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rgb-cln/openingd/openingd.c

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/*~ Welcome to the opening daemon: gateway to channels!
*
* This daemon handles a single peer. It's happy to trade gossip with the
* peer until either lightningd asks it to fund a channel, or the peer itself
* asks to fund a channel. Then it goes through with the channel opening
* negotiations. It's important to note that until this negotiation is complete,
* there's nothing permanent about the channel: lightningd will only have to
* commit to the database once openingd succeeds.
*/
#include <bitcoin/block.h>
#include <bitcoin/chainparams.h>
#include <bitcoin/privkey.h>
#include <bitcoin/psbt.h>
#include <bitcoin/script.h>
#include <ccan/array_size/array_size.h>
#include <ccan/breakpoint/breakpoint.h>
#include <ccan/cast/cast.h>
#include <ccan/fdpass/fdpass.h>
#include <ccan/mem/mem.h>
#include <ccan/tal/str/str.h>
#include <common/crypto_sync.h>
#include <common/derive_basepoints.h>
#include <common/features.h>
#include <common/fee_states.h>
#include <common/gossip_rcvd_filter.h>
#include <common/gossip_store.h>
#include <common/initial_channel.h>
#include <common/initial_commit_tx.h>
#include <common/key_derive.h>
#include <common/memleak.h>
#include <common/overflows.h>
#include <common/peer_billboard.h>
#include <common/peer_failed.h>
#include <common/peer_status_wiregen.h>
#include <common/penalty_base.h>
#include <common/pseudorand.h>
#include <common/read_peer_msg.h>
#include <common/status.h>
#include <common/subdaemon.h>
#include <common/type_to_string.h>
#include <common/version.h>
#include <common/wire_error.h>
#include <errno.h>
#include <gossipd/gossipd_peerd_wiregen.h>
#include <hsmd/hsmd_wiregen.h>
#include <inttypes.h>
#include <openingd/common.h>
#include <openingd/openingd_wiregen.h>
#include <poll.h>
#include <secp256k1.h>
#include <stdio.h>
#include <wally_bip32.h>
#include <wire/common_wiregen.h>
#include <wire/peer_wire.h>
#include <wire/wire.h>
#include <wire/wire_sync.h>
/* stdin == lightningd, 3 == peer, 4 == gossipd, 5 = gossip_store, 6 = hsmd */
#define REQ_FD STDIN_FILENO
#define HSM_FD 6
#if DEVELOPER
/* If --dev-force-tmp-channel-id is set, it ends up here */
static struct channel_id *dev_force_tmp_channel_id;
#endif /* DEVELOPER */
/* Global state structure. This is only for the one specific peer and channel */
struct state {
struct per_peer_state *pps;
/* Features they offered */
u8 *their_features;
/* Constraints on a channel they open. */
u32 minimum_depth;
u32 min_feerate, max_feerate;
struct amount_msat min_effective_htlc_capacity;
/* Limits on what remote config we accept. */
u32 max_to_self_delay;
/* These are the points lightningd told us to use when accepting or
* opening a channel. */
struct basepoints our_points;
struct pubkey our_funding_pubkey;
/* Information we need between funding_start and funding_complete */
struct basepoints their_points;
struct pubkey their_funding_pubkey;
/* hsmd gives us our first per-commitment point, and peer tells us
* theirs */
struct pubkey first_per_commitment_point[NUM_SIDES];
/* Initially temporary, then final channel id. */
struct channel_id channel_id;
/* Funding and feerate: set by opening peer. */
struct amount_sat funding;
struct amount_msat push_msat;
u32 feerate_per_kw;
struct bitcoin_txid funding_txid;
u16 funding_txout;
/* If non-NULL, this is the scriptpubkey we/they *must* close with */
u8 *upfront_shutdown_script[NUM_SIDES];
/* This is a cluster of fields in open_channel and accept_channel which
* indicate the restrictions each side places on the channel. */
struct channel_config localconf, remoteconf;
/* The channel structure, as defined in common/initial_channel.h. While
* the structure has room for HTLCs, those routines are channeld-specific
* as initial channels never have HTLCs. */
struct channel *channel;
bool option_static_remotekey;
bool option_anchor_outputs;
struct feature_set *our_features;
};
static u8 *no_upfront_shutdown_script(const tal_t *ctx, struct state *state)
{
#if DEVELOPER
/* This is a hack, for feature testing */
const char *e = getenv("DEV_OPENINGD_UPFRONT_SHUTDOWN_SCRIPT");
if (e)
return tal_hexdata(ctx, e, strlen(e));
#endif
/* BOLT #2:
*
* - if both nodes advertised the `option_upfront_shutdown_script`
* feature:
* - MUST include `upfront_shutdown_script` with either a valid
* `shutdown_scriptpubkey` as required by `shutdown`
* `scriptpubkey`, or a zero-length `shutdown_scriptpubkey`
* (ie. `0x0000`).
*/
if (feature_negotiated(state->our_features, state->their_features,
OPT_UPFRONT_SHUTDOWN_SCRIPT))
return tal_arr(ctx, u8, 0);
return NULL;
}
/*~ If we can't agree on parameters, we fail to open the channel. If we're
* the opener, we need to tell lightningd, otherwise it never really notices. */
static void negotiation_aborted(struct state *state, bool am_opener,
const char *why)
{
status_debug("aborted opening negotiation: %s", why);
/*~ The "billboard" (exposed as "status" in the JSON listpeers RPC
* call) is a transient per-channel area which indicates important
* information about what is happening. It has a "permanent" area for
* each state, which can be used to indicate what went wrong in that
* state (such as here), and a single transient area for current
* status. */
peer_billboard(true, why);
/* If necessary, tell master that funding failed. */
if (am_opener) {
u8 *msg = towire_openingd_funder_failed(NULL, why);
wire_sync_write(REQ_FD, take(msg));
}
/* Default is no shutdown_scriptpubkey: free any leftover ones. */
state->upfront_shutdown_script[LOCAL]
= tal_free(state->upfront_shutdown_script[LOCAL]);
state->upfront_shutdown_script[REMOTE]
= tal_free(state->upfront_shutdown_script[REMOTE]);
/*~ Reset state. We keep gossipping with them, even though this open
* failed. */
memset(&state->channel_id, 0, sizeof(state->channel_id));
state->channel = tal_free(state->channel);
}
/*~ For negotiation failures: we tell them the parameter we didn't like. */
static void negotiation_failed(struct state *state, bool am_opener,
const char *fmt, ...)
