Function msg_for_remote_commit

openingd/dualopend.c:1101–1162

}

static u8 *msg_for_remote_commit(const tal_t *ctx,
				 const struct state *state,
				 struct penalty_base **pbase,
				 char **error)
{
	struct wally_tx_output *direct_outputs[NUM_SIDES];
	struct bitcoin_tx *remote_commit;
	struct bitcoin_signature local_sig;
	u32 feerate = 0; // unused since there are no htlcs
	u64 commit_num = 0;
        u8 *msg;

	/* Create commitment tx signatures for remote */
	remote_commit = initial_channel_tx(NULL, NULL, state->channel,
					   &state->first_per_commitment_point[REMOTE],
					   REMOTE, direct_outputs, error);

	if (!remote_commit) {
		return NULL;
	}

	/* We ask the HSM to sign their commitment transaction for us: it knows
	 * our funding key, it just needs the remote funding key to create the
	 * witness script.  It also needs the amount of the funding output,
	 * as segwit signatures commit to that as well, even though it doesn't
	 * explicitly appear in the transaction itself. */
	msg = towire_hsmd_sign_remote_commitment_tx(NULL,
						    remote_commit,
						    &state->channel->funding_pubkey[REMOTE],
						    &state->first_per_commitment_point[REMOTE],
						    true,
						    commit_num,
						    NULL, /* no HTLCS */
						    feerate);
	wire_sync_write(HSM_FD, take(msg));
	msg = wire_sync_read(tmpctx, HSM_FD);
	if (!fromwire_hsmd_sign_tx_reply(msg, &local_sig))
		status_failed(STATUS_FAIL_HSM_IO,
			      "Bad sign_tx_reply %s", tal_hex(tmpctx, msg));

	/* You can tell this has been a problem before, since there's a debug
	 * message here: */
	status_debug("signature %s on tx %s using key %s",
		     fmt_bitcoin_signature(tmpctx, &local_sig),
		     fmt_bitcoin_tx(tmpctx, remote_commit),
		     fmt_pubkey(tmpctx,
				&state->our_funding_pubkey));


	assert(local_sig.sighash_type == SIGHASH_ALL);

	if (pbase && direct_outputs[LOCAL])
		*pbase = penalty_base_new(ctx, 0, remote_commit,
					  direct_outputs[LOCAL]);
	else if (pbase)
		*pbase = NULL;

	tal_free(remote_commit);