lightning/lightningd/peer_control.c

#include "lightningd.h"
#include "peer_control.h"
#include "subd.h"
#include <bitcoin/script.h>
#include <bitcoin/tx.h>
#include <ccan/crypto/ripemd160/ripemd160.h>
#include <ccan/io/io.h>
#include <ccan/noerr/noerr.h>
#include <ccan/take/take.h>
#include <ccan/tal/str/str.h>
#include <daemon/chaintopology.h>
#include <daemon/dns.h>
#include <daemon/invoice.h>
#include <daemon/jsonrpc.h>
#include <daemon/log.h>
#include <daemon/sphinx.h>
#include <errno.h>
#include <inttypes.h>
#include <lightningd/build_utxos.h>
#include <lightningd/channel.h>
#include <lightningd/channel/gen_channel_wire.h>
#include <lightningd/funding_tx.h>
#include <lightningd/gossip/gen_gossip_wire.h>
#include <lightningd/handshake/gen_handshake_wire.h>
#include <lightningd/hsm/gen_hsm_wire.h>
#include <lightningd/key_derive.h>
#include <lightningd/opening/gen_opening_wire.h>
#include <lightningd/pay.h>
#include <netinet/in.h>
#include <overflows.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <wire/gen_onion_wire.h>
#include <wire/gen_peer_wire.h>

static void destroy_peer(struct peer *peer)
{
	list_del_from(&peer->ld->peers, &peer->list);
	if (peer->fd >= 0)
		close(peer->fd);
	if (peer->connect_cmd)
		command_fail(peer->connect_cmd, "Failed after %s",
			     peer->condition);
}

void peer_set_condition(struct peer *peer, const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	tal_free(peer->condition);
	peer->condition = tal_vfmt(peer, fmt, ap);
	va_end(ap);
	log_info(peer->log, "condition: %s", peer->condition);
}

static struct peer *new_peer(struct lightningd *ld,
			     struct io_conn *conn,
			     const char *in_or_out,
			     struct command *cmd)
{
	static u64 id_counter;
	struct peer *peer = tal(ld, struct peer);
	const char *netname;

	peer->ld = ld;
	peer->unique_id = id_counter++;
	peer->owner = NULL;
	peer->id = NULL;
	peer->fd = io_conn_fd(conn);
	peer->connect_cmd = cmd;
	peer->funding_txid = NULL;
	peer->seed = NULL;
	peer->locked = false;
	peer->balance = NULL;

	/* Max 128k per peer. */
	peer->log_book = new_log_book(peer, 128*1024,
				      get_log_level(ld->dstate.log_book));
	peer->log = new_log(peer, peer->log_book,
			    "peer %"PRIu64":", peer->unique_id);

	/* FIXME: Don't assume protocol here! */
	if (!netaddr_from_fd(peer->fd, SOCK_STREAM, IPPROTO_TCP,
			     &peer->netaddr)) {
		log_unusual(ld->log, "Failed to get netaddr for outgoing: %s",
			    strerror(errno));
		return tal_free(peer);
	}
	netname = netaddr_name(peer, &peer->netaddr);
	peer->condition = tal_fmt(peer, "%s %s", in_or_out, netname);
	tal_free(netname);
	list_add_tail(&ld->peers, &peer->list);
	tal_add_destructor(peer, destroy_peer);
	return peer;
}

struct peer *peer_by_unique_id(struct lightningd *ld, u64 unique_id)
{
	struct peer *p;

	list_for_each(&ld->peers, p, list)
		if (p->unique_id == unique_id)
			return p;
	return NULL;
}

struct peer *peer_by_id(struct lightningd *ld, const struct pubkey *id)
{
	struct peer *p;

	list_for_each(&ld->peers, p, list)
		if (pubkey_eq(p->id, id))
			return p;
	return NULL;
}

static bool handshake_succeeded(struct subd *hs, const u8 *msg, const int *fds,
				struct peer *peer)
{
	struct crypto_state cs;

	assert(tal_count(fds) == 1);
	peer->fd = fds[0];
	if (!peer->id) {
		struct pubkey id;

		if (!fromwire_handshake_responder_reply(msg, NULL, &id, &cs))
			goto err;
		peer->id = tal_dup(peer, struct pubkey, &id);
		log_info_struct(hs->log, "Peer in from %s",
				struct pubkey, peer->id);
	} else {
		if (!fromwire_handshake_initiator_reply(msg, NULL, &cs))
			goto err;
		log_info_struct(hs->log, "Peer out to %s",
				struct pubkey, peer->id);
	}

	/* FIXME: Look for peer duplicates! */

	peer->owner = peer->ld->gossip;
	tal_steal(peer->owner, peer);
	peer_set_condition(peer, "Beginning gossip");

	/* Tell gossip to handle it now. */
	msg = towire_gossipctl_new_peer(peer, peer->unique_id, &cs);
	subd_send_msg(peer->ld->gossip, take(msg));
	subd_send_fd(peer->ld->gossip, peer->fd);

	/* Peer struct longer owns fd. */
	peer->fd = -1;

	/* Tell handshaked to exit. */
	return false;

err:
	log_broken(hs->log, "Malformed resp: %s", tal_hex(peer, msg));
	close(peer->fd);
	tal_free(peer);
	return false;
}

static bool peer_got_handshake_hsmfd(struct subd *hsm, const u8 *msg,
				     const int *fds,
				     struct peer *peer)
{
	const u8 *req;

	assert(tal_count(fds) == 1);
	if (!fromwire_hsmctl_hsmfd_ecdh_fd_reply(msg, NULL)) {
		log_unusual(peer->ld->log, "Malformed hsmfd response: %s",
			    tal_hex(peer, msg));
		goto error;
	}

	/* Give handshake daemon the hsm fd. */
	/* FIXME! */
	peer->owner = new_subd(peer->ld, peer->ld,
			       "lightningd_handshake", peer,
			       handshake_wire_type_name,
			       NULL, NULL,
			       fds[0], peer->fd, -1);
	if (!peer->owner) {
		log_unusual(peer->ld->log, "Could not subdaemon handshake: %s",
			    strerror(errno));
		peer_set_condition(peer, "Failed to subdaemon handshake");
		goto error;
	}

	/* Peer struct longer owns fd. */
	peer->fd = -1;

	if (peer->id) {
		req = towire_handshake_initiator(peer, &peer->ld->dstate.id,
						 peer->id);
		peer_set_condition(peer, "Starting handshake as initiator");
	} else {
		req = towire_handshake_responder(peer, &peer->ld->dstate.id);
		peer_set_condition(peer, "Starting handshake as responder");
	}

	/* Now hand peer request to the handshake daemon: hands it
	 * back on success */
	subd_req(peer, peer->owner, take(req), -1, 1, handshake_succeeded, peer);
	return true;

error:
	close(fds[0]);
	tal_free(peer);
	return true;
}

/* FIXME: timeout handshake if taking too long? */
static struct io_plan *peer_in(struct io_conn *conn, struct lightningd *ld)
{
	struct peer *peer = new_peer(ld, conn, "Incoming from", NULL);

	if (!peer)
		return io_close(conn);

	/* Get HSM fd for this peer. */
	subd_req(peer, ld->hsm,
		 take(towire_hsmctl_hsmfd_ecdh(ld, peer->unique_id)),
		 -1, 1, peer_got_handshake_hsmfd, peer);

