kex_input_ext_info
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
int kex_input_ext_info(int, u_int32_t, struct ssh *);
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info);
&kex_input_ext_info : &input_userauth_error);