Until now, the window size (channel->remote.window_size) was being
updated just after receiving the packet from the transport layer.
That behaviour is wrong because the channel queue may grow uncontrolled
when data arrives from the network faster that the upper layer consumes
it.
This patch adds a new counter, read_avail, which keeps a count of the
bytes available from the packet queue for reading. Also, now the window
size is adjusted when the data is actually read by an upper layer.
That way, if the upper layer stops reading data, the window will
eventually fill and the remote host will stop sending data. When the
upper layers reads enough data, a window adjust packet is delivered and
the transfer resumes.
The read_avail counter is used to detect the situation when the remote
server tries to send data surpassing the window size. In that case, the
extra data is discarded.
Signed-off-by: Salvador <sfandino@yahoo.com>
In _libssh2_packet_add, called by _libssh2_packet_read, a call to
_libssh2_packet_send that is supposed to send a one-byte message
SSH_MSG_REQUEST_FAILURE would send an uninitialized byte upon re-entry
if its call to _send returns _EAGAIN.
Fixes#259
When calling _libssh2_channel_receive_window_adjust() internally, we now
always use the 'force' option to prevent libssh2 to avoid sending the
update if the update isn't big enough.
It isn't fully analyzed but we have seen corner cases which made a
necessary window update not get send due to this and then the other side
doesn't send data our side then sits waiting for forever.
When receiving more data than what the window size allows on a
particular channel, make sure that the window size is adjusted in that
case too. Previously it would only adjust the window in the non-error
case.
I added size checks in several places. I fixed the code flow to be easier
to read in some places.
I removed unnecessary zeroing of structs. I removed unused struct fields.
We don't like magic numbers in the code. Now the acceptable failure
codes sent in the SSH_MSG_CHANNEL_OPEN_FAILURE message are added as
defined values in the private header file.
The new function takes two data areas, combines them and sends them as a
single SSH packet. This allows several functions to allocate and copy
less data.
I also found and fixed a mixed up use of the compression function
arguments that I introduced in my rewrite in a recent commit.
To get the blocking vs non-blocking to work as smooth as possible
and behave better internally, we avoid using the external
interfaces when calling functions internally.
Renamed a few internal functions to use _libssh2 prefix when not
being private within a file, and removed the libssh2_ for one
that was private within the file.
I'll introduce a new internal function set named
_libssh2_store_u32
_libssh2_store_u64
_libssh2_store_str
That can be used all through the library to build binary outgoing
packets. Using these instead of the current approach removes
hundreds of lines from the library while at the same time greatly
enhances readability. I've not yet fully converted everything to
use these functions.
I've converted LOTS of 'unsigned long' to 'size_t' where
data/string lengths are dealt with internally. This is The Right
Thing and it will help us make the transition to our
size_t-polished API later on as well.
I'm removing the PACKET_* error codes. They were originally
introduced as a set of separate error codes from the transport
layer, but having its own set of errors turned out to be very
awkward and they were then converted into a set of #defines that
simply maps them to the global libssh2 error codes instead. Now,
I'l take the next logical step and simply replace the PACKET_*
defines with the actual LIBSSH2_ERROR_* defines. It will increase
readability and decrease confusion.
I also separated packet stuff into its own packet.h header file.
We reserve ^libssh2_ for public symbols and we use _libssh2 as
prefix for internal ones. I fixed the intendation of all these
edits with emacs afterwards, which then changed it slightly more
than just _libssh2_error() expressions but I didn't see any
obvious problems.
Suyog Jadhav pointed out that when receiving a window adjust to
a channel not found, the code would reference a NULL pointer.
Now it will instead output a message about that fact.
libssh2_error() no longer allocates a string and only accepts a const
error string. I also made a lot of functions use the construct of
return libssh2_error(...) instead of having one call to
libssh2_error() and then a separate return call. In several of those
cases I then also changed the former -1 return code to a more
detailed one - something that I think will not change behaviors
anywhere but it's worth keeping an eye open for any such.
The forward accepting was not done right before, and the
packet_queue_listener function didn't assign a necessary
variable. All fixed by Juzna. I (Daniel) modified the
forward_accept() change somewhat.
I made this change just to easier grep for "return .*EAGAIN" cases
as they should be very rare or done wrongly. Already worked to find
a flaw, marked with "TODO FIXME THIS IS WRONG" in channel.c. I also
fixed a few cases to become more general returns now when we have
more unified return codes internally.
_libssh2_channel_receive_window_adjust is the new replacement that
is both the correct internal version instead of the external API one,
and it has the return code flaw fixed. I also fixed more return
codes to pass long the correct error found.
and introduced a transport.h header.
* Fixed the blocking mode to only change behavior not the actual underlying
socket mode so we now always work with non-blocking sockets. This also
introduces a new rule of thumb in libssh2 code: we don't call the
external function calls internally. We use the internal (non-blocking)
ones!
* libssh2_channel_receive_window_adjust2 was added and
libssh2_channel_receive_window_adjust is now deprecated
* Introduced "local" header files with prototypes etc for different parts
instead of cramming everything into libssh2_priv.h. channel.h is the
first.
some tests:
* cut off "_ex" from several internal function names
* corrected some log outputs
* simplified libssh2_channel_read_ex() and made it much faster in the process
* cut out {{{ and }}} comments that were incorrect anyway
* fixed sftp_packet_ask() to return the correct packet by using memcmp() and
not strncmp()
* fixed mkdir()'s wait for packet to use the correct request_id - it
semi-worked previously because strncmp() in sftp_packet_ask() made it
match far too easily.
* took away the polling functionality from sftp_packet_ask() since it wasn't
used
