response.py
from collections import OrderedDict
from datetime import datetime, timedelta
import Cookie
import json
import types
import uuid
import socket
from .constants import response_codes
from .logger import get_logger
missing = object()
class Response(object):
"""Object representing the response to a HTTP request
:param handler: RequestHandler being used for this response
:param request: Request that this is the response for
.. attribute:: request
Request associated with this Response.
.. attribute:: encoding
The encoding to use when converting unicode to strings for output.
.. attribute:: add_required_headers
Boolean indicating whether mandatory headers should be added to the
response.
.. attribute:: send_body_for_head_request
Boolean, default False, indicating whether the body content should be
sent when the request method is HEAD.
.. attribute:: explicit_flush
Boolean indicating whether output should be flushed automatically or only
when requested.
.. attribute:: writer
The ResponseWriter for this response
.. attribute:: status
Status tuple (code, message). Can be set to an integer, in which case the
message part is filled in automatically, or a tuple.
.. attribute:: headers
List of HTTP headers to send with the response. Each item in the list is a
tuple of (name, value).
.. attribute:: content
The body of the response. This can either be a string or a iterable of response
parts. If it is an iterable, any item may be a string or a function of zero
parameters which, when called, returns a string."""
def __init__(self, handler, request):
self.request = request
self.encoding = "utf8"
self.add_required_headers = True
self.send_body_for_head_request = False
self.explicit_flush = False
self.close_connection = False
self.writer = ResponseWriter(handler, self)
self._status = (200, None)
self.headers = ResponseHeaders()
self.content = []
self.logger = get_logger()
@property
def status(self):
return self._status
@status.setter
def status(self, value):
if hasattr(value, "__len__"):
if len(value) != 2:
raise ValueError
else:
self._status = (int(value[0]), str(value[1]))
else:
self._status = (int(value), None)
def set_cookie(self, name, value, path="/", domain=None, max_age=None,
expires=None, secure=False, httponly=False, comment=None):
"""Set a cookie to be sent with a Set-Cookie header in the
response
:param name: String name of the cookie
:param value: String value of the cookie
:param max_age: datetime.timedelta int representing the time (in seconds)
until the cookie expires
:param path: String path to which the cookie applies
:param domain: String domain to which the cookie applies
:param secure: Boolean indicating whether the cookie is marked as secure
:param httponly: Boolean indicating whether the cookie is marked as
HTTP Only
:param comment: String comment
:param expires: datetime.datetime or datetime.timedelta indicating a
time or interval from now when the cookie expires
"""
days = dict((i+1, name) for i, name in enumerate(["jan", "feb", "mar",
"apr", "may", "jun",
"jul", "aug", "sep",
"oct", "nov", "dec"]))
if value is None:
value = ''
max_age = 0
expires = timedelta(days=-1)
if isinstance(expires, timedelta):
expires = datetime.utcnow() + expires
if expires is not None:
expires_str = expires.strftime("%d %%s %Y %H:%M:%S GMT")
expires_str = expires_str % days[expires.month]
expires = expires_str
if max_age is not None:
if hasattr(max_age, "total_seconds"):
max_age = int(max_age.total_seconds())
max_age = "%.0d" % max_age
m = Cookie.Morsel()
def maybe_set(key, value):
if value is not None and value is not False:
m[key] = value
m.set(name, value, value)
maybe_set("path", path)
maybe_set("domain", domain)
maybe_set("comment", comment)
maybe_set("expires", expires)
maybe_set("max-age", max_age)
maybe_set("secure", secure)
maybe_set("httponly", httponly)
self.headers.append("Set-Cookie", m.OutputString())
def unset_cookie(self, name):
"""Remove a cookie from those that are being sent with the response"""
cookies = self.headers.get("Set-Cookie")
parser = Cookie.BaseCookie()
for cookie in cookies:
parser.load(cookie)
if name in parser.keys():
del self.headers["Set-Cookie"]
for m in parser.values():
if m.key != name:
self.headers.append(("Set-Cookie", m.OutputString()))
def delete_cookie(self, name, path="/", domain=None):
"""Delete a cookie on the client by setting it to the empty string
and to expire in the past"""
self.set_cookie(name, None, path=path, domain=domain, max_age=0,
expires=timedelta(days=-1))
def iter_content(self, read_file=False):
"""Iterator returning chunks of response body content.
If any part of the content is a function, this will be called
and the resulting value (if any) returned.
:param read_file: - boolean controlling the behaviour when content
is a file handle. When set to False the handle will be returned directly
allowing the file to be passed to the output in small chunks. When set to
True, the entire content of the file will be returned as a string facilitating
non-streaming operations like template substitution.
