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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/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/tal/str/str.h>
#include <common/crypto_sync.h>
#include <common/derive_basepoints.h>
#include <common/funding_tx.h>
#include <common/gen_peer_status_wire.h>
#include <common/initial_channel.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/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 <hsmd/gen_hsm_wire.h>
#include <inttypes.h>
#include <openingd/gen_opening_wire.h>
#include <poll.h>
#include <secp256k1.h>
#include <stdio.h>
#include <wally_bip32.h>
#include <wire/gen_peer_wire.h>
#include <wire/peer_wire.h>
#include <wire/wire.h>
#include <wire/wire_sync.h>
/* stdin == lightningd, 3 == peer, 4 == gossipd, 5 = hsmd */
#define REQ_FD STDIN_FILENO
#define PEER_FD 3
#define GOSSIP_FD 4
#define HSM_FD 5
/* Global state structure. This is only for the one specific peer and channel */
struct state {
/* Cryptographic state needed to exchange messages with the peer (as
* featured in BOLT #8) */
struct crypto_state cs;
/* Constraints on a channel they open. */
u32 minimum_depth;
u32 min_feerate, max_feerate;
u64 min_effective_htlc_capacity_msat;
/* 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;
/* 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. */
u64 funding_satoshis, push_msat;
u32 feerate_per_kw;
struct bitcoin_txid funding_txid;
u16 funding_txout;
/* 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;
/*~ We only allow one active channel at a time per peer. Otherwise
* all our per-peer daemons would have to handle multiple channels,
* or we would need some other daemon to demux the messages.
* Thus, lightningd tells is if/when there's no active channel. */
bool can_accept_channel;
/* Which chain we're on, so we can check/set `chain_hash` fields */
const struct chainparams *chainparams;
};
/*~ If we can't agree on parameters, we fail to open the channel. If we're
* the funder, we need to tell lightningd, otherwise it never really notices. */
static void negotiation_aborted(struct state *state, bool am_funder,
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_funder) {
u8 *msg = towire_opening_funder_failed(NULL, why);
wire_sync_write(REQ_FD, take(msg));
}
/*~ 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_funder,
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->cs, PEER_FD, take(msg));
negotiation_aborted(state, am_funder, errmsg);
}
/*~ This is the key function that checks that their configuration is reasonable:
* it applied for both the case where they're trying to open a channel, and when
* they've accepted our open. */
static bool check_config_bounds(struct state *state,
const struct channel_config *remoteconf,
bool am_funder)
{
u64 capacity_msat;
u64 reserve_msat;
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `to_self_delay` is unreasonably large.
*/
if (remoteconf->to_self_delay > state->max_to_self_delay) {
negotiation_failed(state, am_funder,
"to_self_delay %u larger than %u",
remoteconf->to_self_delay,
state->max_to_self_delay);
return false;
}
/* BOLT #2:
*
* The receiving node MAY fail the channel if:
*...
* - `funding_satoshis` is too small.
* - it considers `htlc_minimum_msat` too large.
* - it considers `max_htlc_value_in_flight_msat` too small.
* - it considers `channel_reserve_satoshis` too large.
* - it considers `max_accepted_htlcs` too small.
