Source code for wsgidav.dav_error

# (c) 2009-2024 Martin Wendt and contributors; see WsgiDAV https://github.com/mar10/wsgidav
# Original PyFileServer (c) 2005 Ho Chun Wei.
# Licensed under the MIT license:
# http://www.opensource.org/licenses/mit-license.php
"""
Implements a DAVError class that is used to signal WebDAV and HTTP errors.
"""
import datetime
from html import escape as html_escape

from wsgidav import util, xml_tools
from wsgidav.xml_tools import etree

__docformat__ = "reStructuredText"

# ========================================================================
# List of HTTP Response Codes.
# ========================================================================
HTTP_CONTINUE = 100
HTTP_SWITCHING_PROTOCOLS = 101
HTTP_PROCESSING = 102

HTTP_OK = 200
HTTP_CREATED = 201
HTTP_ACCEPTED = 202
HTTP_NON_AUTHORITATIVE_INFO = 203
HTTP_NO_CONTENT = 204
HTTP_RESET_CONTENT = 205
HTTP_PARTIAL_CONTENT = 206
HTTP_MULTI_STATUS = 207
HTTP_IM_USED = 226

HTTP_MULTIPLE_CHOICES = 300
HTTP_MOVED = 301
HTTP_FOUND = 302
HTTP_SEE_OTHER = 303
HTTP_NOT_MODIFIED = 304
HTTP_USE_PROXY = 305
HTTP_TEMP_REDIRECT = 307

HTTP_BAD_REQUEST = 400
HTTP_UNAUTHORIZED = 401
HTTP_PAYMENT_REQUIRED = 402
HTTP_FORBIDDEN = 403
HTTP_NOT_FOUND = 404
HTTP_METHOD_NOT_ALLOWED = 405
HTTP_NOT_ACCEPTABLE = 406
HTTP_PROXY_AUTH_REQUIRED = 407
HTTP_REQUEST_TIMEOUT = 408
HTTP_CONFLICT = 409
HTTP_GONE = 410
HTTP_LENGTH_REQUIRED = 411
HTTP_PRECONDITION_FAILED = 412
HTTP_REQUEST_ENTITY_TOO_LARGE = 413
HTTP_REQUEST_URI_TOO_LONG = 414
HTTP_MEDIATYPE_NOT_SUPPORTED = 415
HTTP_RANGE_NOT_SATISFIABLE = 416
HTTP_EXPECTATION_FAILED = 417
HTTP_UNPROCESSABLE_ENTITY = 422
HTTP_LOCKED = 423
HTTP_FAILED_DEPENDENCY = 424
HTTP_UPGRADE_REQUIRED = 426

HTTP_INTERNAL_ERROR = 500
HTTP_NOT_IMPLEMENTED = 501
HTTP_BAD_GATEWAY = 502
HTTP_SERVICE_UNAVAILABLE = 503
HTTP_GATEWAY_TIMEOUT = 504
HTTP_VERSION_NOT_SUPPORTED = 505
HTTP_INSUFFICIENT_STORAGE = 507
HTTP_NOT_EXTENDED = 510


# ========================================================================
# if ERROR_DESCRIPTIONS exists for an error code, the error description will be
# sent as the error response code.
# Otherwise only the numeric code itself is sent.
# ========================================================================
# TODO: paste.httpserver may raise exceptions, if a status code is not
# followed by a description, so should define all of them.
ERROR_DESCRIPTIONS = {
    HTTP_OK: "200 OK",
    HTTP_CREATED: "201 Created",
    HTTP_NO_CONTENT: "204 No Content",
    HTTP_NOT_MODIFIED: "304 Not Modified",
    HTTP_BAD_REQUEST: "400 Bad Request",
    HTTP_UNAUTHORIZED: "401 Unauthorized",
    HTTP_FORBIDDEN: "403 Forbidden",
    HTTP_METHOD_NOT_ALLOWED: "405 Method Not Allowed",
    HTTP_NOT_FOUND: "404 Not Found",
    HTTP_CONFLICT: "409 Conflict",
    HTTP_PRECONDITION_FAILED: "412 Precondition Failed",
    HTTP_MEDIATYPE_NOT_SUPPORTED: "415 Media Type Not Supported",
    HTTP_RANGE_NOT_SATISFIABLE: "416 Range Not Satisfiable",
    HTTP_LOCKED: "423 Locked",
    HTTP_FAILED_DEPENDENCY: "424 Failed Dependency",
    HTTP_INTERNAL_ERROR: "500 Internal Server Error",
    HTTP_NOT_IMPLEMENTED: "501 Not Implemented",
    HTTP_BAD_GATEWAY: "502 Bad Gateway",
}

# ========================================================================
# if ERROR_RESPONSES exists for an error code, a html output will be sent as response
# body including the ERROR_RESPONSES value. Otherwise a null response body is sent.
# Mostly for browser viewing
# ========================================================================

ERROR_RESPONSES = {
    HTTP_BAD_REQUEST: "An invalid request was specified",
    HTTP_NOT_FOUND: "The specified resource was not found",
    HTTP_UNAUTHORIZED: "Invalid authentication credentials for the requested resource",
    HTTP_FORBIDDEN: "Access denied to the specified resource",
    HTTP_INTERNAL_ERROR: "An internal server error occurred",
    HTTP_NOT_IMPLEMENTED: "Not implemented",
}


