dissectors/packet-gsm_osmux.c
@@ -0,0 +1,309 @@
+/* packet-gsm_osmux.c
+ * Routines for packet dissection of Osmux voice/signalling multiplex protocol
+ * Copyright 2016 sysmocom s.f.m.c Daniel Willmann <dwillmann@sysmocom.de>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * 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 "config.h"
+
+#include <string.h>
+#include <stdio.h>
+
+#include <epan/packet.h>
+#include <epan/stats_tree.h>
+#include <epan/tap.h>
+#include <epan/to_str.h>
+#include <epan/strutil.h>
+#include "packet-gsm_osmux.h"
+
+void proto_register_osmux(void);
+void proto_reg_handoff_osmux(void);
+
+static const value_string osmux_ft_vals[] =
+{
+    {0x00, "Signalling"},
+    {0x01, "AMR"},
+    {0x02, "Dummy"},
+    {0, NULL}
+};
+
+/* Initialize the protocol and registered fields */
+static dissector_handle_t osmux_handle;
+static int proto_osmux = -1;
+static int osmux_tap = -1;
+
+static int hf_osmux_ft_ctr = -1;
+static int hf_osmux_ft = -1;
+static int hf_osmux_ctr = -1;
+static int hf_osmux_amr_f = -1;
+static int hf_osmux_amr_q = -1;
+static int hf_osmux_seq = -1;
+static int hf_osmux_circuit_id = -1;
+static int hf_osmux_amr_ft_cmr = -1;
+static int hf_osmux_amr_ft = -1;
+static int hf_osmux_amr_cmr = -1;
+static int hf_osmux_amr_data = -1;
+
+/* Initialize the subtree pointers */
+static gint ett_osmux = -1;
+static gint ett_osmux_ft_ctr = -1;
+static gint ett_osmux_amr_ft_cmr = -1;
+
+
+/* Code to actually dissect the packets */
+static gint
+dissect_osmux(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
+{
+    static const gint *ft_ctr_fields[] = {
+        &hf_osmux_ft,
+        &hf_osmux_ctr,
+        &hf_osmux_amr_f,
+        &hf_osmux_amr_q,
+        NULL
+    };
+    static const gint *amr_ft_cmr_fields[] = {
+        &hf_osmux_amr_ft,
+        &hf_osmux_amr_cmr,
+        NULL
+    };
+
+    int offset = 0;
+
+    struct osmux_hdr *osmuxh;
+    proto_item *ti;
+    proto_tree *osmux_tree = NULL;
+    guint8 ft_ctr;
+    guint32 cid;
+    guint64 amr_ft_cmr;
+
+    col_set_str(pinfo->cinfo, COL_PROTOCOL, "Osmux");
+    col_clear(pinfo->cinfo, COL_INFO);
+
+    osmuxh = wmem_new0(wmem_packet_scope(), struct osmux_hdr);
+
+    ft_ctr = tvb_get_guint8(tvb, offset);
+
+    osmuxh->ft = ft_ctr >> 5;
+    osmuxh->ctr = (ft_ctr >> 2) & 0x7;
+    osmuxh->amr_q = !!(ft_ctr & 0x02);
+    osmuxh->amr_f = !!(ft_ctr & 0x01);
+
+    col_append_fstr(pinfo->cinfo, COL_INFO, "Osmux ");
+
+    ti = proto_tree_add_protocol_format(tree, proto_osmux, tvb, offset, -1,
+            "Osmux type %s frame",
+            val_to_str(osmuxh->ft, osmux_ft_vals, "unknown 0x%02x"));
+    osmux_tree = proto_item_add_subtree(ti, ett_osmux);
+
+    /* Two-byte dummy packets for firewalls (starts with 0x23) */
+    if (ft_ctr == 0x23 && tvb_reported_length(tvb) >= 2) {
+        proto_tree_add_item_ret_uint(osmux_tree, hf_osmux_circuit_id, tvb, offset+1, 1, ENC_BIG_ENDIAN, &cid);
+        col_append_fstr(pinfo->cinfo, COL_INFO, "Dummy frame (CID %u)", cid);
+        return 2;
+    }
+
+    col_append_fstr(pinfo->cinfo, COL_INFO, "%s ",
+                    val_to_str(osmuxh->ft, osmux_ft_vals,