	/* We don't need conn, we'll pass fd to handshaked. */
	return io_close_taken_fd(conn);
}

static int make_listen_fd(struct lightningd *ld,
			  int domain, void *addr, socklen_t len)
{
	int fd = socket(domain, SOCK_STREAM, 0);
	if (fd < 0) {
		log_debug(ld->log, "Failed to create %u socket: %s",
			  domain, strerror(errno));
		return -1;
	}

	if (addr) {
		int on = 1;

		/* Re-use, please.. */
		if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
			log_unusual(ld->log, "Failed setting socket reuse: %s",
				    strerror(errno));

		if (bind(fd, addr, len) != 0) {
			log_unusual(ld->log, "Failed to bind on %u socket: %s",
				    domain, strerror(errno));
			goto fail;
		}
	}

	if (listen(fd, 5) != 0) {
		log_unusual(ld->log, "Failed to listen on %u socket: %s",
			    domain, strerror(errno));
		goto fail;
	}
	return fd;

fail:
	close_noerr(fd);
	return -1;
}

void setup_listeners(struct lightningd *ld)
{
	struct sockaddr_in addr;
	struct sockaddr_in6 addr6;
	socklen_t len;
	int fd1, fd2;

	if (!ld->dstate.portnum) {
		log_debug(ld->log, "Zero portnum, not listening for incoming");
		return;
	}

	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_port = htons(ld->dstate.portnum);

	memset(&addr6, 0, sizeof(addr6));
	addr6.sin6_family = AF_INET6;
	addr6.sin6_addr = in6addr_any;
	addr6.sin6_port = htons(ld->dstate.portnum);

	/* IPv6, since on Linux that (usually) binds to IPv4 too. */
	fd1 = make_listen_fd(ld, AF_INET6, &addr6, sizeof(addr6));
	if (fd1 >= 0) {
		struct sockaddr_in6 in6;

		len = sizeof(in6);
		if (getsockname(fd1, (void *)&in6, &len) != 0) {
			log_unusual(ld->log, "Failed get IPv6 sockname: %s",
				    strerror(errno));
			close_noerr(fd1);
			fd1 = -1;
		} else {
			addr.sin_port = in6.sin6_port;
			assert(ld->dstate.portnum == ntohs(addr.sin_port));
			log_debug(ld->log, "Creating IPv6 listener on port %u",
				  ld->dstate.portnum);
			io_new_listener(ld, fd1, peer_in, ld);
		}
	}

	/* Just in case, aim for the same port... */
	fd2 = make_listen_fd(ld, AF_INET, &addr, sizeof(addr));
	if (fd2 >= 0) {
		len = sizeof(addr);
		if (getsockname(fd2, (void *)&addr, &len) != 0) {
			log_unusual(ld->log, "Failed get IPv4 sockname: %s",
				    strerror(errno));
			close_noerr(fd2);
			fd2 = -1;
		} else {
			assert(ld->dstate.portnum == ntohs(addr.sin_port));
			log_debug(ld->log, "Creating IPv4 listener on port %u",
				  ld->dstate.portnum);
			io_new_listener(ld, fd2, peer_in, ld);
		}
	}

	if (fd1 < 0 && fd2 < 0)
		fatal("Could not bind to a network address on port %u",
		      ld->dstate.portnum);
}

struct json_connecting {
	/* This owns us, so we're freed after command_fail or command_success */
	struct command *cmd;
	const char *name, *port;
	struct pubkey id;
};

/* FIXME: timeout handshake if taking too long? */
static struct io_plan *peer_out(struct io_conn *conn,
				struct lightningd_state *dstate,
				struct json_connecting *jc)
{
	struct lightningd *ld = ld_from_dstate(jc->cmd->dstate);
	struct peer *peer = new_peer(ld, conn, "Outgoing to", jc->cmd);

	if (!peer)
		return io_close(conn);

	/* We already know ID we're trying to reach. */
	peer->id = tal_dup(peer, struct pubkey, &jc->id);

	/* Get HSM fd for this peer. */
	subd_req(peer, ld->hsm,
		 take(towire_hsmctl_hsmfd_ecdh(ld, peer->unique_id)),
		 -1, 1, peer_got_handshake_hsmfd, peer);

	/* We don't need conn, we'll pass fd to handshaked. */
	return io_close_taken_fd(conn);
}

static void connect_failed(struct lightningd_state *dstate,
			   struct json_connecting *connect)
{
	/* FIXME: Better diagnostics! */
	command_fail(connect->cmd, "Failed to connect to peer %s:%s",
		     connect->name, connect->port);
}

static void json_connect(struct command *cmd,
			 const char *buffer, const jsmntok_t *params)
{
	struct json_connecting *connect;
	jsmntok_t *host, *port, *idtok;
	const tal_t *tmpctx = tal_tmpctx(cmd);

	if (!json_get_params(buffer, params,
			     "host", &host,
			     "port", &port,
			     "id", &idtok,
			     NULL)) {
		command_fail(cmd, "Need host, port and id to connect");
		return;
	}

	connect = tal(cmd, struct json_connecting);
	connect->cmd = cmd;
	connect->name = tal_strndup(connect, buffer + host->start,
				    host->end - host->start);
	connect->port = tal_strndup(connect, buffer + port->start,
				    port->end - port->start);

	if (!pubkey_from_hexstr(buffer + idtok->start,
				idtok->end - idtok->start, &connect->id)) {
		command_fail(cmd, "id %.*s not valid",
			     idtok->end - idtok->start,
			     buffer + idtok->start);
		return;
	}

	if (!dns_resolve_and_connect(cmd->dstate, connect->name, connect->port,
				     peer_out, connect_failed, connect)) {
		command_fail(cmd, "DNS failed");
		return;
	}

	tal_free(tmpctx);
}

static const struct json_command connect_command = {
	"connect",
	json_connect,
	"Connect to a {host} at {port} expecting node {id}",
	"Returns the {id} on success (once channel established)"
};
AUTODATA(json_command, &connect_command);

struct log_info {
	enum log_level level;
	struct json_result *response;
};

/* FIXME: Share this with jsonrpc.c's code! */
static void log_to_json(unsigned int skipped,
			struct timerel diff,
			enum log_level level,
			const char *prefix,
			const char *log,
			struct log_info *info)
{
	if (level < info->level)
		return;

	if (level != LOG_IO)
		json_add_string(info->response, NULL, log);
}

static void json_getpeers(struct command *cmd,
			  const char *buffer, const jsmntok_t *params)
{
	struct lightningd *ld = ld_from_dstate(cmd->dstate);
	struct peer *p;
	struct json_result *response = new_json_result(cmd);
	jsmntok_t *leveltok;
	struct log_info info;

	json_get_params(buffer, params, "?level", &leveltok, NULL);

	if (!leveltok)
		;
	else if (json_tok_streq(buffer, leveltok, "debug"))
		info.level = LOG_DBG;
	else if (json_tok_streq(buffer, leveltok, "info"))
		info.level = LOG_INFORM;
	else if (json_tok_streq(buffer, leveltok, "unusual"))
		info.level = LOG_UNUSUAL;
	else if (json_tok_streq(buffer, leveltok, "broken"))
		info.level = LOG_BROKEN;
	else {
		command_fail(cmd, "Invalid level param");
		return;
	}

