261 lines
8.6 KiB
Python
261 lines
8.6 KiB
Python
import sys
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from traceback import extract_tb, format_exc
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from sanic.exceptions import (
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INTERNAL_SERVER_ERROR_HTML,
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TRACEBACK_BORDER,
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TRACEBACK_LINE_HTML,
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TRACEBACK_STYLE,
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TRACEBACK_WRAPPER_HTML,
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TRACEBACK_WRAPPER_INNER_HTML,
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ContentRangeError,
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HeaderNotFound,
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InvalidRangeType,
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SanicException,
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)
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from sanic.log import logger
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from sanic.response import html, text
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class ErrorHandler:
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"""
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Provide :class:`sanic.app.Sanic` application with a mechanism to handle
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and process any and all uncaught exceptions in a way the application
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developer will set fit.
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This error handling framework is built into the core that can be extended
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by the developers to perform a wide range of tasks from recording the error
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stats to reporting them to an external service that can be used for
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realtime alerting system.
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"""
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handlers = None
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cached_handlers = None
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_missing = object()
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def __init__(self):
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self.handlers = []
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self.cached_handlers = {}
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self.debug = False
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def _render_exception(self, exception):
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frames = extract_tb(exception.__traceback__)
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frame_html = []
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for frame in frames:
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frame_html.append(TRACEBACK_LINE_HTML.format(frame))
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return TRACEBACK_WRAPPER_INNER_HTML.format(
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exc_name=exception.__class__.__name__,
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exc_value=exception,
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frame_html="".join(frame_html),
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)
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def _render_traceback_html(self, exception, request):
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exc_type, exc_value, tb = sys.exc_info()
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exceptions = []
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while exc_value:
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exceptions.append(self._render_exception(exc_value))
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exc_value = exc_value.__cause__
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return TRACEBACK_WRAPPER_HTML.format(
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style=TRACEBACK_STYLE,
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exc_name=exception.__class__.__name__,
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exc_value=exception,
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inner_html=TRACEBACK_BORDER.join(reversed(exceptions)),
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path=request.path,
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)
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def add(self, exception, handler):
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"""
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Add a new exception handler to an already existing handler object.
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:param exception: Type of exception that need to be handled
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:param handler: Reference to the method that will handle the exception
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:type exception: :class:`sanic.exceptions.SanicException` or
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:class:`Exception`
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:type handler: ``function``
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:return: None
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"""
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self.handlers.append((exception, handler))
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def lookup(self, exception):
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"""
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Lookup the existing instance of :class:`ErrorHandler` and fetch the
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registered handler for a specific type of exception.
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This method leverages a dict lookup to speedup the retrieval process.
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:param exception: Type of exception
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:type exception: :class:`sanic.exceptions.SanicException` or
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:class:`Exception`
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:return: Registered function if found ``None`` otherwise
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"""
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handler = self.cached_handlers.get(type(exception), self._missing)
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if handler is self._missing:
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for exception_class, handler in self.handlers:
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if isinstance(exception, exception_class):
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self.cached_handlers[type(exception)] = handler
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return handler
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self.cached_handlers[type(exception)] = None
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handler = None
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return handler
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def response(self, request, exception):
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"""Fetches and executes an exception handler and returns a response
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object
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:param request: Instance of :class:`sanic.request.Request`
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:param exception: Exception to handle
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:type request: :class:`sanic.request.Request`
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:type exception: :class:`sanic.exceptions.SanicException` or
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:class:`Exception`
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:return: Wrap the return value obtained from :func:`default`
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or registered handler for that type of exception.
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"""
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handler = self.lookup(exception)
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response = None
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try:
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if handler:
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response = handler(request, exception)
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if response is None:
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response = self.default(request, exception)
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except Exception:
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self.log(format_exc())
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try:
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url = repr(request.url)
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except AttributeError:
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url = "unknown"
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response_message = (
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"Exception raised in exception handler " '"%s" for uri: %s'
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)
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logger.exception(response_message, handler.__name__, url)
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if self.debug:
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return text(response_message % (handler.__name__, url), 500)
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else:
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return text("An error occurred while handling an error", 500)
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return response
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def log(self, message, level="error"):
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"""
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Deprecated, do not use.
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"""
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def default(self, request, exception):
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"""
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Provide a default behavior for the objects of :class:`ErrorHandler`.
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If a developer chooses to extent the :class:`ErrorHandler` they can
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provide a custom implementation for this method to behave in a way
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they see fit.
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:param request: Incoming request
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:param exception: Exception object
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:type request: :class:`sanic.request.Request`
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:type exception: :class:`sanic.exceptions.SanicException` or
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:class:`Exception`
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:return:
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"""
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self.log(format_exc())
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try:
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url = repr(request.url)
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except AttributeError:
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url = "unknown"
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response_message = "Exception occurred while handling uri: %s"
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logger.exception(response_message, url)
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if issubclass(type(exception), SanicException):
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return text(
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"Error: {}".format(exception),
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status=getattr(exception, "status_code", 500),
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headers=getattr(exception, "headers", dict()),
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)
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elif self.debug:
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html_output = self._render_traceback_html(exception, request)
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return html(html_output, status=500)
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else:
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return html(INTERNAL_SERVER_ERROR_HTML, status=500)
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class ContentRangeHandler:
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"""
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A mechanism to parse and process the incoming request headers to
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extract the content range information.
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:param request: Incoming api request
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:param stats: Stats related to the content
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:type request: :class:`sanic.request.Request`
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:type stats: :class:`posix.stat_result`
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:ivar start: Content Range start
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:ivar end: Content Range end
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:ivar size: Length of the content
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:ivar total: Total size identified by the :class:`posix.stat_result`
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instance
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:ivar ContentRangeHandler.headers: Content range header ``dict``
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"""
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__slots__ = ("start", "end", "size", "total", "headers")
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def __init__(self, request, stats):
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self.total = stats.st_size
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_range = request.headers.get("Range")
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if _range is None:
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raise HeaderNotFound("Range Header Not Found")
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unit, _, value = tuple(map(str.strip, _range.partition("=")))
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if unit != "bytes":
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raise InvalidRangeType(
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"%s is not a valid Range Type" % (unit,), self
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)
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start_b, _, end_b = tuple(map(str.strip, value.partition("-")))
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try:
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self.start = int(start_b) if start_b else None
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except ValueError:
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raise ContentRangeError(
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"'%s' is invalid for Content Range" % (start_b,), self
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)
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try:
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self.end = int(end_b) if end_b else None
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except ValueError:
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raise ContentRangeError(
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"'%s' is invalid for Content Range" % (end_b,), self
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)
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if self.end is None:
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if self.start is None:
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raise ContentRangeError(
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"Invalid for Content Range parameters", self
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)
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else:
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# this case represents `Content-Range: bytes 5-`
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self.end = self.total - 1
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else:
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if self.start is None:
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# this case represents `Content-Range: bytes -5`
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self.start = self.total - self.end
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self.end = self.total - 1
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if self.start >= self.end:
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raise ContentRangeError(
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"Invalid for Content Range parameters", self
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)
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self.size = self.end - self.start + 1
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self.headers = {
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"Content-Range": "bytes %s-%s/%s"
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% (self.start, self.end, self.total)
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}
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def __bool__(self):
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return self.size > 0
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