kex: acknowledge error code from libssh2_dh_key_pair()
Fixes a segfault using ssh-agent on Windows
This commit fixes a segfault seen dereferencing a null pointer on
Windows when using ssh-agent. The problem ended up being that errors
weren't being communicated all the way through, causing null pointers to
be used when functions should have bailed out sooner.
The `_libssh2_dh_key_pair` function for WinCNG was modified to propagate
errors, and then the two callsites in kex.c of
`diffie_hellman_sha{1,256}` were updated to recognize this error and
bail out.
Fixes #162
Closes #163
2 files changed