*/
/* We accumulate this into an effective bandwidth minimum. */
/* Add both reserves to deduct from capacity. */
if (mul_overflows_u64(remoteconf->channel_reserve_satoshis, 1000)
|| add_overflows_u64(remoteconf->channel_reserve_satoshis * 1000,
state->localconf.channel_reserve_satoshis * 1000)) {
negotiation_failed(state, am_funder,
"channel_reserve_satoshis %"PRIu64
" too large",
remoteconf->channel_reserve_satoshis);
return false;
}
reserve_msat = remoteconf->channel_reserve_satoshis * 1000
+ state->localconf.channel_reserve_satoshis * 1000;
/* We checked this before, or it's ours. */
assert(!mul_overflows_u64(state->funding_satoshis, 1000));
/* If reserves are larger than total msat, we fail. */
if (reserve_msat > state->funding_satoshis * 1000) {
negotiation_failed(state, am_funder,
"channel_reserve_satoshis %"PRIu64
" and %"PRIu64" too large for funding_satoshis %"PRIu64,
remoteconf->channel_reserve_satoshis,
state->localconf.channel_reserve_satoshis,
state->funding_satoshis);
return false;
}
capacity_msat = state->funding_satoshis * 1000 - reserve_msat;
/* If they set the max HTLC value to less than that number, it caps
* the channel capacity. */
if (remoteconf->max_htlc_value_in_flight_msat < capacity_msat)
capacity_msat = remoteconf->max_htlc_value_in_flight_msat;
/* If the minimum htlc is greater than the capacity, the channel is
* useless. */
if (mul_overflows_u64(remoteconf->htlc_minimum_msat, 1000)
|| remoteconf->htlc_minimum_msat * (u64)1000 > capacity_msat) {
negotiation_failed(state, am_funder,
"htlc_minimum_msat %"PRIu64
" too large for funding_satoshis %"PRIu64
" capacity_msat %"PRIu64,
remoteconf->htlc_minimum_msat,
state->funding_satoshis,
capacity_msat);
return false;
}
/* If the resulting channel doesn't meet our minimum "effective capacity"
* set by lightningd, don't bother opening it. */
if (capacity_msat < state->min_effective_htlc_capacity_msat) {
negotiation_failed(state, am_funder,
"channel capacity with funding %"PRIu64" msat,"
" reserves %"PRIu64"/%"PRIu64" msat,"
" max_htlc_value_in_flight_msat %"PRIu64
" is %"PRIu64" msat, which is below %"PRIu64" msat",
state->funding_satoshis * 1000,
remoteconf->channel_reserve_satoshis * 1000,
state->localconf.channel_reserve_satoshis * 1000,
remoteconf->max_htlc_value_in_flight_msat,
capacity_msat,
state->min_effective_htlc_capacity_msat);
return false;
}
/* We don't worry about how many HTLCs they accept, as long as > 0! */
if (remoteconf->max_accepted_htlcs == 0) {
negotiation_failed(state, am_funder,
"max_accepted_htlcs %u invalid",
remoteconf->max_accepted_htlcs);
return false;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `max_accepted_htlcs` is greater than 483.
*/
if (remoteconf->max_accepted_htlcs > 483) {
negotiation_failed(state, am_funder,
"max_accepted_htlcs %u too large",
remoteconf->max_accepted_htlcs);
return false;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `dust_limit_satoshis` is greater than `channel_reserve_satoshis`.
*/
if (remoteconf->dust_limit_satoshis
> remoteconf->channel_reserve_satoshis) {
negotiation_failed(state, am_funder,
"dust_limit_satoshis %"PRIu64
" too large for channel_reserve_satoshis %"
PRIu64,
remoteconf->dust_limit_satoshis,
remoteconf->channel_reserve_satoshis);
return false;
}
return true;
}
/* We always set channel_reserve_satoshis to 1%, rounded up. */
static void set_reserve(struct state *state)
{
state->localconf.channel_reserve_satoshis
= (state->funding_satoshis + 99) / 100;
/* BOLT #2:
*
* The sending node:
*...
* - MUST set `channel_reserve_satoshis` greater than or equal to
* `dust_limit_satoshis`.
*/
if (state->localconf.channel_reserve_satoshis
< state->localconf.dust_limit_satoshis)
state->localconf.channel_reserve_satoshis
= state->localconf.dust_limit_satoshis;
}
/* 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_funder)
{
/* 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, PEER_FD, GOSSIP_FD,
&state->cs, &from_gossipd);
/* Use standard helper for gossip msgs (forwards, if it's an
* error, exits). */
if (from_gossipd) {
handle_gossip_msg(PEER_FD, &state->cs, take(msg));
continue;
}
/* Some messages go straight to gossipd. */
if (is_msg_for_gossipd(msg)) {
wire_sync_write(GOSSIP_FD, take(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_funder) {
msg = towire_opening_funder_failed(NULL,
err);
wire_sync_write(REQ_FD, take(msg));
}
peer_failed_received_errmsg(PEER_FD, GOSSIP_FD,
&state->cs, err,
NULL);
}
negotiation_aborted(state, am_funder,
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_trace("Rejecting %s for unknown channel_id %s",
wire_type_name(fromwire_peektype(msg)),
type_to_string(tmpctx, struct channel_id,
&actual));
sync_crypto_write(&state->cs, PEER_FD,
take(towire_errorfmt(NULL, &actual,
"Multiple channels"
" unsupported")));
tal_free(msg);
continue;
}
/* If we get here, it's an interesting message. */
return msg;
}
}
/*~ OK, let's fund a channel! Returns the reply for lightningd on success,
* or NULL if something goes wrong. */
static u8 *funder_channel(struct state *state,
u64 change_satoshis, u32 change_keyindex,
u8 channel_flags,
struct utxo **utxos TAKES,
const struct ext_key *bip32_base)
{
struct channel_id id_in;
u8 *msg;
struct bitcoin_tx *tx;
struct basepoints theirs;
struct pubkey their_funding_pubkey;
struct pubkey *changekey;
struct bitcoin_signature sig;
u32 minimum_depth;
const u8 *wscript;
struct bitcoin_tx *funding;
/*~ 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);
/* BOLT #2:
*
* The sending node:
*...