+                               "unknown 0x%02x"));
+
+    proto_tree_add_bitmask(osmux_tree, tvb, offset, hf_osmux_ft_ctr,
+            ett_osmux_ft_ctr, ft_ctr_fields, ENC_BIG_ENDIAN);
+    offset++;
+
+    proto_tree_add_item_ret_uint(osmux_tree, hf_osmux_seq, tvb, offset, 1, ENC_BIG_ENDIAN, &osmuxh->seq);
+    offset++;
+    proto_tree_add_item_ret_uint(osmux_tree, hf_osmux_circuit_id, tvb, offset, 1, ENC_BIG_ENDIAN, &osmuxh->circuit_id);
+    offset++;
+
+    proto_tree_add_bitmask_ret_uint64(osmux_tree, tvb, offset, hf_osmux_amr_ft_cmr,
+            ett_osmux_amr_ft_cmr, amr_ft_cmr_fields, ENC_BIG_ENDIAN, &amr_ft_cmr);
+    offset++;
+    osmuxh->amr_ft = (amr_ft_cmr & 0xf0) >> 4;
+    osmuxh->amr_cmr = amr_ft_cmr & 0x0f;
+
+
+    proto_tree_add_item(osmux_tree, hf_osmux_amr_data, tvb, offset, tvb_reported_length_remaining(tvb, offset), ENC_NA);
+
+    tap_queue_packet(osmux_tap, pinfo, osmuxh);
+
+    return tvb_reported_length(tvb);
+}
+
+/* Statistics */
+static const gchar *st_str_pkts = "Osmux Packets";
+static const gchar *st_str_pkts_by_cid = "Osmux Packets by CID";
+static const gchar *st_str_pkts_by_ctr = "Osmux Packets by AMR frame count";
+static const gchar *st_str_pkts_by_src = "Osmux Packets by src Addr";
+static const gchar *st_str_pkts_by_dst = "Osmux Packets by dst Addr";
+static const gchar *st_str_pkts_by_conn = "Osmux Packets by stream";
+
+static int st_osmux_stats = -1;
+static int st_osmux_stats_cid = -1;
+static int st_osmux_stats_ctr = -1;
+static int st_osmux_stats_src = -1;
+static int st_osmux_stats_dst = -1;
+static int st_osmux_stats_conn = -1;
+
+static void osmux_stats_tree_init(stats_tree *st)
+{
+    st_osmux_stats = stats_tree_create_node(st, st_str_pkts, 0, TRUE);
+    st_osmux_stats_cid = stats_tree_create_node(st, st_str_pkts_by_cid, st_osmux_stats, TRUE);
+    st_osmux_stats_ctr = stats_tree_create_node(st, st_str_pkts_by_ctr, st_osmux_stats, TRUE);
+    st_osmux_stats_src = stats_tree_create_node(st, st_str_pkts_by_src, st_osmux_stats, TRUE);
+    st_osmux_stats_dst = stats_tree_create_node(st, st_str_pkts_by_dst, st_osmux_stats, TRUE);
+    st_osmux_stats_conn = stats_tree_create_node(st, st_str_pkts_by_conn, st_osmux_stats, TRUE);
+}
+
+static int osmux_stats_tree_packet(stats_tree *st, packet_info *pinfo,
+        epan_dissect_t *edt _U_, const void *p _U_)
+{
+    gchar *ip_str, *ip2_str;
+    gchar temp[40];
+    struct osmux_hdr *osmuxh = (struct osmux_hdr*) p;
+
+
+    tick_stat_node(st, st_str_pkts, 0, FALSE);
+
+    tick_stat_node(st, st_str_pkts_by_cid, st_osmux_stats, FALSE);
+    g_snprintf(temp, 30, "%i", osmuxh->circuit_id);
+    tick_stat_node(st, temp, st_osmux_stats_cid, TRUE);
+
+    tick_stat_node(st, st_str_pkts_by_ctr, st_osmux_stats, FALSE);
+    g_snprintf(temp, 30, "%i", osmuxh->ctr);
+    tick_stat_node(st, temp, st_osmux_stats_ctr, TRUE);
+
+    tick_stat_node(st, st_str_pkts_by_src, 0, FALSE);
+    ip_str = address_to_str(NULL, &pinfo->src);
+    tick_stat_node(st, ip_str, st_osmux_stats_src, TRUE);
+
+    tick_stat_node(st, st_str_pkts_by_dst, 0, FALSE);
+    ip2_str = address_to_str(NULL, &pinfo->dst);
