Commit 70b199f47659a74b8778c528beccf893843e5ecb introduced a parsing
bug in file_read_publickey() which made the algorithm name contain an
extra trailing space character, breaking all publickey authentication.
While this is code not currently in use, it is part of the generic linked
list code and since I found the error I thought I'd better fix it since we
might bring in this function into the code one day.
In case of failure we must make sure that the data we return
doesn't point to a memory area already freed. Reported anonymously
in the bug report #2910103.
Commit 683aa0f6b52fb1014873c961709102b5006372fc made send_existing() send
more than just the second part of a packet when the kernel did not accept
the full packet, but the function still overlooked the SSH protocol
overhead in each packet, often 48 bytes.
If only the last few bytes of a packet remained, then the packet would
erroneously be considered completely sent, and the next call to write
more data in the session would return a -39 error.
DSA signatures consist of two 160-bit integers called r and s. In ssh-dss
signature blobs r and s are stored directly after each other in binary
representation, making up a 320-bit (40 byte) string. (See RFC4253 p14.)
The crypto wrappers in libssh2 would either pack r and s incorrectly, or
fail, when at least one integer was small enough to be stored in 19 bytes
or less.
The patch ensures that r and s are always stored as two 160 bit numbers.
When libssh2_transport_write() is called to continue sending a
partially sent packet the write direction flag must not be cleared
until the previous packet has been completely sent, or the app would
hang if the packet still isn't sent completely, since select() gets
called by the internal blocking emulation layer in libssh2 but would
then not be watching the socket for writability.
Clear the flag only once processing of previous packet data is
complete and a new packet is about to be prepared.
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.
