libssh2_knownhost_checkp took 0 as a magic port number that indicated
a 'generic' check should be performed. However, 0 is a valid port
number in its own right so this commit changes the magic value to any
negative int.
OpenSSH has ways to add hosts to the knownhosts file that include
a specific port number which makes the key associated with only
that specific host+port pair. libssh2 previously did not support
this, and I was forced to add a new function to the API to
properly expose this ability to applications:
libssh2_knownhost_checkp()
To *add* such hosts to the knownhosts file, you make sure to pass
on the host name in that manner to the libssh2_knownhost_addc()
function.
There was some stub-like parts of an implementation for
implementing kex language negotiation that caused clang-analyzer
to warn and as it did nothing I've now removed the dead code.
The clang-analyzer report made it look into this function and
I've went through it to remove a potential use of an
uninitialized variable and I also added some validation of input
data received from the server.
In general, lots of more code in this file need to validate the
input before assuming it is correct: there are servers out there
that have bugs or just have another idea of how to do the SFTP
protocol.
The errors mentioned in this man page are possible return codes
but not necessarily the only return codes that this can return.
Also reformatted the typ prototypes somewhat.
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.
This was triggered by a clang-analyzer complaint that turned out
to be valid, and it made me dig deeper and fix some generic non-
blocking problems I disovered in the code.
While cleaning this up, I moved session-specific stuff over to a
new session.h header from the libssh2_priv.h header.
By making 'data' and 'data_len' more local in several places in
this file it will be easier to spot how they are used and we'll
get less risks to accidentally do bad things with them.