{
va_list ap;
const char *errmsg;
u8 *msg;
va_start(ap, fmt);
errmsg = tal_vfmt(tmpctx, fmt, ap);
va_end(ap);
msg = towire_errorfmt(NULL, &state->channel_id,
"You gave bad parameters: %s", errmsg);
sync_crypto_write(state->pps, take(msg));
negotiation_aborted(state, am_opener, errmsg);
}
/* We always set channel_reserve_satoshis to 1%, rounded down. */
static void set_reserve(struct state *state)
{
state->localconf.channel_reserve = amount_sat_div(state->funding, 100);
/* BOLT #2:
*
* The sending node:
*...
* - MUST set `channel_reserve_satoshis` greater than or equal to
* `dust_limit_satoshis`.
*/
if (amount_sat_greater(state->localconf.dust_limit,
state->localconf.channel_reserve))
state->localconf.channel_reserve
= state->localconf.dust_limit;
}
/* BOLT #2:
*
* The sending node:
*...
* - MUST ensure `temporary_channel_id` is unique from any other channel ID
* with the same peer.
*/
static void temporary_channel_id(struct channel_id *channel_id)
{
size_t i;
/* Randomness FTW. */
for (i = 0; i < sizeof(*channel_id); i++)
channel_id->id[i] = pseudorand(256);
}
/*~ Handle random messages we might get during opening negotiation, (eg. gossip)
* returning the first non-handled one, or NULL if we aborted negotiation. */
static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
bool am_opener)
{
/* This is an event loop of its own. That's generally considered poor
* form, but we use it in a very limited way. */
for (;;) {
u8 *msg;
bool from_gossipd;
char *err;
bool all_channels;
struct channel_id actual;
/* The event loop is responsible for freeing tmpctx, so our
* temporary allocations don't grow unbounded. */
clean_tmpctx();
/* This helper routine polls both the peer and gossipd. */
msg = peer_or_gossip_sync_read(ctx, state->pps, &from_gossipd);
/* Use standard helper for gossip msgs (forwards, if it's an
* error, exits). */
if (from_gossipd) {
handle_gossip_msg(state->pps, take(msg));
continue;
}
/* Some messages go straight to gossipd. */
if (is_msg_for_gossipd(msg)) {
gossip_rcvd_filter_add(state->pps->grf, msg);
wire_sync_write(state->pps->gossip_fd, take(msg));
continue;
}
/* BOLT #1:
*
* A receiving node:
* - upon receiving a message of _odd_, unknown type:
* - MUST ignore the received message.
*/
if (is_unknown_msg_discardable(msg))
continue;
/* Might be a timestamp filter request: handle. */
if (handle_timestamp_filter(state->pps, msg))
continue;
/* A helper which decodes an error. */
if (is_peer_error(tmpctx, msg, &state->channel_id,
&err, &all_channels)) {
/* BOLT #1:
*
* - if no existing channel is referred to by the
* message:
* - MUST ignore the message.
*/
/* In this case, is_peer_error returns true, but sets
* err to NULL */
if (!err) {
tal_free(msg);
continue;
}
/* Close connection on all_channels error. */
if (all_channels) {
if (am_opener) {
msg = towire_openingd_funder_failed(NULL,
err);
wire_sync_write(REQ_FD, take(msg));
}
peer_failed_received_errmsg(state->pps, err,
NULL, false);
}
negotiation_aborted(state, am_opener,
tal_fmt(tmpctx, "They sent error %s",
err));
/* Return NULL so caller knows to stop negotiating. */
return NULL;
}
/*~ We do not support multiple "live" channels, though the
* protocol has a "channel_id" field in all non-gossip messages
* so it's possible. Our one-process-one-channel mechanism
* keeps things simple: if we wanted to change this, we would
* probably be best with another daemon to de-multiplex them;
* this could be connectd itself, in fact. */
if (is_wrong_channel(msg, &state->channel_id, &actual)) {
status_debug("Rejecting %s for unknown channel_id %s",
peer_wire_name(fromwire_peektype(msg)),
type_to_string(tmpctx, struct channel_id,
&actual));
sync_crypto_write(state->pps,
take(towire_errorfmt(NULL, &actual,
"Multiple channels"
" unsupported")));
tal_free(msg);
continue;
}
/* If we get here, it's an interesting message. */
return msg;
}
}
static bool setup_channel_funder(struct state *state)
{
/*~ For symmetry, we calculate our own reserve even though lightningd
* could do it for the we-are-funding case. */
set_reserve(state);
/*~ Grab a random ID until the funding tx is created (we can't do that
* until we know their funding_pubkey) */
temporary_channel_id(&state->channel_id);
#if DEVELOPER
/* --dev-force-tmp-channel-id specified */
if (dev_force_tmp_channel_id)
state->channel_id = *dev_force_tmp_channel_id;
#endif
/* BOLT #2:
*
* The sending node:
*...
* - if both nodes advertised `option_support_large_channel`:
* - MAY set `funding_satoshis` greater than or equal to 2^24 satoshi.
* - otherwise:
* - MUST set `funding_satoshis` to less than 2^24 satoshi.