"""
if isinstance(self.content, types.StringTypes):
yield self.content
elif hasattr(self.content, "read"):
if read_file:
yield self.content.read()
else:
yield self.content
else:
for item in self.content:
if hasattr(item, "__call__"):
value = item()
else:
value = item
if value:
yield value
def write_status_headers(self):
"""Write out the status line and headers for the response"""
self.writer.write_status(*self.status)
for item in self.headers:
self.writer.write_header(*item)
self.writer.end_headers()
def write_content(self):
"""Write out the response content"""
if self.request.method != "HEAD" or self.send_body_for_head_request:
for item in self.iter_content():
self.writer.write_content(item)
def write(self):
"""Write the whole response"""
self.write_status_headers()
self.write_content()
def set_error(self, code, message=""):
"""Set the response status headers and body to indicate an
error"""
err = {"code": code,
"message": message}
data = json.dumps({"error": err})
self.status = code
self.headers = [("Content-Type", "application/json"),
("Content-Length", len(data))]
self.content = data
if code == 500:
self.logger.error(message)
class MultipartContent(object):
def __init__(self, boundary=None, default_content_type=None):
self.items = []
if boundary is None:
boundary = str(uuid.uuid4())
self.boundary = boundary
self.default_content_type = default_content_type
def __call__(self):
boundary = "--" + self.boundary
rv = ["", boundary]
for item in self.items:
rv.append(str(item))
rv.append(boundary)
rv[-1] += "--"
return "\r\n".join(rv)
def append_part(self, data, content_type=None, headers=None):
if content_type is None:
content_type = self.default_content_type
self.items.append(MultipartPart(data, content_type, headers))
def __iter__(self):
#This is hackish; when writing the response we need an iterable
#or a string. For a multipart/byterange response we want an
#iterable that contains a single callable; the MultipartContent
#object itself
yield self
class MultipartPart(object):
def __init__(self, data, content_type=None, headers=None):
self.headers = ResponseHeaders()
if content_type is not None:
self.headers.set("Content-Type", content_type)
if headers is not None:
for name, value in headers:
if name.lower() == "content-type":
func = self.headers.set
else:
func = self.headers.append
func(name, value)
self.data = data
def __str__(self):
rv = []
for item in self.headers:
rv.append("%s: %s" % item)
rv.append("")
rv.append(self.data)
return "\r\n".join(rv)
class ResponseHeaders(object):
"""Dictionary-like object holding the headers for the response"""
def __init__(self):
self.data = OrderedDict()
def set(self, key, value):
"""Set a header to a specific value, overwriting any previous header
with the same name
:param key: Name of the header to set
:param value: Value to set the header to
"""
self.data[key.lower()] = (key, [value])
def append(self, key, value):
"""Add a new header with a given name, not overwriting any existing
headers with the same name
:param key: Name of the header to add
:param value: Value to set for the header
"""
if key.lower() in self.data:
self.data[key.lower()][1].append(value)
else:
self.set(key, value)
def get(self, key, default=missing):
"""Get the set values for a particular header."""
try:
return self[key]
except KeyError:
if default is missing:
return []
return default
def __getitem__(self, key):
"""Get a list of values for a particular header
"""
return self.data[key.lower()][1]
def __delitem__(self, key):
del self.data[key.lower()]
def __contains__(self, key):
return key.lower() in self.data
def __setitem__(self, key, value):
self.set(key, value)
def __iter__(self):
for key, values in self.data.itervalues():
for value in values:
yield key, value
def items(self):
return list(self)
def update(self, items_iter):
for name, value in items_iter:
self.append(name, value)
def __repr__(self):
return repr(self.data)
class ResponseWriter(object):
"""Object providing an API to write out a HTTP response.
:param handler: The RequestHandler being used.
:param response: The Response associated with this writer.
After each part of the response is written, the output is
flushed unless response.explicit_flush is False, in which case
the user must call .flush() explicitly."""
def __init__(self, handler, response):
self._wfile = handler.wfile
self._response = response
self._handler = handler
self._headers_seen = set()
self._headers_complete = False
self.content_written = False
self.request = response.request
self.file_chunk_size = 32 * 1024
def write_status(self, code, message=None):
"""Write out the status line of a response.
:param code: The integer status code of the response.
:param message: The message of the response. Defaults to the message commonly used
with the status code."""
if message is None:
if code in response_codes:
message = response_codes[code][0]
else:
message = ''
self.write("%s %d %s\r\n" %
(self._response.request.protocol_version, code, message))
def write_header(self, name, value):
"""Write out a single header for the response.
:param name: Name of the header field
:param value: Value of the header field
"""
self._headers_seen.add(name.lower())
self.write("%s: %s\r\n" % (name, value))
if not self._response.explicit_flush:
self.flush()
def write_default_headers(self):
for name, f in [("Server", self._handler.version_string),
("Date", self._handler.date_time_string)]:
if name.lower() not in self._headers_seen:
self.write_header(name, f())
if (type(self._response.content) in (str, unicode) and
"content-length" not in self._headers_seen):
#Would be nice to avoid double-encoding here
self.write_header("Content-Length", len(self.encode(self._response.content)))
def end_headers(self):
"""Finish writing headers and write the separator.
Unless add_required_headers on the response is False,
this will also add HTTP-mandated headers that have not yet been supplied
to the response headers"""
if self._response.add_required_headers:
self.write_default_headers()
self.write("\r\n")
if "content-length" not in self._headers_seen:
self._response.close_connection = True
if not self._response.explicit_flush:
self.flush()
self._headers_complete = True
def write_content(self, data):
"""Write the body of the response."""
if isinstance(data, types.StringTypes):
self.write(data)
else:
self.write_content_file(data)
if not self._response.explicit_flush:
self.flush()
def write(self, data):
"""Write directly to the response, converting unicode to bytes
according to response.encoding. Does not flush."""
self.content_written = True
try:
self._wfile.write(self.encode(data))
except socket.error:
# This can happen if the socket got closed by the remote end
pass
def write_content_file(self, data):
"""Write a file-like object directly to the response in chunks.
Does not flush."""
self.content_written = True
while True:
buf = data.read(self.file_chunk_size)
if not buf:
break
try:
self._wfile.write(buf)
except socket.error:
break
data.close()
def encode(self, data):
"""Convert unicode to bytes according to response.encoding."""
if isinstance(data, str):
return data
elif isinstance(data, unicode):
return data.encode(self._response.encoding)
else:
raise ValueError
def flush(self):
"""Flush the output. Returns False if the flush failed due to
the socket being closed by the remote end."""
try:
self._wfile.flush()
return True
except socket.error:
# This can happen if the socket got closed by the remote end
return False
