ssh_gssapi_get_buffer_desc
if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
(r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
(r = ssh_gssapi_get_buffer_desc(m, out)) != 0)
int ssh_gssapi_get_buffer_desc(struct sshbuf *, gss_buffer_desc *);