*/
if (!feature_negotiated(state->our_features,
state->their_features, OPT_LARGE_CHANNELS)
&& amount_sat_greater(state->funding, chainparams->max_funding)) {
status_failed(STATUS_FAIL_MASTER_IO,
"funding_satoshis must be < %s, not %s",
type_to_string(tmpctx, struct amount_sat,
&chainparams->max_funding),
type_to_string(tmpctx, struct amount_sat,
&state->funding));
return false;
}
return true;
}
/* We start the 'open a channel' negotation with the supplied peer, but
* stop when we get to the part where we need the funding txid */
static u8 *funder_channel_start(struct state *state, u8 channel_flags)
{
u8 *msg;
u8 *funding_output_script;
struct channel_id id_in;
struct tlv_open_channel_tlvs *open_tlvs;
struct tlv_accept_channel_tlvs *accept_tlvs;
char *err_reason;
if (!setup_channel_funder(state))
return NULL;
if (!state->upfront_shutdown_script[LOCAL])
state->upfront_shutdown_script[LOCAL] = no_upfront_shutdown_script(state, state);
open_tlvs = tlv_open_channel_tlvs_new(tmpctx);
open_tlvs->upfront_shutdown_script
= state->upfront_shutdown_script[LOCAL];
msg = towire_open_channel(NULL,
&chainparams->genesis_blockhash,
&state->channel_id,
state->funding,
state->push_msat,
state->localconf.dust_limit,
state->localconf.max_htlc_value_in_flight,
state->localconf.channel_reserve,
state->localconf.htlc_minimum,
state->feerate_per_kw,
state->localconf.to_self_delay,
state->localconf.max_accepted_htlcs,
&state->our_funding_pubkey,
&state->our_points.revocation,
&state->our_points.payment,
&state->our_points.delayed_payment,
&state->our_points.htlc,
&state->first_per_commitment_point[LOCAL],
channel_flags,
open_tlvs);
sync_crypto_write(state->pps, take(msg));
/* This is usually a very transient state... */
peer_billboard(false,
"Funding channel start: offered, now waiting for accept_channel");
/* ... since their reply should be immediate. */
msg = opening_negotiate_msg(tmpctx, state, true);
if (!msg)
return NULL;
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `funding_pubkey`, `revocation_basepoint`, `htlc_basepoint`,
* `payment_basepoint`, or `delayed_payment_basepoint` are not
* valid secp256k1 pubkeys in compressed format.
*/
accept_tlvs = tlv_accept_channel_tlvs_new(tmpctx);
if (!fromwire_accept_channel(msg, &id_in,
&state->remoteconf.dust_limit,
&state->remoteconf.max_htlc_value_in_flight,
&state->remoteconf.channel_reserve,
&state->remoteconf.htlc_minimum,
&state->minimum_depth,
&state->remoteconf.to_self_delay,
&state->remoteconf.max_accepted_htlcs,
&state->their_funding_pubkey,
&state->their_points.revocation,
&state->their_points.payment,
&state->their_points.delayed_payment,
&state->their_points.htlc,
&state->first_per_commitment_point[REMOTE],
accept_tlvs)) {
peer_failed(state->pps,
&state->channel_id,
"Parsing accept_channel %s", tal_hex(msg, msg));
}
state->upfront_shutdown_script[REMOTE]
= tal_steal(state, accept_tlvs->upfront_shutdown_script);
/* BOLT #2:
*
* The `temporary_channel_id` MUST be the same as the
* `temporary_channel_id` in the `open_channel` message. */
if (!channel_id_eq(&id_in, &state->channel_id))
/* In this case we exit, since we don't know what's going on. */
peer_failed(state->pps,
&state->channel_id,
"accept_channel ids don't match: sent %s got %s",
type_to_string(msg, struct channel_id, &id_in),
type_to_string(msg, struct channel_id,
&state->channel_id));
if (amount_sat_greater(state->remoteconf.dust_limit,
state->localconf.channel_reserve)) {
negotiation_failed(state, true,
"dust limit %s"
" would be above our reserve %s",
type_to_string(tmpctx, struct amount_sat,
&state->remoteconf.dust_limit),
type_to_string(tmpctx, struct amount_sat,
&state->localconf.channel_reserve));
return NULL;
}
if (!check_config_bounds(tmpctx, state->funding,
state->feerate_per_kw,
state->max_to_self_delay,
state->min_effective_htlc_capacity,
&state->remoteconf,
&state->localconf,
true,
state->option_anchor_outputs,
&err_reason)) {
negotiation_failed(state, true, "%s", err_reason);
return NULL;
}
funding_output_script =
scriptpubkey_p2wsh(tmpctx,
bitcoin_redeem_2of2(tmpctx,
&state->our_funding_pubkey,
&state->their_funding_pubkey));
/* Update the billboard with our infos */
peer_billboard(false,
"Funding channel start: awaiting funding_txid with output to %s",
tal_hex(tmpctx, funding_output_script));
return towire_openingd_funder_start_reply(state,
funding_output_script,
feature_negotiated(
state->our_features,
state->their_features,
OPT_UPFRONT_SHUTDOWN_SCRIPT));
}
static bool funder_finalize_channel_setup(struct state *state,
struct amount_msat local_msat,
struct bitcoin_signature *sig,
struct bitcoin_tx **tx,
struct penalty_base **pbase)
{
u8 *msg;
struct channel_id id_in;
const u8 *wscript;
struct channel_id cid;
char *err_reason;
struct wally_tx_output *direct_outputs[NUM_SIDES];
/*~ Now we can initialize the `struct channel`. This represents
* the current channel state and is how we can generate the current
* commitment transaction.
*
* The routines to support `struct channel` are split into a common
* part (common/initial_channel) which doesn't support HTLCs and is
* enough for us here, and the complete channel support required by
* `channeld` which lives in channeld/full_channel. */
derive_channel_id(&cid,
&state->funding_txid, state->funding_txout);
state->channel = new_initial_channel(state,
&cid,
&state->funding_txid,
state->funding_txout,
state->minimum_depth,
state->funding,
local_msat,
take(new_fee_states(NULL, LOCAL,
&state->feerate_per_kw)),
&state->localconf,
&state->remoteconf,
&state->our_points,
&state->their_points,
&state->our_funding_pubkey,
&state->their_funding_pubkey,
state->option_static_remotekey,
state->option_anchor_outputs,
/* Opener is local */
LOCAL);
/* We were supposed to do enough checks above, but just in case,
* new_initial_channel will fail to create absurd channels */
if (!state->channel)
peer_failed(state->pps,
&state->channel_id,
"could not create channel with given config");
/* BOLT #2:
*
* ### The `funding_created` Message
*
* This message describes the outpoint which the funder has created
* for the initial commitment transactions. After receiving the
* peer's signature, via `funding_signed`, it will broadcast the funding
* transaction.
