handlers.py

# Copyright 2001-2002 by Vinay Sajip. All Rights Reserved.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted,
# provided that the above copyright notice appear in all copies and that
# both that copyright notice and this permission notice appear in
# supporting documentation, and that the name of Vinay Sajip
# not be used in advertising or publicity pertaining to distribution
# of the software without specific, written prior permission.
# VINAY SAJIP DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
# ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# VINAY SAJIP BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
# ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
# IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

"""
Logging package for Python. Based on PEP 282 and comments thereto in
comp.lang.python, and influenced by Apache's log4j system.

Should work under Python versions >= 1.5.2, except that source line
information is not available unless 'inspect' is.

Copyright (C) 2001-2002 Vinay Sajip. All Rights Reserved.

To use, simply 'import logging' and log away!
"""

import sys, logging, socket, types, os, string, cPickle, struct

from SocketServer import ThreadingTCPServer, StreamRequestHandler

#
# Some constants...
#

DEFAULT_TCP_LOGGING_PORT    = 9020
DEFAULT_UDP_LOGGING_PORT    = 9021
DEFAULT_HTTP_LOGGING_PORT   = 9022
DEFAULT_SOAP_LOGGING_PORT   = 9023
SYSLOG_UDP_PORT             = 514


class RotatingFileHandler(logging.FileHandler):
    def __init__(self, filename, mode="a", maxBytes=0, backupCount=0):
        """
        Open the specified file and use it as the stream for logging.

        By default, the file grows indefinitely. You can specify particular
        values of maxBytes and backupCount to allow the file to rollover at
        a predetermined size.

        Rollover occurs whenever the current log file is nearly maxBytes in
        length. If backupCount is >= 1, the system will successively create
        new files with the same pathname as the base file, but with extensions
        ".1", ".2" etc. appended to it. For example, with a backupCount of 5
        and a base file name of "app.log", you would get "app.log",
        "app.log.1", "app.log.2", ... through to "app.log.5". The file being
        written to is always "app.log" - when it gets filled up, it is closed
        and renamed to "app.log.1", and if files "app.log.1", "app.log.2" etc.
        exist, then they are renamed to "app.log.2", "app.log.3" etc.
        respectively.

        If maxBytes is zero, rollover never occurs.
        """
        logging.FileHandler.__init__(self, filename, mode)
        self.maxBytes = maxBytes
        self.backupCount = backupCount
        if maxBytes > 0:
            self.mode = "a"

    def doRollover(self):
        """
        Do a rollover, as described in __init__().
        """

        self.stream.close()
        if self.backupCount > 0:
            for i in range(self.backupCount - 1, 0, -1):
                sfn = "%s.%d" % (self.baseFilename, i)
                dfn = "%s.%d" % (self.baseFilename, i + 1)
                if os.path.exists(sfn):
                    #print "%s -> %s" % (sfn, dfn)
                    if os.path.exists(dfn):
                        os.remove(dfn)
                    os.rename(sfn, dfn)
            dfn = self.baseFilename + ".1"
            if os.path.exists(dfn):
                os.remove(dfn)
            os.rename(self.baseFilename, dfn)
            #print "%s -> %s" % (self.baseFilename, dfn)
        self.stream = open(self.baseFilename, "w")

    def emit(self, record):
        """
        Emit a record.

        Output the record to the file, catering for rollover as described
        in setRollover().
        """
        if self.maxBytes > 0:                   # are we rolling over?
            msg = "%s\n" % self.format(record)
            #print msg
            if self.stream.tell() + len(msg) >= self.maxBytes:
                self.doRollover()
        logging.FileHandler.emit(self, record)


class SocketHandler(logging.Handler):
    """
    A handler class which writes logging records, in pickle format, to
    a streaming socket. The socket is kept open across logging calls.
    If the peer resets it, an attempt is made to reconnect on the next call.
    Note that the very simple wire protocol used means that packet sizes
    are expected to be encodable within 16 bits (i.e. < 32767 bytes).
    """

    def __init__(self, host, port):
        """
        Initializes the handler with a specific host address and port.