* - MUST set `funding_satoshis` to less than 2^24 satoshi.
*/
if (state->funding_satoshis > state->chainparams->max_funding_satoshi)
status_failed(STATUS_FAIL_MASTER_IO,
"funding_satoshis must be < %"PRIu64", not %"PRIu64,
state->chainparams->max_funding_satoshi,
state->funding_satoshis);
/* BOLT #2:
*
* The sending node:
*...
* - MUST set `push_msat` to equal or less than 1000 *
* `funding_satoshis`.
*/
if (state->push_msat > 1000 * state->funding_satoshis)
status_failed(STATUS_FAIL_MASTER_IO,
"push-msat must be < %"PRIu64,
1000 * state->funding_satoshis);
msg = towire_open_channel(NULL,
&state->chainparams->genesis_blockhash,
&state->channel_id,
state->funding_satoshis, state->push_msat,
state->localconf.dust_limit_satoshis,
state->localconf.max_htlc_value_in_flight_msat,
state->localconf.channel_reserve_satoshis,
state->localconf.htlc_minimum_msat,
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);
sync_crypto_write(&state->cs, PEER_FD, take(msg));
/* This is usually a very transient state... */
peer_billboard(false,
"Funding channel: offered, now waiting for accept_channel");
/* ... since their reply should be immediate. */
msg = opening_negotiate_msg(tmpctx, state, true);
if (!msg)
goto fail;
/* 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 DER-encoded compressed secp256k1 pubkeys.
*/
if (!fromwire_accept_channel(msg, &id_in,
&state->remoteconf.dust_limit_satoshis,
&state->remoteconf
.max_htlc_value_in_flight_msat,
&state->remoteconf
.channel_reserve_satoshis,
&state->remoteconf.htlc_minimum_msat,
&minimum_depth,
&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]))
peer_failed(&state->cs,
&state->channel_id,
"Parsing accept_channel %s", tal_hex(msg, msg));
/* 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->cs,
&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));
/* BOLT #2:
*
* The receiver:
* - if `minimum_depth` is unreasonably large:
* - MAY reject the channel.
*/
if (minimum_depth > 10) {
/* negotiation_failed just tells peer and lightningd
* (hence fundchannel call) that this opening failed. */
negotiation_failed(state, true,
"minimum_depth %u larger than %u",
minimum_depth, 10);
goto fail;
}
/* BOLT #2:
*
* The receiver:
*...
* - if `channel_reserve_satoshis` is less than `dust_limit_satoshis`
* within the `open_channel` message:
* - MUST reject the channel.
*
* - if `channel_reserve_satoshis` from the `open_channel` message is
* less than `dust_limit_satoshis`:
* - MUST reject the channel.
*/
if (state->remoteconf.channel_reserve_satoshis
< state->localconf.dust_limit_satoshis) {
negotiation_failed(state, true,
"channel reserve %"PRIu64
" would be below our dust %"PRIu64,
state->remoteconf.channel_reserve_satoshis,
state->localconf.dust_limit_satoshis);
goto fail;
}
if (state->localconf.channel_reserve_satoshis
< state->remoteconf.dust_limit_satoshis) {
negotiation_failed(state, true,
"dust limit %"PRIu64
" would be above our reserve %"PRIu64,
state->remoteconf.dust_limit_satoshis,
state->localconf.channel_reserve_satoshis);
goto fail;
}
if (!check_config_bounds(state, &state->remoteconf, true))
goto fail;
/*~ If lightningd told us to create change, use change index to do
* that. */
if (change_satoshis) {
changekey = tal(tmpctx, struct pubkey);
if (!bip32_pubkey(bip32_base, changekey, change_keyindex))
status_failed(STATUS_FAIL_MASTER_IO,
"Bad change key %u", change_keyindex);
} else
changekey = NULL;
/*~ We (and they) actually just need the funding txid and output
* number, so we can create the commitment transaction which spends
* it; lightningd will recreate it (and have the HSM sign it) when
* we've completed opening negotiation.