	json_object_start(response, NULL);
	json_array_start(response, "peers");
	list_for_each(&ld->peers, p, list) {
		json_object_start(response, NULL);
		json_add_u64(response, "unique_id", p->unique_id);
		json_add_string(response, "condition", p->condition);
		json_add_string(response, "netaddr",
				netaddr_name(response, &p->netaddr));
		if (p->id)
			json_add_pubkey(response, "peerid", p->id);
		if (p->owner)
			json_add_string(response, "owner", p->owner->name);
		if (p->balance) {
			json_add_u64(response, "msatoshi_to_us",
				     p->balance[LOCAL]);
			json_add_u64(response, "msatoshi_to_them",
				     p->balance[REMOTE]);
		}
		if (leveltok) {
			info.response = response;
			json_array_start(response, "log");
			log_each_line(p->log_book, log_to_json, &info);
			json_array_end(response);
		}
		json_object_end(response);
	}
	json_array_end(response);
	json_object_end(response);
	command_success(cmd, response);
}

static const struct json_command getpeers_command = {
	"getpeers",
	json_getpeers,
	"List the current peers, if {level} is set, include {log}s",
	"Returns a 'peers' array"
};
AUTODATA(json_command, &getpeers_command);

struct peer *peer_from_json(struct lightningd *ld,
			    const char *buffer,
			    jsmntok_t *peeridtok)
{
	struct pubkey peerid;

	if (!pubkey_from_hexstr(buffer + peeridtok->start,
				peeridtok->end - peeridtok->start, &peerid))
		return NULL;

	return peer_by_id(ld, &peerid);
}

struct funding_channel {
	struct peer *peer;
	struct command *cmd;
	u64 satoshi;
	const struct utxo **utxomap;
	u64 change;
	u32 change_keyindex;
	struct crypto_state *cs;

	struct pubkey local_fundingkey, remote_fundingkey;
	struct bitcoin_tx *funding_tx;
};

static void fail_fundchannel_command(struct funding_channel *fc)
{
	/* FIXME: More details? */
	command_fail(fc->cmd, "Peer died");
}

static void funding_broadcast_failed(struct peer *peer,
				     int exitstatus, const char *err)
{
	log_unusual(peer->log, "Funding broadcast exited with %i: %s",
		    exitstatus, err);
	/* FIXME: send PKT_ERR to peer if this happens. */
	tal_free(peer);
}

static enum watch_result funding_depth_cb(struct peer *peer,
					  unsigned int depth,
					  const struct sha256_double *txid,
					  void *unused)
{
	const char *txidstr = type_to_string(peer, struct sha256_double, txid);
	struct txlocator *loc = locate_tx(peer, peer->ld->topology, txid);
	struct short_channel_id scid;
	scid.blocknum = loc->blkheight;
	scid.txnum = loc->index;
	scid.outnum = peer->funding_outnum;
	loc = tal_free(loc);

	log_debug(peer->log, "Funding tx %s depth %u of %u",
		  txidstr, depth, peer->minimum_depth);

	if (depth < peer->minimum_depth)
		return KEEP_WATCHING;

	/* In theory, it could have been buried before we got back
	 * from accepting openingd: just wait for next one. */
	if (!peer->owner || !streq(peer->owner->name, "lightningd_channel")) {
		log_unusual(peer->log, "Funding tx confirmed, but peer %s",
			    peer->owner ? peer->owner->name : "unowned");
		return KEEP_WATCHING;
	}

	/* Make sure we notify `channeld` just once. */
	if (!peer->locked) {
		peer_set_condition(peer, "Funding tx reached depth %u", depth);
		subd_send_msg(peer->owner, take(towire_channel_funding_locked(peer, &scid)));
		peer->locked = true;
	}

	/* With the above this is max(funding_depth, 6) before
	 * announcing the channel */
	if (depth < ANNOUNCE_MIN_DEPTH) {
		return KEEP_WATCHING;
	}
	subd_send_msg(peer->owner, take(towire_channel_funding_announce_depth(peer)));
	return DELETE_WATCH;
}

static bool opening_got_hsm_funding_sig(struct subd *hsm, const u8 *resp,
					const int *fds,
					struct funding_channel *fc)
{
	secp256k1_ecdsa_signature *sigs;
	struct bitcoin_tx *tx = fc->funding_tx;
	size_t i;

	if (!fromwire_hsmctl_sign_funding_reply(fc, resp, NULL, &sigs))
		fatal("HSM gave bad sign_funding_reply %s",
		      tal_hex(fc, resp));

	if (tal_count(sigs) != tal_count(tx->input))
		fatal("HSM gave %zu sigs, needed %zu",
		      tal_count(sigs), tal_count(tx->input));

	peer_set_condition(fc->peer, "Waiting for our funding tx");
	/* FIXME: Defer until after funding locked. */
	tal_del_destructor(fc, fail_fundchannel_command);
	command_success(fc->cmd, null_response(fc->cmd));
	fc->cmd = NULL;

	/* Create input parts from signatures. */
	for (i = 0; i < tal_count(tx->input); i++) {
		struct pubkey key;

		if (!bip32_pubkey(fc->peer->ld->bip32_base,
				  &key, fc->utxomap[i]->keyindex))
			fatal("Cannot generate BIP32 key for UTXO %u",
			      fc->utxomap[i]->keyindex);

		/* P2SH inputs have same witness. */
		tx->input[i].witness
			= bitcoin_witness_p2wpkh(tx, &sigs[i], &key);
	}

	/* Send it out and watch for confirms. */
	broadcast_tx(hsm->ld->topology, fc->peer, tx, funding_broadcast_failed);
	watch_tx(fc->peer, fc->peer->ld->topology, fc->peer, tx,
		 funding_depth_cb, NULL);
	tal_free(fc);
	return true;
}

struct decoding_htlc {
	struct peer *peer;
	u64 id;
	u32 amount_msat;
	u32 cltv_expiry;
	struct sha256 payment_hash;
	u8 onion[1254];
	u8 shared_secret[32];
};

static void fail_htlc(struct peer *peer, u64 htlc_id, const u8 *msg)
{
	enum onion_type failcode = fromwire_peektype(msg);

	log_broken(peer->log, "failed htlc %"PRIu64" code 0x%04x (%s)",
		   htlc_id, failcode, onion_type_name(failcode));

	/* We don't do BADONION here */
	assert(!(failcode & BADONION));

	/* FIXME: encrypt msg! */
	subd_send_msg(peer->owner,
		      take(towire_channel_fail_htlc(peer, htlc_id, msg)));
	if (taken(msg))
		tal_free(msg);
}

static u8 *make_failmsg(const tal_t *ctx, const struct htlc_end *hend,
			enum onion_type failcode)
{
	struct sha256 *onion_sha = NULL;
	u8 *channel_update = NULL;

	if (failcode & BADONION) {
		/* FIXME: need htlc_end->sha? */
	}
	if (failcode & UPDATE) {
		/* FIXME: Ask gossip daemon for channel_update. */
	}