        The attribute 'closeOnError' is set to 1 - which means that if
        a socket error occurs, the socket is silently closed and then
        reopened on the next logging call.
        """
        logging.Handler.__init__(self)
        self.host = host
        self.port = port
        self.sock = None
        self.closeOnError = 0

    def makeSocket(self):
        """
        A factory method which allows subclasses to define the precise
        type of socket they want.
        """
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((self.host, self.port))
        return s

    def send(self, s):
        """
        Send a pickled string to the socket.

        This function allows for partial sends which can happen when the
        network is busy.
        """
        v = sys.version_info
        if v[0] >= 2 and v[1] >= 2:
            self.sock.sendall(s)
        else:
            sentsofar = 0
            left = len(s)
            while left > 0:
                sent = self.sock.send(s[sentsofar:])
                sentsofar = sentsofar + sent
                left = left - sent

    def makePickle(self, record):
        """
        Pickles the record in binary format with a length prefix, and
        returns it ready for transmission across the socket.
        """
        s = cPickle.dumps(record.__dict__, 1)
        #n = len(s)
        #slen = "%c%c" % ((n >> 8) & 0xFF, n & 0xFF)
        slen = struct.pack(">L", len(s))
        return slen + s

    def handleError(self):
        """
        Handle an error during logging.

        An error has occurred during logging. Most likely cause -
        connection lost. Close the socket so that we can retry on the
        next event.
        """
        if self.closeOnError and self.sock:
            self.sock.close()
            self.sock = None        #try to reconnect next time
        else:
            logging.Handler.handleError(self)

    def emit(self, record):
        """
        Emit a record.

        Pickles the record and writes it to the socket in binary format.
        If there is an error with the socket, silently drop the packet.
        If there was a problem with the socket, re-establishes the
        socket.
        """
        try:
            s = self.makePickle(record)
            if not self.sock:
                self.sock = self.makeSocket()
            self.send(s)
        except:
            self.handleError()

    def close(self):
        """
        Closes the socket.
        """
        if self.sock:
            self.sock.close()
            self.sock = None

class DatagramHandler(SocketHandler):
    """
    A handler class which writes logging records, in pickle format, to
    a datagram socket. Note that the very simple wire protocol used means
    that packet sizes are expected to be encodable within 16 bits
    (i.e. < 32767 bytes).

    """
    def __init__(self, host, port):
        """
        Initializes the handler with a specific host address and port.
        """
        SocketHandler.__init__(self, host, port)
        self.closeOnError = 0

    def makeSocket(self):
        """
        The factory method of SocketHandler is here overridden to create
        a UDP socket (SOCK_DGRAM).
        """
        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        return s

    def send(self, s):
        """
        Send a pickled string to a socket.

        This function no longer allows for partial sends which can happen
        when the network is busy - UDP does not guarantee delivery and
        can deliver packets out of sequence.
        """
        #old code
        #sentsofar = 0
        #left = len(s)
        #addr = (self.host, self.port)
        #while left > 0:
        #    sent = self.sock.sendto(s[sentsofar:], addr)
        #    sentsofar = sentsofar + sent
        #    left = left - sent
        self.sock.sendto(s, (self.host, self.port))

class SysLogHandler(logging.Handler):
    """
    A handler class which sends formatted logging records to a syslog
    server. Based on Sam Rushing's syslog module:
    http://www.nightmare.com/squirl/python-ext/misc/syslog.py
    Contributed by Nicolas Untz (after which minor refactoring changes
    have been made).
    """

    # from <linux/sys/syslog.h>:
    # ======================================================================
    # priorities/facilities are encoded into a single 32-bit quantity, where
    # the bottom 3 bits are the priority (0-7) and the top 28 bits are the
    # facility (0-big number). Both the priorities and the facilities map
    # roughly one-to-one to strings in the syslogd(8) source code.  This
    # mapping is included in this file.
    #
    # priorities (these are ordered)

    LOG_EMERG     = 0       #  system is unusable
    LOG_ALERT     = 1       #  action must be taken immediately
    LOG_CRIT      = 2       #  critical conditions
    LOG_ERR       = 3       #  error conditions
    LOG_WARNING   = 4       #  warning conditions
    LOG_NOTICE    = 5       #  normal but significant condition
    LOG_INFO      = 6       #  informational
    LOG_DEBUG     = 7       #  debug-level messages

