Read the full incoming TLS/SSL record at once in libwebsocket_service_fd().
SSL_read() is called until no more pending data for the current record is buffered in SSL.
SSL_read() is never requested more than the pending data size for the current record
to ensure that the fd is not read again for new data, which would be copied in the SSL buffer otherwise.
Suggested by a Windows log where leaf.jpg meets EAGAIN and after
issuing the truncated send buffer, never sends any more
https://github.com/warmcat/libwebsockets/issues/111#issuecomment-39873129
Added note in README.coding about WRITEABLE callbacks able to
be generated by lws.
Signed-off-by: Andy Green <andy.green@linaro.org>
This gets rid of all the platform-dependent #ifdef stuff and
migrates it into the new lws-plat-xxx.c files.
These are then included in a one-time test in libwebsockets.c
according basically to Windows or not.
The idea is from now on, all Windows-specific code should go in
lws-plat-win.c, where any kind of Windows perversion like DWORD
is fine.
Any new functions going in there should be named lws_plat_...
and be defined in all the lws-plat-xxx.c file (currently just
win32 and unix platforms are supported).
Signed-off-by: Andy Green <andy.green@linaro.org>
Also change from looking at wsi->truncated_send_malloc to see if we are in the middle of
dealing with a truncated send to looking for nonzero wsi->truncated_send_len
Signed-off-by: Andy Green <andy.green@linaro.org>
Add a special implementation with CreateFile(), ReadFile() and CloseFile()
for serving HTTP file request to allow compilation on all Windows platforms.
This patch deploys the truncated send work to buffer output in case
either send() or the SSL send return a temporary "unable to send"
condition even though they signalled as writeable.
I added a by-default #if 0 test jig which enforces only half of what
you want to send is sendable, this is working when enabled.
One subtle change is that the pipe reports choked if there is any
pending remaining truncated send. Otherwise it should be transparent.
Hopefully...
Signed-off-by: Andy Green <andy.green@linaro.org>
The only part that actually goes to this label is inside such an ifdef,
so building without extension support makes gcc bail out since an unused
label is considered an error in this project.
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>
