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rgb-cln/onchaind/onchain.c

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#include <bitcoin/script.h>
#include <ccan/crypto/shachain/shachain.h>
#include <ccan/mem/mem.h>
#include <ccan/structeq/structeq.h>
#include <ccan/tal/str/str.h>
#include <common/derive_basepoints.h>
#include <common/htlc_tx.h>
#include <common/initial_commit_tx.h>
#include <common/key_derive.h>
#include <common/keyset.h>
#include <common/peer_billboard.h>
#include <common/status.h>
#include <common/subdaemon.h>
#include <common/type_to_string.h>
#include <common/utils.h>
#include <common/version.h>
#include <errno.h>
#include <inttypes.h>
#include <lightningd/channel_state.h>
#include <onchaind/gen_onchain_wire.h>
#include <onchaind/onchain_types.h>
#include <stdio.h>
#include <unistd.h>
#include <wire/wire_sync.h>
#include "gen_onchain_types_names.h"
/* stdin == requests */
#define REQ_FD STDIN_FILENO
/* Required in various places: keys for commitment transaction. */
static const struct keyset *keyset;
/* The feerate to use when we generate transactions. */
static u32 feerate_per_kw;
/* The dust limit to use when we generate transactions. */
static u64 dust_limit_satoshis;
/* The CSV delays for each side. */
static u32 to_self_delay[NUM_SIDES];
/* Where we send money to (our wallet) */
static struct pubkey our_wallet_pubkey;
/* Private keys for spending HTLC outputs via HTLC txs, delayed, and directly. */
static struct privkey htlc_privkey, delayed_payment_privkey, payment_privkey;
/* Private keys for spending HTLC for penalty (only if they cheated). */
static struct privkey *revocation_privkey;
/* one value is useful for a few witness scripts */
static const u8 ONE = 0x1;
/* When to tell master about HTLCs which are missing/timed out */
static u32 reasonable_depth;
/* The messages to send at that depth. */
static u8 **missing_htlc_msgs;
/* If we broadcast a tx, or need a delay to resolve the output. */
struct proposed_resolution {
/* This can be NULL if our proposal is to simply ignore it after depth */
const struct bitcoin_tx *tx;
/* Non-zero if this is CSV-delayed. */
u32 depth_required;
enum tx_type tx_type;
};
/* How it actually got resolved. */
struct resolution {
struct bitcoin_txid txid;
unsigned int depth;
enum tx_type tx_type;
};
struct tracked_output {
enum tx_type tx_type;
struct bitcoin_txid txid;
u32 tx_blockheight;
/* FIXME: Convert all depths to blocknums, then just get new blk msgs */
u32 depth;
u32 outnum;
u64 satoshi;
enum output_type output_type;
/* If it is an HTLC, these are non-NULL */
const struct htlc_stub *htlc;
const u8 *wscript;
/* If it's an HTLC off our unilateral, this is their sig for htlc_tx */
const secp256k1_ecdsa_signature *remote_htlc_sig;
/* Our proposed solution (if any) */
struct proposed_resolution *proposal;
/* If it is resolved. */
struct resolution *resolved;
};
/* We use the same feerate for htlcs and commit transactions; we don't
* record what it was, so we brute-force it. */
struct {
u32 min, max;
} feerate_range;
static void init_feerate_range(u64 funding_satoshi,
const struct bitcoin_tx *commit_tx)
{
size_t i, max_untrimmed_htlcs;
u64 fee = funding_satoshi;
for (i = 0; i < tal_count(commit_tx->output); i++)
fee -= commit_tx->output[i].amount;
/* We don't know how many trimmed HTLCs there are, so they could
* be making fee entirely. */
feerate_range.min = 0;
/* But we can estimate the maximum fee rate:
*
* fee = feerate_per_kw * (724 + 172 * num_untrimmed) / 1000;
*/
if (tal_count(commit_tx->output) < 2)
max_untrimmed_htlcs = 0;
else
max_untrimmed_htlcs = tal_count(commit_tx->output) - 2;
feerate_range.max = (fee + 999) * 1000
/ (724 + 172 * max_untrimmed_htlcs);
status_trace("Initial feerate %u to %u",
feerate_range.min, feerate_range.max);
}
static void narrow_feerate_range(u64 fee, u32 multiplier)
{
u32 min, max;
/* fee = feerate_per_kw * multiplier / 1000; */
max = (fee + 999) * 1000 / multiplier;
if (fee < 999)
min = 0;
else
min = (fee - 999) * 1000 / multiplier;
status_trace("Fee %"PRIu64" gives feerate min/max %u/%u",
fee, min, max);
if (max < feerate_range.max)
feerate_range.max = max;
if (min > feerate_range.min)
feerate_range.min = min;
status_trace("Feerate now %u to %u",
feerate_range.min, feerate_range.max);
}
/* We vary feerate until signature they offered matches: we're more
* likely to be near max. */
static bool grind_feerate(struct bitcoin_tx *commit_tx,
const secp256k1_ecdsa_signature *remotesig,
const u8 *wscript,
u64 multiplier)
{
u64 prev_fee = UINT64_MAX;
u64 input_amount = *commit_tx->input[0].amount;
for (s64 i = feerate_range.max; i >= feerate_range.min; i--) {
u64 fee = i * multiplier / 1000;
if (fee > input_amount)
continue;
/* Minor optimization: don't check same fee twice */
if (fee == prev_fee)
continue;
prev_fee = fee;
commit_tx->output[0].amount = input_amount - fee;
if (!check_tx_sig(commit_tx, 0, NULL, wscript,
&keyset->other_htlc_key, remotesig))
continue;
narrow_feerate_range(fee, multiplier);
return true;
}
return false;
}
static const char *tx_type_name(enum tx_type tx_type)
{
size_t i;
for (i = 0; enum_tx_type_names[i].name; i++)
if (enum_tx_type_names[i].v == tx_type)
return enum_tx_type_names[i].name;
return "unknown";
}
static const char *output_type_name(enum output_type output_type)
{
size_t i;
for (i = 0; enum_output_type_names[i].name; i++)
if (enum_output_type_names[i].v == output_type)
return enum_output_type_names[i].name;
return "unknown";
}
/*
* This covers:
* 1. to-us output spend (`<local_delayedsig> 0`)
* 2. the their-commitment, our HTLC timeout case (`<remotehtlcsig> 0`),
* 3. the their-commitment, our HTLC redeem case (`<remotehtlcsig> <payment_preimage>`)
* 4. the their-revoked-commitment, to-local (`<revocation_sig> 1`)
* 5. the their-revoked-commitment, htlc (`<revocation_sig> <revocationkey>`)
*/
static struct bitcoin_tx *tx_to_us(const tal_t *ctx,
struct tracked_output *out,
u32 to_self_delay,
u32 locktime,
const void *elem, size_t elemsize,
const u8 *wscript,
const struct privkey *privkey,
const struct pubkey *pubkey)
{
struct bitcoin_tx *tx;
u64 fee;
secp256k1_ecdsa_signature sig;
tx = bitcoin_tx(ctx, 1, 1);
tx->lock_time = locktime;
tx->input[0].sequence_number = to_self_delay;
tx->input[0].txid = out->txid;
tx->input[0].index = out->outnum;
tx->input[0].amount = tal_dup(tx->input, u64, &out->satoshi);
tx->output[0].amount = out->satoshi;
tx->output[0].script = scriptpubkey_p2wpkh(tx->output,
&our_wallet_pubkey);
/* Worst-case sig is 73 bytes */
fee = feerate_per_kw * (measure_tx_weight(tx)
+ 1 + 3 + 73 + 0 + tal_len(wscript))
/ 1000;
/* Result is trivial? Just eliminate output. */
