This patch adds code to handle the situation that a prepared user buffer could not all be sent on the
socket at once. There are two kinds of situation to handle
1) User code handles it: The connection only has extensions active that do not rewrite the buffer.
In this case, the patch caused libwebsocket_write() to simply return the amount of user buffer that
was consumed (this is specifically the amount of user buffer used in sending what was accepted,
nothing else). So user code can just advance its buffer that much and resume sending when the socket
is writable again. This continues the frame rather than starting a new one or new fragment.
2) The connections has extensions active which actually send something quite different than what the
user buffer contains, for example a compression extension. In this case, libwebsockets will dynamically
malloc a buffer to contain a copy of the remaining unsent data, request notifiction when writeable again,
and automatically spill and free this buffer with the highest priority before passing on the writable
notification to anything else. For this situation, the call to write will return that it used the
whole user buffer, even though part is still rebuffered.
This patch should enable libwebsockets to detect the two cases and take the appropriate action.
There are also two choices for user code to deal with partial sends.
1) Leave the no_buffer_all_partial_tx member in the protocol struct at zero. The library will dyamically
buffer anything you send that did not get completely written to the socket, and automatically spill it next
time the socket is writable. You can use this method if your sent frames are relatvely small and unlikely to get
truncated anyway.
2) Set the no_buffer_all_partial_tx member in the protocol struct. User code now needs to take care of the
return value from libwebsocket_write() and deal with resending the remainder if not all of the requested amount
got sent. You should use this method if you are sending large messages and want to maximize throughput and efficiency.
Since the new member no_buffer_all_partial_tx will be zero by default, this patch will auto-rebuffer any
partial sends by default. That's good for most cases but if you attempt to send large blocks, make sure you
follow option 2) above.
Signed-off-by: Andy Green <andy.green@linaro.org>
under load, writing packet sizes to the socket that are normally fine
can do partial writes, eg asking to write 4096 may only take 2800 of
it and return 2800 from the actual send.
Until now lws assumed that if it was safe to send, it could take any
size buffer, that's not the case under load.
This patch changes lws_write to return the amount actually taken...
that and the meaning of it becomes tricky when dealing with
compressed links, the amount taken and the amount sent differ. Also
there is no way to recover at the moment from a protocol-encoded
frame only being partially accepted... however for http file send
content it can and does recover now.
Small frames don't have to take any care about it but large atomic
sends (> 2K) have been seen to fail under load.
Signed-off-by: Andy Green <andy.green@linaro.org>
This brings the library sources into compliance with checkpatch
style except for three or four exceptions like WIN32 related stuff
and one long string constant I don't want to break into multiple
sprintf calls.
There should be no functional or compilability change from all
this (hopefully).
Signed-off-by: Andy Green <andy.green@linaro.org>
This gets rid of the stack buffer while serving files, and the
PATH_MAX char array that used to hold the filepath in the wsi.
It holds an extra file descriptor open while serving the file,
however it attempts to stuff the socket with as much of the
file as it can take. For files of a few KB, that typically
completes (without blocking) in the call to
libwebsockets_serve_http_file() and then closes the file
descriptor before returning.
Signed-off-by: Andy Green <andy.green@linaro.org>
Libwebsockets is fundamentally singlethreaded... the existence of the
fork and broadcast support, especially in the sample server is
giving the wrong idea about how to use it.
This replaces broadcast in the sample server with
libwebsocket_callback_on_writable_all_protocol(). The whole idea of
'broadcast' is removed.
All of the broadcast proxy stuff is removed: data must now be sent
from the callback only. Doing othherwise is not reliable since the
service loop may close the socket and free the wsi at any time,
invalidating a wsi pointer held by another thread (don't do that!)
Likewise the confirm_legit_wsi api added recently does not help the
other thread case, since if the wsi has been freed dereferencing the
wsi to study if it is legit or not will segfault in that case. So
this is removed too.
The overall effect is to push user code to only operate inside the
protocol callbacks or external poll loops, ie, single thread context.
Signed-off-by: Andy Green <andy.green@linaro.org>
Large chunks of struct libwebsocket members actually have a mutually
exclusive lifecycle, eg, once the http headers are finished they sit
there unused until the instance is destroyed.
This makes a big improvement in memory efficiency by making four
categories of member: always needed, needed for header processing,
needed for http processing, and needed for ws processing. The last
three are mutually exclusive and bound into a union inside the wsi.
Care needs taking now at "union transitions", although we zeroed down
the struct at init, the other union siblings have been writing the
same memory by the time later member siblings start to use it. So
it must be cleared down appropriately when we cross from one
mutually-exclusive use to another.
Signed-off-by: Andy Green <andy.green@linaro.org>
Since v13 was defined as the released ietf version the older versions
are deprecated. This patch strips out everything to do with the older
versions and gets rid of the option to send stuff unmasked.
The in-tree md5 implementation is then also deleted as nothing needs
it any more, 1280 loc are shed in all
Signed-off-by: Andy Green <andy.green@linaro.org>
The new --without-extensions config flag completely removes all code
and data related to extensions from the build throughout the library
when given.
Signed-off-by: Andy Green <andy.green@linaro.org>