	switch (failcode) {
	case WIRE_INVALID_REALM:
		return towire_invalid_realm(ctx);
	case WIRE_TEMPORARY_NODE_FAILURE:
		return towire_temporary_node_failure(ctx);
	case WIRE_PERMANENT_NODE_FAILURE:
		return towire_permanent_node_failure(ctx);
	case WIRE_REQUIRED_NODE_FEATURE_MISSING:
		return towire_required_node_feature_missing(ctx);
	case WIRE_INVALID_ONION_VERSION:
		return towire_invalid_onion_version(ctx, onion_sha);
	case WIRE_INVALID_ONION_HMAC:
		return towire_invalid_onion_hmac(ctx, onion_sha);
	case WIRE_INVALID_ONION_KEY:
		return towire_invalid_onion_key(ctx, onion_sha);
	case WIRE_TEMPORARY_CHANNEL_FAILURE:
		return towire_temporary_channel_failure(ctx);
	case WIRE_PERMANENT_CHANNEL_FAILURE:
		return towire_permanent_channel_failure(ctx);
	case WIRE_REQUIRED_CHANNEL_FEATURE_MISSING:
		return towire_required_channel_feature_missing(ctx);
	case WIRE_UNKNOWN_NEXT_PEER:
		return towire_unknown_next_peer(ctx);
	case WIRE_AMOUNT_BELOW_MINIMUM:
		return towire_amount_below_minimum(ctx, hend->msatoshis, channel_update);
	case WIRE_FEE_INSUFFICIENT:
		return towire_fee_insufficient(ctx, hend->msatoshis, channel_update);
	case WIRE_INCORRECT_CLTV_EXPIRY:
		/* FIXME: ctlv! */
		return towire_incorrect_cltv_expiry(ctx, 0, channel_update);
	case WIRE_EXPIRY_TOO_SOON:
		return towire_expiry_too_soon(ctx, channel_update);
	case WIRE_UNKNOWN_PAYMENT_HASH:
		return towire_unknown_payment_hash(ctx);
	case WIRE_INCORRECT_PAYMENT_AMOUNT:
		return towire_incorrect_payment_amount(ctx);
	case WIRE_FINAL_EXPIRY_TOO_SOON:
		return towire_final_expiry_too_soon(ctx);
	case WIRE_FINAL_INCORRECT_CLTV_EXPIRY:
		/* FIXME: ctlv! */
		return towire_final_incorrect_cltv_expiry(ctx, 0);
	case WIRE_FINAL_INCORRECT_HTLC_AMOUNT:
		return towire_final_incorrect_htlc_amount(ctx, hend->msatoshis);
	}
	abort();
}

/* BOLT #4:
 *
 * * `amt_to_forward` - The amount in milli-satoshi to forward to the next
 *    (outgoing) hop specified within the routing information.
 *
 *    This value MUST factor in the computed fee for this particular hop. When
 *    processing an incoming Sphinx packet along with the HTLC message it's
 *    encapsulated within, if the following inequality doesn't hold, then the
 *    HTLC should be rejected as it indicates a prior node in the path has
 *    deviated from the specified paramters:
 *
 *       incoming_htlc_amt - fee >= amt_to_forward
 *
 *    Where `fee` is calculated according to the receving node's advertised fee
 *    schema as described in [BOLT 7](https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md#htlc-fees), or 0 if this node is the
 *    final hop.
 */
static bool check_amount(struct htlc_end *hend,
			 u64 amt_to_forward, u64 amt_in_htlc, u64 fee)
{
	if (amt_in_htlc - fee >= amt_to_forward)
		return true;
	log_debug(hend->peer->ld->log, "HTLC %"PRIu64" incorrect amount:"
		  " %"PRIu64" in, %"PRIu64" out, fee reqd %"PRIu64,
		  hend->htlc_id, amt_in_htlc, amt_to_forward, fee);
	return false;
}

/* BOLT #4:
 *
 *  * `outgoing_cltv_value` - The CLTV value that the _outgoing_ HTLC carrying
 *     the packet should have.
 *
 *        cltv-expiry - cltv-expiry-delta = outgoing_cltv_value
 *
 *     Inclusion of this field allows a node to both authenticate the information
 *     specified by the original sender and the paramaters of the HTLC forwarded,
 *	 and ensure the original sender is using the current `cltv-expiry-delta`  value.
 *     If there is no next hop, `cltv-expiry-delta` is zero.
 *     If the values don't correspond, then the HTLC should be failed+rejected as
 *     this indicates the incoming node has tampered with the intended HTLC
 *     values, or the origin has an obsolete `cltv-expiry-delta` value.
 *     The node MUST be consistent in responding to an unexpected
 *     `outgoing_cltv_value` whether it is the final hop or not, to avoid
 *     leaking that information.
 */
static bool check_ctlv(struct htlc_end *hend,
		       u32 ctlv_expiry, u32 outgoing_cltv_value, u32 delta)
{
	if (ctlv_expiry - delta == outgoing_cltv_value)
		return true;
	log_debug(hend->peer->ld->log, "HTLC %"PRIu64" incorrect CLTV:"
		  " %u in, %u out, delta reqd %u",
		  hend->htlc_id, ctlv_expiry, outgoing_cltv_value, delta);
	return false;
}

static void fulfill_htlc(struct htlc_end *hend, const struct preimage *preimage)
{
	u8 *msg;

	hend->peer->balance[LOCAL] += hend->msatoshis;
	hend->peer->balance[REMOTE] -= hend->msatoshis;

	/* FIXME: fail the peer if it doesn't tell us that htlc fulfill is
	 * committed before deadline.
	 */
	msg = towire_channel_fulfill_htlc(hend->peer, hend->htlc_id, preimage);
	subd_send_msg(hend->peer->owner, take(msg));
}

static void handle_localpay(struct htlc_end *hend,
			    u32 cltv_expiry,
			    const struct sha256 *payment_hash,
			    u64 amt_to_forward,
			    u32 outgoing_cltv_value)
{
	u8 *err;
	struct invoice *invoice;

	/* BOLT #4:
	 *
	 * If the `amt_to_forward` does not match the `incoming_htlc_amt` of
	 * the HTLC at the final hop:
	 *
	 * 1. type: 19 (`final_incorrect_htlc_amount`)
	 * 2. data:
	 *    * [4:incoming-htlc-amt]
	 */
	if (!check_amount(hend, amt_to_forward, hend->msatoshis, 0)) {
		err = towire_final_incorrect_htlc_amount(hend, hend->msatoshis);
		goto fail;
	}

	/* BOLT #4:
	 *
	 * If the `outgoing_cltv_value` does not match the `ctlv-expiry` of
	 * the HTLC at the final hop:
	 *
	 * 1. type: 18 (`final_incorrect_cltv_expiry`)
	 * 2. data:
	 *   * [4:cltv-expiry]
	 */
	if (!check_ctlv(hend, cltv_expiry, outgoing_cltv_value, 0)) {
		err = towire_final_incorrect_cltv_expiry(hend, cltv_expiry);
		goto fail;
	}

	invoice = find_unpaid(hend->peer->ld->dstate.invoices, payment_hash);
	if (!invoice) {
		err = towire_unknown_payment_hash(hend);
		goto fail;
	}

	/* BOLT #4:
	 *
	 * If the amount paid is less than the amount expected, the final node
	 * MUST fail the HTLC.  If the amount paid is more than twice the
	 * amount expected, the final node SHOULD fail the HTLC.  This allows
	 * the sender to reduce information leakage by altering the amount,
	 * without allowing accidental gross overpayment:
	 *
	 * 1. type: PERM|16 (`incorrect_payment_amount`)
	 */
	if (hend->msatoshis < invoice->msatoshi) {
		err = towire_incorrect_payment_amount(hend);
		goto fail;
	} else if (hend->msatoshis > invoice->msatoshi * 2) {
		err = towire_incorrect_payment_amount(hend);
		goto fail;
	}