if (tx->output[0].amount < dust_limit_satoshis + fee)
tal_resize(&tx->output, 0);
else
tx->output[0].amount -= fee;
sign_tx_input(tx, 0, NULL, wscript, privkey, pubkey, &sig);
tx->input[0].witness = bitcoin_witness_sig_and_element(tx->input,
&sig,
elem, elemsize,
wscript);
return tx;
}
static struct tracked_output *
new_tracked_output(struct tracked_output ***outs,
const struct bitcoin_txid *txid,
u32 tx_blockheight,
enum tx_type tx_type,
u32 outnum,
u64 satoshi,
enum output_type output_type,
const struct htlc_stub *htlc,
const u8 *wscript,
const secp256k1_ecdsa_signature *remote_htlc_sig)
{
size_t n = tal_count(*outs);
struct tracked_output *out = tal(*outs, struct tracked_output);
status_trace("Tracking output %u of %s: %s/%s",
outnum,
type_to_string(trc, struct bitcoin_txid, txid),
tx_type_name(tx_type),
output_type_name(output_type));
out->tx_type = tx_type;
out->txid = *txid;
out->tx_blockheight = tx_blockheight;
out->depth = 0;
out->outnum = outnum;
out->satoshi = satoshi;
out->output_type = output_type;
out->proposal = NULL;
out->resolved = NULL;
out->htlc = htlc;
out->wscript = wscript;
out->remote_htlc_sig = remote_htlc_sig;
tal_resize(outs, n+1);
(*outs)[n] = out;
return out;
}
static void ignore_output(struct tracked_output *out)
{
status_trace("Ignoring output %u of %s: %s/%s",
out->outnum,
type_to_string(trc, struct bitcoin_txid, &out->txid),
tx_type_name(out->tx_type),
output_type_name(out->output_type));
out->resolved = tal(out, struct resolution);
out->resolved->txid = out->txid;
out->resolved->depth = 0;
out->resolved->tx_type = SELF;
}
static void proposal_meets_depth(struct tracked_output *out)
{
/* If we simply wanted to ignore it after some depth */
if (!out->proposal->tx) {
ignore_output(out);
return;
}
status_trace("Broadcasting %s (%s) to resolve %s/%s",
tx_type_name(out->proposal->tx_type),
type_to_string(trc, struct bitcoin_tx, out->proposal->tx),
tx_type_name(out->tx_type),
output_type_name(out->output_type));
wire_sync_write(REQ_FD,
take(towire_onchain_broadcast_tx(NULL,
out->proposal->tx)));
/* We will get a callback when it's in a block. */
}
static void propose_resolution(struct tracked_output *out,
const struct bitcoin_tx *tx,
unsigned int depth_required,
enum tx_type tx_type)
{
status_trace("Propose handling %s/%s by %s (%s) in %u blocks",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tx_type_name(tx_type),
tx ? type_to_string(trc, struct bitcoin_tx, tx):"IGNORING",
depth_required);
out->proposal = tal(out, struct proposed_resolution);
out->proposal->tx = tal_steal(out->proposal, tx);
out->proposal->depth_required = depth_required;
out->proposal->tx_type = tx_type;
if (depth_required == 0)
proposal_meets_depth(out);
}
static void propose_resolution_at_block(struct tracked_output *out,
const struct bitcoin_tx *tx,
unsigned int block_required,
enum tx_type tx_type)
{
u32 depth;
/* Expiry could be in the past! */
if (block_required < out->tx_blockheight)
depth = 0;
else
depth = block_required - out->tx_blockheight;
propose_resolution(out, tx, depth, tx_type);
}
/* This simple case: true if this was resolved by our proposal. */
static bool resolved_by_proposal(struct tracked_output *out,
const struct bitcoin_txid *txid)
{
/* If there's no TX associated, it's not us. */
if (!out->proposal->tx)
return false;
out->resolved = tal(out, struct resolution);
bitcoin_txid(out->proposal->tx, &out->resolved->txid);
/* Not the same as what we proposed? */
if (!structeq(&out->resolved->txid, txid)) {
out->resolved = tal_free(out->resolved);
/* Don't need proposal any more */
out->proposal = tal_free(out->proposal);
return false;
}
status_trace("Resolved %s/%s by our proposal %s (%s)",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tx_type_name(out->proposal->tx_type),
type_to_string(trc, struct bitcoin_tx, out->proposal->tx));
out->resolved->depth = 0;
out->resolved->tx_type = out->proposal->tx_type;
/* Don't need proposal any more */
out->proposal = tal_free(out->proposal);
return true;
}
/* Otherwise, we figure out what happened and then call this. */
static void resolved_by_other(struct tracked_output *out,
const struct bitcoin_txid *txid,
enum tx_type tx_type)
{
out->resolved = tal(out, struct resolution);
out->resolved->txid = *txid;
out->resolved->depth = 0;
out->resolved->tx_type = tx_type;
status_trace("Resolved %s/%s by %s (%s)",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tx_type_name(tx_type),
type_to_string(trc, struct bitcoin_txid, txid));
}
static void unknown_spend(struct tracked_output *out,
const struct bitcoin_tx *tx)
{
out->resolved = tal(out, struct resolution);
bitcoin_txid(tx, &out->resolved->txid);
out->resolved->depth = 0;
out->resolved->tx_type = UNKNOWN_TXTYPE;
/* FIXME: we need a louder warning! */
status_trace("Unknown spend of %s/%s by %s",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
type_to_string(trc, struct bitcoin_tx, tx));
}
static u64 unmask_commit_number(const struct bitcoin_tx *tx,
enum side funder,
const struct pubkey *local_payment_basepoint,
const struct pubkey *remote_payment_basepoint)
{
u64 obscurer;
const struct pubkey *keys[NUM_SIDES];
keys[LOCAL] = local_payment_basepoint;
keys[REMOTE] = remote_payment_basepoint;
/* BOLT #3:
*
* The 48-bit commitment transaction number is obscured by
* `XOR` with the lower 48 bits of...
*/
obscurer = commit_number_obscurer(keys[funder], keys[!funder]);
/* BOLT #3:
*
* * locktime: upper 8 bits are 0x20, lower 24 bits are the
* lower 24 bits of the obscured commitment transaction
* number.
*...
* * `txin[0]` sequence: upper 8 bits are 0x80, lower 24 bits
* are upper 24 bits of the obscured commitment
* transaction number.
*/
return ((tx->lock_time & 0x00FFFFFF)
| (tx->input[0].sequence_number & (u64)0x00FFFFFF) << 24)
^ obscurer;
}
static bool is_mutual_close(const struct bitcoin_tx *tx,
const u8 *local_scriptpubkey,
const u8 *remote_scriptpubkey)
{
size_t i;
bool local_matched = false, remote_matched = false;
for (i = 0; i < tal_count(tx->output); i++) {
/* To be paranoid, we only let each one match once. */
if (scripteq(tx->output[i].script, local_scriptpubkey)
&& !local_matched)
local_matched = true;
else if (scripteq(tx->output[i].script, remote_scriptpubkey)
&& !remote_matched)
remote_matched = true;
else
return false;
}
return true;
}
/* We only ever send out one, so matching it is easy. */
static bool is_local_commitment(const struct bitcoin_txid *txid,
const struct bitcoin_txid *our_broadcast_txid)
{
return structeq(txid, our_broadcast_txid);
}
/* BOLT #5:
*
* Outputs which are *resolved* are considered *irrevocably resolved*
* once their *resolving* transaction is included in a block at least 100
* deep on the most-work blockchain.