*/
/* This gives us their first commitment transaction. */
*tx = initial_channel_tx(state, &wscript, state->channel,
&state->first_per_commitment_point[REMOTE],
REMOTE, direct_outputs, &err_reason);
if (!*tx) {
/* This should not happen: we should never create channels we
* can't afford the fees for after reserve. */
negotiation_failed(state, true,
"Could not meet their fees and reserve: %s", err_reason);
goto fail;
}
if (direct_outputs[LOCAL])
*pbase = penalty_base_new(state, 0, *tx, direct_outputs[LOCAL]);
else
*pbase = 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,
*tx,
&state->channel->funding_pubkey[REMOTE],
&state->first_per_commitment_point[REMOTE],
state->channel->option_static_remotekey);
wire_sync_write(HSM_FD, take(msg));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsmd_sign_tx_reply(msg, 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",
type_to_string(tmpctx, struct bitcoin_signature, sig),
type_to_string(tmpctx, struct bitcoin_tx, *tx),
type_to_string(tmpctx, struct pubkey,
&state->our_funding_pubkey));
/* Now we give our peer the signature for their first commitment
* transaction. */
msg = towire_funding_created(state, &state->channel_id,
&state->funding_txid,
state->funding_txout,
&sig->s);
sync_crypto_write(state->pps, msg);
/* BOLT #2:
*
* ### The `funding_signed` Message
*
* This message gives the funder the signature it needs for the first
* commitment transaction, so it can broadcast the transaction knowing
* that funds can be redeemed, if need be.
*/
peer_billboard(false,
"Funding channel: create first tx, now waiting for their signature");
/* Now they send us their signature for that first commitment
* transaction. */
msg = opening_negotiate_msg(tmpctx, state, true);
if (!msg)
goto fail;
sig->sighash_type = SIGHASH_ALL;
if (!fromwire_funding_signed(msg, &id_in, &sig->s))
peer_failed(state->pps,
&state->channel_id,
"Parsing funding_signed: %s", tal_hex(msg, msg));
/* BOLT #2:
*
* This message introduces the `channel_id` to identify the channel.
* It's derived from the funding transaction by combining the
* `funding_txid` and the `funding_output_index`, using big-endian
* exclusive-OR (i.e. `funding_output_index` alters the last 2
* bytes).
*/
/*~ Back in Milan, we chose to allow multiple channels between peers in
* the protocol. I insisted that we multiplex these over the same
* socket, and (even though I didn't plan on implementing it anytime
* soon) that we put it into the first version of the protocol
* because it would be painful to add in later.
*
* My logic seemed sound: we treat new connections as an implication
* that the old connection has disconnected, which happens more often
* than you'd hope on modern networks. However, supporting multiple
* channels via multiple connections would be far easier for us to
* support with our (introduced-since) separate daemon model.
*
* Let this be a lesson: beware premature specification, even if you
* suspect "we'll need it later!". */
state->channel_id = cid;
if (!channel_id_eq(&id_in, &state->channel_id))
peer_failed(state->pps, &id_in,
"funding_signed ids don't match: expected %s got %s",
type_to_string(msg, struct channel_id,
&state->channel_id),
type_to_string(msg, struct channel_id, &id_in));
/* BOLT #2:
*
* The recipient:
* - if `signature` is incorrect:
* - MUST fail the channel.
*/
/* So we create *our* initial commitment transaction, and check the
* signature they sent against that. */
*tx = initial_channel_tx(state, &wscript, state->channel,
&state->first_per_commitment_point[LOCAL],
LOCAL, direct_outputs, &err_reason);
if (!*tx) {
negotiation_failed(state, true,
"Could not meet our fees and reserve: %s", err_reason);
goto fail;
}
if (!check_tx_sig(*tx, 0, NULL, wscript, &state->their_funding_pubkey, sig)) {
peer_failed(state->pps,
&state->channel_id,
"Bad signature %s on tx %s using key %s",
type_to_string(tmpctx, struct bitcoin_signature,
sig),
type_to_string(tmpctx, struct bitcoin_tx, *tx),
type_to_string(tmpctx, struct pubkey,
&state->their_funding_pubkey));
}
/* We save their sig to our first commitment tx */
if (!psbt_input_set_signature((*tx)->psbt, 0,
&state->their_funding_pubkey,
sig))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Unable to set signature internally");
peer_billboard(false, "Funding channel: opening negotiation succeeded");
return true;
fail:
tal_free(wscript);
return false;
}
static u8 *funder_channel_complete(struct state *state)
{
/* Remote commitment tx */
struct bitcoin_tx *tx;
struct bitcoin_signature sig;
struct amount_msat local_msat;
struct penalty_base *pbase;
/* Update the billboard about what we're doing*/
peer_billboard(false,
"Funding channel con't: continuing with funding_txid %s",
type_to_string(tmpctx, struct bitcoin_txid, &state->funding_txid));
/* We recalculate the local_msat from cached values; should
* succeed because we checked it earlier */
if (!amount_sat_sub_msat(&local_msat, state->funding, state->push_msat))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"push_msat %s > funding %s?",
type_to_string(tmpctx, struct amount_msat,
&state->push_msat),
type_to_string(tmpctx, struct amount_sat,
&state->funding));
if (!funder_finalize_channel_setup(state, local_msat, &sig, &tx,
&pbase))
return NULL;
return towire_openingd_funder_reply(state,
&state->remoteconf,
tx,
pbase,
&sig,
state->pps,
&state->their_points.revocation,
&state->their_points.payment,
&state->their_points.htlc,
&state->their_points.delayed_payment,
&state->first_per_commitment_point[REMOTE],
state->minimum_depth,
&state->their_funding_pubkey,
&state->funding_txid,
state->funding_txout,
state->feerate_per_kw,
state->localconf.channel_reserve,
state->upfront_shutdown_script[REMOTE]);
}
/*~ The peer sent us an `open_channel`, that means we're the fundee. */
static u8 *fundee_channel(struct state *state, const u8 *open_channel_msg)
{
struct channel_id id_in;
struct basepoints theirs;
struct pubkey their_funding_pubkey;
struct bitcoin_signature theirsig, sig;
struct bitcoin_tx *local_commit, *remote_commit;
struct bitcoin_blkid chain_hash;
u8 *msg;
const u8 *wscript;
u8 channel_flags;
char* err_reason;
struct wally_tx_output *direct_outputs[NUM_SIDES];
struct penalty_base *pbase;
struct tlv_accept_channel_tlvs *accept_tlvs;
struct tlv_open_channel_tlvs *open_tlvs
= tlv_open_channel_tlvs_new(tmpctx);
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `funding_pubkey`, `revocation_basepoint`, `htlc_basepoint`,
* `payment_basepoint`, or `delayed_payment_basepoint` are not valid
* secp256k1 pubkeys in compressed format.