	/* BOLT #4:
	 *
	 * If the `cltv-expiry` is too low, the final node MUST fail the HTLC:
	 */
	if (get_block_height(hend->peer->ld->topology)
	    + hend->peer->ld->dstate.config.deadline_blocks >= cltv_expiry) {
		log_debug(hend->peer->log,
			  "Expiry cltv %u too close to current %u + deadline %u",
			  cltv_expiry,
			  get_block_height(hend->peer->ld->topology),
			  hend->peer->ld->dstate.config.deadline_blocks);
		err = towire_final_expiry_too_soon(hend);
		goto fail;
	}

	connect_htlc_end(&hend->peer->ld->htlc_ends, hend);

	log_info(hend->peer->ld->log, "Resolving invoice '%s' with HTLC %"PRIu64,
		 invoice->label, hend->htlc_id);
	fulfill_htlc(hend, &invoice->r);
	resolve_invoice(&hend->peer->ld->dstate, invoice);
	return;

fail:
	fail_htlc(hend->peer, hend->htlc_id, take(err));
	tal_free(hend);
}

static struct peer *peer_by_pkhash(struct lightningd *ld, const u8 pkhash[20])
{
	struct peer *peer;
	u8 addr[20];

	list_for_each(&ld->peers, peer, list) {
		pubkey_hash160(addr, peer->id);
		if (memcmp(addr, pkhash, sizeof(addr)) == 0)
			return peer;
	}
	return NULL;
}

/*
 * A catchall in case outgoing peer disconnects before getting fwd.
 *
 * We could queue this and wait for it to come back, but this is simple.
 */
static void hend_subd_died(struct htlc_end *hend)
{
	u8 *failmsg = towire_temporary_channel_failure(hend->other_end);
	u8 *msg = towire_channel_fail_htlc(hend->other_end,
					   hend->other_end->htlc_id,
					   failmsg);
	log_debug(hend->other_end->peer->owner->log,
		  "Failing HTLC %"PRIu64" due to peer death",
		  hend->other_end->htlc_id);
	subd_send_msg(hend->other_end->peer->owner, take(msg));
	tal_free(failmsg);
}

static bool rcvd_htlc_reply(struct subd *subd, const u8 *msg, const int *fds,
			    struct htlc_end *hend)
{
	u16 failure_code;
	u8 *failurestr;

	if (!fromwire_channel_offer_htlc_reply(msg, msg, NULL,
					       &hend->htlc_id,
					       &failure_code,
					       &failurestr)) {
		log_broken(subd->log, "Bad channel_offer_htlc_reply");
		tal_free(hend);
		return false;
	}

	if (failure_code) {
		log_debug(hend->other_end->peer->owner->log,
			  "HTLC failed from other daemon: %s (%.*s)",
			  onion_type_name(failure_code),
			  (int)tal_len(failurestr), (char *)failurestr);

		msg = make_failmsg(msg, hend->other_end, failure_code);
		subd_send_msg(hend->other_end->peer->owner, take(msg));
		tal_free(hend);
		return true;
	}

	tal_del_destructor(hend, hend_subd_died);

	/* Add it to lookup table. */
	connect_htlc_end(&hend->peer->ld->htlc_ends, hend);
	return true;
}

static void forward_htlc(struct htlc_end *hend,
			 u32 cltv_expiry,
			 const struct sha256 *payment_hash,
			 u64 amt_to_forward,
			 u32 outgoing_cltv_value,
			 const u8 next_hop[20],
			 const u8 next_onion[TOTAL_PACKET_SIZE])
{
	u8 *err, *msg;
	u64 fee;
	struct lightningd *ld = hend->peer->ld;
	struct peer *next = peer_by_pkhash(ld, next_hop);

	if (!next) {
		err = towire_unknown_next_peer(hend);
		goto fail;
	}
	/* FIXME: These checks are horrible, use a peer flag to say it's
	 * ready to forward! */
	if (!next->owner || !streq(next->owner->name, "lightningd_channel")
	    || !streq(next->condition, "Normal operation")) {
		err = towire_unknown_next_peer(hend);
		goto fail;
	}

	/* BOLT #7:
	 *
	 * The node creating `channel_update` SHOULD accept HTLCs which pay a
	 * fee equal or greater than:
	 *
	 *    fee-base-msat + htlc-amount-msat * fee-proportional-millionths / 1000000
	 */
	if (mul_overflows_u64(amt_to_forward,
			      ld->dstate.config.fee_per_satoshi)) {
		/* FIXME: Add channel update */
		err = towire_fee_insufficient(hend, hend->msatoshis, NULL);
		goto fail;
	}
	fee = ld->dstate.config.fee_base
		+ amt_to_forward * ld->dstate.config.fee_per_satoshi / 1000000;
	if (!check_amount(hend, amt_to_forward, hend->msatoshis, fee)) {
		/* FIXME: Add channel update */
		err = towire_fee_insufficient(hend, hend->msatoshis, NULL);
		goto fail;
	}

	if (!check_ctlv(hend, cltv_expiry, outgoing_cltv_value,
			ld->dstate.config.deadline_blocks)) {
		/* FIXME: Add channel update */
		err = towire_incorrect_cltv_expiry(hend, cltv_expiry, NULL);
		goto fail;
	}

	/* BOLT #4:
	 *
	 * If the ctlv-expiry is too near, we tell them the the current channel
	 * setting for the outgoing channel:
	 * 1. type: UPDATE|14 (`expiry_too_soon`)
	 * 2. data:
	 *    * [2:len]
	 *    * [len:channel_update]
	 */
	if (get_block_height(next->ld->topology)
	    + next->ld->dstate.config.deadline_blocks >= outgoing_cltv_value) {
		log_debug(hend->peer->log,
			  "Expiry cltv %u too close to current %u + deadline %u",
			  outgoing_cltv_value,
			  get_block_height(next->ld->topology),
			  next->ld->dstate.config.deadline_blocks);
		/* FIXME: Add channel update */
		err = towire_expiry_too_soon(hend, NULL);
		goto fail;
	}

	/* Make sure daemon owns it, in case it fails. */
	hend->other_end = tal(next->owner, struct htlc_end);
	hend->other_end->which_end = HTLC_DST;
	hend->other_end->peer = next;
	hend->other_end->other_end = hend;
	hend->other_end->pay_command = NULL;
	hend->other_end->msatoshis = amt_to_forward;
	tal_add_destructor(hend->other_end, hend_subd_died);

	msg = towire_channel_offer_htlc(next, amt_to_forward,
					outgoing_cltv_value,
					payment_hash, next_onion);
	subd_req(next->owner, next->owner, take(msg), -1, 0,
		 rcvd_htlc_reply, hend->other_end);
	return;

fail:
	fail_htlc(hend->peer, hend->htlc_id, take(err));
	tal_free(hend);
}

static int peer_accepted_htlc(struct peer *peer, const u8 *msg)
{
	u64 id;
	u32 cltv_expiry, amount_msat;
	struct sha256 payment_hash;
	u8 next_onion[TOTAL_PACKET_SIZE];
	u8 next_hop[20];
	bool forward;
	u64 amt_to_forward;
	u32 outgoing_cltv_value;
	struct htlc_end *hend;

	if (!fromwire_channel_accepted_htlc(msg, NULL, &id, &amount_msat,
					    &cltv_expiry, &payment_hash,
					    next_onion, &forward,
					    &amt_to_forward,
					    &outgoing_cltv_value,
					    next_hop)) {
		log_broken(peer->log, "bad fromwire_channel_accepted_htlc %s",
			   tal_hex(peer, msg));
		return -1;
	}

