# (c) 2005 Ian Bicking and contributors; written for Paste (http://pythonpaste.org)
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
"""
Error handler middleware
"""
import sys
import traceback
import cgi
from six.moves import cStringIO as StringIO
from paste.exceptions import formatter, collector, reporter
from paste import wsgilib
from paste import request
import six
__all__ = ['ErrorMiddleware', 'handle_exception']
class _NoDefault(object):
def __repr__(self):
return '<NoDefault>'
NoDefault = _NoDefault()
class ErrorMiddleware(object):
"""
Error handling middleware
Usage::
error_catching_wsgi_app = ErrorMiddleware(wsgi_app)
Settings:
``debug``:
If true, then tracebacks will be shown in the browser.
``error_email``:
an email address (or list of addresses) to send exception
reports to
``error_log``:
a filename to append tracebacks to
``show_exceptions_in_wsgi_errors``:
If true, then errors will be printed to ``wsgi.errors``
(frequently a server error log, or stderr).
``from_address``, ``smtp_server``, ``error_subject_prefix``, ``smtp_username``, ``smtp_password``, ``smtp_use_tls``:
variables to control the emailed exception reports
``error_message``:
When debug mode is off, the error message to show to users.
``xmlhttp_key``:
When this key (default ``_``) is in the request GET variables
(not POST!), expect that this is an XMLHttpRequest, and the
response should be more minimal; it should not be a complete
HTML page.
Environment Configuration:
``paste.throw_errors``:
If this setting in the request environment is true, then this
middleware is disabled. This can be useful in a testing situation
where you don't want errors to be caught and transformed.
``paste.expected_exceptions``:
When this middleware encounters an exception listed in this
environment variable and when the ``start_response`` has not
yet occurred, the exception will be re-raised instead of being
caught. This should generally be set by middleware that may
(but probably shouldn't be) installed above this middleware,
and wants to get certain exceptions. Exceptions raised after
``start_response`` have been called are always caught since
by definition they are no longer expected.
"""
def __init__(self, application, global_conf=None,
debug=NoDefault,
error_email=None,
error_log=None,
show_exceptions_in_wsgi_errors=NoDefault,
from_address=None,
smtp_server=None,
smtp_username=None,
smtp_password=None,
smtp_use_tls=False,
error_subject_prefix=None,
error_message=None,
xmlhttp_key=None):
from paste.util import converters
self.application = application
# @@: global_conf should be handled elsewhere in a separate
# function for the entry point
if global_conf is None:
global_conf = {}
if debug is NoDefault:
debug = converters.asbool(global_conf.get('debug'))
if show_exceptions_in_wsgi_errors is NoDefault:
show_exceptions_in_wsgi_errors = converters.asbool(global_conf.get('show_exceptions_in_wsgi_errors'))
self.debug_mode = converters.asbool(debug)
if error_email is None:
error_email = (global_conf.get('error_email')
or global_conf.get('admin_email')
or global_conf.get('webmaster_email')
or global_conf.get('sysadmin_email'))
self.error_email = converters.aslist(error_email)
self.error_log = error_log
self.show_exceptions_in_wsgi_errors = show_exceptions_in_wsgi_errors
if from_address is None:
from_address = global_conf.get('error_from_address', 'errors@localhost')
self.from_address = from_address
if smtp_server is None:
smtp_server = global_conf.get('smtp_server', 'localhost')
self.smtp_server = smtp_server
self.smtp_username = smtp_username or global_conf.get('smtp_username')
self.smtp_password = smtp_password or global_conf.get('smtp_password')
self.smtp_use_tls = smtp_use_tls or converters.asbool(global_conf.get('smtp_use_tls'))
self.error_subject_prefix = error_subject_prefix or ''
if error_message is None:
error_message = global_conf.get('error_message')
self.error_message = error_message
if xmlhttp_key is None:
xmlhttp_key = global_conf.get('xmlhttp_key', '_')
self.xmlhttp_key = xmlhttp_key
def __call__(self, environ, start_response):
"""
The WSGI application interface.