*/
static size_t num_not_irrevocably_resolved(struct tracked_output **outs)
{
size_t i, num = 0;
for (i = 0; i < tal_count(outs); i++) {
if (!outs[i]->resolved || outs[i]->resolved->depth < 100)
num++;
}
return num;
}
static u32 prop_blockheight(const struct tracked_output *out)
{
return out->tx_blockheight + out->proposal->depth_required;
}
static void billboard_update(struct tracked_output **outs)
{
const struct tracked_output *best = NULL;
/* Highest priority is to report on proposals we have */
for (size_t i = 0; i < tal_count(outs); i++) {
if (!outs[i]->proposal)
continue;
if (!best || prop_blockheight(outs[i]) < prop_blockheight(best))
best = outs[i];
}
if (best) {
/* If we've broadcast and not seen yet, this happens */
if (best->proposal->depth_required <= best->depth) {
peer_billboard(false,
"%u outputs unresolved: waiting confirmation that we spent %s (%s:%u) using %s",
num_not_irrevocably_resolved(outs),
output_type_name(best->output_type),
type_to_string(trc, struct bitcoin_txid,
&best->txid),
best->outnum,
tx_type_name(best->proposal->tx_type));
} else {
peer_billboard(false,
"%u outputs unresolved: in %u blocks will spend %s (%s:%u) using %s",
num_not_irrevocably_resolved(outs),
best->proposal->depth_required - best->depth,
output_type_name(best->output_type),
type_to_string(trc, struct bitcoin_txid,
&best->txid),
best->outnum,
tx_type_name(best->proposal->tx_type));
}
return;
}
/* Now, just report on the last thing we're waiting out. */
for (size_t i = 0; i < tal_count(outs); i++) {
/* FIXME: Can this happen? No proposal, no resolution? */
if (!outs[i]->resolved)
continue;
if (!best || outs[i]->resolved->depth < best->resolved->depth)
best = outs[i];
}
if (best) {
peer_billboard(false,
"All outputs resolved:"
" waiting %u more blocks before forgetting"
" channel",
best->resolved->depth < 100
? 100 - best->resolved->depth : 0);
return;
}
/* Not sure this can happen, but take last one (there must be one!) */
best = outs[tal_count(outs)-1];
peer_billboard(false, "%u outputs unresolved: %s is one (depth %u)",
num_not_irrevocably_resolved(outs),
output_type_name(best->output_type), best->depth);
}
static void unwatch_tx(const struct bitcoin_tx *tx)
{
u8 *msg;
struct bitcoin_txid txid;
bitcoin_txid(tx, &txid);
msg = towire_onchain_unwatch_tx(tx, &txid);
wire_sync_write(REQ_FD, take(msg));
}
static void handle_htlc_onchain_fulfill(struct tracked_output *out,
const struct bitcoin_tx *tx)
{
const u8 *witness_preimage;
struct preimage preimage;
struct sha256 sha;
struct ripemd160 ripemd;
/* Our HTLC, they filled (must be an HTLC-success tx). */
if (out->tx_type == THEIR_UNILATERAL) {
/* BOLT #3:
*
* ## HTLC-Timeout and HTLC-Success Transactions
*
* ... `txin[0]` witness stack: `0 <remotehtlcsig> <localhtlcsig>
* <payment_preimage>` for HTLC-Success
*/
if (tal_count(tx->input[0].witness) != 5) /* +1 for wscript */
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"%s/%s spent with weird witness %zu",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tal_count(tx->input[0].witness));
witness_preimage = tx->input[0].witness[3];
} else if (out->tx_type == OUR_UNILATERAL) {
/* BOLT #3:
*
* The remote node can redeem the HTLC with the witness:
*
* <remotehtlcsig> <payment_preimage>
*/
if (tal_count(tx->input[0].witness) != 3) /* +1 for wscript */
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"%s/%s spent with weird witness %zu",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tal_count(tx->input[0].witness));
witness_preimage = tx->input[0].witness[1];
} else
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"onchain_fulfill for %s/%s?",
tx_type_name(out->tx_type),
output_type_name(out->output_type));
if (tal_len(witness_preimage) != sizeof(preimage))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"%s/%s spent with bad witness length %zu",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tal_len(witness_preimage));
memcpy(&preimage, witness_preimage, sizeof(preimage));
sha256(&sha, &preimage, sizeof(preimage));
ripemd160(&ripemd, &sha, sizeof(sha));
if (!structeq(&ripemd, &out->htlc->ripemd))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"%s/%s spent with bad preimage %s (ripemd not %s)",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
type_to_string(trc, struct preimage, &preimage),
type_to_string(trc, struct ripemd160,
&out->htlc->ripemd));
/* Tell master we found a preimage. */
status_trace("%s/%s gave us preimage %s",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
type_to_string(trc, struct preimage, &preimage));
wire_sync_write(REQ_FD,
take(towire_onchain_extracted_preimage(NULL,
&preimage)));
}
static void resolve_htlc_tx(struct tracked_output ***outs,
size_t out_index,
const struct bitcoin_tx *htlc_tx,
const struct bitcoin_txid *htlc_txid,
u32 tx_blockheight)
{
struct tracked_output *out;
struct bitcoin_tx *tx;
u8 *wscript = bitcoin_wscript_htlc_tx(htlc_tx, to_self_delay[LOCAL],
&keyset->self_revocation_key,
&keyset->self_delayed_payment_key);
/* BOLT #5:
*
* A node SHOULD resolve its own HTLC transaction output by spending
* it to a convenient address. A node MUST wait until the
* `OP_CHECKSEQUENCEVERIFY` delay has passed (as specified by the
* other node's `open_channel` `to_self_delay` field) before spending
* the output.
*/
out = new_tracked_output(outs, htlc_txid, tx_blockheight,
(*outs)[out_index]->resolved->tx_type,
0, htlc_tx->output[0].amount,
DELAYED_OUTPUT_TO_US,
NULL, NULL, NULL);
/* BOLT #3:
*
* ## HTLC-Timeout and HTLC-Success Transactions
*
* These HTLC transactions are almost identical, except the
* HTLC-Timeout transaction is timelocked.
*
* ... to collect the output the local node uses an input with
* nSequence `to_self_delay` and a witness stack `<local_delayedsig>
* 0`
*/
tx = tx_to_us(*outs, out, to_self_delay[LOCAL], 0, NULL, 0,
wscript,
&delayed_payment_privkey,
&keyset->self_delayed_payment_key);
propose_resolution(out, tx, to_self_delay[LOCAL],
OUR_DELAYED_RETURN_TO_WALLET);
}
/* BOLT #5:
*
* 5. _B's HTLC-timeout transaction_: The node MUST *resolve* this by
* spending using the revocation key.
*/
/* BOLT #5:
*
* 6. _B's HTLC-success transaction_: The node MUST *resolve* this by
* spending using the revocation key. The node SHOULD extract
* the payment preimage from the transaction input witness if not
* already known.
*/
static void steal_htlc_tx(struct tracked_output *out)
{
struct bitcoin_tx *tx;
/* BOLT #3:
*
* To spend this via penalty, the remote node uses a witness stack
* `<revocationsig> 1`
*/
tx = tx_to_us(out, out, 0xFFFFFFFF, 0,
&ONE, sizeof(ONE),
out->wscript,
revocation_privkey,
&keyset->self_revocation_key);
propose_resolution(out, tx, 0, OUR_PENALTY_TX);
}
/* An output has been spent: see if it resolves something we care about. */
static void output_spent(struct tracked_output ***outs,
const struct bitcoin_tx *tx,
u32 input_num,
u32 tx_blockheight)
{
struct bitcoin_txid txid;
bitcoin_txid(tx, &txid);
for (size_t i = 0; i < tal_count(*outs); i++) {
struct tracked_output *out = (*outs)[i];
if (out->resolved)
continue;
if (tx->input[input_num].index != out->outnum)
continue;
if (!structeq(&tx->input[input_num].txid, &out->txid))
continue;
/* Was this our resolution? */
if (resolved_by_proposal(out, &txid)) {
/* If it's our htlc tx, we need to resolve that, too. */
if (out->resolved->tx_type == OUR_HTLC_SUCCESS_TX
|| out->resolved->tx_type == OUR_HTLC_TIMEOUT_TX)
resolve_htlc_tx(outs, i, tx, &txid,
tx_blockheight);
return;
}
switch (out->output_type) {
case OUTPUT_TO_US:
case DELAYED_OUTPUT_TO_US:
unknown_spend(out, tx);
break;
case THEIR_HTLC:
if (out->tx_type == THEIR_REVOKED_UNILATERAL) {
steal_htlc_tx(out);
} else {
/* We ignore this timeout tx, since we should
* resolve by ignoring once we reach depth. */
}
break;
case OUR_HTLC:
/* The only way they can spend this: fulfill; even
* if it's revoked: */
/* BOLT #5:
*
* 6. _B's HTLC-success transaction_: ... The node
* SHOULD extract the payment preimage from the
* transaction input witness if not already known.
*/
handle_htlc_onchain_fulfill(out, tx);
if (out->tx_type == THEIR_REVOKED_UNILATERAL)
steal_htlc_tx(out);
else {
/* BOLT #5:
*
* If the HTLC output is spent using the
* payment preimage, the HTLC output is
* considered *irrevocably resolved*, and the
* node MUST extract the payment preimage from
* the transaction input witness.
*/
ignore_output(out);
}
break;
case FUNDING_OUTPUT:
/* Master should be restarting us, as this implies
* that our old tx was unspent. */
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Funding output spent again!");
/* Um, we don't track these! */
case OUTPUT_TO_THEM:
case DELAYED_OUTPUT_TO_THEM:
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Tracked spend of %s/%s?",
tx_type_name(out->tx_type),
output_type_name(out->output_type));
}
return;
}
/* Not interesting to us, so unwatch the tx and all its outputs */
status_trace("Notified about tx %s output %u spend, but we don't care",
type_to_string(trc, struct bitcoin_txid,
&tx->input[input_num].txid),
tx->input[input_num].index);
unwatch_tx(tx);
}
static void update_resolution_depth(struct tracked_output *out, u32 depth)
{
bool reached_reasonable_depth;
status_trace("%s/%s->%s depth %u",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
tx_type_name(out->resolved->tx_type),
depth);
/* We only set this once. */
reached_reasonable_depth = (out->resolved->depth < reasonable_depth
&& depth >= reasonable_depth);
/* BOLT #5:
*
* If the HTLC output has *timed out* and not been *resolved*,
* the node MUST *resolve* the output and MUST fail the
* corresponding incoming HTLC (if any) once the resolving
* transaction has reached reasonable depth. */
if ((out->resolved->tx_type == OUR_HTLC_TIMEOUT_TX
|| out->resolved->tx_type == OUR_HTLC_TIMEOUT_TO_US)
&& reached_reasonable_depth) {
u8 *msg;
status_trace("%s/%s reached reasonable depth %u",
tx_type_name(out->tx_type),
output_type_name(out->output_type),
depth);
msg = towire_onchain_htlc_timeout(out, out->htlc);
wire_sync_write(REQ_FD, take(msg));
}
out->resolved->depth = depth;
}
static void tx_new_depth(struct tracked_output **outs,
const struct bitcoin_txid *txid, u32 depth)
{
size_t i;
/* Special handling for commitment tx reaching depth */
if (structeq(&outs[0]->resolved->txid, txid)
&& depth >= reasonable_depth
&& missing_htlc_msgs) {
status_trace("Sending %zu missing htlc messages",
tal_count(missing_htlc_msgs));
for (i = 0; i < tal_count(missing_htlc_msgs); i++)
wire_sync_write(REQ_FD, missing_htlc_msgs[i]);
/* Don't do it again. */
missing_htlc_msgs = tal_free(missing_htlc_msgs);
}
for (i = 0; i < tal_count(outs); i++) {
/* Update output depth. */
if (structeq(&outs[i]->txid, txid))
outs[i]->depth = depth;
/* Is this tx resolving an output? */
if (outs[i]->resolved) {
if (structeq(&outs[i]->resolved->txid, txid)) {
update_resolution_depth(outs[i], depth);
}
continue;
}
/* Otherwise, is this something we have a pending
* resolution for? */
if (outs[i]->proposal
&& structeq(&outs[i]->txid, txid)
&& depth >= outs[i]->proposal->depth_required) {
proposal_meets_depth(outs[i]);
}
}
}
/* BOLT #5:
*
* If the node receives (or already knows) a payment preimage for an
* unresolved HTLC output it was offered for which it has committed to an
* outgoing HTLC, it MUST *resolve* the output by spending it. Otherwise, if
* the other node is not irrevocably committed to the HTLC, it MUST NOT
* *resolve* the output by spending it.