	hend = tal(peer, struct htlc_end);
	hend->which_end = HTLC_SRC;
	hend->peer = peer;
	hend->htlc_id = id;
	hend->other_end = NULL;
	hend->pay_command = NULL;
	hend->msatoshis = amount_msat;

	if (forward)
		forward_htlc(hend, cltv_expiry, &payment_hash,
			     amt_to_forward, outgoing_cltv_value,
			     next_hop, next_onion);
	else
		handle_localpay(hend, cltv_expiry, &payment_hash,
				amt_to_forward, outgoing_cltv_value);
	return 0;
}

static int peer_fulfilled_htlc(struct peer *peer, const u8 *msg)
{
	u64 id;
	struct preimage preimage;
	struct htlc_end *hend;

	if (!fromwire_channel_fulfilled_htlc(msg, NULL, &id, &preimage)) {
		log_broken(peer->log, "bad fromwire_channel_fulfilled_htlc %s",
			   tal_hex(peer, msg));
		return -1;
	}

	hend = find_htlc_end(&peer->ld->htlc_ends, peer, id, HTLC_DST);
	if (!hend) {
		log_broken(peer->log,
			   "channel_fulfilled_htlc unknown htlc %"PRIu64,
			   id);
		return -1;
	}

	/* They fulfilled our HTLC.  Credit them, forward as required. */
	peer->balance[REMOTE] += hend->msatoshis;
	peer->balance[LOCAL] -= hend->msatoshis;

	if (hend->other_end)
		fulfill_htlc(hend->other_end, &preimage);
	else
		payment_succeeded(peer->ld, hend, &preimage);
	tal_free(hend);

	return 0;
}

static int peer_failed_htlc(struct peer *peer, const u8 *msg)
{
	u64 id;
	u8 *reason;
	struct htlc_end *hend;
	enum onion_type failcode;

	if (!fromwire_channel_failed_htlc(msg, msg, NULL, &id, &reason)) {
		log_broken(peer->log, "bad fromwire_channel_failed_htlc %s",
			   tal_hex(peer, msg));
		return -1;
	}

	hend = find_htlc_end(&peer->ld->htlc_ends, peer, id, HTLC_DST);
	if (!hend) {
		log_broken(peer->log,
			   "channel_failed_htlc unknown htlc %"PRIu64,
			   id);
		return -1;
	}

	failcode = fromwire_peektype(reason);

	log_info(peer->log, "htlc %"PRIu64" failed with code 0x%04x (%s)",
		 id, failcode, onion_type_name(failcode));

	if (hend->other_end) {
		fail_htlc(hend->other_end->peer, hend->other_end->htlc_id,
			  reason);
	} else {
		/* FIXME: Decrypt reason, determine sender! */
		payment_failed(peer->ld, hend, NULL, failcode);
	}
	tal_free(hend);

	return 0;
}

static int channel_msg(struct subd *sd, const u8 *msg, const int *unused)
{
	enum channel_wire_type t = fromwire_peektype(msg);

	switch (t) {
	case WIRE_CHANNEL_RECEIVED_FUNDING_LOCKED:
		peer_set_condition(sd->peer, "Received funding locked");
		break;
	case WIRE_CHANNEL_NORMAL_OPERATION:
		peer_set_condition(sd->peer, "Normal operation");
		break;
	case WIRE_CHANNEL_ACCEPTED_HTLC:
		return peer_accepted_htlc(sd->peer, msg);
	case WIRE_CHANNEL_FULFILLED_HTLC:
		return peer_fulfilled_htlc(sd->peer, msg);
	case WIRE_CHANNEL_FAILED_HTLC:
		return peer_failed_htlc(sd->peer, msg);
	case WIRE_CHANNEL_MALFORMED_HTLC:
		/* FIXME: Forward. */
		abort();
		break;

	/* We never see fatal ones. */
	case WIRE_CHANNEL_BAD_COMMAND:
	case WIRE_CHANNEL_HSM_FAILED:
	case WIRE_CHANNEL_CRYPTO_FAILED:
	case WIRE_CHANNEL_INTERNAL_ERROR:
	case WIRE_CHANNEL_PEER_WRITE_FAILED:
	case WIRE_CHANNEL_PEER_READ_FAILED:
	case WIRE_CHANNEL_PEER_BAD_MESSAGE:
	/* And we never get these from channeld. */
	case WIRE_CHANNEL_INIT:
	case WIRE_CHANNEL_FUNDING_LOCKED:
	case WIRE_CHANNEL_FUNDING_ANNOUNCE_DEPTH:
	case WIRE_CHANNEL_OFFER_HTLC:
	case WIRE_CHANNEL_FULFILL_HTLC:
	case WIRE_CHANNEL_FAIL_HTLC:
	case WIRE_CHANNEL_PING:
	/* Replies go to requests. */
	case WIRE_CHANNEL_OFFER_HTLC_REPLY:
	case WIRE_CHANNEL_PING_REPLY:
		break;
	}

	return 0;
}

struct channeld_start {
	struct peer *peer;
	const u8 *initmsg;
};

/* We've got fd from HSM for channeld */
static bool peer_start_channeld_hsmfd(struct subd *hsm, const u8 *resp,
				      const int *fds,
				      struct channeld_start *cds)
{
	cds->peer->owner = new_subd(cds->peer->ld, cds->peer->ld,
				    "lightningd_channel", cds->peer,
				    channel_wire_type_name,
				    channel_msg, NULL,
				    cds->peer->fd,
				    cds->peer->gossip_client_fd, fds[0], -1);
	if (!cds->peer->owner) {
		log_unusual(cds->peer->log, "Could not subdaemon channel: %s",
			    strerror(errno));
		peer_set_condition(cds->peer, "Failed to subdaemon channel");
		tal_free(cds->peer);
		return true;
	}
	cds->peer->fd = -1;

	peer_set_condition(cds->peer, "Waiting for funding confirmations");
	/* We don't expect a response: we are triggered by funding_depth_cb. */
	subd_send_msg(cds->peer->owner, take(cds->initmsg));
	tal_free(cds);
	return true;
}

/* opening is done, start lightningd_channel for peer. */
static void peer_start_channeld(struct peer *peer, enum side funder,
				const struct channel_config *their_config,
				const struct crypto_state *crypto_state,
				const secp256k1_ecdsa_signature *commit_sig,
				const struct pubkey *remote_fundingkey,
				const struct basepoints *theirbase,
				const struct pubkey *their_per_commit_point)
{
	struct channeld_start *cds = tal(peer, struct channeld_start);

	/* Unowned: back to being owned by main daemon. */
	peer->owner = NULL;
	tal_steal(peer->ld, peer);

	peer_set_condition(peer, "Waiting for HSM file descriptor");

	/* Now we can consider balance set. */
	peer->balance = tal_arr(peer, u64, NUM_SIDES);
	peer->balance[funder] = peer->funding_satoshi * 1000 - peer->push_msat;
	peer->balance[!funder] = peer->push_msat;

	cds->peer = peer;
	/* Prepare init message now while we have access to all the data. */
	cds->initmsg = towire_channel_init(cds,
					   peer->funding_txid,
					   peer->funding_outnum,
					   &peer->our_config,
					   their_config,
					   commit_sig,
					   crypto_state,
					   remote_fundingkey,
					   &theirbase->revocation,
					   &theirbase->payment,
					   &theirbase->delayed_payment,
					   their_per_commit_point,
					   funder == LOCAL,
					   /* FIXME: real feerate! */
					   15000,
					   peer->funding_satoshi,
					   peer->push_msat,
					   peer->seed,
					   &peer->ld->dstate.id,
					   peer->id,
					   time_to_msec(peer->ld->dstate.config
							.commit_time));