# ========================================================================
# Condition codes
# http://www.webdav.org/specs/rfc4918.html#precondition.postcondition.xml.elements
# ========================================================================

PRECONDITION_CODE_ProtectedProperty = "{DAV:}cannot-modify-protected-property"
PRECONDITION_CODE_MissingLockToken = "{DAV:}lock-token-submitted"
PRECONDITION_CODE_LockTokenMismatch = "{DAV:}lock-token-matches-request-uri"
PRECONDITION_CODE_LockConflict = "{DAV:}no-conflicting-lock"
PRECONDITION_CODE_PropfindFiniteDepth = "{DAV:}propfind-finite-depth"


[docs] class DAVErrorCondition: """May be embedded in :class:`DAVError` instances to store additional data.""" def __init__(self, condition_code): self.condition_code = condition_code self.hrefs = [] def __str__(self): return f"{self.condition_code}({self.hrefs})"
[docs] def add_href(self, href): assert href.startswith("/") assert self.condition_code in ( PRECONDITION_CODE_LockConflict, PRECONDITION_CODE_MissingLockToken, ) if href not in self.hrefs: self.hrefs.append(href)
[docs] def as_xml(self): if self.condition_code == PRECONDITION_CODE_MissingLockToken: assert ( len(self.hrefs) > 0 ), "lock-token-submitted requires at least one href" error_el = etree.Element("{DAV:}error") cond_el = etree.SubElement(error_el, self.condition_code) for href in self.hrefs: etree.SubElement(cond_el, "{DAV:}href").text = href return error_el
[docs] def as_string(self): return util.to_str(xml_tools.xml_to_bytes(self.as_xml(), pretty=True))
# ======================================================================== # DAVError # ======================================================================== # @@: I prefer having a separate exception type for each response, # as in paste.httpexceptions. This way you can catch just the exceptions # you want (or you can catch an abstract superclass to get any of them)
[docs] class DAVError(Exception): """General error class that is used to signal HTTP and WEBDAV errors. May contain a :class:`DAVErrorCondition`. """ # TODO: Ian Bicking proposed to add an additional 'comment' arg, but # couldn't we use the existing 'context_info'? # @@: This should also take some message value, for a detailed error message. # This would be helpful for debugging. def __init__( self, status_code, context_info=None, *, src_exception=None, err_condition=None, add_headers=None, ): # allow passing of Pre- and Postconditions, see # http://www.webdav.org/specs/rfc4918.html#precondition.postcondition.xml.elements self.value = int(status_code) self.context_info = context_info self.src_exception = src_exception self.err_condition = err_condition self.add_headers = add_headers if util.is_str(err_condition): self.err_condition = DAVErrorCondition(err_condition) assert ( self.err_condition is None or type(self.err_condition) is DAVErrorCondition ) def __repr__(self): return f"DAVError({self.get_user_info()})" def get_user_info(self): """Return readable string.""" if self.value in ERROR_DESCRIPTIONS: s = f"{ERROR_DESCRIPTIONS[self.value]}" else: s = f"{self.value}" if self.context_info: s += f": {self.context_info}" elif self.value in ERROR_RESPONSES: s += f": {ERROR_RESPONSES[self.value]}" if self.src_exception: s += f"\n Source exception: {self.src_exception!r}" if self.err_condition: s += f"\n Error condition: {self.err_condition!r}" # if self.add_headers: # s += f"\n Add headers: {self.add_headers}" return s def get_response_page(self): """Return a tuple (content-type, response page).""" # If it has pre- or post-condition: return as XML response if self.err_condition: return ( "application/xml; charset=utf-8", util.to_bytes(self.err_condition.as_string()), ) # Else return as HTML status = get_http_status_string(self) html = [] html.append( "<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01//EN' " "'http://www.w3.org/TR/html4/strict.dtd'>" ) html.append("<html><head>") html.append( " <meta http-equiv='Content-Type' content='text/html; charset=utf-8'>" ) html.append(f" <title>{status}</title>") html.append("</head><body>") html.append(f" <h1>{status}</h1>") html.append(f" <p>{html_escape(self.get_user_info())}</p>") html.append("<hr/>") html.append( "<a href='https://github.com/mar10/wsgidav/'>{}</a> - {}".format( util.public_wsgidav_info, html_escape(str(datetime.datetime.now()), "utf-8"), ) ) html.append("</body></html>") html = "\n".join(html) return ("text/html; charset=utf-8", util.to_bytes(html))
[docs] def get_http_status_code(v): """Return HTTP response code as integer, e.g. 204.""" if hasattr(v, "value"): return int(v.value) # v is a DAVError return int(v)
[docs] def get_http_status_string(v): """Return HTTP response string, e.g. 204 -> ('204 No Content'). The return string always includes descriptive text, to satisfy Apache mod_dav. `v`: status code or DAVError """ code = get_http_status_code(v) try: return ERROR_DESCRIPTIONS[code] except KeyError: return f"{code} Status"
[docs] def get_response_page(v): v = as_DAVError(v) return v.get_response_page()
[docs] def as_DAVError(e): """Convert any non-DAVError exception to HTTP_INTERNAL_ERROR.""" if isinstance(e, DAVError): return e elif isinstance(e, Exception): # traceback.print_exc() return DAVError(HTTP_INTERNAL_ERROR, src_exception=e) else: return DAVError(HTTP_INTERNAL_ERROR, f"{e}")