Authenticate a session with a public key, with the help of ssh-agent
#include <libssh2.h>
int libssh2_agent_userauth(LIBSSH2_AGENT *agent,
const char *username, struct libssh2_agent_publickey *identity);
agent - ssh-agent handle as returned by libssh2_agent_init(3)
username - Remote user name to authenticate as.
identity - Public key to authenticate with, as returned by libssh2_agent_get_identity(3)
Attempt public key authentication with the help of ssh-agent.
Returns 0 if succeeded, or a negative value for error.
Added in libssh2 1.2