strace-rild: add

Add scripts used to figure out IMS related AT commands.

src/trace-rild/README.md

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+Scripts to run strace + tcpdump on mtkfusionrild and to extract AT commands
+from the strace dump.
+
+Preparation:
+- Rooted Android
+- Termux installed, sshd enabled and running
+- strace, tsu, tcpdump installed
+
+Usage:
+1. run dump.sh
+2. run parse_strace.py to get AT commands form the strace dump

src/trace-rild/dump.sh

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+#!/bin/sh -ex
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+
+dump_name="$(date "+%Y-%m-%d_%H%M%S")"
+
+adb push dump_run_on_phone.sh /mnt/sdcard/Download/
+adb forward tcp:8022 tcp:8022
+ssh -p 8022 localhost \
+	sh -e /mnt/sdcard/Download/dump_run_on_phone.sh "$dump_name"
+
+mkdir -p dump
+adb pull /mnt/sdcard/Download/dump/"$dump_name" dump/"$dump_name"

src/trace-rild/dump_run_on_phone.sh

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+#!/bin/sh -e
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+#
+# dump.sh copies this file to Android and runs it
+
+rild="mtkfusionrild"
+strsize="1000"
+dump_name="$1"
+pid="$(sudo ps ax | grep "$rild" | grep -v grep | head -n1 | awk '{print $1}')"
+outdir="/mnt/sdcard/Download/dump/$1"
+
+clean_up() {
+	sudo killall -9 strace tcpdump || true 2>/dev/null
+}
+
+if [ -d "$outdir" ]; then
+	echo "ERROR: outdir already exists: $outdir"
+	exit 1
+fi
+
+if [ -z "$pid" ]; then
+	echo "ERROR: failed to get pid of $rild"
+	exit 1
+fi
+
+mkdir -p "$outdir"
+set -x
+
+clean_up
+
+sudo tcpdump \
+	-U \
+	-i any \
+	-n not port 8022 \
+	-s0 \
+	-w "$outdir/$1.pcap" \
+	&
+
+sudo strace \
+	-f \
+	-o "$outdir/$1_$rild.strace" \
+	-p "$pid" \
+	-r \
+	-s "$strsize" \
+	-ttt \
+	-v \
+	-y \
+	&
+
+sleep 1
+
+set +x
+echo
+echo
+echo "rild: $rild (pid: $pid)"
+echo "Capturing to: $outdir"
+echo "Press return to stop capturing"
+echo
+echo
+read foo
+
+set -x
+clean_up
+echo "Capture stopped"

src/trace-rild/parse_strace.py

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+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+import argparse
+import sys
+import datetime
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(prog="parse_strace")
+    parser.add_argument("strace_file",
+                        help="an strace file generated by dump.sh")
+    args = parser.parse_args()
+    return args
+
+def parse_iov_str(iov):
+    """
+    :param iov: strace iov string, looks like this:
+                '[{iov_base="AT\0", iov_len=3}, {iov_base="[0] AT< +EXLCE:...'
+    :returns: list of iov strings, e.g.:
+                ["AT", "[0] AT< +EXLCE:...", ...]
+    """
+    ret = []
+
+    assert iov.startswith("[{")
+    rest = iov[2:]
+    while rest:
+        if rest.startswith("iov_base=\""):
+            key_value, rest = rest.split(', iov_len', 1)
+            value = key_value.split('"', 1)[1]
+            ret += [value]
+        elif rest.startswith("="):
+            iov_len, rest = rest.split("}", 1)
+        elif rest.startswith(", {"):
+            _, rest = rest.split("{", 1)
+        elif rest.startswith("]"):
+            # parts at the end of writev are not interesting: iov count and
+            # bytes written
+            break
+        else:
+            assert False, f"failed to parse rest of iov:" \
+                          f"\n\niov: {iov}" \
+                          f"\n\nrest: {rest}"
+    return ret
+
+
+def parse_at(cmd):
+    is_at = False
+    i = 0
+    for i in range(len(cmd["iov"])):
+        iov_base = cmd["iov"][i]
+        if iov_base.startswith("[0] AT"):
+            is_at = True
+            break
+    if not is_at:
+        return
+
+    desc = "\n   ".join(cmd["iov"][i:])
+
+    # Cut '[0 AT< '
+    desc = desc[8:]
+
+    # Cut suffixes like ' (RIL_URC_READER, tid:502968382704)'
+    desc = desc.split(" (RIL_URC_", 1)[0]
+    desc = desc.split(" (RIL_CMD_", 1)[0]
+    desc = desc.split(" (RIL_ATCI_", 1)[0]
+
+    if desc.endswith("\\n\\0"):
+        desc=desc[:-4]
+
+
+
+    cmd["type"] = "at"
+    cmd["desc"] = desc
+    cmd["towards_modem"] = "AT>" in iov_base
+
+
+def parse_writev(strace_file):
+    """
+    :param strace_file: path to strace file generated by dump.sh
+    :returns: a list of writev calls found in the strace file, looks like this:
+              [{"desc": "AT+EXCLE",  # human readable short version
+                "fd": "74<socket:[8970]>"
+                "iov": ["AT", "[0 AT< +EXLCE:...", ...],
+                "pid": 985,
+                "time": 1632220184.069225,
+                "time_rel": 0.000077,
+                "towards_modem": True,
+                "type": "at"}, ...]
+              type is one of:
+                * "at"
+                * "unknown"
+    """
+    ret = []
+    failed = 0
+    with open(strace_file) as handle:
+        for line in handle:
+            if "writev(" not in line:
+                continue
+            cmd = {}
+            rest = line.rstrip()
+
+            # Cut pid, time, time_rel
+            # rest = '985   1632220184.068694 (+     0.000148) writev(...'
+            # => ['985', '1632220184.068694', '(+', '0.000148)', 'writev(...'
+            pid, time, _, time_rel, rest = rest.split(None, 4)
+            cmd["pid"] = int(pid)
+            cmd["time"] = float(time)
+            cmd["time_rel"] = time_rel.split(")")[0]
+
+            # Cut writev
+            # rest = 'writev(74<socket:[8970]>, [{iov_base="...'
+            writev, rest = rest.split("(", 1)
+            assert writev == "writev"
+
+            # Cut fd
+            # rest = '74<socket:[8970]>, [{iov_base="...'
+            cmd["fd"], rest = rest.split(", ", 1)
+
+            cmd["iov"] = parse_iov_str(rest)
+
+            cmd["type"] = "unknown"
+            cmd["desc"] = cmd["iov"]
+            cmd["towards_modem"] = True
+
+            parse_at(cmd)
+
+            ret += [cmd]
+
+    return ret
+
+
+def print_cmds(cmds):
+    """ :param cmds: return of parse_at_cmds() """
+    for cmd in cmds:
+        if cmd["type"] == "unknown":
+            continue
+
+        direction = " ->" if cmd["towards_modem"] else "<- "
+        time = datetime.datetime.fromtimestamp(cmd["time"]).strftime('%H:%M:%S')
+
+        print(f"{time} (ril {direction} modem) {cmd['desc']}")
+
+
+def main():
+    args = parse_args()
+    cmds = parse_writev(args.strace_file)
+    print_cmds(cmds)
+
+
+if __name__ == "__main__":
+    sys.exit(main())