*/
/* Master makes sure we only get told preimages once other node is committed. */
static void handle_preimage(struct tracked_output **outs,
const struct preimage *preimage)
{
size_t i;
struct sha256 sha;
struct ripemd160 ripemd;
sha256(&sha, preimage, sizeof(*preimage));
ripemd160(&ripemd, &sha, sizeof(sha));
for (i = 0; i < tal_count(outs); i++) {
struct bitcoin_tx *tx;
secp256k1_ecdsa_signature sig;
if (outs[i]->output_type != THEIR_HTLC)
continue;
if (!structeq(&outs[i]->htlc->ripemd, &ripemd))
continue;
/* Too late? */
if (outs[i]->resolved) {
/* FIXME: We need a better warning method! */
status_trace("WARNING: HTLC already resolved by %s"
" when we found preimage",
tx_type_name(outs[i]->resolved->tx_type));
return;
}
/* Discard any previous resolution. Could be a timeout,
* could be due to multiple identical rhashes in tx. */
outs[i]->proposal = tal_free(outs[i]->proposal);
/* BOLT #5:
*
* To spend an offered HTLC output: if the transaction is the
* node's own commitment transaction, then it MUST use the
* HTLC-success transaction, and the HTLC-success transaction
* output MUST be *resolved* as described in "On-chain HTLC
* Transaction Handling"
*/
if (outs[i]->remote_htlc_sig) {
tx = htlc_success_tx(outs[i], &outs[i]->txid,
outs[i]->outnum,
outs[i]->satoshi * 1000,
to_self_delay[LOCAL],
0,
keyset);
/* BOLT #3:
*
* The fee for an HTLC-success transaction MUST BE
* calculated to match:
*
* 1. Multiply `feerate_per_kw` by 703 and divide by
* 1000 (rounding down).
*/
if (!grind_feerate(tx, outs[i]->remote_htlc_sig,
outs[i]->wscript, 703))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not find feerate for"
" signature on HTLC success"
" between %u and %u",
feerate_range.min,
feerate_range.max);
sign_tx_input(tx, 0, NULL, outs[i]->wscript,
&htlc_privkey,
&keyset->self_htlc_key,
&sig);
tx->input[0].witness
= bitcoin_witness_htlc_success_tx(tx->input,
&sig,
outs[i]->remote_htlc_sig,
preimage,
outs[i]->wscript);
propose_resolution(outs[i], tx, 0, OUR_HTLC_SUCCESS_TX);
} else {
/* BOLT #5:
*
* otherwise, it MUST spend the output to a convenient
* address.
*/
tx = tx_to_us(outs[i], outs[i], 0, 0,
preimage, sizeof(*preimage),
outs[i]->wscript,
&htlc_privkey,
&keyset->other_htlc_key);
propose_resolution(outs[i], tx, 0,
THEIR_HTLC_FULFILL_TO_US);
}
}
}
/* BOLT #5:
*
* Once a node has broadcast a funding transaction or sent a commitment
* signature for a commitment transaction which contains an HTLC output,
* it MUST monitor the blockchain for transactions which spend any output
* which is not *irrevocably resolved* until all outputs are *irrevocably
* resolved*.
*/
static void wait_for_resolved(struct tracked_output **outs)
{
billboard_update(outs);
while (num_not_irrevocably_resolved(outs) != 0) {
u8 *msg = wire_sync_read(outs, REQ_FD);
struct bitcoin_txid txid;
struct bitcoin_tx *tx;
u32 input_num, depth, tx_blockheight;
struct preimage preimage;
status_trace("Got new message %s",
onchain_wire_type_name(fromwire_peektype(msg)));
if (fromwire_onchain_depth(msg, &txid, &depth))
tx_new_depth(outs, &txid, depth);
else if (fromwire_onchain_spent(msg, msg, &tx, &input_num,
&tx_blockheight))
output_spent(&outs, tx, input_num, tx_blockheight);
else if (fromwire_onchain_known_preimage(msg, &preimage))
handle_preimage(outs, &preimage);
else
master_badmsg(-1, msg);
billboard_update(outs);
tal_free(msg);
}
wire_sync_write(REQ_FD,
take(towire_onchain_all_irrevocably_resolved(outs)));
}
static void set_state(enum channel_state state)
{
wire_sync_write(REQ_FD, take(towire_onchain_init_reply(NULL, state)));
}
static void handle_mutual_close(const struct bitcoin_txid *txid,
struct tracked_output **outs)
{
set_state(ONCHAIND_MUTUAL);
peer_billboard(true, "Tracking mutual close transaction");
/* BOLT #5:
*
* A mutual close transaction *resolves* the funding transaction output.
*
* A node doesn't need to do anything else as it has already agreed to
* the output, which is sent to its specified `scriptpubkey`
*/
resolved_by_other(outs[0], txid, MUTUAL_CLOSE);
wait_for_resolved(outs);
}
static u8 **derive_htlc_scripts(const struct htlc_stub *htlcs, enum side side)
{
size_t i;
u8 **htlc_scripts = tal_arr(htlcs, u8 *, tal_count(htlcs));
for (i = 0; i < tal_count(htlcs); i++) {
if (htlcs[i].owner == side)
htlc_scripts[i] = htlc_offered_wscript(htlc_scripts,
&htlcs[i].ripemd,
keyset);
else {
/* FIXME: remove abs_locktime */
struct abs_locktime ltime;
if (!blocks_to_abs_locktime(htlcs[i].cltv_expiry,
&ltime))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not convert cltv_expiry %u to locktime",
htlcs[i].cltv_expiry);
htlc_scripts[i] = htlc_received_wscript(htlc_scripts,
&htlcs[i].ripemd,
&ltime,
keyset);
}
}
return htlc_scripts;
}
static void resolve_our_htlc_ourcommit(struct tracked_output *out)
{
struct bitcoin_tx *tx;
secp256k1_ecdsa_signature localsig;
/* BOLT #5:
*
* # On-chain HTLC Output Handling: Our Offers
* ...
*
* If the HTLC output has *timed out* and not been *resolved*, the
* node MUST *resolve* the output and MUST fail the corresponding
* incoming HTLC (if any) once the resolving transaction has reached
* reasonable depth. If the transaction is the node's
* own commitment transaction, it MUST *resolve* the output by
* spending it using the HTLC-timeout transaction, and the
* HTLC-timeout transaction output MUST be *resolved* as described in
* "On-chain HTLC Transaction Handling".
*/
tx = htlc_timeout_tx(out, &out->txid, out->outnum, out->satoshi * 1000,
out->htlc->cltv_expiry,
to_self_delay[LOCAL], 0, keyset);
/* BOLT #3:
*
* The fee for an HTLC-timeout transaction MUST BE calculated to
* match:
*
* 1. Multiply `feerate_per_kw` by 663 and divide by 1000 (rounding
* down).
*/
if (!grind_feerate(tx, out->remote_htlc_sig, out->wscript, 663))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not find feerate for signature on"
" HTLC timeout between %u and %u",
feerate_range.min, feerate_range.max);
sign_tx_input(tx, 0, NULL, out->wscript, &htlc_privkey,
&keyset->self_htlc_key, &localsig);
tx->input[0].witness
= bitcoin_witness_htlc_timeout_tx(tx->input,
&localsig,
out->remote_htlc_sig,
out->wscript);
propose_resolution_at_block(out, tx, out->htlc->cltv_expiry,
OUR_HTLC_TIMEOUT_TX);
}
static void resolve_our_htlc_theircommit(struct tracked_output *out)
{
struct bitcoin_tx *tx;
/* BOLT #5:
*
* # On-chain HTLC Output Handling: Our Offers
* ...
