File contents

#!/usr/bin/python
"""check_nrpe clone in python

Tested on Mac OS X 10.5 by Alan Brenner <alan.brenner@ithaka.org>.
"""
import OpenSSL # non-standard, see http://pyopenssl.sourceforge.net/
import optparse
import os
import signal
import socket
import struct
import sys
import time

### Values from nrpe-2.12/include/common.h
STATE_UNKNOWN  = 3
STATE_CRITICAL = 2
STATE_WARNING  = 1
STATE_OK       = 0

QUERY_PACKET    = 1
RESPONSE_PACKET = 2

NRPE_PACKET_VERSION_3 = 3
NRPE_PACKET_VERSION_2 = 2               
NRPE_PACKET_VERSION_1 = 1

# max amount of data we'll send in one query/response
MAX_PACKETBUFFER_LENGTH = 1024


### Values from the Nagios configuration
COMMAND_FILE = '/var/local/log/nagios/rw/nagios.cmd'
if not os.path.exists(COMMAND_FILE):
    sys.exit(STATE_CRITICAL)

### Configure this dictionary.
m_dMapping = {'check_rootkit': 'ChkRootKit',
              'check_yum': 'RPM Updates'}
# This maps the third field returned from the monitored system
# into the Nagios service name.

def debug(sMessage):
    """Send a string to STDERR"""
    if DEBUG:
        sys.stderr.write("%s\n" % sMessage)

def write_to_pipe(sMessage):
    """Send a pre-formatted string to Nagios"""
    hPipe = open(COMMAND_FILE, 'w')
    hPipe.write(sMessage + "\n")
    hPipe.close()

class DataPacket:
    """A Python implementation of the C struct, packet."""
    def __init__(self, packet_version, packet_type):
        self.nPacketVersion = packet_version # int16
        self.nPacketType = packet_type # int16
        self.nCRC32 = 0 # u_int32
        self.nResultCode = 2324 # int16
        self.sData = ''
        self.tCRC32 = (
             0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
             0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
             0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
             0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
             0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
             0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
             0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
             0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
             0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
             0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
             0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
             0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
             0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
             0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
             0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
             0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
             0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
             0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
             0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
             0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
             0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
             0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
             0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
             0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
             0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
             0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
             0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
             0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
             0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
             0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
             0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
             0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
             0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
             0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
             0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
             0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
             0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
             0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
             0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
             0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
             0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
             0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
             0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
             0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
             0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
             0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
             0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
             0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
             0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
             0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
             0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
             0x2d02ef8d)

    def __str__(self):
        # Turn whatever string data we have into a null terminated string
        if len(self.sData) < MAX_PACKETBUFFER_LENGTH:
            sData = self.sData + "\0" * (MAX_PACKETBUFFER_LENGTH - len(self.sData))
            sData += "SR" # not sure about this, from perl
        elif len(self.sData) == MAX_PACKETBUFFER_LENGTH + 2:
            sData = self.sData
        else:
            raise ValueError("CHECK_NRPE: invalid input")
        # Return a string that equals the C struct, not something printable
        return struct.pack("!hhLh" + str(len(sData)) + "s", self.nPacketVersion,
            self.nPacketType, self.nCRC32, self.nResultCode, sData)

    def __len__(self):
        return len(self.__str__())

    def dumpself(self):
        """Debugging output for self as C structure.
        
        Not normally used."""
        sElf = self.__str__()
        sPrev = sElf[0:1]
        nCount = 0
        ii = -1
        for sChar in sElf[1:]:
            ii += 1
            if sChar == sPrev:
                nCount += 1
                continue
            if nCount:
                print "%d\t%d *" % (ii - nCount, nCount + 1),
                nCount = 0
            else:
                print "%d\t" % ii,
            print "\t'%s' (%d)" % (sPrev, ord(sPrev))
            sPrev = sChar
        print "%d\t\t'%s' (%d)" % (ii + 1, sPrev, ord(sPrev))

    def calculate_crc32(self):
        """Calculate the CRC32 value for the string version of self."""
        nCRC = 0xFFFFFFFF
        for ii in self.__str__():
            nIndex = (nCRC ^ ord(ii)) & 0xFF
            nCRC = ((nCRC >> 8) & 0x00FFFFFF) ^ self.tCRC32[nIndex]
        self.nCRC32 = nCRC ^ 0xFFFFFFFF
        debug("DataPacket.calculate_crc32 = %d" % self.nCRC32)

    def extract(self, sQuery):
        """Turn a string into the DataPacket attributes."""
        debug("DataPacket.extract(%d)" % len(sQuery))
        tVals = struct.unpack("!hhLh" + str(len(sQuery) - 10) + "s", sQuery)
        self.nPacketVersion = tVals[0]
        self.nPacketType = tVals[1]
        self.nCRC32 = tVals[2]
        self.nResultCode = tVals[3]
        self.sData = tVals[4]


m_nTimeout = 0
def alarm_handler(nSignum, oFrame):
    """Timeout catcher"""
    raise KeyboardInterrupt("CHECK_NRPE: Socket timeout after %d seconds." %
        m_nTimeout)


class NrpeClient(DataPacket):
    """Everything needed to send a message to an NRPE server and get data back.
    """
    def __init__(self, server_name, server_port=5666, use_ssl=True, timeout=10,
                 packet_version=NRPE_PACKET_VERSION_2):
        DataPacket.__init__(self, packet_version, QUERY_PACKET)
        self.sServer = server_name
        self.nPort = server_port
        self.bUseSSL = use_ssl
        self.nTimeout = timeout

    def run_query(self, sQuery):
        """Connect to the NRPE server, send the query and get back data.
        """
        # initialize alarm signal handling and set timeout
        signal.signal(signal.SIGALRM, alarm_handler)
        signal.alarm(self.nTimeout)

        # try to connect to the host at the given port number
        oSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        # do SSL handshake
        if self.bUseSSL:
            oContext = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_METHOD)
            oContext.set_cipher_list('ADH')
            oConnection = OpenSSL.SSL.Connection(oContext, oSocket)
        else:
            oConnection = oSocket
        oConnection.connect((self.sServer, self.nPort))

        # we're connected and ready to go
        self.sData = sQuery
        self.nCRC32 = 0
        self.calculate_crc32()

        # send the packet
        oConnection.send(str(self))

        # wait for the response packet
        sRval = oConnection.recv(len(self))

        # close the connection
        if self.bUseSSL and not oConnection.shutdown():
            try:
                sRval += oConnection.recv(len(self))
            except OpenSSL.SSL.ZeroReturnError:
                pass
        oSocket.close()
        del oSocket, oConnection
        if self.bUseSSL:
            del oContext

        # reset timeout
        signal.alarm(0)

        if len(sRval) == 0:
            raise IOError("CHECK_NRPE: Received 0 bytes from daemon." + 
                "Check the remote server logs for error messages.")
        elif len(sRval) < len(self):
            raise IOError("CHECK_NRPE: Receive underflow - only " +
                "%d bytes received (%d expected)." % (len(sRval), len(self)))

        # Become the received data
        self.extract(sRval)

        # check the crc 32 value
        nRvalCRC = self.nCRC32
        self.nCRC32 = 0
        self.calculate_crc32()
        if nRvalCRC != self.nCRC32:
            raise ValueError("CHECK_NRPE: Response packet had invalid CRC32.")

        # check packet version
        if self.nPacketVersion != NRPE_PACKET_VERSION_2:
            raise ValueError("CHECK_NRPE: Invalid packet version received from server.")

        # check packet type
        if self.nPacketType != RESPONSE_PACKET:
            raise ValueError("CHECK_NRPE: Invalid packet type received from server.")

