Initial support for Linux 802.11 Netlink (nl80211) dissection

Only commands and top-level attributes are recognized, no specialization
is done (yet?) since it is a large protocol.

Fields are extracted from Linux v4.10-rc4-749-g8585989d146c using the
"tools/generate-nl80211-fields.py --update" command.
Depends on the Generic Netlink (genl) dissector.

Change-Id: I7f81b91e3beacca8ebcb853137212406004f65e8
Ping-Bug: 13561
Reviewed-on: https://code.wireshark.org/review/20914
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 204 insertions, 0 deletions

diff --git a/tools/generate-nl80211-fields.py b/tools/generate-nl80211-fields.py
new file mode 100755
index 0000000000..24b21b7d17
--- /dev/null
+++ b/tools/generate-nl80211-fields.py
@@ -0,0 +1,204 @@
+#!/usr/bin/env python
+# Parses the nl80211.h interface and generate appropriate enums and fields
+# (value_string) for packet-netlink-nl80211.c
+#
+# Copyright (c) 2017, Peter Wu <peter@lekensteyn.nl>
+#
+# 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.
+#
+#
+# To update the dissector source file, run this from the source directory:
+#
+#   python tools/generate-nl80211-fields.py --update
+#
+
+import argparse
+import re
+import requests
+import sys
+
+# Begin of comment, followed by the actual array definition
+HEADER = "/* Definitions from linux/nl80211.h {{{ */\n"
+FOOTER = "/* }}} */\n"
+# Enums to extract from the header file
+EXPORT_ENUMS = ("nl80211_commands", "nl80211_attrs")
+# File to be patched
+SOURCE_FILE = "epan/dissectors/packet-netlink-nl80211.c"
+# URL where the latest version can be found
+URL = "https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/include/uapi/linux/nl80211.h"
+
+def make_enum(name, values, indent):
+    code = 'enum ws_%s {\n' % name
+    for value in values:
+        code += '%sWS_%s,\n' % (indent, value)
+    code += '};\n'
+    return code
+
+def make_value_string(name, values, indent):
+    code = 'static const value_string ws_%s_vals[] = {\n' % name
+    align = 40
+    for value in values:
+        code += indent + ('{ WS_%s,' % value).ljust(align - 1) + ' '
+        code += '"%s" },\n' % value
+    code += '%s{ 0, NULL }\n' % indent
+    code += '};\n'
+    code += 'static value_string_ext ws_%s_vals_ext =' % name
+    code += ' VALUE_STRING_EXT_INIT(ws_%s_vals);\n' % name
+    return code
+
+class EnumStore(object):
+    def __init__(self, name):
+        self.name = name
+        self.values = []
+        self.active = True
+
+    def update(self, line):
+        if not self.active:
+            return
+
+        # Skip comments and remove trailing comma
+        line = re.sub(r'\s*/\*.*?\*/\s*', '', line).rstrip(",")
+        if not line:
+            return
+
+        # Try to match a name. Allow aliases only for the previous item.
+        m = re.match(r'^(?P<name>\w+)(?: *= *(?P<alias_of>\w+))?$', line)
+        assert m, "Failed to find match in %r" % line
+        name, alias_of = m.groups()
+        if alias_of:
+            # Alias must match previous item, skip it otherwise.
+            assert alias_of == self.values[-1]
+        elif name.startswith("__"):
+            # Skip after hitting "__NL80211_CMD_AFTER_LAST"
+            self.active = False
+        else:
+            self.values.append(name)
+
+    def finish(self):
+        assert not self.active
+        assert self.values
+        return self.name, self.values
+
+def parse_header(f):
+    enum_store = None
+    enums = []
+    for line in f:
+        line = line.strip()
+        if line.startswith("enum "):
+            assert not enum_store
+            enum_keyword, enum_name, trailer = line.split()
+            assert trailer == "{"
+            if enum_name in EXPORT_ENUMS:
+                enum_store = EnumStore(enum_name)
+        elif enum_store:
+            if line == "};":
+                enums.append(enum_store.finish())
+                enum_store = None
+            elif line:
+                enum_store.update(line)
+    return enums
+
+def parse_source():
+    """
+    Reads the source file and tries to split it in the parts before, inside and
+    after the block.
+    """
+    begin, block, end = '', '', ''
+    # Stages: 1 (before block), 2 (in block, skip), 3 (after block)
+    stage = 1
+    with open(SOURCE_FILE) as f:
+        for line in f:
+            if line == FOOTER and stage == 2:
+                stage = 3   # End of block
+            if stage == 1:
+                begin += line
+                if line == HEADER:
+                    stage = 2   # Begin of block
+            elif stage == 2:
+                block += line
+            elif stage == 3:
+                end += line
+    if stage != 3:
+        raise RuntimeError("Could not parse file (in stage %d)" % stage)
+    return begin, block, end
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--update", action="store_true",
+        help="Update %s as needed instead of writing to stdout" % SOURCE_FILE)
+parser.add_argument("--indent", default=" " * 4,
+        help="indentation (use \\t for tabs, default 4 spaces)")
+parser.add_argument("header_file", nargs="?", default=URL,
+        help="nl80211.h header file (use - for stdin or a HTTP(S) URL, "
+             "default %(default)s)")
+
+def main():
+    args = parser.parse_args()
+
+    indent = args.indent.replace("\\t", "\t")
+
+    if any(args.header_file.startswith(proto) for proto in ('http:', 'https')):
+        r = requests.get(args.header_file)
+        r.raise_for_status()
+        enums = parse_header(r.text.splitlines())
+    elif args.header_file == "-":
+        enums = parse_header(sys.stdin)
+    else:
+        with open(args.header_file) as f:
+            enums = parse_header(f)
+
+    assert len(enums) == len(EXPORT_ENUMS), \
+            "Could not parse data, found %d/%d results" % \
+            (len(enums), len(EXPORT_ENUMS))
+
+    code_enums, code_vals = '', ''
+    for enum_name, enum_values in enums:
+        code_enums += make_enum(enum_name, enum_values, indent) + '\n'
+        code_vals += make_value_string(enum_name, enum_values, indent) + '\n'
+
+    code = code_enums + code_vals
+    code = code.rstrip("\n") + "\n"
+
+    if args.update:
+        begin, block, end = parse_source()
+        if block == code:
+            print("File is up-to-date")
+        else:
+            with open(SOURCE_FILE, "w") as f:
+                f.write(begin)
+                f.write(code)
+                f.write(end)
+            print("Updated %s" % SOURCE_FILE)
+    else:
+        print(code)
+
+if __name__ == '__main__':
+    main()
+
+#
+# Editor modelines  -  https://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:
+#