*
* If the HTLC output has *timed out* and not been *resolved*, the
* node MUST *resolve* the output and MUST fail the corresponding
* incoming HTLC (if any) once the resolving transaction has reached
* reasonable depth. If the transaction is the node's own commitment
* transaction, .... Otherwise it MUST resolve the output by spending
* it to a convenient address.
*/
tx = tx_to_us(out, out, 0, out->htlc->cltv_expiry, NULL, 0,
out->wscript,
&htlc_privkey,
&keyset->other_htlc_key);
propose_resolution_at_block(out, tx, out->htlc->cltv_expiry,
OUR_HTLC_TIMEOUT_TO_US);
}
static void resolve_their_htlc(struct tracked_output *out)
{
/* BOLT #5:
*
* # On-chain HTLC Output Handling: Their Offers
*
*...
* ## Requirements
*...
* If not otherwise resolved, once the HTLC output has expired, it is
* considered *irrevocably resolved*.
*/
/* If we hit timeout depth, resolve by ignoring. */
propose_resolution_at_block(out, NULL, out->htlc->cltv_expiry,
THEIR_HTLC_TIMEOUT_TO_THEM);
}
static int match_htlc_output(const struct bitcoin_tx *tx,
unsigned int outnum,
u8 **htlc_scripts)
{
/* Must be a p2wsh output */
if (!is_p2wsh(tx->output[outnum].script, NULL))
return -1;
for (size_t i = 0; i < tal_count(htlc_scripts); i++) {
struct sha256 sha;
if (!htlc_scripts[i])
continue;
sha256(&sha, htlc_scripts[i], tal_len(htlc_scripts[i]));
if (memeq(tx->output[outnum].script + 2,
tal_len(tx->output[outnum].script) - 2,
&sha, sizeof(sha)))
return i;
}
return -1;
}
/* Tell master about any we didn't use, if it wants to know. */
static void note_missing_htlcs(u8 **htlc_scripts,
const struct htlc_stub *htlcs,
const bool *tell_if_missing,
const bool *tell_immediately)
{
for (size_t i = 0; i < tal_count(htlcs); i++) {
u8 *msg;
/* Used. */
if (!htlc_scripts[i])
continue;
/* Doesn't care. */
if (!tell_if_missing[i])
continue;
msg = towire_onchain_missing_htlc_output(missing_htlc_msgs,
&htlcs[i]);
if (tell_immediately[i])
wire_sync_write(REQ_FD, take(msg));
else {
size_t n = tal_count(missing_htlc_msgs);
tal_resize(&missing_htlc_msgs, n+1);
missing_htlc_msgs[n] = msg;
}
}
}
static void handle_our_unilateral(const struct bitcoin_tx *tx,
u32 tx_blockheight,
const struct bitcoin_txid *txid,
const struct secrets *secrets,
const struct sha256 *shaseed,
const struct pubkey *remote_revocation_basepoint,
const struct pubkey *remote_payment_basepoint,
const struct pubkey *local_payment_basepoint,
const struct pubkey *remote_htlc_basepoint,
const struct pubkey *local_htlc_basepoint,
const struct pubkey *local_delayed_payment_basepoint,
u64 commit_num,
const struct htlc_stub *htlcs,
const bool *tell_if_missing,
const bool *tell_immediately,
const secp256k1_ecdsa_signature *remote_htlc_sigs,
struct tracked_output **outs)
{
const tal_t *tmpctx = tal_tmpctx(NULL);
u8 **htlc_scripts;
u8 *local_wscript, *script[NUM_SIDES];
struct pubkey local_per_commitment_point;
struct keyset *ks;
size_t i;
set_state(ONCHAIND_OUR_UNILATERAL);
peer_billboard(true, "Tracking our own unilateral close");
init_feerate_range(outs[0]->satoshi, tx);
/* BOLT #5:
*
* There are two cases to consider here: in the first case, node A
* sees its own *commitment transaction*, in the second, it sees the
* node B's unrevoked *commitment transaction*.
*
* Either transaction *resolves* the funding transaction output.
*/
resolved_by_other(outs[0], txid, OUR_UNILATERAL);
/* Figure out what delayed to-us output looks like */
if (!per_commit_point(shaseed, &local_per_commitment_point, commit_num))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving local_per_commit_point for %"PRIu64,
commit_num);
/* keyset is const, we need a non-const ptr to set it up */
keyset = ks = tal(tx, struct keyset);
if (!derive_keyset(&local_per_commitment_point,
local_payment_basepoint,
remote_payment_basepoint,
local_htlc_basepoint,
remote_htlc_basepoint,
local_delayed_payment_basepoint,
remote_revocation_basepoint,
ks))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving keyset for %"PRIu64, commit_num);
status_trace("Deconstructing unilateral tx: %"PRIu64
" using keyset: "
" self_revocation_key: %s"
" self_delayed_payment_key: %s"
" self_payment_key: %s"
" other_payment_key: %s"
" self_htlc_key: %s"
" other_htlc_key: %s",
commit_num,
type_to_string(trc, struct pubkey,
&keyset->self_revocation_key),
type_to_string(trc, struct pubkey,
&keyset->self_delayed_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_payment_key),
type_to_string(trc, struct pubkey,
&keyset->other_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_htlc_key),
type_to_string(trc, struct pubkey,
&keyset->other_htlc_key));
if (!derive_simple_privkey(&secrets->delayed_payment_basepoint_secret,
local_delayed_payment_basepoint,
&local_per_commitment_point,
&delayed_payment_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving delayed_payment_privkey for %"PRIu64,
commit_num);
if (!derive_simple_privkey(&secrets->payment_basepoint_secret,
local_payment_basepoint,
&local_per_commitment_point,
&payment_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving payment_privkey for %"PRIu64,
commit_num);
if (!derive_simple_privkey(&secrets->htlc_basepoint_secret,
local_htlc_basepoint,
&local_per_commitment_point,
&htlc_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving htlc_privkey for %"PRIu64,
commit_num);
local_wscript = to_self_wscript(tmpctx, to_self_delay[LOCAL], keyset);
/* Figure out what to-us output looks like. */
script[LOCAL] = scriptpubkey_p2wsh(tmpctx, local_wscript);
/* Figure out what direct to-them output looks like. */
script[REMOTE] = scriptpubkey_p2wpkh(tmpctx, &keyset->other_payment_key);
/* Calculate all the HTLC scripts so we can match them */
htlc_scripts = derive_htlc_scripts(htlcs, LOCAL);
status_trace("Script to-me: %u: %s (%s)",
to_self_delay[LOCAL],
tal_hex(trc, script[LOCAL]),
tal_hex(trc, local_wscript));
status_trace("Script to-them: %s",
tal_hex(trc, script[REMOTE]));
for (i = 0; i < tal_count(tx->output); i++) {
status_trace("Output %zu: %s",
i, tal_hex(trc, tx->output[i].script));
}
/* BOLT #5:
*
* When node A sees its own *commitment transaction*:
*
* 1. _A's main output_:...
* 2. _B's main output_:...
* 3. _A's offered HTLCs_:...
* 4. _B's offered HTLCs_:...
*/
for (i = 0; i < tal_count(tx->output); i++) {
struct tracked_output *out;
int j;
if (script[LOCAL]
&& scripteq(tx->output[i].script, script[LOCAL])) {
struct bitcoin_tx *to_us;
/* BOLT #5:
*
* 1. _A's main output_: A node SHOULD spend this
* output to a convenient address.
