feat(cli): Regex based IP detection

This commit implements regex based IP detection. This is intended to use
for logfiles where column based detection doesn't work.

See RFC (DigitaleGesellschaft#44) for more information.

Closes DigitaleGesellschaft#44

README.md

@@ -34,6 +34,7 @@ Using shell redirects, it's also possible to rewrite existing log files.
  - Masks IP addresses in log files
  - Configurable amount of masked bits
  - The column containing the IP address can freely be chosen
+ - Alternatively use a regex to point anonip to the location(s) of the IP(s). See [this RFC](https://github.com/DigitaleGesellschaft/Anonip/issues/44) for more information.
  - Works for both access.log- and error.log files
 
 ## Officially supported python versions
@@ -57,7 +58,7 @@ For python versions <3.3:
 ```
 usage: anonip.py [-h] [-4 INTEGER] [-6 INTEGER] [-i INTEGER] [-o FILE]
                  [--input FILE] [-c INTEGER [INTEGER ...]] [-l STRING]
-                 [-r STRING] [-p] [-d] [-v]
+                 [--regex STRING [STRING ...]] [-r STRING] [-p] [-d] [-v]
 
 Anonip is a tool to anonymize IP-addresses in log files.
 
@@ -77,13 +78,18 @@ optional arguments:
                         default: 1)
   -l STRING, --delimiter STRING
                         log delimiter (default: " ")
+  --regex STRING [STRING ...]
+                        regex for detecting IP addresses (use instead of -c)
   -r STRING, --replace STRING
                         replacement string in case address parsing fails
                         (Example: 0.0.0.0)
   -p, --skip-private    do not mask addresses in private ranges. See IANA
                         Special-Purpose Address Registry.
   -d, --debug           print debug messages
   -v, --version         show program's version number and exit
+
+Example-usage in apache-config:
+CustomLog "| /path/to/anonip.py [OPTIONS] --output /path/to/log" combined
 ```
 
 ## Usage

anonip.py

@@ -41,6 +41,7 @@
 
 import argparse
 import logging
+import re
 import sys
 from io import open
 
@@ -78,6 +79,7 @@ def __init__(
         increment=0,
         delimiter=" ",
         replace=None,
+        regex=None,
         skip_private=False,
     ):
         """
@@ -98,6 +100,7 @@ def __init__(
         self.increment = increment
         self.delimiter = delimiter
         self.replace = replace
+        self.regex = regex
         self.skip_private = skip_private
 
     @property
@@ -154,6 +157,7 @@ def run(self, input_file=None):
             logger.debug("Got line: %r", line)
 
             yield self.process_line(line)
+
             line = input_file.readline()
 
     def process_ip(self, ip):
@@ -176,9 +180,36 @@ def process_ip(self, ip):
                     )
             return trunc_ip
 
-    def process_line(self, line):
+    def process_line_regex(self, line):
         """
-        This function processes a single line.
+        This function processes a single line based on the provided regex.
+
+        It returns the anonymized log line as string.
+
+        :param line: str
+        :return: str
+        """
+        match = re.match(self.regex, line)
+        if not match:
+            logger.debug("Regex did not match!")
+            return line
+        groups = match.groups()
+
+        for m in set(groups):
+            if not m:
+                continue
+            ip_str, ip = self.extract_ip(m)
+            if ip:
+                trunc_ip = self.process_ip(ip)
+                line = line.replace(ip_str, str(trunc_ip))
+            elif self.replace:
+                line = line.replace(m, self.replace)
+
+        return line
+
+    def process_line_column(self, line):
+        """
+        This function processes a single line based on the provided columns.
 
         It returns the anonymized log line as string.
 
@@ -206,6 +237,18 @@ def process_line(self, line):
 
         return self.delimiter.join(loglist)
 
+    def process_line(self, line):
+        """
+        This function processes a single line.
+        It returns the anonymized log line as string.
+
+        :param line: str
+        :return: str
+        """
+        if self.regex:
+            return self.process_line_regex(line)
+        return self.process_line_column(line)
+
     @staticmethod
     def extract_ip(column):
         """
@@ -297,6 +340,18 @@ def _validate_integer_ht_0(value):
     return value
 
 
+def regex_arg_type(value):
+    try:
+        re.compile(value)
+    except re.error as e:
+        msg = "must be a valid regex."
+        if hasattr(e, "msg"):  # pragma: no cover
+            # not available on py27
+            msg = "must be a valid regex. Error: {}".format(e.msg)
+        raise argparse.ArgumentTypeError(msg)
+    return value
+
+
 def parse_arguments(args):
     """
     Parse all given arguments.
@@ -350,15 +405,20 @@ def parse_arguments(args):
         type=lambda x: _validate_integer_ht_0(x),
         help="assume IP address is in column n (1-based indexed; default: 1)",
     )
-    parser.set_defaults(column=[1])
     parser.add_argument(
         "-l",
         "--delimiter",
         metavar="STRING",
         type=str,
         help='log delimiter (default: " ")',
     )
-    parser.set_defaults(delimiter=" ")
+    parser.add_argument(
+        "--regex",
+        metavar="STRING",
+        nargs="+",
+        help="regex for detecting IP addresses (use optionally instead of -c)",
+        type=regex_arg_type,
+    )
     parser.add_argument(
         "-r",
         "--replace",
@@ -380,6 +440,20 @@ def parse_arguments(args):
 
     args = parser.parse_args(args)
 
