The implementation now stores all the lines of the request in a buffer
and makes a single send() call when the request is finished,
specifically when endheaders() is called.
This appears to improve performance. The old code called send() for
each line. The sends are all short, so they caused bad interactions
with the Nagle algorithm and delayed acknowledgements. In simple
tests, the second packet was delayed by 100s of ms. The second send was
delayed by the Nagle algorithm, waiting for the ack. The delayed ack
strategy delays the ack in hopes of piggybacking it on a data packet,
but the server won't send any data until it receives the complete
request.
This change minimizes the problem that Nagle + delayed ack will cause
a problem, although a request large enough to be broken into two
packets will still suffer some delay. Luckily the MSS is large enough
to accomodate most single packets.
XXX Bug fix candidate?
The recent SSL changes resulted in important, but subtle changes to
close() semantics. Since builtin socket makefile() is not called for
SSL connections, we don't get separately closeable fds for connection
and response. Comments in the code explain how to restore makefile
semantics.
Bug fix candidate.
If multiple header fields with the same name occur, they are combined
according to the rules in RFC 2616 sec 4.2:
Appending each subsequent field-value to the first, each separated by
a comma. The order in which header fields with the same field-name are
received is significant to the interpretation of the combined field
value.
Section 19.6 of RFC 2616 (HTTP/1.1):
It is beyond the scope of a protocol specification to mandate
compliance with previous versions. HTTP/1.1 was deliberately
designed, however, to make supporting previous versions easy....
And we would expect HTTP/1.1 clients to:
- recognize the format of the Status-Line for HTTP/1.0 and 1.1
responses;
- understand any valid response in the format of HTTP/0.9, 1.0, or
1.1.
The changes to the code do handle response in the format of HTTP/0.9.
Some users may consider this a bug because all responses with a
sufficiently corrupted status line will look like an HTTP/0.9
response. These users can pass strict=1 to the HTTP constructors to
get a BadStatusLine exception instead.
While this is a new feature of sorts, it enhances the robustness of
the code (be tolerant in what you accept). Thus, I consider it a bug
fix candidate.
XXX strict needs to be documented.
The HTTPResponse class now handles 100 continue responses, instead of
choking on them. It detects them internally in the _begin() method
and ignores them. Based on a patch by Bob Kline.
This closes SF bugs 498149 and 551273.
The FakeSocket class (for SSL) is now usable with HTTP/1.1
connections. The old version of the code could not work with
persistent connections, because the makefile() implementation read
until EOF before returning. If the connection is persistent, the
server sends a response and leaves the connection open. A client that
reads until EOF will block until the server gives up on the connection
-- more than a minute in my test case.
The problem was fixed by implementing a reasonable makefile(). It
reads data only when it is needed by the layers above it. It's
implementation uses an internal buffer with a default size of 8192.
Also, rename begin() method of HTTPResponse to _begin() because it
should only be called by the HTTPConnection.
FakeSocket class. Without it, the sendall() call got the method on
the underlying socket object, and that messed up SSL.
Does httplib use other methods of sockets that FakeSocket doesn't support?
Someone should take a look... (I'll try to give it a once-over.)
2.2.1 bugfix candidate.