*/
if (!fromwire_open_channel(open_channel_msg, &chain_hash,
&state->channel_id,
&state->funding,
&state->push_msat,
&state->remoteconf.dust_limit,
&state->remoteconf.max_htlc_value_in_flight,
&state->remoteconf.channel_reserve,
&state->remoteconf.htlc_minimum,
&state->feerate_per_kw,
&state->remoteconf.to_self_delay,
&state->remoteconf.max_accepted_htlcs,
&their_funding_pubkey,
&theirs.revocation,
&theirs.payment,
&theirs.delayed_payment,
&theirs.htlc,
&state->first_per_commitment_point[REMOTE],
&channel_flags,
open_tlvs))
peer_failed(state->pps,
&state->channel_id,
"Parsing open_channel %s", tal_hex(tmpctx, open_channel_msg));
state->upfront_shutdown_script[REMOTE]
= tal_steal(state, open_tlvs->upfront_shutdown_script);
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
* - the `chain_hash` value is set to a hash of a chain
* that is unknown to the receiver.
*/
if (!bitcoin_blkid_eq(&chain_hash, &chainparams->genesis_blockhash)) {
negotiation_failed(state, false,
"Unknown chain-hash %s",
type_to_string(tmpctx,
struct bitcoin_blkid,
&chain_hash));
return NULL;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `funding_satoshis` is greater than or equal to 2^24 and the receiver does not support
* `option_support_large_channel`. */
/* We choose to require *negotiation*, not just support! */
if (!feature_negotiated(state->our_features, state->their_features,
OPT_LARGE_CHANNELS)
&& amount_sat_greater(state->funding, chainparams->max_funding)) {
negotiation_failed(state, false,
"funding_satoshis %s too large",
type_to_string(tmpctx, struct amount_sat,
&state->funding));
return NULL;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
* ...
* - `push_msat` is greater than `funding_satoshis` * 1000.
*/
if (amount_msat_greater_sat(state->push_msat, state->funding)) {
peer_failed(state->pps,
&state->channel_id,
"Their push_msat %s"
" would be too large for funding_satoshis %s",
type_to_string(tmpctx, struct amount_msat,
&state->push_msat),
type_to_string(tmpctx, struct amount_sat,
&state->funding));
return NULL;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - it considers `feerate_per_kw` too small for timely processing or
* unreasonably large.
*/
if (state->feerate_per_kw < state->min_feerate) {
negotiation_failed(state, false,
"feerate_per_kw %u below minimum %u",
state->feerate_per_kw, state->min_feerate);
return NULL;
}
if (state->feerate_per_kw > state->max_feerate) {
negotiation_failed(state, false,
"feerate_per_kw %u above maximum %u",
state->feerate_per_kw, state->max_feerate);
return NULL;
}
/* This reserves 1% of the channel (rounded up) */
set_reserve(state);
/* BOLT #2:
*
* The sender:
*...
* - MUST set `channel_reserve_satoshis` greater than or equal to
* `dust_limit_satoshis` from the `open_channel` message.
* - MUST set `dust_limit_satoshis` less than or equal to
* `channel_reserve_satoshis` from the `open_channel` message.
*/
if (amount_sat_greater(state->remoteconf.dust_limit,
state->localconf.channel_reserve)) {
negotiation_failed(state, false,
"Our channel reserve %s"
" would be below their dust %s",
type_to_string(tmpctx, struct amount_sat,
&state->localconf.channel_reserve),
type_to_string(tmpctx, struct amount_sat,
&state->remoteconf.dust_limit));
return NULL;
}
if (amount_sat_greater(state->localconf.dust_limit,
state->remoteconf.channel_reserve)) {
negotiation_failed(state, false,
"Our dust limit %s"
" would be above their reserve %s",
type_to_string(tmpctx, struct amount_sat,
&state->localconf.dust_limit),
type_to_string(tmpctx, struct amount_sat,
&state->remoteconf.channel_reserve));
return NULL;
}
/* These checks are the same whether we're opener or accepter... */
if (!check_config_bounds(tmpctx, state->funding,
state->feerate_per_kw,
state->max_to_self_delay,
state->min_effective_htlc_capacity,
&state->remoteconf,
&state->localconf,
false,
state->option_anchor_outputs,
&err_reason)) {
negotiation_failed(state, false, "%s", err_reason);
return NULL;
}
/* Check with lightningd that we can accept this? In particular,
* if we have an existing channel, we don't support it. */
msg = towire_openingd_got_offer(NULL,
state->funding,
state->push_msat,
state->remoteconf.dust_limit,
state->remoteconf.max_htlc_value_in_flight,
state->remoteconf.channel_reserve,
state->remoteconf.htlc_minimum,
state->feerate_per_kw,
state->remoteconf.to_self_delay,
state->remoteconf.max_accepted_htlcs,
channel_flags,
state->upfront_shutdown_script[REMOTE]);
wire_sync_write(REQ_FD, take(msg));
msg = wire_sync_read(tmpctx, REQ_FD);
/* We don't allocate off tmpctx, because that's freed inside
* opening_negotiate_msg */
if (!fromwire_openingd_got_offer_reply(state, msg, &err_reason,
&state->upfront_shutdown_script[LOCAL]))
master_badmsg(WIRE_OPENINGD_GOT_OFFER_REPLY, msg);
/* If they give us a reason to reject, do so. */
if (err_reason) {
u8 *errmsg = towire_errorfmt(NULL, &state->channel_id,
"%s", err_reason);
sync_crypto_write(state->pps, take(errmsg));
tal_free(err_reason);
return NULL;
}
if (!state->upfront_shutdown_script[LOCAL])
state->upfront_shutdown_script[LOCAL] = no_upfront_shutdown_script(state, state);
/* OK, we accept! */
accept_tlvs = tlv_accept_channel_tlvs_new(tmpctx);
accept_tlvs->upfront_shutdown_script
= state->upfront_shutdown_script[LOCAL];
msg = towire_accept_channel(NULL, &state->channel_id,
state->localconf.dust_limit,
state->localconf.max_htlc_value_in_flight,
state->localconf.channel_reserve,
state->localconf.htlc_minimum,
state->minimum_depth,
state->localconf.to_self_delay,
state->localconf.max_accepted_htlcs,
&state->our_funding_pubkey,
&state->our_points.revocation,
&state->our_points.payment,
&state->our_points.delayed_payment,
&state->our_points.htlc,
&state->first_per_commitment_point[LOCAL],
accept_tlvs);
sync_crypto_write(state->pps, take(msg));
peer_billboard(false,
"Incoming channel: accepted, now waiting for them to create funding tx");
/* This is a loop which handles gossip until we get a non-gossip msg */
msg = opening_negotiate_msg(tmpctx, state, false);
if (!msg)
return NULL;
/* The message should be "funding_created" which tells us what funding
* tx they generated; the sighash type is implied, so we set it here. */
theirsig.sighash_type = SIGHASH_ALL;
if (!fromwire_funding_created(msg, &id_in,
&state->funding_txid,
&state->funding_txout,
&theirsig.s))
peer_failed(state->pps,
&state->channel_id,
"Parsing funding_created");
/* BOLT #2:
*
* The `temporary_channel_id` MUST be the same as the
* `temporary_channel_id` in the `open_channel` message.