	/* Get fd from hsm. */
	subd_req(peer, peer->ld->hsm,
		 take(towire_hsmctl_hsmfd_channeld(peer, peer->unique_id)),
		 -1, 1, peer_start_channeld_hsmfd, cds);
}

static bool opening_release_tx(struct subd *opening, const u8 *resp,
			       const int *fds,
			       struct funding_channel *fc)
{
	u8 *msg;
	size_t i;
	struct channel_config their_config;
	struct crypto_state crypto_state;
	secp256k1_ecdsa_signature commit_sig;
	struct pubkey their_per_commit_point;
	struct basepoints theirbase;
	/* FIXME: marshal code wants array, not array of pointers. */
	struct utxo *utxos = tal_arr(fc, struct utxo, tal_count(fc->utxomap));

	assert(tal_count(fds) == 1);
	fc->peer->fd = fds[0];

	if (!fromwire_opening_open_funding_reply(resp, NULL,
						 &their_config,
						 &commit_sig,
						 &crypto_state,
						 &theirbase.revocation,
						 &theirbase.payment,
						 &theirbase.delayed_payment,
						 &their_per_commit_point,
						 &fc->peer->minimum_depth)) {
		log_broken(fc->peer->log, "bad OPENING_OPEN_FUNDING_REPLY %s",
			   tal_hex(resp, resp));
		tal_free(fc->peer);
		return false;
	}
	peer_set_condition(fc->peer, "Getting HSM to sign funding tx");

	/* Get HSM to sign the funding tx. */
	for (i = 0; i < tal_count(fc->utxomap); i++)
		utxos[i] = *fc->utxomap[i];

	msg = towire_hsmctl_sign_funding(fc, fc->satoshi, fc->change,
					 fc->change_keyindex,
					 &fc->local_fundingkey,
					 &fc->remote_fundingkey,
					 utxos);
	tal_free(utxos);
	subd_req(fc, fc->peer->ld->hsm, take(msg), -1, 0,
		 opening_got_hsm_funding_sig, fc);

	/* Start normal channel daemon. */
	peer_start_channeld(fc->peer, LOCAL,
			    &their_config, &crypto_state, &commit_sig,
			    &fc->remote_fundingkey, &theirbase,
			    &their_per_commit_point);

	/* Tell opening daemon to exit. */
	return false;
}

static bool opening_gen_funding(struct subd *opening, const u8 *reply,
				const int *fds, struct funding_channel *fc)
{
	u8 *msg;
	struct pubkey changekey;

	peer_set_condition(fc->peer, "Created funding transaction for channel");
	if (!fromwire_opening_open_reply(reply, NULL,
					 &fc->local_fundingkey,
					 &fc->remote_fundingkey)) {
		log_broken(fc->peer->log, "Bad opening_open_reply %s",
			   tal_hex(fc, reply));
		/* Free openingd and peer */
		return false;
	}

	if (fc->change
	    && !bip32_pubkey(fc->peer->ld->bip32_base,
			     &changekey, fc->change_keyindex))
		fatal("Error deriving change key %u", fc->change_keyindex);

	fc->funding_tx = funding_tx(fc, &fc->peer->funding_outnum,
				    fc->utxomap, fc->satoshi,
				    &fc->local_fundingkey,
				    &fc->remote_fundingkey,
				    fc->change, &changekey,
				    fc->peer->ld->bip32_base);
	fc->peer->funding_txid = tal(fc->peer, struct sha256_double);
	bitcoin_txid(fc->funding_tx, fc->peer->funding_txid);

	msg = towire_opening_open_funding(fc, fc->peer->funding_txid,
					  fc->peer->funding_outnum);
	subd_req(fc, fc->peer->owner, take(msg), -1, 1, opening_release_tx, fc);
	return true;
}

static bool opening_accept_finish_response(struct subd *opening,
					   const u8 *reply,
					   const int *fds,
					   struct peer *peer)
{
	struct channel_config their_config;
	secp256k1_ecdsa_signature first_commit_sig;
	struct crypto_state crypto_state;
	struct basepoints theirbase;
	struct pubkey remote_fundingkey, their_per_commit_point;

	log_debug(peer->log, "Got opening_accept_finish_response");
	assert(tal_count(fds) == 1);
	peer->fd = fds[0];

	if (!fromwire_opening_accept_finish_reply(reply, NULL,
						  &peer->funding_outnum,
						  &their_config,
						  &first_commit_sig,
						  &crypto_state,
						  &remote_fundingkey,
						  &theirbase.revocation,
						  &theirbase.payment,
						  &theirbase.delayed_payment,
						  &their_per_commit_point,
						  &peer->funding_satoshi,
						  &peer->push_msat)) {
		log_broken(peer->log, "bad OPENING_ACCEPT_FINISH_REPLY %s",
			   tal_hex(reply, reply));
		return false;
	}

	/* On to normal operation! */
	peer_start_channeld(peer, REMOTE, &their_config, &crypto_state,
			    &first_commit_sig, &remote_fundingkey, &theirbase,
			    &their_per_commit_point);

	/* Tell opening daemon to exit. */
	return false;
}

static bool opening_accept_reply(struct subd *opening, const u8 *reply,
				 const int *fds,
				 struct peer *peer)
{
	peer->funding_txid = tal(peer, struct sha256_double);
	if (!fromwire_opening_accept_reply(reply, NULL, peer->funding_txid)) {
		log_broken(peer->log, "bad OPENING_ACCEPT_REPLY %s",
			   tal_hex(reply, reply));
		return false;
	}

	log_debug(peer->log, "Watching funding tx %s",
		     type_to_string(reply, struct sha256_double,
				    peer->funding_txid));
	watch_txid(peer, peer->ld->topology, peer, peer->funding_txid,
		   funding_depth_cb, NULL);

	/* Tell it we're watching. */
	subd_req(peer, opening, towire_opening_accept_finish(reply),
		 -1, 1,
		 opening_accept_finish_response, peer);
	return true;
}

static void channel_config(struct lightningd *ld,
			   struct channel_config *ours,
			   u32 *max_to_self_delay,
			   u32 *max_minimum_depth,
			   u64 *min_effective_htlc_capacity_msat)
{
	/* FIXME: depend on feerate. */
	*max_to_self_delay = ld->dstate.config.locktime_max;
	*max_minimum_depth = ld->dstate.config.anchor_confirms_max;
	/* This is 1c at $1000/BTC */
	*min_effective_htlc_capacity_msat = 1000000;

	/* BOLT #2:
	 *
	 * The sender SHOULD set `dust-limit-satoshis` to a sufficient
	 * value to allow commitment transactions to propagate through
	 * the Bitcoin network.
	 */
	ours->dust_limit_satoshis = 546;
	ours->max_htlc_value_in_flight_msat = UINT64_MAX;

	/* Don't care */
	ours->htlc_minimum_msat = 0;

