http_wsgibase, wsgi: Move request transfer encoding handling out of wsgi.

As per WSGI specs, transfer encoding (and other hop-by-hop headers) must
not be processed by WSGI applications.

caucase/http_wsgibase.py

@@ -23,9 +23,77 @@ Separate from .http because of different-licensed code in the middle.
 from __future__ import absolute_import
 from wsgiref.simple_server import ServerHandler
 
+class ProxyFile(object):
+  """
+  Passes any non-overridden calls to the actual_file object.
+  """
+  def __init__(self, actual_file):
+    self._actual_file = actual_file
+
+  def __getattr__(self, name):
+    return getattr(self._actual_file, name)
+
+MAX_CHUNKED_HEADER_LENGTH = 64 * 1024
+class ChunkedFile(ProxyFile):
+  """
+  Implement chunked-encoding.
+  """
+  _at_eof = False
+
+  def __init__(self, actual_file):
+    super(ChunkedFile, self).__init__(actual_file)
+    self._recv_buf = ''
+
+  def read(self, length=None):
+    result = self._recv_buf
+    if not self._at_eof:
+      readline = self.readline
+      read = self.__getattr__('read')
+      while length is None or len(result) < length:
+        chunk_header = readline(MAX_CHUNKED_HEADER_LENGTH + 1)
+        if len(chunk_header) > MAX_CHUNKED_HEADER_LENGTH:
+          raise ValueError('Chunked encoding header too long')
+        try:
+          chunk_length = int(chunk_header.split(' ', 1)[0], 16)
+        except ValueError:
+          raise ValueError('Invalid chunked encoding header')
+        if not chunk_length:
+          trailer = readline(MAX_CHUNKED_HEADER_LENGTH + 1)
+          if len(trailer) > MAX_CHUNKED_HEADER_LENGTH:
+            raise ValueError('Chunked encoding trailer too long')
+          self._at_eof = True
+          break
+        result += read(chunk_length)
+        if read(2) != '\r\n':
+          raise ValueError('Invalid chunked encoding separator')
+    if length is None:
+      self._recv_buf = ''
+      return result
+    self._recv_buf = result[length:]
+    return result[:length]
+
 class CleanServerHandler(ServerHandler):
   """
+  - Handle chunked transfer encoding.
   - Do not include OS environment variables in each request's WSGI environment.
     Seriously, what the fsck, python ?
   """
   os_environ = {}
+
+  def setup_environ(self):
+    ServerHandler.setup_environ(self)
+    environ = self.environ
+    try:
+      request_major, request_minor = environ[
+        'SERVER_PROTOCOL'
+      ].upper().split('/', 1)[1].split('.', 1)
+      request_version = (int(request_major), int(request_minor))
+    except (KeyError, ValueError):
+      request_version = (0, 9)
+    if request_version > (1, 0):
+      if environ.get('HTTP_TRANSFER_ENCODING', '').lower() == 'chunked':
+        # XXX: does not support multiple encodings specified at once
+        # (ex: chunked + gzip).
+        # We handle this, hide it from Application
+        del environ['HTTP_TRANSFER_ENCODING']
+        environ['wsgi.input'] = ChunkedFile(environ['wsgi.input'])

caucase/wsgi.py

@@ -98,7 +98,6 @@ STATUS_OK = _getStatus(httplib.OK)
 STATUS_CREATED = _getStatus(httplib.CREATED)
 STATUS_NO_CONTENT = _getStatus(httplib.NO_CONTENT)
 MAX_BODY_LENGTH = 10 * 1024 * 1024 # 10 MB
-MAX_CHUNKED_HEADER_LENGTH = 64 * 1024
 
 class Application(object):
   """
@@ -213,40 +212,13 @@ class Application(object):
     Raises TooLarge if Content-Length if over MAX_BODY_LENGTH.
     If Content-Length is not set, reads at most MAX_BODY_LENGTH bytes.
     """
-    # XXX: WSGI (...at least the reference implementation in python 2.7)
-    # has no way of sending "100 Continue". So ignore "Expect" header and let
-    # client timeout.
-    infile = environ['wsgi.input']
-    transfer_encoding = environ.get('HTTP_TRANSFER_ENCODING')
-    if transfer_encoding == 'chunked':
-      result = ''
-      while True:
-        chunk_header = infile.readline(MAX_CHUNKED_HEADER_LENGTH + 1)
-        if len(chunk_header) > MAX_CHUNKED_HEADER_LENGTH:
-          raise BadRequest('Chunked encoding header too long')
     try:
-          length = int(chunk_header.split(' ', 1)[0], 16)
-        except ValueError:
-          raise BadRequest('Invalid chunked encoding header')
-        if not length:
-          trailer = infile.readline(MAX_CHUNKED_HEADER_LENGTH + 1)
-          if len(trailer) > MAX_CHUNKED_HEADER_LENGTH:
-            raise BadRequest('Chunked encoding trailer too long')
-          break
-        if len(result) + length > MAX_BODY_LENGTH:
-          raise TooLarge('Content-Length limit exceeded')
-        result += infile.read(length)
-        if infile.read(2) != '\r\n':
-          raise BadRequest('Invalid chunked encoding separator')
-    else: # Assume identity
-      try:
-        length = int(environ.get('CONTENT_LENGTH', MAX_BODY_LENGTH))
+      length = int(environ.get('CONTENT_LENGTH') or MAX_BODY_LENGTH)
     except ValueError:
       raise BadRequest('Invalid Content-Length')
     if length > MAX_BODY_LENGTH:
       raise TooLarge('Content-Length limit exceeded')
-      result = infile.read(length)
-    return result
+    return environ['wsgi.input'].read(length)
 
   def _authenticate(self, environ, header_list):
     """