"""
# We want to be careful about not sending headers twice,
# and the content type that the app has committed to (if there
# is an exception in the iterator body of the response)
if environ.get('paste.throw_errors'):
return self.application(environ, start_response)
environ['paste.throw_errors'] = True
try:
__traceback_supplement__ = Supplement, self, environ
sr_checker = ResponseStartChecker(start_response)
app_iter = self.application(environ, sr_checker)
return self.make_catching_iter(app_iter, environ, sr_checker)
except:
exc_info = sys.exc_info()
try:
for expect in environ.get('paste.expected_exceptions', []):
if isinstance(exc_info[1], expect):
raise
start_response('500 Internal Server Error',
[('content-type', 'text/html')],
exc_info)
# @@: it would be nice to deal with bad content types here
response = self.exception_handler(exc_info, environ)
if six.PY3:
response = response.encode('utf8')
return [response]
finally:
# clean up locals...
exc_info = None
def make_catching_iter(self, app_iter, environ, sr_checker):
if isinstance(app_iter, (list, tuple)):
# These don't raise
return app_iter
return CatchingIter(app_iter, environ, sr_checker, self)
def exception_handler(self, exc_info, environ):
simple_html_error = False
if self.xmlhttp_key:
get_vars = request.parse_querystring(environ)
if dict(get_vars).get(self.xmlhttp_key):
simple_html_error = True
return handle_exception(
exc_info, environ['wsgi.errors'],
html=True,
debug_mode=self.debug_mode,
error_email=self.error_email,
error_log=self.error_log,
show_exceptions_in_wsgi_errors=self.show_exceptions_in_wsgi_errors,
error_email_from=self.from_address,
smtp_server=self.smtp_server,
smtp_username=self.smtp_username,
smtp_password=self.smtp_password,
smtp_use_tls=self.smtp_use_tls,
error_subject_prefix=self.error_subject_prefix,
error_message=self.error_message,
simple_html_error=simple_html_error)
class ResponseStartChecker(object):
def __init__(self, start_response):
self.start_response = start_response
self.response_started = False
def __call__(self, *args):
self.response_started = True
self.start_response(*args)
class CatchingIter(object):
"""
A wrapper around the application iterator that will catch
exceptions raised by the a generator, or by the close method, and
display or report as necessary.
"""
def __init__(self, app_iter, environ, start_checker, error_middleware):
self.app_iterable = app_iter
self.app_iterator = iter(app_iter)
self.environ = environ
self.start_checker = start_checker
self.error_middleware = error_middleware
self.closed = False
def __iter__(self):
return self
def next(self):
__traceback_supplement__ = (
Supplement, self.error_middleware, self.environ)
if self.closed:
raise StopIteration
try:
return self.app_iterator.next()
except StopIteration:
self.closed = True
close_response = self._close()
if close_response is not None:
return close_response
else:
raise StopIteration
except:
self.closed = True
close_response = self._close()
exc_info = sys.exc_info()
response = self.error_middleware.exception_handler(
exc_info, self.environ)
if close_response is not None:
response += (
'<hr noshade>Error in .close():<br>%s'
% close_response)
if not self.start_checker.response_started:
self.start_checker('500 Internal Server Error',
[('content-type', 'text/html')],
exc_info)
if six.PY3:
response = response.encode('utf8')
return response
__next__ = next
def close(self):
# This should at least print something to stderr if the
# close method fails at this point
if not self.closed:
self._close()
def _close(self):
"""Close and return any error message"""
if not hasattr(self.app_iterable, 'close'):
return None
try:
self.app_iterable.close()
return None
except:
close_response = self.error_middleware.exception_handler(
sys.exc_info(), self.environ)
return close_response
class Supplement(object):
"""
This is a supplement used to display standard WSGI information in
the traceback.