    #  facility codes
    LOG_KERN      = 0       #  kernel messages
    LOG_USER      = 1       #  random user-level messages
    LOG_MAIL      = 2       #  mail system
    LOG_DAEMON    = 3       #  system daemons
    LOG_AUTH      = 4       #  security/authorization messages
    LOG_SYSLOG    = 5       #  messages generated internally by syslogd
    LOG_LPR       = 6       #  line printer subsystem
    LOG_NEWS      = 7       #  network news subsystem
    LOG_UUCP      = 8       #  UUCP subsystem
    LOG_CRON      = 9       #  clock daemon
    LOG_AUTHPRIV  = 10  #  security/authorization messages (private)

    #  other codes through 15 reserved for system use
    LOG_LOCAL0    = 16      #  reserved for local use
    LOG_LOCAL1    = 17      #  reserved for local use
    LOG_LOCAL2    = 18      #  reserved for local use
    LOG_LOCAL3    = 19      #  reserved for local use
    LOG_LOCAL4    = 20      #  reserved for local use
    LOG_LOCAL5    = 21      #  reserved for local use
    LOG_LOCAL6    = 22      #  reserved for local use
    LOG_LOCAL7    = 23      #  reserved for local use

    priority_names = {
        "alert":    LOG_ALERT,
        "crit":     LOG_CRIT,
        "critical": LOG_CRIT,
        "debug":    LOG_DEBUG,
        "emerg":    LOG_EMERG,
        "err":      LOG_ERR,
        "error":    LOG_ERR,        #  DEPRECATED
        "info":     LOG_INFO,
        "notice":   LOG_NOTICE,
        "panic":    LOG_EMERG,      #  DEPRECATED
        "warn":     LOG_WARNING,    #  DEPRECATED
        "warning":  LOG_WARNING,
        }

    facility_names = {
        "auth":     LOG_AUTH,
        "authpriv": LOG_AUTHPRIV,
        "cron":     LOG_CRON,
        "daemon":   LOG_DAEMON,
        "kern":     LOG_KERN,
        "lpr":      LOG_LPR,
        "mail":     LOG_MAIL,
        "news":     LOG_NEWS,
        "security": LOG_AUTH,       #  DEPRECATED
        "syslog":   LOG_SYSLOG,
        "user":     LOG_USER,
        "uucp":     LOG_UUCP,
        "local0":   LOG_LOCAL0,
        "local1":   LOG_LOCAL1,
        "local2":   LOG_LOCAL2,
        "local3":   LOG_LOCAL3,
        "local4":   LOG_LOCAL4,
        "local5":   LOG_LOCAL5,
        "local6":   LOG_LOCAL6,
        "local7":   LOG_LOCAL7,
        }

    def __init__(self, address=('localhost', SYSLOG_UDP_PORT), facility=LOG_USER):
        """
        Initialize a handler.

        If address is specified as a string, UNIX socket is used.
        If facility is not specified, LOG_USER is used.
        """
        logging.Handler.__init__(self)

        self.address = address
        self.facility = facility
        if type(address) == types.StringType:
            self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
            self.socket.connect(address)
            self.unixsocket = 1
        else:
            self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
            self.unixsocket = 0

        self.formatter = None

    # curious: when talking to the unix-domain '/dev/log' socket, a
    #   zero-terminator seems to be required.  this string is placed
    #   into a class variable so that it can be overridden if
    #   necessary.
    log_format_string = '<%d>%s\000'

    def encodePriority (self, facility, priority):
        """
        Encode the facility and priority. You can pass in strings or
        integers - if strings are passed, the facility_names and
        priority_names mapping dictionaries are used to convert them to
        integers.
        """
        if type(facility) == types.StringType:
            facility = self.facility_names[facility]
        if type(priority) == types.StringType:
            priority = self.priority_names[priority]
        return (facility << 3) | priority

    def close (self):
        """
        Closes the socket.
        """
        if self.unixsocket:
            self.socket.close()

    def emit(self, record):
        """
        Emit a record.

        The record is formatted, and then sent to the syslog server. If
        exception information is present, it is NOT sent to the server.
        """
        msg = self.format(record)
        """
        We need to convert record level to lowercase, maybe this will
        change in the future.
        """
        msg = self.log_format_string % (
            self.encodePriority(self.facility,
                                string.lower(record.levelname)),
            msg)
        try:
            if self.unixsocket:
                self.socket.send(msg)
            else:
                self.socket.sendto(msg, self.address)
        except:
            self.handleError()

class SMTPHandler(logging.Handler):
    """
    A handler class which sends an SMTP email for each logging event.
    """
    def __init__(self, mailhost, fromaddr, toaddrs, subject):
        """
        Initialize the handler.

        Initialize the instance with the from and to addresses and subject
        line of the email. To specify a non-standard SMTP port, use the
        (host, port) tuple format for the mailhost argument.
        """
        logging.Handler.__init__(self)
        if type(mailhost) == types.TupleType:
            host, port = mailhost
            self.mailhost = host
            self.mailport = port
        else:
            self.mailhost = mailhost
            self.mailport = None
        self.fromaddr = fromaddr
        self.toaddrs = toaddrs
        self.subject = subject

    def getSubject(self, record):
        """
        Determine the subject for the email.

        If you want to specify a subject line which is record-dependent,
        override this method.
        """
        return self.subject

    def emit(self, record):
        """
        Emit a record.

        Format the record and send it to the specified addressees.
        """
        try:
            import smtplib
            port = self.mailport
            if not port:
                port = smtplib.SMTP_PORT
            smtp = smtplib.SMTP(self.mailhost, port)
            msg = self.format(record)
            msg = "From: %s\r\nTo: %s\r\nSubject: %s\r\n\r\n%s" % (
                            self.fromaddr,
                            string.join(self.toaddrs, ","),
                            self.getSubject(record), msg
                            )
            smtp.sendmail(self.fromaddr, self.toaddrs, msg)
            smtp.quit()
        except:
            self.handleError()

class NTEventLogHandler(logging.Handler):
    """
    A handler class which sends events to the NT Event Log. Adds a
    registry entry for the specified application name. If no dllname is
    provided, win32service.pyd (which contains some basic message
    placeholders) is used. Note that use of these placeholders will make
    your event logs big, as the entire message source is held in the log.
    If you want slimmer logs, you have to pass in the name of your own DLL
    which contains the message definitions you want to use in the event log.
    """
    def __init__(self, appname, dllname=None, logtype="Application"):
        logging.Handler.__init__(self)
        try:
            import win32evtlogutil, win32evtlog
            self.appname = appname
            self._welu = win32evtlogutil
            if not dllname:
                dllname = os.path.split(self._welu.__file__)
                dllname = os.path.split(dllname[0])
                dllname = os.path.join(dllname[0], r'win32service.pyd')
            self.dllname = dllname
            self.logtype = logtype
            self._welu.AddSourceToRegistry(appname, dllname, logtype)
            self.deftype = win32evtlog.EVENTLOG_ERROR_TYPE
            self.typemap = {
                logging.DEBUG   : win32evtlog.EVENTLOG_INFORMATION_TYPE,
                logging.INFO    : win32evtlog.EVENTLOG_INFORMATION_TYPE,
                logging.WARN    : win32evtlog.EVENTLOG_WARNING_TYPE,
                logging.ERROR   : win32evtlog.EVENTLOG_ERROR_TYPE,
                logging.CRITICAL: win32evtlog.EVENTLOG_ERROR_TYPE,
         }
        except ImportError:
            print "The Python Win32 extensions for NT (service, event "\
                        "logging) appear not to be available."
            self._welu = None

    def getMessageID(self, record):
        """
        Return the message ID for the event record. If you are using your
        own messages, you could do this by having the msg passed to the
        logger being an ID rather than a formatting string. Then, in here,
        you could use a dictionary lookup to get the message ID. This
        version returns 1, which is the base message ID in win32service.pyd.
        """
        return 1

    def getEventCategory(self, record):
        """
        Return the event category for the record.

        Override this if you want to specify your own categories. This version
        returns 0.
        """
        return 0

    def getEventType(self, record):
        """
        Return the event type for the record.

        Override this if you want to specify your own types. This version does
        a mapping using the handler's typemap attribute, which is set up in
        __init__() to a dictionary which contains mappings for DEBUG, INFO,
        WARN, ERROR and CRITICAL. If you are using your own levels you will
        either need to override this method or place a suitable dictionary in
        the handler's typemap attribute.
        """
        return self.typemap.get(record.levelno, self.deftype)

    def emit(self, record):
        """
        Emit a record.