+    tick_stat_node(st, ip2_str, st_osmux_stats_dst, TRUE);
+
+    tick_stat_node(st, st_str_pkts_by_conn, 0, FALSE);
+    g_snprintf(temp, 40, "%s->%s:%i", ip_str, ip2_str, osmuxh->circuit_id);
+    tick_stat_node(st, temp, st_osmux_stats_conn, TRUE);
+
+    wmem_free(NULL, ip_str);
+    wmem_free(NULL, ip2_str);
+
+    return 1;
+}
+
+void proto_register_osmux(void)
+{
+    static hf_register_info hf[] = {
+        {&hf_osmux_ft_ctr,
+         {"FTCTRByte", "osmux.ft_ctr",
+          FT_UINT8, BASE_DEC, NULL, 0x00,
+          "Byte with Fieldtype, Counter", HFILL}
+        },
+        {&hf_osmux_ft,
+         {"FieldType", "osmux.ft",
+          FT_UINT8, BASE_DEC, VALS(osmux_ft_vals), 0xe0,
+          "Type of data in packet", HFILL}
+         },
+        {&hf_osmux_ctr,
+         {"CTR", "osmux.ctr",
+          FT_UINT8, BASE_HEX, NULL, 0x1c,
+          "Number of AMR packets inside", HFILL}
+         },
+        {&hf_osmux_amr_q,
+         {"AMR f", "osmux.amr_f",
+          FT_BOOLEAN, 8, NULL, 0x02,
+          "AMR f parameter", HFILL}
+         },
+        {&hf_osmux_amr_f,
+         {"AMR q", "osmux.amr_q",
+          FT_BOOLEAN, 8, NULL, 0x01,
+          "AMR q parameter", HFILL}
+         },
+        {&hf_osmux_seq,
+         {"Seq", "osmux.seq",
+          FT_UINT8, BASE_HEX, NULL, 0x0,
+          "Sequence number", HFILL}
+         },
+        {&hf_osmux_circuit_id,
+         {"Circuit ID", "osmux.circuit_id",
+          FT_UINT8, BASE_HEX, NULL, 0x0,
+          NULL, HFILL}
+         },
+        {&hf_osmux_amr_ft_cmr,
+         {"AMR info", "osmux.amr_ft_cmr",
+          FT_UINT8, BASE_DEC, NULL, 0x00,
+          "Byte with AMR params ft and cmr", HFILL}
+        },
+        {&hf_osmux_amr_ft,
+         {"AMR ft", "osmux.amr_ft",
+          FT_UINT8, BASE_HEX, NULL, 0xf0,
+          "AMR parameter ft", HFILL}
+         },
+        {&hf_osmux_amr_cmr,
+         {"AMR cmr", "osmux.amr_cmr",
+          FT_UINT8, BASE_HEX, NULL, 0x0f,
+          "AMR parameter cmr", HFILL}
+         },
+        {&hf_osmux_amr_data,
+         {"AMR data", "osmux.amr_data",
+          FT_BYTES, BASE_NONE, NULL, 0x00,
+          "AMR voice data", HFILL}
+         },
+    };
+
+    static gint *ett[] = {
+        &ett_osmux,
+        &ett_osmux_ft_ctr,
+        &ett_osmux_amr_ft_cmr,
+    };
+
+    proto_osmux = proto_register_protocol("GSM multiplexing for AMR", "GSM Osmux", "osmux");
+
+    proto_register_field_array(proto_osmux, hf, array_length(hf));
+    proto_register_subtree_array(ett, array_length(ett));
+}
+
+
+void proto_reg_handoff_osmux(void)
+{
+    static gboolean osmux_initialized = FALSE;
+
+    if (!osmux_initialized) {
+        osmux_handle = create_dissector_handle(dissect_osmux, proto_osmux);
+        dissector_add_for_decode_as("udp.port", osmux_handle);
+        osmux_tap = register_tap("osmux");
+        osmux_initialized = TRUE;
+        stats_tree_register("osmux", "osmux", "Osmux/Packets", 0,
+                osmux_stats_tree_packet, osmux_stats_tree_init,
+                NULL);
+    }
+}
+
+/*
+ * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */