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If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/README.rst b/README.rst new file mode 100644 index 0000000..d98fecb --- /dev/null +++ b/README.rst @@ -0,0 +1,87 @@ +What is sioscgi? +================ + +sioscgi is an implementation of the Simple Common Gateway Interface (SCGI) +protocol under the Sans-I/O philosophy. + + +What is SCGI? +============= + +SCGI is a protocol used for communication between HTTP servers and Web +applications. Compared to CGI, SCGI is more efficient because it does not fork +and execute a separate instance of the application for every request; instead, +the application is launched ahead of time and receives multiple requests +(either sequentially or concurrently) via socket connections. Compared to +FastCGI, SCGI is a much simpler protocol as it uses a separate socket +connection for each request, rather than including framing within a single +connection to multiplex requests (a feature which is rarely used in FastCGI +anyway due to the lack of per-request flow control). + +See the Wikipedia_ and Python_ SCGI pages for more information. + + +What is Sans-I/O? +================= + +Sans-I/O is a philosophy for developing protocol processing libraries in which +the library does not do any I/O. Instead, a user of the library is responsible +for transferring blocks of bytes between the socket or pipe and the protocol +library, and for receiving application-level protocol items from and sending +them to the library. This obviously makes a sans-I/O library a little more +difficult to use, but comes with the advantage that the same library can be +used with any I/O and concurrency mechanism: the same library should be usable +in a single-request-at-a-time server, a process-per-request or +thread-per-request blocking server, a server using select/poll and +continuations, or a server using asyncio, Twisted, or any other asynchronous +framework. + +See SansIO_ for more information. + + +How do I install it? +==================== + +sioscgi’s releases are published on PyPI for installation through pip. You can +run ``pip install sioscgi``. + +For development, the source is available at GitLab_ and GitHub_. + + +How do I use it? +================ + +In general terms, as follows: + +1. Accept an SCGI connection from the HTTP server (or other SCGI client). +2. Construct an ``SCGIConnection`` object. +3. Receive the request from the SCGI client by repeating the following until a + ``RequestEnd`` event occurs: + + a) Read some bytes from the connection and pass them to + ``SCGIConnection.receive_data``. + b) Call ``SCGIConnection.next_event`` to receive high-level events + corresponding to the received data (one ``RequestHeaders``, zero or more + ``RequestBody`` events, and one ``RequestEnd``). + +4. Send the response to the SCGI client using ``SCGIConnection.send``, sending + first a ``ResponseHeaders`` event, then zero or more ``ResponseBody`` events, + then a ``ResponseEnd`` event, and sending the returned bytes over the + connection. + +This being a sans-I/O library, how exactly you implement each step will depend +on what I/O and application framework you’re working under. For example, for a +thread-per-request or process-per-request server, you would likely do a +blocking receive from a normal function in step 3.1; in an asyncio-based server +you would instead ``await`` new data from a coroutine. + +For detailed information about the classes and methods available, see the +module documentation provided in the docstrings by running ``import sioscgi`` +followed by ``help(sioscgi)``. + + +.. _Wikipedia: https://en.wikipedia.org/wiki/Simple_Common_Gateway_Interface +.. _Python: http://www.python.ca/scgi/ +.. _SansIO: https://sans-io.readthedocs.io/ +.. _GitLab: https://gitlab.com/Hawk777/sioscgi +.. _GitHub: https://github.com/Hawk777/sioscgi diff --git a/setup.cfg b/setup.cfg new file mode 100644 index 0000000..37788ca --- /dev/null +++ b/setup.cfg @@ -0,0 +1,28 @@ +[metadata] +name = sioscgi +version = 1.0.0 +url = https://github.com/Hawk777/sioscgi +author = Christopher Head +classifiers = + Development Status :: 5 - Production/Stable + Intended Audience :: Developers + License :: OSI Approved :: GNU General Public License v3 (GPLv3) + Operating System :: OS Independent + Programming Language :: Python :: 3 + Topic :: Internet :: WWW/HTTP :: Dynamic Content :: CGI Tools/Libraries + Topic :: Software Development :: Libraries :: Python Modules +description = A sans-I/O implementation of the SCGI specification. +long_description = file:README.rst +long_description_content_type = text/x-rst + +[options] +zip_safe = True +package_dir = + =src +py_modules = sioscgi + +[options.packages.find] +where = src + +[pycodestyle] +ignore = E501 diff --git a/setup.py b/setup.py new file mode 100644 index 0000000..b908cbe --- /dev/null +++ b/setup.py @@ -0,0 +1,3 @@ +import setuptools + +setuptools.setup() diff --git a/src/sioscgi.py b/src/sioscgi.py new file mode 100644 index 0000000..9dee335 --- /dev/null +++ b/src/sioscgi.py @@ -0,0 +1,501 @@ +""" +Implements the SCGI protocol. +""" + +import collections +import enum +import logging +import wsgiref.headers +import wsgiref.util + + +@enum.unique +class State(enum.Enum): + """ + The possible states the connection can be in. + """ + + RX_HEADER_LENGTH = enum.auto() + RX_HEADERS = enum.auto() + RX_BODY = enum.auto() + TX_HEADERS = enum.auto() + TX_BODY = enum.auto() + TX_NO_BODY = enum.auto() + DONE = enum.auto() + ERROR = enum.auto() + + +class ProtocolError(Exception): + """ + Raised when a violation of protocol occurs, by either the remote peer or + the local application. + + This is the base class of LocalProtocolError and RemoteProtocolError. + """ + pass + + +class LocalProtocolError(ProtocolError): + """ + Raised when the local application violates protocol. + """ + pass + + +class RemoteProtocolError(ProtocolError): + """ + Raised when the remote peer violates protocol. + """ + pass + + +class Event(object): + """ + The base class of all events returned by an SCGIConnection. + """ + __slots__ = () + + +class RequestHeaders(Event): + """ + Reports that a request has started and carries the environment data. + """ + __slots__ = ("environment") + + def __init__(self, environment): + self.environment = environment + """The environment variables, as a dict from name to value""" + + def __repr__(self): + return "RequestHeaders({})".format(self.environment) + + +class RequestBody(Event): + """ + Transports some request body data. + + In between a RequestHeaders and a RequestEnd, zero or more RequestBody + events are delivered, each carrying a chunk of the request body. + + No RequestBody event carries an empty chunk; consequently, a request + without a body never generates RequestBody events. + """ + __slots__ = ("data") + + def __init__(self, data): + self.data = data + """The body data chunk""" + + def __repr__(self): + return "RequestBody({})".format(repr(self.data)) + + +class RequestEnd(Event): + """ + Reports that a request has finished and both headers and all body data have + been delivered in preceding events. + + Once this event has been delivered, the application can start sending the + response. + """ + __slots__ = () + + def __repr__(self): + return "RequestEnd()" + + +class ResponseHeaders(Event): + """ + Sends the headers of a response to the SCGI client. + + This event must be sent after RequestEnd is received. After sending + ResponseHeaders, if appropriate to the response, one or more ResponseBody + events should be sent, followed by a ResponseEnd. + """ + __slots__ = ("status", "content_type", "location", "other_headers") + + def __init__(self, status, headers): + """ + Construct a ResponseHeaders. + + status -- the HTTP status code and string (e.g. “200 OK”), or None if a + local redirect or client redirect without document is being + generated + headers -- a list of (name, value) tuples of HTTP headers + """ + self.status = status + self.other_headers = wsgiref.headers.Headers(list(headers)) + self.content_type = self.other_headers["Content-Type"] + del self.other_headers["Content-Type"] + self.location = self.other_headers["Location"] + del self.other_headers["Location"] + self._sanity_check() + + def encode(self): + """ + Convert this event into its encoding as raw bytes. + """ + if self.status is None: + # This is a local redirect or client redirect without document, + # which should be served as a Location header and nothing else. + return B"Location: " + self.location.encode("ISO-8859-1") + B"\r\n\r\n" + elif self.location is not None: + # This is a client redirect with document, which should be served + # as Location, then Status, then Content-Type, then everything + # else. + return B"Location: " + self.location.encode("ISO-8859-1") + B"\r\nStatus: " + self.status.encode("ISO-8859-1") + B"\r\nContent-Type: " + self.content_type.encode("ISO-8859-1") + B"\r\n" + bytes(self.other_headers) + else: + # This is a document response, which should be served as + # Content-Type, then Status, then everything else. + return B"Content-Type: " + self.content_type.encode("ISO-8859-1") + B"\r\nStatus: " + self.status.encode("ISO-8859-1") + B"\r\n" + bytes(self.other_headers) + + @property + def succeeding_state(self): + """ + Return the state the state machine should be in after sending these + headers. + """ + if self.status is not None: + return State.TX_BODY + else: + return State.TX_NO_BODY + + def __repr__(self): + return "ResponseHeaders(status={}, content_type={}, location={}, other_headers={})".format(self.status, self.content_type, self.location, repr(self.other_headers)) + + def _sanity_check(self): + # The application must not specify any hop-by-hop headers. + for name in self.other_headers.keys(): + if wsgiref.util.is_hop_by_hop(name): + raise LocalProtocolError("Header {} is hop-by-hop and therefore illegal".format(name)) + try: + # The name and value of every header must be encodable in ISO-8859-1… + bytes(self.other_headers) + # … including Content-Type and Location… + if self.content_type is not None: + self.content_type.encode("ISO-8859-1") + if self.location is not None: + self.location.encode("ISO-8859-1") + # … as must the status line. + if self.status is not None: + self.status.encode("ISO-8859-1") + except UnicodeError: + raise LocalProtocolError("A header is not ISO-8859-1-encodable") + if self.status is not None: + self._sanity_check_with_document() + else: + self._sanity_check_without_document() + + def _sanity_check_with_document(self): + # A response with a document must contain a Content-Type header. + if self.content_type is None: + raise LocalProtocolError("Header Content-Type is mandatory for document response") + + def _sanity_check_without_document(self): + # A response without a document must contain a Location header and + # nothing else. + if self.location is None: + raise LocalProtocolError("Header Location is mandatory for non-document response") + if self.content_type is not None or len(self.other_headers) != 0: + raise LocalProtocolError("Headers other than Location are prohibited for non-document response") + + +class ResponseBody(Event): + """ + Sends a chunk of response body to the SCGI client. + """ + __slots__ = ("data") + + def __init__(self, data): + """ + Construct a ResponseBody. + + data -- the bytes to send + """ + self.data = data + + def __repr__(self): + return "ResponseBody({})".format(repr(self.data)) + + +class ResponseEnd(Event): + """ + Ends the response. + + This event must be the last one sent in a normal response. + """ + __slots__ = () + + def __repr__(self): + return "ResponseEnd()" + + +class SCGIConnection(object): + """ + An SCGI connection. + + This class implements the SCGI protocol as a sans-I/O state machine, which + simply translates between chunks of bytes and sequences of protocol events. + """ + + __slots__ = ( + "_state", + "_error_class", + "_error_msg", + "_event_queue", + "_rx_buffer", + "_rx_buffer_length", + "_rx_buffer_limit", + "_rx_eof", + "_rx_env_length", + "_rx_body_remaining", + ) + + def __init__(self, rx_buffer_limit=65536): + """ + Construct a new SCGIConnection. + + rx_buffer_limit -- the maximum number of received bytes that can be + buffered locally before being turned into an event; this value + bounds the size of request environment + """ + super().__init__() + self._state = State.RX_HEADER_LENGTH + self._error_class = None + self._error_msg = None + self._event_queue = collections.deque() + self._rx_buffer = collections.deque() + self._rx_buffer_length = 0 + self._rx_buffer_limit = rx_buffer_limit + self._rx_eof = False + self._rx_env_length = None + self._rx_body_remaining = None + + @property + def state(self): + """ + The state the connection is currently in. + + Events and state transitions are generated on receipt of data, not on + call to next_event, so this value reflects the state of the connection + as it will be after all events have been consumed. + """ + return self._state + + def receive_data(self, data): + """ + Provide data received over the network to the SCGI connection. + + data -- the received bytes, or a zero-length bytes object if the remote + peer closed its end of the connection + + This method raises LocalProtocolError if a nonzero-length data is + passed in after a zero-length data has previously been passed. It does + not raise exceptions for any other reason. + """ + if data: + if self._rx_eof: + logging.getLogger(__name__).debug("Received %d bytes after EOF", len(data)) + self._report_local_error("Data received after EOF") + raise self._error_class(self._error_msg) + if self._state != State.ERROR: + logging.getLogger(__name__).debug("Received %d bytes", len(data)) + self._rx_buffer.append(data) + self._rx_buffer_length += len(data) + else: + logging.getLogger(__name__).debug("Received EOF") + self._rx_eof = True + self._parse_events() + + def next_event(self): + """ + Return the next event in the event queue. + + This