        Determine the message ID, event category and event type. Then
        log the message in the NT event log.
        """
        if self._welu:
            try:
                id = self.getMessageID(record)
                cat = self.getEventCategory(record)
                type = self.getEventType(record)
                msg = self.format(record)
                self._welu.ReportEvent(self.appname, id, cat, type, [msg])
            except:
                self.handleError()

    def close(self):
        """
        Clean up this handler.

        You can remove the application name from the registry as a
        source of event log entries. However, if you do this, you will
        not be able to see the events as you intended in the Event Log
        Viewer - it needs to be able to access the registry to get the
        DLL name.
        """
        #self._welu.RemoveSourceFromRegistry(self.appname, self.logtype)
        pass

class HTTPHandler(logging.Handler):
    """
    A class which sends records to a Web server, using either GET or
    POST semantics.
    """
    def __init__(self, host, url, method="GET"):
        """
        Initialize the instance with the host, the request URL, and the method
        ("GET" or "POST")
        """
        logging.Handler.__init__(self)
        method = string.upper(method)
        if method not in ["GET", "POST"]:
            raise ValueError, "method must be GET or POST"
        self.host = host
        self.url = url
        self.method = method

    def emit(self, record):
        """
        Emit a record.

        Send the record to the Web server as an URL-encoded dictionary
        """
        try:
            import httplib, urllib
            h = httplib.HTTP(self.host)
            url = self.url
            data = urllib.urlencode(record.__dict__)
            if self.method == "GET":
                if (string.find(url, '?') >= 0):
                    sep = '&'
                else:
                    sep = '?'
                url = url + "%c%s" % (sep, data)
            h.putrequest(self.method, url)
            if self.method == "POST":
                h.putheader("Content-length", str(len(data)))
            h.endheaders()
            if self.method == "POST":
                h.send(data)
            h.getreply()    #can't do anything with the result
        except:
            self.handleError()

class BufferingHandler(logging.Handler):
    """
  A handler class which buffers logging records in memory. Whenever each
  record is added to the buffer, a check is made to see if the buffer should
  be flushed. If it should, then flush() is expected to do what's needed.
    """
    def __init__(self, capacity):
        """
        Initialize the handler with the buffer size.
        """
        logging.Handler.__init__(self)
        self.capacity = capacity
        self.buffer = []

    def shouldFlush(self, record):
        """
        Should the handler flush its buffer?

        Returns true if the buffer is up to capacity. This method can be
        overridden to implement custom flushing strategies.
        """
        return (len(self.buffer) >= self.capacity)

    def emit(self, record):
        """
        Emit a record.

        Append the record. If shouldFlush() tells us to, call flush() to process
        the buffer.
        """
        self.buffer.append(record)
        if self.shouldFlush(record):
            self.flush()

    def flush(self):
        """
        Override to implement custom flushing behaviour.

        This version just zaps the buffer to empty.
        """
        self.buffer = []

class MemoryHandler(BufferingHandler):
    """
    A handler class which buffers logging records in memory, periodically
    flushing them to a target handler. Flushing occurs whenever the buffer
    is full, or when an event of a certain severity or greater is seen.
    """
    def __init__(self, capacity, flushLevel=logging.ERROR, target=None):
        """
        Initialize the handler with the buffer size, the level at which
        flushing should occur and an optional target.

        Note that without a target being set either here or via setTarget(),
        a MemoryHandler is no use to anyone!
        """
        BufferingHandler.__init__(self, capacity)
        self.flushLevel = flushLevel
        self.target = target

    def shouldFlush(self, record):
        """
        Check for buffer full or a record at the flushLevel or higher.
        """
        return (len(self.buffer) >= self.capacity) or \
                (record.levelno >= self.flushLevel)

    def setTarget(self, target):
        """
        Set the target handler for this handler.
        """
        self.target = target

    def flush(self):
        """
        For a MemoryHandler, flushing means just sending the buffered
        records to the target, if there is one. Override if you want
        different behaviour.
        """
        if self.target:
            for record in self.buffer:
                self.target.handle(record)
            self.buffer = []

    def close(self):
        """
        Flush, set the target to None and lose the buffer.
        """
        self.flush()
        self.target = None
        self.buffer = []