*/
funding = funding_tx(state, &state->funding_txout,
cast_const2(const struct utxo **, utxos),
state->funding_satoshis,
&state->our_funding_pubkey,
&their_funding_pubkey,
change_satoshis, changekey,
bip32_base);
bitcoin_txid(funding, &state->funding_txid);
/*~ 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 hgere, and the complete channel support required by
* `channeld` which lives in channeld/full_channel. */
state->channel = new_initial_channel(state,
&state->chainparams->genesis_blockhash,
&state->funding_txid,
state->funding_txout,
state->funding_satoshis,
state->funding_satoshis * 1000
- state->push_msat,
state->feerate_per_kw,
&state->localconf,
&state->remoteconf,
&state->our_points, &theirs,
&state->our_funding_pubkey,
&their_funding_pubkey,
/* Funder 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->cs,
&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);
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");
goto fail;
}
/* 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_hsm_sign_remote_commitment_tx(NULL,
tx,
&state->channel->funding_pubkey[REMOTE],
state->channel->funding_msat / 1000);
wire_sync_write(HSM_FD, take(msg));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsm_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_trace("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->cs, PEER_FD, 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->cs,
&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!". */
derive_channel_id(&state->channel_id,
&state->funding_txid, state->funding_txout);
if (!channel_id_eq(&id_in, &state->channel_id))
peer_failed(&state->cs, &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);
if (!tx) {
negotiation_failed(state, true,
"Could not meet our fees and reserve");
goto fail;
}
if (!check_tx_sig(tx, 0, NULL, wscript, &their_funding_pubkey, &sig)) {
peer_failed(&state->cs,
&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,
&their_funding_pubkey));
}
peer_billboard(false, "Funding channel: opening negotiation succeeded");
if (taken(utxos))
tal_free(utxos);
/* BOLT #2:
*
* The recipient:
*...
* - on receipt of a valid `funding_signed`:
* - SHOULD broadcast the funding transaction.
*/
/*~ lightningd will save the new channel to the database, and
* broadcast the tx. */
return towire_opening_funder_reply(state,
&state->remoteconf,
tx,
&sig,
&state->cs,
&theirs.revocation,
&theirs.payment,
&theirs.htlc,
&theirs.delayed_payment,
&state->first_per_commitment_point[REMOTE],
minimum_depth,
&their_funding_pubkey,
&state->funding_txid,
state->feerate_per_kw,
state->localconf.channel_reserve_satoshis);
fail:
if (taken(utxos))
tal_free(utxos);
return NULL;
}
/*~ 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;
/* 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
* DER-encoded compressed secp256k1 pubkeys.
*/
if (!fromwire_open_channel(open_channel_msg, &chain_hash,
&state->channel_id,
&state->funding_satoshis, &state->push_msat,
&state->remoteconf.dust_limit_satoshis,
&state->remoteconf.max_htlc_value_in_flight_msat,
&state->remoteconf.channel_reserve_satoshis,
&state->remoteconf.htlc_minimum_msat,
&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))
peer_failed(&state->cs, NULL,
"Bad open_channel %s",
tal_hex(open_channel_msg, open_channel_msg));
/* We can't handle talking about more than one channel at once. */
if (!state->can_accept_channel) {
u8 *errmsg;
errmsg = towire_errorfmt(NULL, &state->channel_id,
"Already have active channel");
sync_crypto_write(&state->cs, PEER_FD, take(errmsg));
return NULL;
}
/* 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,
&state->chainparams->genesis_blockhash)) {
negotiation_failed(state, false,
"Unknown chain-hash %s",
type_to_string(tmpctx,
struct bitcoin_blkid,
&chain_hash));
return NULL;
}
/* BOLT #2 FIXME:
*
* The receiving node ... MUST fail the channel if `funding-satoshis`
* is greater than or equal to 2^24 */
if (state->funding_satoshis > state->chainparams->max_funding_satoshi) {
negotiation_failed(state, false,
"funding_satoshis %"PRIu64" too large",
state->funding_satoshis);
return NULL;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
* ...