	/* BOLT #2:
	 *
	 * The sender SHOULD set `to-self-delay` sufficient to ensure
	 * the sender can irreversibly spend a commitment transaction
	 * output in case of misbehavior by the receiver.
	 */
	 ours->to_self_delay = ld->dstate.config.locktime_blocks;

	 /* BOLT #2:
	  *
	  * It MUST fail the channel if `max-accepted-htlcs` is greater than
	  * 483.
	  */
	 ours->max_accepted_htlcs = 483;

	 /* This is filled in by lightningd_opening, for consistency. */
	 ours->channel_reserve_satoshis = 0;
};

/* Peer has spontaneously exited from gossip due to msg */
void peer_accept_open(struct peer *peer,
		      const struct crypto_state *cs, const u8 *from_peer)
{
	struct lightningd *ld = peer->ld;
	u32 max_to_self_delay, max_minimum_depth;
	u64 min_effective_htlc_capacity_msat;
	u8 *msg;

	/* Note: gossipd handles unknown packets, so we don't have to worry
	 * about ignoring odd ones here. */
	if (fromwire_peektype(from_peer) != WIRE_OPEN_CHANNEL) {
		log_unusual(peer->log, "Strange message to exit gossip: %u",
			    fromwire_peektype(from_peer));
		peer_set_condition(peer, "Bad message during gossiping");
		tal_free(peer);
		return;
	}

	peer_set_condition(peer, "Starting opening daemon");
	peer->owner = new_subd(ld, ld, "lightningd_opening", peer,
			       opening_wire_type_name,
			       NULL, NULL,
			       peer->fd, -1);
	if (!peer->owner) {
		log_unusual(ld->log, "Could not subdaemon opening: %s",
			    strerror(errno));
		peer_set_condition(peer, "Failed to subdaemon opening");
		tal_free(peer);
		return;
	}
	/* We handed off peer fd */
	peer->fd = -1;

	/* BOLT #2:
	 *
	 * The sender SHOULD set `minimum-depth` to an amount where
	 * the sender considers reorganizations to be low risk.
	 */
	peer->minimum_depth = ld->dstate.config.anchor_confirms;

	channel_config(ld, &peer->our_config,
		       &max_to_self_delay, &max_minimum_depth,
		       &min_effective_htlc_capacity_msat);

	peer->seed = tal(peer, struct privkey);
	derive_peer_seed(ld, peer->seed, peer->id);
	msg = towire_opening_init(peer, &peer->our_config,
				  max_to_self_delay,
				  min_effective_htlc_capacity_msat,
				  cs, peer->seed);

	subd_send_msg(peer->owner, take(msg));
	msg = towire_opening_accept(peer, peer->minimum_depth,
				    7500, 150000, from_peer);

	/* Careful here!  Their message could push us overlength! */
	if (tal_len(msg) >= 65536) {
		peer_set_condition(peer, "Unacceptably long open_channel");
		tal_free(peer);
		return;
	}
	subd_req(peer, peer->owner, take(msg), -1, 0, opening_accept_reply, peer);
}

/* Peer has been released from gossip.  Start opening. */
static bool gossip_peer_released(struct subd *gossip,
				 const u8 *resp,
				 const int *fds,
				 struct funding_channel *fc)
{
	struct lightningd *ld = fc->peer->ld;
	u32 max_to_self_delay, max_minimum_depth;
	u64 min_effective_htlc_capacity_msat;
	u64 id;
	u8 *msg;
	struct subd *opening;

	assert(tal_count(fds) == 2);
	fc->peer->fd = fds[0];
	fc->peer->gossip_client_fd = fds[1];

	fc->cs = tal(fc, struct crypto_state);
	if (!fromwire_gossipctl_release_peer_reply(resp, NULL, &id, fc->cs))
		fatal("Gossup daemon gave invalid reply %s",
		      tal_hex(gossip, resp));

	if (id != fc->peer->unique_id)
		fatal("Gossup daemon release gave %"PRIu64" not %"PRIu64,
		      id, fc->peer->unique_id);

	peer_set_condition(fc->peer, "Starting opening daemon");
	opening = new_subd(fc->peer->ld, ld,
			   "lightningd_opening", fc->peer,
			   opening_wire_type_name,
			   NULL, NULL,
			   fc->peer->fd, -1);
	if (!opening) {
		log_unusual(ld->log, "Could not subdaemon opening: %s",
			    strerror(errno));
		peer_set_condition(fc->peer, "Failed to subdaemon opening");
		tal_free(fc->peer);
		return true;
	}
	fc->peer->owner = opening;

	/* They took our fd. */
	fc->peer->fd = -1;

	channel_config(ld, &fc->peer->our_config,
		       &max_to_self_delay, &max_minimum_depth,
		       &min_effective_htlc_capacity_msat);

	fc->peer->seed = tal(fc->peer, struct privkey);
	derive_peer_seed(ld, fc->peer->seed, fc->peer->id);
	msg = towire_opening_init(fc, &fc->peer->our_config,
				  max_to_self_delay,
				  min_effective_htlc_capacity_msat,
				  fc->cs, fc->peer->seed);

	fc->peer->funding_satoshi = fc->satoshi;
	/* FIXME: Support push_msat? */
	fc->peer->push_msat = 0;

	subd_send_msg(opening, take(msg));
	/* FIXME: Real feerate! */
	msg = towire_opening_open(fc, fc->peer->funding_satoshi,
				  fc->peer->push_msat,
				  15000, max_minimum_depth);
	subd_req(fc, opening, take(msg), -1, 0, opening_gen_funding, fc);
	return true;
}

static void json_fund_channel(struct command *cmd,
			      const char *buffer, const jsmntok_t *params)
{
	struct lightningd *ld = ld_from_dstate(cmd->dstate);
	jsmntok_t *peertok, *satoshitok;
	struct funding_channel *fc = tal(cmd, struct funding_channel);
	u8 *msg;

	if (!json_get_params(buffer, params,
			     "id", &peertok,
			     "satoshi", &satoshitok,
			     NULL)) {
		command_fail(cmd, "Need peerid and satoshi");
		return;
	}

	fc->cmd = cmd;
	fc->peer = peer_from_json(ld, buffer, peertok);
	if (!fc->peer) {
		command_fail(cmd, "Could not find peer with that peerid");
		return;
	}
	if (fc->peer->owner != ld->gossip) {
		command_fail(cmd, "Peer not ready for connection");
		return;
	}

	if (!json_tok_u64(buffer, satoshitok, &fc->satoshi)) {
		command_fail(cmd, "Invalid satoshis");
		return;
	}

	/* Try to do this now, so we know if insufficient funds. */
	/* FIXME: Feerate & dustlimit */
	fc->utxomap = build_utxos(fc, ld, fc->satoshi, 15000, 600,
				  &fc->change, &fc->change_keyindex);
	if (!fc->utxomap) {
		command_fail(cmd, "Cannot afford funding transaction");
		return;
	}

	msg = towire_gossipctl_release_peer(cmd, fc->peer->unique_id);

	/* Tie this fc lifetime (and hence utxo release) to the peer */
	tal_steal(fc->peer, fc);
	tal_add_destructor(fc, fail_fundchannel_command);
	subd_req(fc, ld->gossip, msg, -1, 2, gossip_peer_released, fc);
}

static const struct json_command fund_channel_command = {
	"fundchannel",
	json_fund_channel,
	"Fund channel with {id} using {satoshi} satoshis",
	"Returns once channel established"
};
AUTODATA(json_command, &fund_channel_command);