#!/usr/bin/env python
# shorewall_accounting v1.3
#
# A munin plugin for tracking traffic as recorded by shorewall accounting rules.
# See "man shorewall-accounting" for all possible accounting rules.
# Basically this plugin examines the output of "shorewall -x show accounting".
# See http://atlee.ca/blog/2006/01/20/munin-shorewall/ for a description of
# the original script by Chris AtLee.
#
# Copyright 2010-2012 Lars Kruse <devel@sumpralle.de>
# Copyright 2006 Chris AtLee <chris@atlee.ca>
#
# Original publication: http://atlee.ca/blog/2006/01/20/munin-shorewall/
# Released under the GPL v3 or later
#
# You can use symlinks of this script according to the following pattern:
#    shorewall-accounting_prot: use only rules with a specific protocol
#    shorewall-accounting_in: use only rules with a specific input interface
#    shorewall-accounting_out: use only rules with a specific output interface
#    shorewall-accounting_source: use only rules with a specific source IP
#    shorewall-accounting_destination: use only rules with a specific destination IP
#    shorewall-accounting_details: use only rules with specific details (e.g. a port)
#
# Here "specific" means: non-default (e.g. a protocol was specified).
# Combinations are allowed:
#    shorewall-accounting_prot_in_source: use only rules with a specific protocol, input interface and source IP
#
# Environment variables:
#    SHOREWALL_BIN - defaults to /sbin/shorewall
#
# Changelog:
# v1.3 - 2012/04/02
#  * renamed plugin file from "shorewall_accounting" to "shorewall-accounting_"
#   * CAUTION: rename your symlinks and plugin config section!
#  * added optional SHOREWALL_BIN environment variable
#  * improved labels for rules (don't mask dots)
#
#%# family=auto
#%# capabilities=autoconf

import sys
import os
import commands
import re

PLUGIN_BASE_NAME = "shorewall-accounting"
SHOREWALL_BIN = os.environ.get("SHOREWALL_BIN", "/sbin/shorewall")
ACCOUNTING_LINE_EXP = re.compile(r"^\s*\d+\s+(\d+)\s+(?P<prot>\w+)\s+(?P<opt>[\w-]+)\s+(?P<in>[\w*]+)\s+(?P<out>[\w*]+)\s+(?P<source>[\w./+-]+)\s+(?P<destination>[\w./+-]+)\s*(?P<details>.*)\s*$")
KEY_ORDER = ["prot", "in", "out", "source", "destination", "details"]
FILTER_PATTERNS = {
        "prot": r"^all$",
        "in": r"^\*$",
        "out": r"^\*$",
        "source": r"^0\.0\.0\.0/0$",
        "destination": r"^0\.0\.0\.0/0$",
        "details": r"^$",
}
REPLACE_PATTERNS = {
        "prot": ("^all$", "allProt"),
        "in": (r"^\*$", "allIn"),
        "out": (r"^\*$", "allOut"),
        "source": (r"^0\.0\.0\.0/0", "allSrc"),
        "destination": (r"^0\.0\.0\.0/0", "allDst"),
        "details": (r"^multiport\s+", ""),
}


def get_accounting_rule_fieldname_and_label(regdict):
    items = []
    # filter and clean all requested keys
    for key in KEY_ORDER:
        raw = regdict[key]
        pattern, replacement = REPLACE_PATTERNS[key]
        value = re.sub(pattern, replacement, raw).strip()
        if value:
            items.append(value)
    result = "_".join(items)
    # clean the fieldname: http://munin-monitoring.org/wiki/notes_on_datasource_names
    result = re.sub(r"^[^A-Za-z_]", "_", result)
    fieldname = re.sub(r"[^A-Za-z0-9_]", "_", result)
    # keep dots (for IP addresses)
    label = re.sub(r"[^A-Za-z0-9_\.]", "_", result)
    return fieldname, label

def is_wanted(regdict, filter_list):
    for item in filter_list:
        # is the item empty?
        if not regdict[item]:
            return False
        # is the default value (unfiltered) set?
        if re.search(FILTER_PATTERNS[item], regdict[item]):
            return False
    return True

def get_bytes_by_chain(filter_list):
    status, output = commands.getstatusoutput("'%s' -x show accounting" \
            % SHOREWALL_BIN)
    if status != 0:
        raise OSError("Error running command (%s)[%i]: %s" % (SHOREWALL_BIN,
                status, output))
    chains = {}
    for line in output.splitlines():
        m = ACCOUNTING_LINE_EXP.match(line)
        if m is not None:
            # check if this line was filtered
            if not is_wanted(m.groupdict(), filter_list):
                continue
            fieldname, label = get_accounting_rule_fieldname_and_label(m.groupdict())
            bytes = int(m.group(1))
            if fieldname in chains:
                chains[fieldname][1] += bytes
            else:
                chains[fieldname] = [label, bytes]
    retval = []
    names = chains.keys()
    names.sort()
    for name in names:
        retval.append((name, chains[name][0], chains[name][1]))
    return retval


# extract the filters from the symlink's name
# (e.g. "shorewall-accounting_in_out_details" -> in, out, details)
call_name = os.path.basename(sys.argv[0])
if call_name.startswith(PLUGIN_BASE_NAME):
    suffix = call_name[len(PLUGIN_BASE_NAME):]
    suffixes = suffix.split("_")
    # use only suffixes that are listed in FILTER_PATTERNS
    filter_list = [item for item in suffixes if item in FILTER_PATTERNS]
else:
    filter_list = []

if len(sys.argv) > 1:
    if sys.argv[1] == "autoconf":
        status, output = commands.getstatusoutput("'%s' -x show accounting" \
                % SHOREWALL_BIN)
        if (status != 0) or not output:
            print "no"
        else:
            print "yes"
    elif sys.argv[1] == "config":
        if not filter_list:
            title_addon = "all"
        else:
            title_addon = " / ".join(filter_list)
        print "graph_title Shorewall accounting: %s" % title_addon
        print "graph_category network"
        print "graph_vlabel bits per ${graph_period}"
        for chain, label, bytes in get_bytes_by_chain(filter_list):
            label = " ".join([item for item in label.split("_")
                    if not item.lower().startswith("all")])
            if not label:
                label = "all"
            print "%s.min 0" % chain
            print "%s.type DERIVE" % chain
            print "%s.label %s" % (chain, label)
            print "%s.cdef %s,8,*" % (chain, chain)
    sys.exit(0)

for chain, label, bytes in get_bytes_by_chain(filter_list):
    print "%s.value %i" % (chain, bytes)