"""
def __init__(self, middleware, environ):
self.middleware = middleware
self.environ = environ
self.source_url = request.construct_url(environ)
def extraData(self):
data = {}
cgi_vars = data[('extra', 'CGI Variables')] = {}
wsgi_vars = data[('extra', 'WSGI Variables')] = {}
hide_vars = ['paste.config', 'wsgi.errors', 'wsgi.input',
'wsgi.multithread', 'wsgi.multiprocess',
'wsgi.run_once', 'wsgi.version',
'wsgi.url_scheme']
for name, value in self.environ.items():
if name.upper() == name:
if value:
cgi_vars[name] = value
elif name not in hide_vars:
wsgi_vars[name] = value
if self.environ['wsgi.version'] != (1, 0):
wsgi_vars['wsgi.version'] = self.environ['wsgi.version']
proc_desc = tuple([int(bool(self.environ[key]))
for key in ('wsgi.multiprocess',
'wsgi.multithread',
'wsgi.run_once')])
wsgi_vars['wsgi process'] = self.process_combos[proc_desc]
wsgi_vars['application'] = self.middleware.application
if 'paste.config' in self.environ:
data[('extra', 'Configuration')] = dict(self.environ['paste.config'])
return data
process_combos = {
# multiprocess, multithread, run_once
(0, 0, 0): 'Non-concurrent server',
(0, 1, 0): 'Multithreaded',
(1, 0, 0): 'Multiprocess',
(1, 1, 0): 'Multi process AND threads (?)',
(0, 0, 1): 'Non-concurrent CGI',
(0, 1, 1): 'Multithread CGI (?)',
(1, 0, 1): 'CGI',
(1, 1, 1): 'Multi thread/process CGI (?)',
}
def handle_exception(exc_info, error_stream, html=True,
debug_mode=False,
error_email=None,
error_log=None,
show_exceptions_in_wsgi_errors=False,
error_email_from='errors@localhost',
smtp_server='localhost',
smtp_username=None,
smtp_password=None,
smtp_use_tls=False,
error_subject_prefix='',
error_message=None,
simple_html_error=False,
):
"""
For exception handling outside of a web context
Use like::
import sys
from paste.exceptions.errormiddleware import handle_exception
try:
do stuff
except:
handle_exception(
sys.exc_info(), sys.stderr, html=False, ...other config...)
If you want to report, but not fully catch the exception, call
``raise`` after ``handle_exception``, which (when given no argument)
will reraise the exception.
"""
reported = False
exc_data = collector.collect_exception(*exc_info)
extra_data = ''
if error_email:
rep = reporter.EmailReporter(
to_addresses=error_email,
from_address=error_email_from,
smtp_server=smtp_server,
smtp_username=smtp_username,
smtp_password=smtp_password,
smtp_use_tls=smtp_use_tls,
subject_prefix=error_subject_prefix)
rep_err = send_report(rep, exc_data, html=html)
if rep_err:
extra_data += rep_err
else:
reported = True
if error_log:
rep = reporter.LogReporter(
filename=error_log)
rep_err = send_report(rep, exc_data, html=html)
if rep_err:
extra_data += rep_err
else:
reported = True
if show_exceptions_in_wsgi_errors:
rep = reporter.FileReporter(
file=error_stream)
rep_err = send_report(rep, exc_data, html=html)
if rep_err:
extra_data += rep_err
else:
reported = True
else:
line = ('Error - %s: %s\n'
% (exc_data.exception_type, exc_data.exception_value))
if six.PY3:
line = line.encode('utf8')
error_stream.write(line)
if html:
if debug_mode and simple_html_error:
return_error = formatter.format_html(
exc_data, include_hidden_frames=False,
include_reusable=False, show_extra_data=False)
reported = True
elif debug_mode and not simple_html_error:
error_html = formatter.format_html(
exc_data,
include_hidden_frames=True,
include_reusable=False)
head_html = formatter.error_css + formatter.hide_display_js
return_error = error_template(
head_html, error_html, extra_data)
extra_data = ''
reported = True
else:
msg = error_message or '''
An error occurred. See the error logs for more information.
(Turn debug on to display exception reports here)
'''
return_error = error_template('', msg, '')
else:
return_error = None
if not reported and error_stream:
err_report = formatter.format_text(exc_data, show_hidden_frames=True)
err_report += '\n' + '-'*60 + '\n'
error_stream.write(err_report)
if extra_data:
error_stream.write(extra_data)
return return_error
def send_report(rep, exc_data, html=True):
try:
rep.report(exc_data)
except:
output = StringIO()
traceback.print_exc(file=output)
if html:
return """
<p>Additionally an error occurred while sending the %s report:
<pre>%s</pre>
</p>""" % (
cgi.escape(str(rep)), output.getvalue())
else:
return (
"Additionally an error occurred while sending the "
"%s report:\n%s" % (str(rep), output.getvalue()))
else:
return ''
def error_template(head_html, exception, extra):
return '''
<html>
<head>
<title>Server Error</title>
%s
</head>
<body>
<h1>Server Error</h1>
%s
%s
</body>
</html>''' % (head_html, exception, extra)
def make_error_middleware(app, global_conf, **kw):
return ErrorMiddleware(app, global_conf=global_conf, **kw)
doc_lines = ErrorMiddleware.__doc__.splitlines(True)
for i in range(len(doc_lines)):
if doc_lines[i].strip().startswith('Settings'):
make_error_middleware.__doc__ = ''.join(doc_lines[i:])
break
del i, doc_lines