*/
if (!channel_id_eq(&id_in, &state->channel_id))
peer_failed(state->pps, &id_in,
"funding_created ids don't match: sent %s got %s",
type_to_string(msg, struct channel_id,
&state->channel_id),
type_to_string(msg, struct channel_id, &id_in));
/* Now we can create the channel structure. */
state->channel = new_initial_channel(state,
&state->channel_id,
&state->funding_txid,
state->funding_txout,
state->minimum_depth,
state->funding,
state->push_msat,
take(new_fee_states(NULL, REMOTE,
&state->feerate_per_kw)),
&state->localconf,
&state->remoteconf,
&state->our_points, &theirs,
&state->our_funding_pubkey,
&their_funding_pubkey,
state->option_static_remotekey,
state->option_anchor_outputs,
REMOTE);
/* We don't expect this to fail, but it does do some additional
* internal sanity checks. */
if (!state->channel)
peer_failed(state->pps,
&state->channel_id,
"We could not create channel with given config");
/* BOLT #2:
*
* The recipient:
* - if `signature` is incorrect:
* - MUST fail the channel.
*/
local_commit = initial_channel_tx(state, &wscript, state->channel,
&state->first_per_commitment_point[LOCAL],
LOCAL, NULL, &err_reason);
/* This shouldn't happen either, AFAICT. */
if (!local_commit) {
negotiation_failed(state, false,
"Could not meet our fees and reserve: %s", err_reason);
return NULL;
}
if (!check_tx_sig(local_commit, 0, NULL, wscript, &their_funding_pubkey,
&theirsig)) {
/* BOLT #1:
*
* ### The `error` Message
*...
* - when failure was caused by an invalid signature check:
* - SHOULD include the raw, hex-encoded transaction in reply
* to a `funding_created`, `funding_signed`,
* `closing_signed`, or `commitment_signed` message.
*/
/*~ This verbosity is not only useful for our own testing, but
* a courtesy to other implementaters whose brains may be so
* twisted by coding in Go, Scala and Rust that they can no
* longer read C code. */
peer_failed(state->pps,
&state->channel_id,
"Bad signature %s on tx %s using key %s",
type_to_string(tmpctx, struct bitcoin_signature,
&theirsig),
type_to_string(tmpctx, struct bitcoin_tx, local_commit),
type_to_string(tmpctx, struct pubkey,
&their_funding_pubkey));
}
/* BOLT #2:
*
* This message introduces the `channel_id` to identify the
* channel. It's derived from the funding transaction by combining the
* `funding_txid` and the `funding_output_index`, using big-endian
* exclusive-OR (i.e. `funding_output_index` alters the last 2 bytes).
*/
derive_channel_id(&state->channel_id,
&state->funding_txid, state->funding_txout);
/*~ We generate the `funding_signed` message here, since we have all
* the data and it's only applicable in the fundee case.
*
* FIXME: Perhaps we should have channeld generate this, so we
* can't possibly send before channel committed to disk?
*/
/* BOLT #2:
*
* ### The `funding_signed` Message
*
* This message gives the funder the signature it needs for the first
* commitment transaction, so it can broadcast the transaction knowing
* that funds can be redeemed, if need be.