method should generally be called repeatedly until it returns None + after a call to receive_data. However, it is legal to leave some events + unprocessed until a more convenient time, or even call receive_data + again before receiving all the events. + + This method raises RemoteProtocolError in the event of a remote + protocol error, or LocalProtocolError in the event that the same + exception was previously raised by some other method. + """ + if self._state is State.ERROR: + raise self._error_class(self._error_msg) + elif self._event_queue: + return self._event_queue.popleft() + else: + return None + + def send(self, event): + """ + Send an event to the peer and return the bytes to send, or None if the + connection should now be closed. + + event -- the event to send + + This method raises LocalProtocolError if event is not acceptable right + now. + """ + logging.getLogger(__name__).debug("Sending %s", type(event)) + if self._state is State.ERROR: + raise self._error_class(self._error_msg) + elif self._state is State.TX_HEADERS and isinstance(event, ResponseHeaders): + self._state = event.succeeding_state + return event.encode() + elif self._state is State.TX_BODY and isinstance(event, (ResponseBody, ResponseEnd)): + if isinstance(event, ResponseBody): + return event.data + else: + self._state = State.DONE + return None + elif self._state is State.TX_NO_BODY and isinstance(event, ResponseEnd): + self._state = State.DONE + return None + else: + self._report_local_error("Event {} prohibited in state {}".format(type(event), self._state)) + raise self._error_class(self._error_msg) + + def _parse_events(self): + # Throughout this method, we assume that at most one element has been + # added to the receive buffer; this is safe because this method is + # called from receive_data, so we eagerly parse as much as we can on + # every received chunk. + logger = logging.getLogger(__name__) + if self._state is State.RX_HEADER_LENGTH: + logger.debug("In RX_HEADER_LENGTH") + if self._rx_buffer: + # The length-of-environment integer ends with a colon. + index = self._rx_buffer[-1].find(B":") + if index >= 0: + logger.debug("Found : at %d", index) + # We have the full length-of-environment integer and its + # terminating colon. Split up received data into the + # length-of-environment integer, the colon (which we + # discard), and any bytes following the colon (residue). + residue = self._rx_buffer[-1][index + 1:] + if index == 0: + self._rx_buffer.pop() + else: + self._rx_buffer[-1] = self._rx_buffer[-1][:index] + consumed = B"".join(self._rx_buffer) + self._rx_buffer.clear() + self._rx_buffer_length = 0 + # Parse the length-of-environment integer. + try: + self._rx_env_length = int(consumed.decode("ASCII")) + except ValueError: + self._report_remote_error("Invalid length-of-environment") + else: + # Sanity check the length-of-environment integer. + if self._rx_env_length <= 0: + self._report_remote_error("Invalid length-of-environment") + elif self._rx_env_length > self._rx_buffer_limit: + self._report_remote_error("Headers too long (got {}, limit {})".format(self._rx_env_length, self._rx_buffer_limit)) + else: + # Advance the state machine, keeping any residual + # bytes. + self._state = State.RX_HEADERS + if residue: + self._rx_buffer.append(residue) + self._rx_buffer_length += len(residue) + logger.debug("Length of headers is %d, residue is %d bytes", self._rx_env_length, len(residue)) + if self._state is State.RX_HEADERS: + logger.debug("In RX_HEADERS") + if self._rx_buffer_length > self._rx_env_length: + # Split the receive buffer into the environment of the + # designated length, the comma, and any bytes following the + # comma (residue). + logger.debug("Got all headers") + last_chunk_start_pos = self._rx_buffer_length - len(self._rx_buffer[-1]) + assert last_chunk_start_pos <= self._rx_env_length + comma_pos = self._rx_env_length - last_chunk_start_pos + comma = self._rx_buffer[-1][comma_pos] + residue = self._rx_buffer[-1][comma_pos + 1:] + if last_chunk_start_pos == self._rx_env_length: + self._rx_buffer.pop() + else: + self._rx_buffer[-1] = self._rx_buffer[-1][:comma_pos] + environment = B"".join(self._rx_buffer) + self._rx_buffer.clear() + self._rx_buffer_length = 0 + # Check that the comma is a comma. + if comma != 0x2C: + self._report_remote_error("Invalid end-of-environment character") + # Check that the last byte of the environment block is a NUL + elif environment[-1] != 0x00: + self._report_remote_error("Environment block not NUL-terminated") + else: + # Split the environment block into NUL-terminated chunks. + environment = environment[:-1].split(B"\x00") + # Check that there are an