+    if args.regex and (args.columns is not None or args.delimiter is not None):
+        raise parser.error(
+            'Ambiguous arguments: When using "--regex", "-c" and "-l" can\'t be used.'
+        )
+    if not args.regex and args.columns is None:
+        args.columns = [1]
+    if not args.regex and args.delimiter is None:
+        args.delimiter = " "
+    if args.regex:
+        try:
+            args.regex = re.compile(r"|".join(args.regex))
+        except re.error:  # pragma: no cover
+            raise argparse.ArgumentTypeError("Failed to compile concatenated regex!")
+
     return args
 
 
@@ -402,6 +476,7 @@ def main():
         args.increment,
         args.delimiter,
         args.replace,
+        args.regex,
         args.skip_private,
     )
 

tests.py

@@ -10,6 +10,7 @@
 
 import argparse
 import logging
+import re
 import sys
 from io import StringIO
 
@@ -128,6 +129,52 @@ def test_column(line, columns, expected):
     assert a.process_line(line) == expected
 
 
+@pytest.mark.parametrize(
+    "line,regex,expected,replace",
+    [
+        (
+            '3.3.3.3 - - [20/May/2015:21:05:01 +0000] "GET / HTTP/1.1" 200 13358 "-" "useragent"',
+            re.compile(r"(?:^([^,]+) - - |.* - somefixedstring: ([^,]+) - .* - ([^,]+))"),
+            '3.3.0.0 - - [20/May/2015:21:05:01 +0000] "GET / HTTP/1.1" 200 13358 "-" "useragent"',
+            None,
+        ),
+        (
+            "blabla/ 3.3.3.3 /blublu",
+            re.compile(r"^blabla/ ([^,]+) /blublu"),
+            "blabla/ 3.3.0.0 /blublu",
+            None,
+        ),
+        (
+            "1.1.1.1 - somefixedstring: 2.2.2.2 - some random stuff - 3.3.3.3",
+            re.compile(r"^([^,]+) - somefixedstring: ([^,]+) - .* - ([^,]+)"),
+            "1.1.0.0 - somefixedstring: 2.2.0.0 - some random stuff - 3.3.0.0",
+            None,
+        ),
+        (
+            "some line that doesn't match the provided regex",
+            re.compile(r"^([^,]+) - somefixedstring: ([^,]+) - .* - ([^,]+)"),
+            "some line that doesn't match the provided regex",
+            None,
+        ),
+        (
+            "match but no ip/ notanip /blublu",
+            re.compile(r"^match but no ip/ ([^,]+) /blublu"),
+            "match but no ip/ notanip /blublu",
+            None,
+        ),
+        (
+            "match but no ip/ notanip /blublu",
+            re.compile(r"^match but no ip/ ([^,]+) /blublu"),
+            "match but no ip/ yeah /blublu",
+            "yeah",
+        ),
+    ],
+)
+def test_regex(line, regex, expected, replace):
+    a = anonip.Anonip(regex=regex, replace=replace)
+    assert a.process_line(line) == expected
+
+
 def test_replace():
     a = anonip.Anonip(replace="replacement")
     assert a.process_line("bla something") == "replacement something"
@@ -178,6 +225,39 @@ def test_cli_generic_args(args, attribute, expected):
     assert getattr(anonip.parse_arguments(args), attribute) == expected
 
 
+@pytest.mark.parametrize(
+    "args,success",
+    [
+        ([], True),
+        (["--regex", "test"], True),
+        (["-c", "4"], True),
+        (["--regex", "test", "-c", "3"], False),
+        (["--regex", "test", "-l", ";"], False),
+        (["--regex", "test", "-l", ";", "-c", "4"], False),
+    ],
+)
+def test_cli_args_ambiguity(args, success):
+    if success:
+        anonip.parse_arguments(args)
+        return
+
+    with pytest.raises(SystemExit) as e:
+        anonip.parse_arguments(args)
+    assert e.value.code == 2
+
+
+@pytest.mark.parametrize(
+    "args,expected",
+    [
+        (["--regex", "test"], "test"),
+        (["--regex", "foo", "bar", "baz"], "foo|bar|baz"),
+    ],
+)
+def test_regex_concat(args, expected):
+    args = anonip.parse_arguments(args)
+    assert args.regex == re.compile(expected)
+
+
 @pytest.mark.parametrize(
     "value,valid,bits",
     [
@@ -207,6 +287,15 @@ def test_cli_validate_integer_ht_0(value, valid):
             anonip._validate_integer_ht_0(value)
 
 
+@pytest.mark.parametrize("value,valid", [("valid (.*)", True), ("\\9", False)])
+def test_regex_arg_type(value, valid):
+    if valid:
+        assert anonip.regex_arg_type(value) == value
+    else:
+        with pytest.raises(argparse.ArgumentTypeError):
+            anonip.regex_arg_type(value)
+
+
 @pytest.mark.parametrize("to_file", [False, True])
 @pytest.mark.parametrize("debug,log_level", [(False, 30), (True, 10)])
 def test_main(