* - `push_msat` is greater than `funding_satoshis` * 1000.
*/
if (state->push_msat > state->funding_satoshis * 1000) {
peer_failed(&state->cs,
&state->channel_id,
"Our push_msat %"PRIu64
" would be too large for funding_satoshis %"PRIu64,
state->push_msat, state->funding_satoshis);
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 (state->localconf.channel_reserve_satoshis
< state->remoteconf.dust_limit_satoshis) {
negotiation_failed(state, false,
"Our channel reserve %"PRIu64
" would be below their dust %"PRIu64,
state->localconf.channel_reserve_satoshis,
state->remoteconf.dust_limit_satoshis);
return NULL;
}
if (state->localconf.dust_limit_satoshis
> state->remoteconf.channel_reserve_satoshis) {
negotiation_failed(state, false,
"Our dust limit %"PRIu64
" would be above their reserve %"PRIu64,
state->localconf.dust_limit_satoshis,
state->remoteconf.channel_reserve_satoshis);
return NULL;
}
/* These checks are the same whether we're funder or fundee... */
if (!check_config_bounds(state, &state->remoteconf, false))
return NULL;
/* OK, we accept! */
msg = towire_accept_channel(NULL, &state->channel_id,
state->localconf.dust_limit_satoshis,
state->localconf
.max_htlc_value_in_flight_msat,
state->localconf.channel_reserve_satoshis,
state->localconf.htlc_minimum_msat,
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]);
sync_crypto_write(&state->cs, PEER_FD, 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->cs,
&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->cs, &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,
&chain_hash,
&state->funding_txid,
state->funding_txout,
state->funding_satoshis,
state->push_msat,
state->feerate_per_kw,
&state->localconf,
&state->remoteconf,
&state->our_points, &theirs,
&state->our_funding_pubkey,
&their_funding_pubkey,
REMOTE);
/* We don't expect this to fail, but it does do some additional
* internal sanity checks. */
if (!state->channel)
peer_failed(&state->cs,
&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);
/* This shouldn't happen either, AFAICT. */
if (!local_commit) {
negotiation_failed(state, false,
"Could not meet our fees and reserve");
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->cs,
&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);
if (!remote_commit) {
negotiation_failed(state, false,
"Could not meet their fees and reserve");
return NULL;
}
/* Make HSM sign it */
msg = towire_hsm_sign_remote_commitment_tx(NULL,
remote_commit,
&state->channel->funding_pubkey[REMOTE],
state->channel->funding_msat / 1000);
wire_sync_write(HSM_FD, take(msg));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsm_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);
return towire_opening_fundee(state,
&state->remoteconf,
local_commit,
&theirsig,
&state->cs,
&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_satoshis,
state->push_msat,
channel_flags,
state->feerate_per_kw,
msg,
state->localconf.channel_reserve_satoshis);
}
/*~ 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->cs, PEER_FD);
enum wire_type t = fromwire_peektype(msg);
struct channel_id channel_id;
switch (t) {
case WIRE_OPEN_CHANNEL:
return fundee_channel(state, msg);
/* These are handled by handle_peer_gossip_or_error. */
case WIRE_PING:
case WIRE_PONG:
case WIRE_CHANNEL_ANNOUNCEMENT:
case WIRE_NODE_ANNOUNCEMENT:
case WIRE_CHANNEL_UPDATE:
case WIRE_QUERY_SHORT_CHANNEL_IDS:
case WIRE_REPLY_SHORT_CHANNEL_IDS_END:
case WIRE_QUERY_CHANNEL_RANGE:
case WIRE_REPLY_CHANNEL_RANGE:
case WIRE_GOSSIP_TIMESTAMP_FILTER:
case WIRE_ERROR:
case WIRE_CHANNEL_REESTABLISH:
/* These are all protocol violations at this stage. */
case WIRE_INIT:
case WIRE_ACCEPT_CHANNEL:
case WIRE_FUNDING_CREATED:
case WIRE_FUNDING_SIGNED:
case WIRE_FUNDING_LOCKED:
case WIRE_SHUTDOWN:
case WIRE_CLOSING_SIGNED:
case WIRE_UPDATE_ADD_HTLC:
case WIRE_UPDATE_FULFILL_HTLC:
case WIRE_UPDATE_FAIL_HTLC:
case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
case WIRE_COMMITMENT_SIGNED:
case WIRE_REVOKE_AND_ACK:
case WIRE_UPDATE_FEE:
case WIRE_ANNOUNCEMENT_SIGNATURES:
/* Standard cases */
if (handle_peer_gossip_or_error(PEER_FD, GOSSIP_FD, &state->cs,
&state->channel_id, msg))
return NULL;
break;
}
sync_crypto_write(&state->cs, PEER_FD,
take(towire_errorfmt(NULL,
extract_channel_id(msg, &channel_id) ? &channel_id : NULL,
"Unexpected message %s: %s",
wire_type_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", wire_type_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, GOSSIP_FD);
if (!msg)
status_failed(STATUS_FAIL_GOSSIP_IO,
"Reading gossip: %s", strerror(errno));
handle_gossip_msg(PEER_FD, &state->cs, 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_enter_allocations(tmpctx, msg, msg);
/* Now delete state and things it has pointers to. */
memleak_remove_referenced(memtable, 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_opening_dev_memleak_reply(NULL,
found_leak)));
}
#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 opening_wire_type t = fromwire_peektype(msg);
u64 change_satoshis;
u32 change_keyindex;
u8 channel_flags;
struct utxo **utxos;
struct ext_key bip32_base;
switch (t) {
case WIRE_OPENING_FUNDER:
if (!fromwire_opening_funder(state, msg,
&state->funding_satoshis,
&state->push_msat,
&state->feerate_per_kw,
&change_satoshis, &change_keyindex,
&channel_flags, &utxos,
&bip32_base))
master_badmsg(WIRE_OPENING_FUNDER, msg);
msg = funder_channel(state,
change_satoshis,
change_keyindex, channel_flags,
take(utxos), &bip32_base);
return msg;
case WIRE_OPENING_CAN_ACCEPT_CHANNEL:
if (!fromwire_opening_can_accept_channel(msg))
master_badmsg(WIRE_OPENING_CAN_ACCEPT_CHANNEL, msg);
state->can_accept_channel = true;
return NULL;
case WIRE_OPENING_DEV_MEMLEAK:
#if DEVELOPER
handle_dev_memleak(state, msg);
return NULL;
#endif
case WIRE_OPENING_DEV_MEMLEAK_REPLY:
case WIRE_OPENING_INIT:
case WIRE_OPENING_FUNDER_REPLY:
case WIRE_OPENING_FUNDEE:
case WIRE_OPENING_FUNDER_FAILED:
break;
}
status_failed(STATUS_FAIL_MASTER_IO,
"Unknown msg %s", tal_hex(tmpctx, msg));
}
int main(int argc, char *argv[])
{
setup_locale();
u8 *msg, *inner;
struct pollfd pollfd[3];
struct state *state = tal(NULL, struct state);
struct bitcoin_blkid chain_hash;
struct secret *none;
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_opening_init(tmpctx, msg,
&chain_hash,
&state->localconf,
&state->max_to_self_delay,
&state->min_effective_htlc_capacity_msat,
&state->cs,
&state->our_points,
&state->our_funding_pubkey,
&state->minimum_depth,
&state->min_feerate, &state->max_feerate,
&state->can_accept_channel,
&inner))
master_badmsg(WIRE_OPENING_INIT, msg);
/*~ 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->cs, PEER_FD, inner);
fail_if_all_error(inner);
}
/*~ Even though I only care about bitcoin, there's still testnet and
* regtest modes, so we have a general "parameters for this chain"
* function. */
state->chainparams = chainparams_by_chainhash(&chain_hash);
/*~ 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 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_hsm_get_per_commitment_point(NULL, 0)));
msg = wire_sync_read(tmpctx, HSM_FD);
if (!fromwire_hsm_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_trace("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 = GOSSIP_FD;
pollfd[1].events = POLLIN;
pollfd[2].fd = 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) {
poll(pollfd, ARRAY_SIZE(pollfd), -1);
/* 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);
/* 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);
fdpass_send(REQ_FD, PEER_FD);
fdpass_send(REQ_FD, GOSSIP_FD);
status_trace("Sent %s with fd",
opening_wire_type_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.
*/