even number of parts. + if len(environment) % 2 == 1: + self._report_remote_error("Environment block missing final value") + else: + # Build the dictionary. + env_dict = {} + for i in range(0, len(environment), 2): + try: + k = environment[i].decode("ISO-8859-1") + v = environment[i + 1].decode("ISO-8859-1") + except UnicodeError: + self._report_remote_error("Environment variable is not ISO-8859-1") + break + if not k: + self._report_remote_error("Environment variable with empty name") + break + if k in env_dict: + self._report_remote_error("Duplicate environment variable {}".format(k)) + break + env_dict[k] = v + if self._state != State.ERROR: + # Check for mandatory environment variables. + if env_dict.get("SCGI", None) != "1": + self._report_remote_error("Mandatory variable SCGI not set to 1") + else: + # Advance the state machine, keeping any residual + # bytes. + self._state = State.RX_BODY + if residue: + self._rx_buffer.append(residue) + self._rx_buffer_length += len(residue) + try: + self._rx_body_remaining = int(env_dict.get("CONTENT_LENGTH", "")) + if self._rx_body_remaining < 0: + raise ValueError() + self._event_queue.append(RequestHeaders(env_dict)) + logger.debug("Retrieved %d headers, residue is %d bytes", len(env_dict), len(residue)) + except ValueError: + self._report_remote_error("CONTENT_LENGTH missing or not a whole number") + if self._state is State.RX_BODY: + logger.debug("In RX_BODY, buffer length = %d, body remaining = %d", self._rx_buffer_length, self._rx_body_remaining) + if self._rx_buffer_length <= self._rx_body_remaining: + for chunk in self._rx_buffer: + self._event_queue.append(RequestBody(chunk)) + self._rx_body_remaining -= self._rx_buffer_length + self._rx_buffer.clear() + self._rx_buffer_length = 0 + if self._rx_body_remaining == 0: + self._event_queue.append(RequestEnd()) + self._state = State.TX_HEADERS + else: + self._report_remote_error("Request body longer than CONTENT_LENGTH") + if self._state in {State.TX_HEADERS, State.TX_BODY, State.DONE}: + logger.debug("In %s", self._state) + if self._rx_buffer_length: + self._report_remote_error("Request body longer than CONTENT_LENGTH") + if self._rx_buffer_length > self._rx_buffer_limit: + self._report_remote_error("Too many bytes buffered") + elif self._rx_eof and self._state in {State.RX_HEADER_LENGTH, State.RX_HEADERS, State.RX_BODY}: + self._report_remote_error("Premature EOF") + + def _report_local_error(self, msg): + self._report_error(LocalProtocolError, msg) + + def _report_remote_error(self, msg): + self._report_error(RemoteProtocolError, msg) + + def _report_error(self, error_class, msg): + self._state = State.ERROR + self._error_class = error_class + self._error_msg = msg diff --git a/tests/__init__.py b/tests/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/tests/test_sioscgi.py b/tests/test_sioscgi.py new file mode 100644 index 0000000..3f595ae --- /dev/null +++ b/tests/test_sioscgi.py @@ -0,0 +1,351 @@ +""" +Tests the sioscgi module. +""" + +import logging +import unittest + +import sioscgi + + +class TestGood(unittest.TestCase): + """ + Test the normal cases where things work properly. + """ + + RX_DATA = B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?" + """The raw received bytes.""" + RX_HEADERS = {"CONTENT_LENGTH": "27", "SCGI": "1", "REQUEST_METHOD": "POST", "REQUEST_URI": "/deepthought"} + """The expected decoded request headers.""" + RX_BODY = B"What is the answer to life?" + """The expected decoded request body.""" + + RESPONSES = [ + ("Standard response with document", + "200 OK", + [("Content-Type", "text/plain; charset=UTF-8"), ("Content-Length", "2")], + B"42", + B"Content-Type: text/plain; charset=UTF-8\r\nStatus: 200 OK\r\nContent-Length: 2\r\n\r\n42"), + ("Local redirect", + None, + [("Location", "/foo")], + None, + B"Location: /foo\r\n\r\n"), + ("Client redirect with document", + "301 Moved Permanently", + [("Content-Type", "text/plain; charset=UTF-8"), ("Content-Length", "5"), ("Location", "/foo")], + B"moved", + B"Location: /foo\r\nStatus: 301 Moved Permanently\r\nContent-Type: text/plain; charset=UTF-8\r\nContent-Length: 5\r\n\r\nmoved"), + ] + """ + The responses to generate. + + Each element is a tuple of (name of subtest, response status, response + headers, response body, expected transmitted data). + """ + + def test_big_buffer(self): + """ + Test the normal cases with a big buffer. + + The incoming raw data is delivered in one full chunk, and the response + body is generated the same way. + """ + for (case_name, response_status, response_headers, response_body, expected_tx) in self.RESPONSES: + with self.subTest(name=case_name): + uut = sioscgi.SCGIConnection() + uut.receive_data(self.RX_DATA) + uut.receive_data(B"") + self.assertIs(uut.state, sioscgi.State.TX_HEADERS) + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestHeaders) + self.assertEqual(e.environment, self.RX_HEADERS) + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestBody) + self.assertEqual(e.data, self.RX_BODY) + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestEnd) + e = uut.next_event() + self.assertIsNone(e) + acc = uut.send(sioscgi.ResponseHeaders(response_status, response_headers)) + if response_body is not None: + acc += uut.send(sioscgi.ResponseBody(response_body)) + self.assertEqual(acc, expected_tx) + eof = uut.send(sioscgi.ResponseEnd()) + self.assertIsNone(eof) + + def test_tiny_buffer(self): + """ + Test the normal cases with a tiny buffer. + + The incoming raw data is delivered a byte at a time, and the response + body is generated the same way. + """ + for (case_name, response_status, response_headers, response_body, expected_tx) in self.RESPONSES: + with self.subTest(name=case_name): + uut = sioscgi.SCGIConnection() + for b in self.RX_DATA: + uut.receive_data(bytes((b, ))) + uut.receive_data(B"") + self.assertIs(uut.state, sioscgi.State.TX_HEADERS) + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestHeaders) + self.assertEqual(e.environment, self.RX_HEADERS) + for b in self.RX_BODY: + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestBody) + self.assertEqual(e.data, bytes((b, ))) + e = uut.next_event() + self.assertIsInstance(e, sioscgi.RequestEnd) + e = uut.next_event() + self.assertIsNone(e) + acc = uut.send(sioscgi.ResponseHeaders(response_status, response_headers)) + if response_body is not None: + for b in response_body: + acc += uut.send(sioscgi.ResponseBody(bytes((b, )))) + self.assertEqual(acc, expected_tx) + eof = uut.send(sioscgi.ResponseEnd()) + self.assertIsNone(eof) + + +class TestBadResponseHeaders(unittest.TestCase): + """ + Check that various occurrences of invalid response header structures are + caught and rejected. + """ + + def test_non_latin1_content_type(self): + """ + Test that a Content-Type header with a non-ISO8859-1-encodable value is + rejected. + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders("200 OK", [("Content-Type", "text/Ω"), ("Content-Length", "0")]) + + def test_non_latin1_location(self): + """ + Test that a Location header with a non-ISO8859-1-encodable value is + rejected. + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders("301 Moved Permanently", [("Location", "/Ω"), ("Content-Type", "text/plain; charset=UTF-8"), ("Content-Length", "0")]) + + def test_non_latin1_other(self): + """ + Test that a header other than Content-Type or Location with a + non-ISO8859-1-encodable value is rejected. + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders("200 OK", [("Content-Type", "text/plain; charset=UTF-8"), ("Content-Length", "0"), ("Other-Thing", "Ω")]) + + def test_local_redirect_with_content_type(self): + """ + Test that a local redirect with a Content-Type header is rejected (a + local redirect must not have any headers other than Location). + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders(None, [("Location", "/foo"), ("Content-Type", "text/plain; charset=UTF-8")]) + + def test_local_redirect_with_other_header(self): + """ + Test that a local redirect with an additional header other than + Content-Type is rejected (a local redirect must not have any headers + other than Location). + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders(None, [("Location", "/foo"), ("Other-Thing", "bar")]) + + def test_client_redirect_without_content_type(self): + """ + Test that a client redirect without a Content-Type is rejected + (anything other than a local redirect must have a Content-Type). + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders("301 Moved Permanently", [("Location", "/foo"), ("Content-Length", "42")]) + + def test_document_without_content_type(self): + """ + Test that a normal document without a Content-Type is rejected + (anything other than a local redirect must have a Content-Type). + """ + with self.assertRaises(sioscgi.LocalProtocolError): + sioscgi.ResponseHeaders("200 OK", [("Content-Length", "42")]) + + +class TestBadRXData(unittest.TestCase): + """ + Test various cases of invalid received data. + """ + + def test_premature_eof(self): + """ + Test that an exception is raised if the received data is truncated. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life") # Note missing final ? + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_no_comma(self): + """ + Test that an exception is raised if the received headers are not + properly netstring-terminated with a comma. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00@What is the answer to life?") # Comma replaced with @ + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_no_SCGI(self): + """ + Test that an exception is raised if the SCGI header is missing. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"63:CONTENT_LENGTH\x0027\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") # Comma replaced with @ + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_no_content_length(self): + """ + Test that an exception is raised if the CONTENT_LENGTH header is missing. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"52:SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00@What is the answer to life?") # Comma replaced with @ + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_no_nul(self): + """ + Test that an exception is raised if the header block does not end with + a NUL. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"69:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought,What is the answer to life?") + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_odd_number(self): + """ + Test that an exception is raised if the number of NUL-terminated + strings in the headers block is odd, implying a key without a value or + a value without a key. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"65:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_wrong_SCGI(self): + """ + Test that an exception is raised if the SCGI header has the wrong + value, implying a different protocol version is in use. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x002\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_length_space(self): + """ + Test that a space starting the netstring length for the headers block + is rejected. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B" ") + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + def test_headers_length_non_integer(self): + """ + Test that a non-integer starting the netstring length for the headers + block is rejected. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"A") + uut.receive_data(B"") + with self.assertRaises(sioscgi.RemoteProtocolError): + uut.next_event() + + +class TestBadResponseSequence(unittest.TestCase): + """ + Test various cases of trying to send response events at the wrong time or + in the wrong order. + """ + + def test_response_before_request(self): + """ + Test trying to start the response before the request has finished + arriving. + """ + rxData = B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?" + for i in range(1, len(rxData) - 1): + rxSubstring = rxData[0:i] + with self.subTest(rxSubstring=rxSubstring): + uut = sioscgi.SCGIConnection() + uut.receive_data(rxSubstring) + while uut.next_event() is not None: + pass + txHeaders = sioscgi.ResponseHeaders("200 OK", [("Content-Type", "text/plain; charset=UTF-8")]) + with self.assertRaises(sioscgi.LocalProtocolError): + uut.send(txHeaders) + + def test_response_body_before_headers(self): + """ + Test trying to send some response body before sending the response + headers. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") + while uut.next_event() is not None: + pass + self.assertIs(uut.state, sioscgi.State.TX_HEADERS) + txBody = sioscgi.ResponseBody(B"abcd") + with self.assertRaises(sioscgi.LocalProtocolError): + uut.send(txBody) + + def test_response_end_before_headers(self): + """ + Test trying to send the response end marker before sending the response + headers. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") + while uut.next_event() is not None: + pass + self.assertIs(uut.state, sioscgi.State.TX_HEADERS) + with self.assertRaises(sioscgi.LocalProtocolError): + uut.send(sioscgi.ResponseEnd()) + + +class TestOtherErrors(unittest.TestCase): + """ + Test other miscellaneous errors. + """ + + def test_rx_after_eof(self): + """ + Test that receiving additional data after EOF raises an exception. + """ + uut = sioscgi.SCGIConnection() + uut.receive_data(B"70:CONTENT_LENGTH\x0027\x00SCGI\x001\x00REQUEST_METHOD\x00POST\x00REQUEST_URI\x00/deepthought\x00,What is the answer to life?") + uut.receive_data(B"") + while uut.next_event() is not None: + pass + # This is considered a local error, not a remote error, because + # receiving bytes after EOF isn’t something that the remote + # peer is *capable* of causing if the local software is written + # properly (once the remote peer sends EOF, the kernel should + # prevent it from being able to send any more data, so if this + # happens, it means the local software detected EOF + # improperly). + with self.assertRaises(sioscgi.LocalProtocolError): + uut.receive_data(B"x")