#
#   sshd.py
#   
#   Find number of ssh logins and authorised users (uses /var/log/auth.log)
#   
#   NOTE: This file is now deprecated in favour of the newer journald mechanism
#   used in sshd-journald.py. This parser is still functional but is slower and
#   has less features. Please switch over if possible.
#

import re

from logparse.formatting import *
from logparse.util import readlog, resolve
from logparse import config
from logparse.load_parsers import Parser

class Sshd(Parser):

    def __init__(self):
        super().__init__()
        self.name = "sshd"
        self.info = "Find number of ssh logins and authorised users (uses /var/log/auth.log)"
        self.deprecated = True

    def parse_log(self):

        logger.warning("NOTE: This sshd parser is now deprecated. Please use sshd-journald if possible.")

        logger.debug("Starting sshd section")
        section = Section("ssh")
        logger.debug("Searching for matches in {0}".format(config.prefs.get("logs", "auth")))
        matches = re.findall('.*sshd.*Accepted publickey for .* from .*', readlog(config.prefs.get("logs", "auth")))    # get all logins
        logger.debug("Finished searching for logins")

        logger.debug("Searching for matches in {0}".format(config.prefs.get("logs", "auth")))
        authlog = readlog(config.prefs.get("logs", "auth"))
       
        matches = re.findall('.*sshd.*Accepted publickey for .* from .*', authlog)    # get all logins
        invalid_matches = re.findall(".*sshd.*Invalid user .* from .*", authlog)
        root_matches = re.findall("Disconnected from authenticating user root", authlog)
        logger.debug("Finished searching for logins")
        
        users = []  # list of users with format [username, number of logins] for each item
        data = []
        num = len(matches)     # total number of logins
        for match in matches:
            entry = re.search('^.*publickey\sfor\s(\w*)\sfrom\s(\S*)', match)  # [('user', 'ip')]

            user = entry.group(1)
            ip = entry.group(2)

            userhost = user + '@' + resolve(ip, fqdn=config.prefs.get("sshd", "sshd-resolve-domains"))
            users.append(userhost)
        logger.debug("Parsed list of authorised users")

        auth_data = Data(subtitle=plural('login', num) + ' from', items=users)

        if (len(auth_data.items) == 1):             # if only one user, do not display no of logins for this user
            logger.debug("found " + str(len(matches)) + " ssh logins for user " + users[0])
            auth_data.subtitle += ' ' + auth_data.items[0]
        auth_data.orderbyfreq()
        auth_data.truncl(config.prefs.getint("logparse", "maxlist"))
        logger.debug("Found " + str(len(matches)) + " ssh logins for users " + str(data))
        section.append_data(auth_data)

        invalid_users = []
        for match in invalid_matches:
            entry = re.search('^.*Invalid user (\S+) from (\S+).*', match)  # [('user', 'ip')]

            try:
                user = entry.group(1)
                ip = entry.group(2)
            except:     # blank user field
                continue

            userhost = user + '@' + ip
            invalid_users.append(userhost)
        logger.debug("Parsed list of invalid users")
        invalid_data = Data(subtitle=plural("attempted login", len(invalid_matches)) + " from " + plural("invalid user", len(invalid_users), print_quantity=False), items=invalid_users)
        if (len(invalid_data.items) == 1):             # if only one user, do not display no of logins for this user
            logger.debug("Found " + str(len(invalid_matches)) + " SSH login attempts for invalid user " + invalid_users[0])
            invalid_data.subtitle += ' ' + invalid_data.items[0]
        invalid_data.orderbyfreq()
        invalid_data.truncl(config.prefs.get("logparse", "maxlist"))
        logger.debug("Found " + str(len(invalid_matches)) + " SSH login attempts for invalid users " + str(data))
        section.append_data(invalid_data)

        logger.debug("Found {0} attempted logins for root".format(str(len(root_matches))))

        section.append_data(Data(subtitle=plural("attempted login", str(len(root_matches))) + " for root"))

        logger.info("Finished sshd section")
        return section