Ignore errors when sending an error response to the client before closing a connection

src/calibre/srv/http.py

@@ -18,7 +18,7 @@ from calibre.constants import __version__
 from calibre.srv.errors import (
     MaxSizeExceeded, NonHTTPConnRequest, HTTP404, IfNoneMatch, BadChunkedInput)
 from calibre.srv.respond import finalize_output, generate_static_output
-from calibre.srv.utils import MultiDict, http_date
+from calibre.srv.utils import MultiDict, http_date, socket_errors_to_ignore
 
 HTTP1  = 'HTTP/1.0'
 HTTP11 = 'HTTP/1.1'
@@ -149,6 +149,14 @@ def http_communicate(conn):
     def repr_for_pair(pair):
         return pair.repr_for_log() if getattr(pair, 'started_request', False) else 'None'
 
+    def simple_response(pair, code, msg=''):
+        if pair and not pair.sent_headers:
+            try:
+                pair.simple_response(code, msg=msg)
+            except socket.error as e:
+                if e.errno not in socket_errors_to_ignore:
+                    raise
+
     try:
         while True:
             # (re)set pair to None so that if something goes wrong in
@@ -177,8 +185,7 @@ def http_communicate(conn):
         if (not request_seen) or (pair and pair.started_request):
             # Don't bother writing the 408 if the response
             # has already started being written.
-            if pair and not pair.sent_headers:
+            simple_response(pair, httplib.REQUEST_TIMEOUT)
-                pair.simple_response(httplib.REQUEST_TIMEOUT)
     except NonHTTPConnRequest:
         raise
     except socket.error:
@@ -188,19 +195,16 @@ def http_communicate(conn):
     except MaxSizeExceeded as e:
         conn.server_loop.log.warn('Too large request body (%d > %d) for request:' % (e.size, e.limit), repr_for_pair(pair))
         # Can happen if the request uses chunked transfer encoding
-        if pair and not pair.sent_headers:
+        simple_response(pair, httplib.REQUEST_ENTITY_TOO_LARGE,
-            pair.simple_response(httplib.REQUEST_ENTITY_TOO_LARGE,
+                        "The entity sent with the request exceeds the maximum "
-                "The entity sent with the request exceeds the maximum "
+                        "allowed bytes (%d)." % pair.max_request_body_size)
-                "allowed bytes (%d)." % pair.max_request_body_size)
     except BadChunkedInput as e:
         conn.server_loop.log.warn('Bad chunked encoding (%s) for request:' % as_unicode(e.message), repr_for_pair(pair))
-        if pair and not pair.sent_headers:
+        simple_response(pair, httplib.BAD_REQUEST,
-            pair.simple_response(httplib.BAD_REQUEST,
+                        'Invalid chunked encoding for request body: %s' % as_unicode(e.message))
-                'Invalid chunked encoding for request body: %s' % as_unicode(e.message))
     except Exception:
         conn.server_loop.log.exception('Error serving request:', pair.repr_for_log() if getattr(pair, 'started_request', False) else 'None')
-        if pair and not pair.sent_headers:
+        simple_response(pair, httplib.INTERNAL_SERVER_ERROR)
-            pair.simple_response(httplib.INTERNAL_SERVER_ERROR)
 
 class FixedSizeReader(object):  # {{{
 
@@ -247,7 +251,7 @@ class ChunkedReader(object):  # {{{
         if len(chunk) < chunk_size:
             raise BadChunkedInput('Bad chunked encoding, chunk truncated: %d < %s' % (len(chunk), chunk_size))
         if not chunk.endswith(b'\r\n'):
-            raise BadChunkedInput('Bad chunked encoding: %r != CRLF' % chunk[:-2])
+            raise BadChunkedInput('Bad chunked encoding: %r != CRLF' % chunk[-2:])
         self.rbuf.seek(0, os.SEEK_END)
         self.bytes_read += chunk_size
         if chunk_size == 2:

src/calibre/srv/loop.py

@@ -6,7 +6,7 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import socket, os, errno, ssl, time, sys
+import socket, os, ssl, time, sys
 from operator import and_
 from Queue import Queue, Full
 from threading import Thread, current_thread, Lock
@@ -15,31 +15,10 @@ from io import DEFAULT_BUFFER_SIZE, BytesIO
 from calibre.srv.errors import NonHTTPConnRequest, MaxSizeExceeded
 from calibre.srv.http import http_communicate
 from calibre.srv.opts import Options
+from calibre.srv.utils import socket_errors_to_ignore, socket_error_eintr, socket_errors_nonblocking
 from calibre.utils.socket_inheritance import set_socket_inherit
 from calibre.utils.logging import ThreadSafeLog
 
-def error_codes(*errnames):
-    ''' Return error numbers for error names, ignoring non-existent names '''
-    ans = {getattr(errno, x, None) for x in errnames}
-    ans.discard(None)
-    return ans
-
-socket_error_eintr = error_codes("EINTR", "WSAEINTR")
-
-socket_errors_to_ignore = error_codes(  # errors indicating a closed connection
-    "EPIPE",
-    "EBADF", "WSAEBADF",
-    "ENOTSOCK", "WSAENOTSOCK",
-    "ETIMEDOUT", "WSAETIMEDOUT",
-    "ECONNREFUSED", "WSAECONNREFUSED",
-    "ECONNRESET", "WSAECONNRESET",
-    "ECONNABORTED", "WSAECONNABORTED",
-    "ENETRESET", "WSAENETRESET",
-    "EHOSTDOWN", "EHOSTUNREACH",
-)
-socket_errors_nonblocking = error_codes(
-    'EAGAIN', 'EWOULDBLOCK', 'WSAEWOULDBLOCK')
-
 class SocketFile(object):  # {{{
     """Faux file object attached to a socket object. Works with non-blocking
     sockets, unlike the fileobject created by socket.makefile() """

src/calibre/srv/utils.py

@@ -6,6 +6,7 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
+import errno
 from urlparse import parse_qs
 import repr as reprlib
 from email.utils import formatdate
@@ -83,3 +84,27 @@ class MultiDict(dict):  # {{{
     def pretty(self, leading_whitespace=''):
         return leading_whitespace + ('\n' + leading_whitespace).join('%s: %s' % (k, v) for k, v in self.items())
 # }}}
+
+def error_codes(*errnames):
+    ''' Return error numbers for error names, ignoring non-existent names '''
+    ans = {getattr(errno, x, None) for x in errnames}
+    ans.discard(None)
+    return ans
+
+socket_error_eintr = error_codes("EINTR", "WSAEINTR")
+
+socket_errors_to_ignore = error_codes(  # errors indicating a closed connection
+    "EPIPE",
+    "EBADF", "WSAEBADF",
+    "ENOTSOCK", "WSAENOTSOCK",
+    "ETIMEDOUT", "WSAETIMEDOUT",
+    "ECONNREFUSED", "WSAECONNREFUSED",
+    "ECONNRESET", "WSAECONNRESET",
+    "ECONNABORTED", "WSAECONNABORTED",
+    "ENETRESET", "WSAENETRESET",
+    "EHOSTDOWN", "EHOSTUNREACH",
+)
+socket_errors_nonblocking = error_codes(
+    'EAGAIN', 'EWOULDBLOCK', 'WSAEWOULDBLOCK')
+
+