        # Turn the input data into a proper python string (chop at first NULL)
        for ii in range(len(self.sData)):
            if self.sData[ii] == "\0":
                break
        self.sData = self.sData[0:ii]


if __name__ == '__main__':
    m_oOpts = optparse.OptionParser()
    #m_oOpts.add_option('--help', '-h', action='store_true')
    m_oOpts.add_option('--verbose', '-v', action='store_true')
    m_oOpts.add_option('--host', '-H', action='store', type='string',
        help='The address of the host running the NRPE daemon (required)')
    m_oOpts.add_option('--ssl', '-n', action='store_false', default=True,
        help='Do no use SSL')
    #m_oOpts.add_option('--unknown', '-u', action='store_true',
    #    help='Make socket timeouts return an UNKNOWN state instead of CRITICAL')
    m_oOpts.add_option('--port', '-p', action='store', type='int', default=5666,
        help='The port on which the daemon is running (default=5666)')
    m_oOpts.add_option('--timeout', '-t', action='store', type='int',
        default=10,
        help='Number of seconds before connection times out (default=10)')
    m_oOpts.add_option('--command', '-c', action='store', type='string',
        default='get_data',
        help='The name of the command that the remote daemon should run.')
    m_oOpts.add_option('--args', '-a', action='store', type='string',
        help='Optional arguments that should be passed to the command. ' +
             'Multiple arguments should be separated by a space.  If ' +
             'provided, this must be the last option supplied on the ' +
             'command line.')
    m_oOptions, m_lArgs = m_oOpts.parse_args()
    DEBUG = m_oOptions.verbose
    m_nTimeout = m_oOptions.timeout
    m_sQuery = m_oOptions.command
    if m_oOptions.args:
        m_sQuery += ' ' + m_oOptions.args
        if m_lArgs:
            m_sQuery += ' ' + ' '.join(m_lArgs)
    if not m_oOptions.host:
        print m_oOpts.format_help()
        sys.exit(0)

    while True:
        m_oNRPE = NrpeClient(m_oOptions.host, m_oOptions.port, m_oOptions.ssl,
            m_oOptions.timeout)
    
        m_oNRPE.run_query(m_sQuery)

        # get the return code from the remote plugin
        debug("packet result code = %d" % m_oNRPE.nResultCode)
        if m_oNRPE.nResultCode == STATE_OK:
            debug("packet results: %s" % m_oNRPE.sData)
            # GET_DATA OK - fetched 1 record with 2 more waiting | data=1222372381;palace;check_rootkit;0;CHKROOTKIT OK
            m_tSplit = m_oNRPE.sData.split('=')
            m_tSplit = m_tSplit[1].split(';', 4)
            if m_tSplit[4].endswith("\n;;"):
                m_tSplit[4] = m_tSplit[4].rstrip(';')
                m_tSplit[4] = m_tSplit[4].rstrip()
            debug(m_tSplit)
            try:
                m_sOut = "[%s] PROCESS_SERVICE_CHECK_RESULT;%s;%s;%s;%s" % (m_tSplit[0],
                    m_tSplit[1], m_dMapping[m_tSplit[2]], m_tSplit[3], m_tSplit[4])
                write_to_pipe(m_sOut)
                debug(m_sOut)
            except KeyError:
                m_sOut = "[%d] PROCESS_SERVICE_CHECK_RESULT;%s;error;%s;%s" % \
                    (time.strftime('%s'), m_oOptions.host, STATE_UNKNOWN,
                     m_oNRPE.sData)
                write_to_pipe(m_sOut)
                sys.exit(STATE_WARNING)
        else:   # My expectation is that these (^ and v) show up in Nagios' log
            m_sOut = "[%d] PROCESS_SERVICE_CHECK_RESULT;%s;error;%s;%s" % \
                (time.strftime('%s'), m_oOptions.host, m_oNRPE.nResultCode,
                 m_oNRPE.sData)
            write_to_pipe(m_sOut)
            sys.exit(m_oNRPE.nResultCode)
        if m_oNRPE.sData.find('more waiting') == -1:
            break
        time.sleep(1)