From 9b207419105c5e07504b1b7bf380eda07c127bb2 Mon Sep 17 00:00:00 2001
From: Alexander Couzens <lynxis@fe80.eu>
Date: Mon, 27 May 2019 03:44:39 +0200
Subject: utils: add gsmtap_logread.py a gsmtap log reader

Receive gsmtap logs and feeds it into the python logging
framework. Allows to use generic logging features and
further utilities.

Change-Id: I24478d8e16066c6118e867bdba54c6418c15e170
---
 utils/gsmtap.py | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 utils/gsmtap.py

(limited to 'utils/gsmtap.py')

diff --git a/utils/gsmtap.py b/utils/gsmtap.py
new file mode 100644
index 00000000..b7211adf
--- /dev/null
+++ b/utils/gsmtap.py
@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# License: MIT
+# Copyright 2019 by Sysmocom s.f.m.c. GmbH
+# Author: Alexander Couzens <lynxis@fe80.eu>
+
+import struct
+
+GSMTAP_VERSION = 0x02
+
+GSMTAP_TYPE_OSMOCORE_LOG = 0x10
+
+class TooSmall(RuntimeError):
+    pass
+
+# struct gsmtap_hdr {
+#     uint8_t version;    /*!< version, set to 0x01 currently */
+#     uint8_t hdr_len;    /*!< length in number of 32bit words */
+#     uint8_t type;       /*!< see GSMTAP_TYPE_* */
+#     uint8_t timeslot;   /*!< timeslot (0..7 on Um) */
+#
+#     uint16_t arfcn;     /*!< ARFCN (frequency) */
+#     int8_t signal_dbm;  /*!< signal level in dBm */
+#     int8_t snr_db;      /*!< signal/noise ratio in dB */
+#
+#     uint32_t frame_number;  /*!< GSM Frame Number (FN) */
+#
+#     uint8_t sub_type;   /*!< Type of burst/channel, see above */
+#     uint8_t antenna_nr; /*!< Antenna Number */
+#     uint8_t sub_slot;   /*!< sub-slot within timeslot */
+#     uint8_t res;        /*!< reserved for future use (RFU) */
+#
+# }
+
+class gsmtap_hdr():
+    def __init__(self, data):
+        if len(data) < 2:
+            raise TooSmall()
+        self.version, self.hdr_len = struct.unpack('!BB', data[0:2])
+        self.hdr_len *= 4
+
+        if self.hdr_len >= 3:
+            self.type = struct.unpack('!B', data[2:3])[0]
+
+# /*! Structure of the GSMTAP libosmocore logging header */
+# struct gsmtap_osmocore_log_hdr {
+# 	struct {
+# 		uint32_t sec;
+# 		uint32_t usec;
+# 	} ts;
+# 	char proc_name[16];	/*!< name of process */
+# 	uint32_t pid;		/*!< process ID */
+# 	uint8_t level;		/*!< logging level */
+# 	uint8_t _pad[3];
+# 	/* TODO: color */
+# 	char subsys[16];	/*!< logging sub-system */
+# 	struct {
+# 		char name[32];	/*!< source file name */
+# 		uint32_t line_nr;/*!< line number */
+# 	} src_file;
+# } __attribute__((packed));
+
+class gsmtap_log():
+    def __init__(self, data):
+        packformat = '!II16sIBxxx16s32sI'
+        packlen = struct.calcsize(packformat)
+        if len(data) < packlen:
+            raise TooSmall()
+        self.sec, self.usec, \
+                self.proc_name, self.pid, \
+                self.level, self.subsys, \
+                self.filename, self.fileline_nr = struct.unpack(packformat, data[:packlen])
+
+        message_len = len(data) - packlen
+        if message_len > 0:
+            self.message = data[packlen:].decode('utf-8')
-- 
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