*/
remote_commit = initial_channel_tx(state, &wscript, state->channel,
&state->first_per_commitment_point[REMOTE],
REMOTE, direct_outputs, &err_reason);
if (!remote_commit) {
negotiation_failed(state, false,
"Could not meet their fees and reserve: %s", err_reason);
return NULL;
}
/* Make HSM sign it */
msg = towire_hsmd_sign_remote_commitment_tx(NULL,
remote_commit,
&state->channel->funding_pubkey[REMOTE],
&state->first_per_commitment_point[REMOTE],
state->channel->option_static_remotekey);
wire_sync_write(HSM_FD, take(msg));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsmd_sign_tx_reply(msg, &sig))
status_failed(STATUS_FAIL_HSM_IO,
"Bad sign_tx_reply %s", tal_hex(tmpctx, msg));
/* We don't send this ourselves: channeld does, because master needs
* to save state to disk before doing so. */
assert(sig.sighash_type == SIGHASH_ALL);
msg = towire_funding_signed(state, &state->channel_id, &sig.s);
if (direct_outputs[LOCAL] != NULL)
pbase = penalty_base_new(tmpctx, 0, remote_commit,
direct_outputs[LOCAL]);
else
pbase = NULL;
return towire_openingd_fundee(state,
&state->remoteconf,
local_commit,
pbase,
&theirsig,
state->pps,
&theirs.revocation,
&theirs.payment,
&theirs.htlc,
&theirs.delayed_payment,
&state->first_per_commitment_point[REMOTE],
&their_funding_pubkey,
&state->funding_txid,
state->funding_txout,
state->funding,
state->push_msat,
channel_flags,
state->feerate_per_kw,
msg,
state->localconf.channel_reserve,
state->upfront_shutdown_script[LOCAL],
state->upfront_shutdown_script[REMOTE]);
}
/*~ Standard "peer sent a message, handle it" demuxer. Though it really only
* handles one message, we use the standard form as principle of least
* surprise. */
static u8 *handle_peer_in(struct state *state)
{
u8 *msg = sync_crypto_read(tmpctx, state->pps);
enum peer_wire t = fromwire_peektype(msg);
struct channel_id channel_id;
if (t == WIRE_OPEN_CHANNEL)
return fundee_channel(state, msg);
#if DEVELOPER
/* Handle custommsgs */
enum peer_wire type = fromwire_peektype(msg);
if (type % 2 == 1 && !peer_wire_is_defined(type)) {
/* The message is not part of the messages we know how to
* handle. Assuming this is a custommsg, we just forward it to the
* master. */
wire_sync_write(REQ_FD, take(towire_custommsg_in(NULL, msg)));
return NULL;
}
#endif
/* Handles standard cases, and legal unknown ones. */
if (handle_peer_gossip_or_error(state->pps,
&state->channel_id, false, msg))
return NULL;
sync_crypto_write(state->pps,
take(towire_errorfmt(NULL,
extract_channel_id(msg, &channel_id) ? &channel_id : NULL,
"Unexpected message %s: %s",
peer_wire_name(t),
tal_hex(tmpctx, msg))));
/* FIXME: We don't actually want master to try to send an
* error, since peer is transient. This is a hack.
*/
status_broken("Unexpected message %s", peer_wire_name(t));
peer_failed_connection_lost();
}
/*~ If we see the gossip_fd readable, we read a whole message. Sure, we might
* block, but we trust gossipd. */
static void handle_gossip_in(struct state *state)
{
u8 *msg = wire_sync_read(NULL, state->pps->gossip_fd);
if (!msg)
status_failed(STATUS_FAIL_GOSSIP_IO,
"Reading gossip: %s", strerror(errno));
handle_gossip_msg(state->pps, take(msg));
}
/*~ Is this message of type `error` with the special zero-id
* "fail-everything"? If lightningd asked us to send such a thing, we're
* done. */
static void fail_if_all_error(const u8 *inner)
{
struct channel_id channel_id;
u8 *data;
if (!fromwire_error(tmpctx, inner, &channel_id, &data)
|| !channel_id_is_all(&channel_id)) {
return;
}
status_info("Master said send err: %s",
sanitize_error(tmpctx, inner, NULL));
exit(0);
}
/* Memory leak detection is DEVELOPER-only because we go to great lengths to
* record the backtrace when allocations occur: without that, the leak
* detection tends to be useless for diagnosing where the leak came from, but
* it has significant overhead. */
#if DEVELOPER
static void handle_dev_memleak(struct state *state, const u8 *msg)
{
struct htable *memtable;
bool found_leak;
/* Populate a hash table with all our allocations (except msg, which
* is in use right now). */
memtable = memleak_find_allocations(tmpctx, msg, msg);
/* Now delete state and things it has pointers to. */
memleak_remove_region(memtable, state, sizeof(*state));
/* If there's anything left, dump it to logs, and return true. */
found_leak = dump_memleak(memtable);
wire_sync_write(REQ_FD,
take(towire_openingd_dev_memleak_reply(NULL,
found_leak)));
}
/* We were told to send a custommsg to the peer by `lightningd`. All the
* verification is done on the side of `lightningd` so we should be good to
* just forward it here. */
static void openingd_send_custommsg(struct state *state, const u8 *msg)
{
sync_crypto_write(state->pps, take(msg));
}
#endif /* DEVELOPER */
/* Standard lightningd-fd-is-ready-to-read demux code. Again, we could hang
* here, but if we can't trust our parent, who can we trust? */
static u8 *handle_master_in(struct state *state)
{
u8 *msg = wire_sync_read(tmpctx, REQ_FD);
enum openingd_wire t = fromwire_peektype(msg);
u8 channel_flags;
struct bitcoin_txid funding_txid;
u16 funding_txout;
switch (t) {
case WIRE_OPENINGD_FUNDER_START:
if (!fromwire_openingd_funder_start(state, msg, &state->funding,
&state->push_msat,
&state->upfront_shutdown_script[LOCAL],
&state->feerate_per_kw,
&channel_flags))
master_badmsg(WIRE_OPENINGD_FUNDER_START, msg);
msg = funder_channel_start(state, channel_flags);
/* We want to keep openingd alive, since we're not done yet */
if (msg)
wire_sync_write(REQ_FD, take(msg));
return NULL;
case WIRE_OPENINGD_FUNDER_COMPLETE:
if (!fromwire_openingd_funder_complete(msg,
&funding_txid,
&funding_txout))
master_badmsg(WIRE_OPENINGD_FUNDER_COMPLETE, msg);
state->funding_txid = funding_txid;
state->funding_txout = funding_txout;
return funder_channel_complete(state);