*/
out = new_tracked_output(&outs, txid, tx_blockheight,
OUR_UNILATERAL, i,
tx->output[i].amount,
DELAYED_OUTPUT_TO_US,
NULL, NULL, NULL);
/* BOLT #3:
*
* It is spent by a transaction with `nSequence` field
* set to `to_self_delay` (which can only be valid
* after that duration has passed), and witness:
*
* <local_delayedsig> 0
*/
to_us = tx_to_us(out, out, to_self_delay[LOCAL], 0,
NULL, 0,
local_wscript,
&delayed_payment_privkey,
&keyset->self_delayed_payment_key);
/* BOLT #5:
*
* If the output is spent (as recommended), the output
* is *resolved* by the spending transaction */
propose_resolution(out, to_us, to_self_delay[LOCAL],
OUR_DELAYED_RETURN_TO_WALLET);
script[LOCAL] = NULL;
continue;
}
if (script[REMOTE]
&& scripteq(tx->output[i].script, script[REMOTE])) {
/* BOLT #5:
*
* 2. _B's main output_: No action required, this
* output is considered *resolved* by the
* *commitment transaction* itself. */
out = new_tracked_output(&outs, txid, tx_blockheight,
OUR_UNILATERAL, i,
tx->output[i].amount,
OUTPUT_TO_THEM,
NULL, NULL, NULL);
ignore_output(out);
script[REMOTE] = NULL;
continue;
}
/* FIXME: limp along when this happens! */
j = match_htlc_output(tx, i, htlc_scripts);
if (j == -1)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not find resolution for output %zu",
i);
if (htlcs[j].owner == LOCAL) {
/* BOLT #5:
*
* 3. _A's offered HTLCs_: See "On-chain HTLC
* Output Handling: Our Offers" below. */
out = new_tracked_output(&outs, txid,
tx_blockheight,
OUR_UNILATERAL, i,
tx->output[i].amount,
OUR_HTLC,
&htlcs[j], htlc_scripts[j],
remote_htlc_sigs);
resolve_our_htlc_ourcommit(out);
} else {
out = new_tracked_output(&outs, txid,
tx_blockheight,
OUR_UNILATERAL, i,
tx->output[i].amount,
THEIR_HTLC,
&htlcs[j],
htlc_scripts[j],
remote_htlc_sigs);
/* BOLT #5:
*
* 4. _B's offered HTLCs_: See "On-chain HTLC
* Output Handling: Their Offers" below. */
resolve_their_htlc(out);
}
/* Each of these consumes one HTLC signature */
remote_htlc_sigs++;
/* We've matched this HTLC, can't do again. */
htlc_scripts[j] = NULL;
}
note_missing_htlcs(htlc_scripts, htlcs,
tell_if_missing, tell_immediately);
wait_for_resolved(outs);
tal_free(tmpctx);
}
/* We produce individual penalty txs. It's less efficient, but avoids them
* using HTLC txs to block our penalties for long enough to pass the CSV
* delay */
static void steal_to_them_output(struct tracked_output *out)
{
const tal_t *tmpctx = tal_tmpctx(NULL);
u8 *wscript;
struct bitcoin_tx *tx;
/* BOLT #3:
*
* If a revoked commitment transaction is published, the other party
* can spend this output immediately with the following witness:
*
* <revocation_sig> 1
*/
wscript = bitcoin_wscript_to_local(tmpctx, to_self_delay[REMOTE],
&keyset->self_revocation_key,
&keyset->self_delayed_payment_key);
tx = tx_to_us(tmpctx, out, 0xFFFFFFFF, 0,
&ONE, sizeof(ONE),
wscript,
revocation_privkey,
&keyset->self_revocation_key);
propose_resolution(out, tx, 0, OUR_PENALTY_TX);
tal_free(tmpctx);
}
static void steal_htlc(struct tracked_output *out)
{
struct bitcoin_tx *tx;
u8 der[PUBKEY_DER_LEN];
/* BOLT #3:
*
* If a revoked commitment transaction is published, the remote node
* can spend this output immediately with the following witness:
*
* <revocation_sig> <revocationkey>
*/
pubkey_to_der(der, &keyset->self_revocation_key);
tx = tx_to_us(out, out, 0xFFFFFFFF, 0,
der, sizeof(der),
out->wscript,
revocation_privkey,
&keyset->self_revocation_key);
propose_resolution(out, tx, 0, OUR_PENALTY_TX);
}
/* BOLT #5:
*
* If a node tries to broadcast old state, we can use the revocation key to
* claim all the funds.
*/
static void handle_their_cheat(const struct bitcoin_tx *tx,
const struct bitcoin_txid *txid,
u32 tx_blockheight,
const struct sha256 *revocation_preimage,
const struct secrets *secrets,
const struct pubkey *local_revocation_basepoint,
const struct pubkey *local_payment_basepoint,
const struct pubkey *remote_payment_basepoint,
const struct pubkey *remote_htlc_basepoint,
const struct pubkey *local_htlc_basepoint,
const struct pubkey *remote_delayed_payment_basepoint,
u64 commit_num,
const struct htlc_stub *htlcs,
const bool *tell_if_missing,
const bool *tell_immediately,
struct tracked_output **outs)
{
const tal_t *tmpctx = tal_tmpctx(NULL);
u8 **htlc_scripts;
u8 *remote_wscript, *script[NUM_SIDES];
struct keyset *ks;
size_t i;
struct secret per_commitment_secret;
struct privkey per_commitment_privkey;
struct pubkey per_commitment_point;
set_state(ONCHAIND_CHEATED);
peer_billboard(true, "Tracking their illegal close: taking all funds");
init_feerate_range(outs[0]->satoshi, tx);
/* BOLT #5:
*
* If a node sees a *commitment transaction* for which it has a
* revocation key, that *resolves* the funding transaction output.
*/
resolved_by_other(outs[0], txid, THEIR_REVOKED_UNILATERAL);
/* FIXME: Types. */
BUILD_ASSERT(sizeof(per_commitment_secret)
== sizeof(*revocation_preimage));
memcpy(&per_commitment_secret, revocation_preimage,
sizeof(per_commitment_secret));
BUILD_ASSERT(sizeof(per_commitment_privkey)
== sizeof(*revocation_preimage));
memcpy(&per_commitment_privkey, revocation_preimage,
sizeof(per_commitment_privkey));
if (!pubkey_from_privkey(&per_commitment_privkey, &per_commitment_point))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Failed derive from per_commitment_secret %s",
type_to_string(trc, struct privkey,
&per_commitment_privkey));
status_trace("Deriving keyset %"PRIu64
": per_commit_point=%s"
" self_payment_basepoint=%s"
" other_payment_basepoint=%s"
" self_htlc_basepoint=%s"
" other_htlc_basepoint=%s"
" self_delayed_basepoint=%s"
" other_revocation_basepoint=%s",
commit_num,
type_to_string(trc, struct pubkey,
&per_commitment_point),
type_to_string(trc, struct pubkey,
remote_payment_basepoint),
type_to_string(trc, struct pubkey,
local_payment_basepoint),
type_to_string(trc, struct pubkey,
remote_htlc_basepoint),
type_to_string(trc, struct pubkey,
local_htlc_basepoint),
type_to_string(trc, struct pubkey,
remote_delayed_payment_basepoint),
type_to_string(trc, struct pubkey,
local_revocation_basepoint));
/* keyset is const, we need a non-const ptr to set it up */
keyset = ks = tal(tx, struct keyset);
if (!derive_keyset(&per_commitment_point,
remote_payment_basepoint,
local_payment_basepoint,
local_htlc_basepoint,
remote_htlc_basepoint,
remote_delayed_payment_basepoint,
local_revocation_basepoint,
ks))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving keyset for %"PRIu64, commit_num);
status_trace("Deconstructing revoked unilateral tx: %"PRIu64
" using keyset: "
" self_revocation_key: %s"
" self_delayed_payment_key: %s"
" self_payment_key: %s"
" other_payment_key: %s"
" self_htlc_key: %s"
" other_htlc_key: %s",
commit_num,
type_to_string(trc, struct pubkey,
&keyset->self_revocation_key),
type_to_string(trc, struct pubkey,
&keyset->self_delayed_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_payment_key),
type_to_string(trc, struct pubkey,
&keyset->other_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_htlc_key),
type_to_string(trc, struct pubkey,
&keyset->other_htlc_key));
revocation_privkey = tal(tx, struct privkey);
if (!derive_revocation_privkey(&secrets->revocation_basepoint_secret,
&per_commitment_secret,
local_revocation_basepoint,
&per_commitment_point,
revocation_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving revocation_privkey for %"PRIu64,
commit_num);
remote_wscript = to_self_wscript(tmpctx, to_self_delay[REMOTE], keyset);
/* Figure out what to-them output looks like. */
script[REMOTE] = scriptpubkey_p2wsh(tmpctx, remote_wscript);
/* Figure out what direct to-us output looks like. */
script[LOCAL] = scriptpubkey_p2wpkh(tmpctx, &keyset->other_payment_key);
/* Calculate all the HTLC scripts so we can match them */
htlc_scripts = derive_htlc_scripts(htlcs, REMOTE);
status_trace("Script to-them: %u: %s (%s)",
to_self_delay[REMOTE],
tal_hex(trc, script[REMOTE]),
tal_hex(trc, remote_wscript));
status_trace("Script to-me: %s",
tal_hex(trc, script[LOCAL]));
for (i = 0; i < tal_count(tx->output); i++) {
status_trace("Output %zu: %s",
i, tal_hex(trc, tx->output[i].script));
}
/* BOLT #5:
*
* A node MUST resolve all unresolved outputs as follows:
*
* 1. _A's main output_: No action is required; this is a simple
* P2WPKH output. This output is considered *resolved* by the
* *commitment transaction*.
*
* 2. _B's main output_: The node MUST *resolve* this by spending
* using the revocation key.
*
* 3. _A's offered HTLCs_: The node MUST *resolve* this in one of three
* ways by spending:
* * the *commitment tx* using the payment revocation
* * the *commitment tx* using the payment preimage if known
* * the *HTLC-timeout tx* if B publishes them
*
* 4. _B's offered HTLCs_: The node MUST *resolve* this in one of two
* ways by spending:
* * the *commitment tx* using the payment revocation
* * the *commitment tx* once the HTLC timeout has passed.
*
* 5. _B's HTLC-timeout transaction_: The node MUST *resolve* this by
* spending using the revocation key.
*
* 6. _B's HTLC-success transaction_: The node MUST *resolve* this by
* spending using the revocation key. The node SHOULD extract
* the payment preimage from the transaction input witness if not
* already known.
*/
for (i = 0; i < tal_count(tx->output); i++) {
struct tracked_output *out;
int j;
if (script[LOCAL]
&& scripteq(tx->output[i].script, script[LOCAL])) {
/* BOLT #5:
*
* 1. _A's main output_: No action is required; this
* is a simple P2WPKH output. This output is
* considered *resolved* by the *commitment
* transaction* itself.
*/
out = new_tracked_output(&outs, txid, tx_blockheight,
THEIR_REVOKED_UNILATERAL,
i, tx->output[i].amount,
OUTPUT_TO_US, NULL, NULL, NULL);
ignore_output(out);
script[LOCAL] = NULL;
continue;
}
if (script[REMOTE]
&& scripteq(tx->output[i].script, script[REMOTE])) {
/* BOLT #5:
*
* 2. _B's main output_: The node MUST *resolve* this
* by spending using the revocation key. */
out = new_tracked_output(&outs, txid, tx_blockheight,
THEIR_REVOKED_UNILATERAL, i,
tx->output[i].amount,
DELAYED_OUTPUT_TO_THEM,
NULL, NULL, NULL);
steal_to_them_output(out);
script[REMOTE] = NULL;
continue;
}
j = match_htlc_output(tx, i, htlc_scripts);
if (j == -1)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not find resolution for output %zu",
i);
if (htlcs[j].owner == LOCAL) {
/* BOLT #5:
*
* 3. _A's offered HTLCs_: The node MUST *resolve* this
* in one of three ways by spending:
* * the *commitment tx* using the payment revocation
* * the *commitment tx* using the payment preimage if
* known
* * the *HTLC-timeout tx* if B publishes them
*/
out = new_tracked_output(&outs, txid,
tx_blockheight,
THEIR_REVOKED_UNILATERAL, i,
tx->output[i].amount,
OUR_HTLC,
&htlcs[j], htlc_scripts[j],
NULL);
steal_htlc(out);
} else {
out = new_tracked_output(&outs, txid,
tx_blockheight,
THEIR_REVOKED_UNILATERAL, i,
tx->output[i].amount,
THEIR_HTLC,
&htlcs[j], htlc_scripts[j],
NULL);
/* BOLT #5:
*
* 4. _B's offered HTLCs_: The node MUST *resolve*
* this in one of two ways by spending:
*
* * the *commitment tx* using the payment revocation
* * the *commitment tx* once the HTLC timeout has
* passed.
*/
steal_htlc(out);
}
htlc_scripts[j] = NULL;
}
note_missing_htlcs(htlc_scripts, htlcs,
tell_if_missing, tell_immediately);
wait_for_resolved(outs);
tal_free(tmpctx);
}
static void handle_their_unilateral(const struct bitcoin_tx *tx,
u32 tx_blockheight,
const struct bitcoin_txid *txid,
const struct secrets *secrets,
const struct pubkey *remote_per_commitment_point,
const struct pubkey *local_revocation_basepoint,
const struct pubkey *local_payment_basepoint,
const struct pubkey *remote_payment_basepoint,
const struct pubkey *remote_htlc_basepoint,
const struct pubkey *local_htlc_basepoint,
const struct pubkey *remote_delayed_payment_basepoint,
u64 commit_num,
const struct htlc_stub *htlcs,
const bool *tell_if_missing,
const bool *tell_immediately,
struct tracked_output **outs)
{
const tal_t *tmpctx = tal_tmpctx(NULL);
u8 **htlc_scripts;
u8 *remote_wscript, *script[NUM_SIDES];
struct keyset *ks;
size_t i;
set_state(ONCHAIND_THEIR_UNILATERAL);
peer_billboard(true, "Tracking their unilateral close");
init_feerate_range(outs[0]->satoshi, tx);
/* BOLT #5:
*
* There are two cases to consider here: in the first case, node A
* sees its own *commitment transaction*, in the second, it sees the
* node B's unrevoked *commitment transaction*.
*
* Either transaction *resolves* the funding transaction output.
*/
resolved_by_other(outs[0], txid, THEIR_UNILATERAL);
status_trace("Deriving keyset %"PRIu64
": per_commit_point=%s"
" self_payment_basepoint=%s"
" other_payment_basepoint=%s"
" self_htlc_basepoint=%s"
" other_htlc_basepoint=%s"
" self_delayed_basepoint=%s"
" other_revocation_basepoint=%s",
commit_num,
type_to_string(trc, struct pubkey,
remote_per_commitment_point),
type_to_string(trc, struct pubkey,
remote_payment_basepoint),
type_to_string(trc, struct pubkey,
local_payment_basepoint),
type_to_string(trc, struct pubkey,
remote_htlc_basepoint),
type_to_string(trc, struct pubkey,
local_htlc_basepoint),
type_to_string(trc, struct pubkey,
remote_delayed_payment_basepoint),
type_to_string(trc, struct pubkey,
local_revocation_basepoint));
/* keyset is const, we need a non-const ptr to set it up */
keyset = ks = tal(tx, struct keyset);
if (!derive_keyset(remote_per_commitment_point,
remote_payment_basepoint,
local_payment_basepoint,
remote_htlc_basepoint,
local_htlc_basepoint,
remote_delayed_payment_basepoint,
local_revocation_basepoint,
ks))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving keyset for %"PRIu64, commit_num);
status_trace("Deconstructing unilateral tx: %"PRIu64
" using keyset: "
" self_revocation_key: %s"
" self_delayed_payment_key: %s"
" self_payment_key: %s"
" other_payment_key: %s"
" self_htlc_key: %s"
" other_htlc_key: %s",
commit_num,
type_to_string(trc, struct pubkey,
&keyset->self_revocation_key),
type_to_string(trc, struct pubkey,
&keyset->self_delayed_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_payment_key),
type_to_string(trc, struct pubkey,
&keyset->other_payment_key),
type_to_string(trc, struct pubkey,
&keyset->self_htlc_key),
type_to_string(trc, struct pubkey,
&keyset->other_htlc_key));
if (!derive_simple_privkey(&secrets->payment_basepoint_secret,
local_payment_basepoint,
remote_per_commitment_point,
&payment_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving local_delayeprivkey for %"PRIu64,
commit_num);
if (!derive_simple_privkey(&secrets->htlc_basepoint_secret,
local_htlc_basepoint,
remote_per_commitment_point,
&htlc_privkey))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Deriving htlc_privkey for %"PRIu64,
commit_num);
remote_wscript = to_self_wscript(tmpctx, to_self_delay[REMOTE], keyset);
/* Figure out what to-them output looks like. */
script[REMOTE] = scriptpubkey_p2wsh(tmpctx, remote_wscript);
/* Figure out what direct to-us output looks like. */
script[LOCAL] = scriptpubkey_p2wpkh(tmpctx, &keyset->other_payment_key);
/* Calculate all the HTLC scripts so we can match them */
htlc_scripts = derive_htlc_scripts(htlcs, REMOTE);
status_trace("Script to-them: %u: %s (%s)",
to_self_delay[REMOTE],
tal_hex(trc, script[REMOTE]),
tal_hex(trc, remote_wscript));
status_trace("Script to-me: %s",
tal_hex(trc, script[LOCAL]));
for (i = 0; i < tal_count(tx->output); i++) {
status_trace("Output %zu: %s",
i, tal_hex(trc, tx->output[i].script));
}
/* BOLT #5:
*
* Similarly, when node A sees a *commitment transaction* from B:
*
* 1. _A's main output_:...
* 2. _B's main output_:...
* 3. _A's offered HTLCs_:...
* 4. _B's offered HTLCs_:...
*/
for (i = 0; i < tal_count(tx->output); i++) {
struct tracked_output *out;
int j;
if (script[LOCAL]
&& scripteq(tx->output[i].script, script[LOCAL])) {
/* BOLT #5:
*
* 1. _A's main output_: No action is required; this
* is a simple P2WPKH output. This output is
* considered *resolved* by the *commitment
* transaction* itself.
*/
out = new_tracked_output(&outs, txid, tx_blockheight,
THEIR_UNILATERAL,
i, tx->output[i].amount,
OUTPUT_TO_US, NULL, NULL, NULL);
ignore_output(out);
script[LOCAL] = NULL;
/* Tell the master that it will want to add
* this UTXO to its outputs */
wire_sync_write(REQ_FD, towire_onchain_add_utxo(
tmpctx, txid, i,
remote_per_commitment_point,
tx->output[i].amount));
continue;
}
if (script[REMOTE]
&& scripteq(tx->output[i].script, script[REMOTE])) {
/* BOLT #5:
*
* 2. _B's main output_: No action required, this
* output is considered *resolved* by the
* *commitment transaction* itself. */
out = new_tracked_output(&outs, txid, tx_blockheight,
THEIR_UNILATERAL, i,
tx->output[i].amount,
DELAYED_OUTPUT_TO_THEM,
NULL, NULL, NULL);
ignore_output(out);
continue;
}
j = match_htlc_output(tx, i, htlc_scripts);
if (j == -1)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not find resolution for output %zu",
i);
if (htlcs[j].owner == LOCAL) {
/* BOLT #5:
*
* 3. _A's offered HTLCs_: See "On-chain HTLC Output
* Handling: Our Offers" below. */
out = new_tracked_output(&outs, txid,
tx_blockheight,
THEIR_UNILATERAL, i,
tx->output[i].amount,
OUR_HTLC,
&htlcs[j], htlc_scripts[j],
NULL);
resolve_our_htlc_theircommit(out);
} else {
out = new_tracked_output(&outs, txid,
tx_blockheight,
THEIR_UNILATERAL, i,
tx->output[i].amount,
THEIR_HTLC,
&htlcs[j], htlc_scripts[j],
NULL);
/* BOLT #5:
*
* 4. _B's offered HTLCs_: See "On-chain HTLC Output
* Handling: Their Offers" below. */
resolve_their_htlc(out);
}
htlc_scripts[j] = NULL;
}
note_missing_htlcs(htlc_scripts, htlcs,
tell_if_missing, tell_immediately);
wait_for_resolved(outs);
tal_free(tmpctx);
}
int main(int argc, char *argv[])
{
const tal_t *ctx = tal_tmpctx(NULL);
u8 *msg;
struct privkey seed;
struct pubkey remote_payment_basepoint, remote_htlc_basepoint,
remote_per_commit_point, old_remote_per_commit_point,
remote_revocation_basepoint, remote_delayed_payment_basepoint;
enum side funder;
struct basepoints basepoints;
struct shachain shachain;
struct bitcoin_tx *tx;
struct secrets secrets;
struct sha256 shaseed;
struct tracked_output **outs;
struct bitcoin_txid our_broadcast_txid, txid;
secp256k1_ecdsa_signature *remote_htlc_sigs;
u64 funding_amount_satoshi, num_htlcs;
u8 *scriptpubkey[NUM_SIDES];
struct htlc_stub *htlcs;
bool *tell_if_missing, *tell_immediately;
u32 tx_blockheight;
subdaemon_setup(argc, argv);
status_setup_sync(REQ_FD);
missing_htlc_msgs = tal_arr(ctx, u8 *, 0);
msg = wire_sync_read(ctx, REQ_FD);
if (!fromwire_onchain_init(ctx, msg,
&seed, &shachain,
&funding_amount_satoshi,
&old_remote_per_commit_point,
&remote_per_commit_point,
&to_self_delay[LOCAL],
&to_self_delay[REMOTE],
&feerate_per_kw,
&dust_limit_satoshis,
&remote_revocation_basepoint,
&our_broadcast_txid,
&scriptpubkey[LOCAL],
&scriptpubkey[REMOTE],
&our_wallet_pubkey,
&funder,
&remote_payment_basepoint,
&remote_htlc_basepoint,
&remote_delayed_payment_basepoint,
&tx,
&tx_blockheight,
&reasonable_depth,
&remote_htlc_sigs,
&num_htlcs)) {
master_badmsg(WIRE_ONCHAIN_INIT, msg);
}
derive_basepoints(&seed, NULL, &basepoints, &secrets, &shaseed);
bitcoin_txid(tx, &txid);
/* FIXME: Filter as we go, don't load them all into mem! */
htlcs = tal_arr(ctx, struct htlc_stub, num_htlcs);
tell_if_missing = tal_arr(ctx, bool, num_htlcs);
tell_immediately = tal_arr(ctx, bool, num_htlcs);
if (!htlcs || !tell_if_missing || !tell_immediately)
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Can't allocate %"PRIu64" htlcs", num_htlcs);
for (u64 i = 0; i < num_htlcs; i++) {
msg = wire_sync_read(ctx, REQ_FD);
if (!fromwire_onchain_htlc(msg, &htlcs[i],
&tell_if_missing[i],
&tell_immediately[i]))
master_badmsg(WIRE_ONCHAIN_HTLC, msg);
}
outs = tal_arr(ctx, struct tracked_output *, 0);
new_tracked_output(&outs, &tx->input[0].txid,
0, /* We don't care about funding blockheight */
FUNDING_TRANSACTION,
tx->input[0].index,
funding_amount_satoshi,
FUNDING_OUTPUT, NULL, NULL, NULL);
status_trace("Remote per-commit point: %s",
type_to_string(trc, struct pubkey,
&remote_per_commit_point));
status_trace("Old remote per-commit point: %s",
type_to_string(trc, struct pubkey,
&old_remote_per_commit_point));
/* BOLT #5:
*
* There are three ways a channel can end:
*
* 1. The good way (*mutual close*): at some point A and B agree on
* closing the channel, they generate a *closing transaction*
* (which is similar to a *commitment transaction* without any
* pending payments), and publish it on the blockchain (see [BOLT
* #2: Channel Close](02-peer-protocol.md#channel-close)).
*/
if (is_mutual_close(tx, scriptpubkey[LOCAL], scriptpubkey[REMOTE]))
handle_mutual_close(&txid, outs);
else {
/* BOLT #5:
*
* 2. The bad way (*unilateral close*): something goes wrong,
* without necessarily any evil intent on either side
* (maybe one party crashed, for instance). Anyway, one
* side publishes its latest *commitment transaction*.
*/
struct sha256 revocation_preimage;
u64 commit_num = unmask_commit_number(tx, funder,
&basepoints.payment,
&remote_payment_basepoint);
status_trace("commitnum = %"PRIu64
", revocations_received = %"PRIu64,
commit_num, revocations_received(&shachain));
if (is_local_commitment(&txid, &our_broadcast_txid))
handle_our_unilateral(tx, tx_blockheight, &txid,
&secrets,
&shaseed,
&remote_revocation_basepoint,
&remote_payment_basepoint,
&basepoints.payment,
&remote_htlc_basepoint,
&basepoints.htlc,
&basepoints.delayed_payment,
commit_num,
htlcs,
tell_if_missing, tell_immediately,
remote_htlc_sigs,
outs);
/* BOLT #5:
*
* 3. The ugly way (*revoked transaction close*): one of the
* parties deliberately tries to cheat by publishing an
* outdated version of its *commitment transaction*
* (presumably one that was more in her favor).
*/
else if (shachain_get_hash(&shachain,
shachain_index(commit_num),
&revocation_preimage)) {
handle_their_cheat(tx, &txid,
tx_blockheight,
&revocation_preimage,
&secrets,
&basepoints.revocation,
&basepoints.payment,
&remote_payment_basepoint,
&basepoints.htlc,
&remote_htlc_basepoint,
&remote_delayed_payment_basepoint,
commit_num,
htlcs,
tell_if_missing, tell_immediately,
outs);
/* BOLT #5:
*
* Note that there can be more than one valid,
* unrevoked *commitment transaction* after a
* signature has been received via `commitment_signed`
* and before the corresponding `revoke_and_ack`.
* Either commitment can serve as B's *commitment
* transaction*, hence the requirement to handle both.
*/
} else if (commit_num == revocations_received(&shachain)) {
status_trace("Their unilateral tx, old commit point");
handle_their_unilateral(tx, tx_blockheight,
&txid, &secrets,
&old_remote_per_commit_point,
&basepoints.revocation,
&basepoints.payment,
&remote_payment_basepoint,
&remote_htlc_basepoint,
&basepoints.htlc,
&remote_delayed_payment_basepoint,
commit_num,
htlcs,
tell_if_missing,
tell_immediately,
outs);
} else if (commit_num == revocations_received(&shachain) + 1) {
status_trace("Their unilateral tx, new commit point");
handle_their_unilateral(tx, tx_blockheight,
&txid, &secrets,
&remote_per_commit_point,
&basepoints.revocation,
&basepoints.payment,
&remote_payment_basepoint,
&remote_htlc_basepoint,
&basepoints.htlc,
&remote_delayed_payment_basepoint,
commit_num,
htlcs,
tell_if_missing,
tell_immediately,
outs);
} else
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Unknown commitment index %"PRIu64
" for tx %s",
commit_num,
type_to_string(ctx, struct bitcoin_tx,
tx));
}
/* We're done! */
tal_free(ctx);
return 0;
}
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