case WIRE_OPENINGD_FUNDER_CANCEL:
/* We're aborting this, simple */
if (!fromwire_openingd_funder_cancel(msg))
master_badmsg(WIRE_OPENINGD_FUNDER_CANCEL, msg);
msg = towire_errorfmt(NULL, &state->channel_id, "Channel open canceled by us");
sync_crypto_write(state->pps, take(msg));
negotiation_aborted(state, true, "Channel open canceled by RPC");
return NULL;
case WIRE_OPENINGD_DEV_MEMLEAK:
#if DEVELOPER
handle_dev_memleak(state, msg);
return NULL;
#endif
case WIRE_OPENINGD_DEV_MEMLEAK_REPLY:
case WIRE_OPENINGD_INIT:
case WIRE_OPENINGD_FUNDER_REPLY:
case WIRE_OPENINGD_FUNDER_START_REPLY:
case WIRE_OPENINGD_FUNDEE:
case WIRE_OPENINGD_FUNDER_FAILED:
case WIRE_OPENINGD_GOT_OFFER:
case WIRE_OPENINGD_GOT_OFFER_REPLY:
break;
}
/* Now handle common messages. */
switch ((enum common_wire)t) {
#if DEVELOPER
case WIRE_CUSTOMMSG_OUT:
openingd_send_custommsg(state, msg);
return NULL;
#else
case WIRE_CUSTOMMSG_OUT:
#endif
/* We send these. */
case WIRE_CUSTOMMSG_IN:
break;
}
status_failed(STATUS_FAIL_MASTER_IO,
"Unknown msg %s", tal_hex(tmpctx, msg));
}
static void try_read_gossip_store(struct state *state)
{
u8 *msg = gossip_store_next(tmpctx, state->pps);
if (msg)
sync_crypto_write(state->pps, take(msg));
}
int main(int argc, char *argv[])
{
setup_locale();
u8 *msg, *inner;
struct pollfd pollfd[3];
struct state *state = tal(NULL, struct state);
struct secret *none;
struct channel_id *force_tmp_channel_id;
subdaemon_setup(argc, argv);
/*~ This makes status_failed, status_debug etc work synchronously by
* writing to REQ_FD */
status_setup_sync(REQ_FD);
/*~ The very first thing we read from lightningd is our init msg */
msg = wire_sync_read(tmpctx, REQ_FD);
if (!fromwire_openingd_init(state, msg,
&chainparams,
&state->our_features,
&state->localconf,
&state->max_to_self_delay,
&state->min_effective_htlc_capacity,
&state->pps,
&state->our_points,
&state->our_funding_pubkey,
&state->minimum_depth,
&state->min_feerate, &state->max_feerate,
&state->their_features,
&state->option_static_remotekey,
&state->option_anchor_outputs,
&inner,
&force_tmp_channel_id,
&dev_fast_gossip))
master_badmsg(WIRE_OPENINGD_INIT, msg);
#if DEVELOPER
dev_force_tmp_channel_id = force_tmp_channel_id;
#endif
/* 3 == peer, 4 == gossipd, 5 = gossip_store, 6 = hsmd */
per_peer_state_set_fds(state->pps, 3, 4, 5);
/*~ If lightningd wanted us to send a msg, do so before we waste time
* doing work. If it's a global error, we'll close immediately. */
if (inner != NULL) {
sync_crypto_write(state->pps, inner);
fail_if_all_error(inner);
tal_free(inner);
}
/*~ Initially we're not associated with a channel, but
* handle_peer_gossip_or_error compares this. */
memset(&state->channel_id, 0, sizeof(state->channel_id));
state->channel = NULL;
/*~ We set these to NULL, meaning no requirements on shutdown */
state->upfront_shutdown_script[LOCAL]
= state->upfront_shutdown_script[REMOTE]
= NULL;
/*~ We need an initial per-commitment point whether we're funding or
* they are, and lightningd has reserved a unique dbid for us already,
* so we might as well get the hsm daemon to generate it now. */
wire_sync_write(HSM_FD,
take(towire_hsmd_get_per_commitment_point(NULL, 0)));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsmd_get_per_commitment_point_reply(tmpctx, msg,
&state->first_per_commitment_point[LOCAL],
&none))
status_failed(STATUS_FAIL_HSM_IO,
"Bad get_per_commitment_point_reply %s",
tal_hex(tmpctx, msg));
/*~ The HSM gives us the N-2'th per-commitment secret when we get the
* N'th per-commitment point. But since N=0, it won't give us one. */
assert(none == NULL);
/*~ Turns out this is useful for testing, to make sure we're ready. */
status_debug("Handed peer, entering loop");
/*~ We manually run a little poll() loop here. With only three fds */
pollfd[0].fd = REQ_FD;
pollfd[0].events = POLLIN;
pollfd[1].fd = state->pps->gossip_fd;
pollfd[1].events = POLLIN;
pollfd[2].fd = state->pps->peer_fd;
pollfd[2].events = POLLIN;
/* We exit when we get a conclusion to write to lightningd: either
* opening_funder_reply or opening_fundee. */
msg = NULL;
while (!msg) {
int t;
struct timerel trel;
if (time_to_next_gossip(state->pps, &trel))
t = time_to_msec(trel);
else
t = -1;
/*~ If we get a signal which aborts the poll() call, valgrind
* complains about revents being uninitialized. I'm not sure
* that's correct, but it's easy to be sure. */
pollfd[0].revents = pollfd[1].revents = pollfd[2].revents = 0;
poll(pollfd, ARRAY_SIZE(pollfd), t);
/* Subtle: handle_master_in can do its own poll loop, so
* don't try to service more than one fd per loop. */
/* First priority: messages from lightningd. */
if (pollfd[0].revents & POLLIN)
msg = handle_master_in(state);
/* Second priority: messages from peer. */
else if (pollfd[2].revents & POLLIN)
msg = handle_peer_in(state);
/* Last priority: chit-chat from gossipd. */
else if (pollfd[1].revents & POLLIN)
handle_gossip_in(state);
else
try_read_gossip_store(state);
/* Since we're the top-level event loop, we clean up */
clean_tmpctx();
}
/*~ Write message and hand back the peer fd and gossipd fd. This also
* means that if the peer or gossipd wrote us any messages we didn't
* read yet, it will simply be read by the next daemon. */
wire_sync_write(REQ_FD, msg);
per_peer_state_fdpass_send(REQ_FD, state->pps);
status_debug("Sent %s with fds",
openingd_wire_name(fromwire_peektype(msg)));
/* This frees the entire tal tree. */
tal_free(state);
/* This frees up everything else. */
daemon_shutdown();
return 0;
}
/*~ Note that there are no other source files in openingd: it really is a fairly
* straight-line daemon.
*
* From here the channel is established: lightningd hands the peer off to
* channeld/channeld.c which runs the normal channel routine for this peer.
*/
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