#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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; 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 (` 0`) * 2. the their-commitment, our HTLC timeout case (` 0`), * 3. the their-commitment, our HTLC redeem case (` `) * 4. the their-revoked-commitment, to-local (` 1`) * 5. the their-revoked-commitment, htlc (` `) */ 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_cost(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->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); 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; 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 bool all_irrevocably_resolved(struct tracked_output **outs) { size_t i; for (i = 0; i < tal_count(outs); i++) { if (!outs[i]->resolved || outs[i]->resolved->depth < 100) return false; } return true; } 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, tal_count(tx->output)); 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 a HTLC-success tx). */ if (out->tx_type == THEIR_UNILATERAL) { /* BOLT #3: * * ## HTLC-Timeout and HTLC-Success Transactions * * ... `txin[0]` witness stack: `0 * ` 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: * * */ 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 ` * 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 * ` 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++) { /* 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) { while (!all_irrevocably_resolved(outs)) { u8 *msg = wire_sync_read(outs, REQ_FD); struct bitcoin_txid txid; struct bitcoin_tx *tx = tal(msg, struct bitcoin_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, NULL, &txid, &depth)) tx_new_depth(outs, &txid, depth); else if (fromwire_onchain_spent(msg, NULL, tx, &input_num, &tx_blockheight)) output_spent(&outs, tx, input_num, tx_blockheight); else if (fromwire_onchain_known_preimage(msg, NULL, &preimage)) handle_preimage(outs, &preimage); else master_badmsg(-1, msg); tal_free(msg); } wire_sync_write(REQ_FD, take(towire_onchain_all_irrevocably_resolved(outs))); } static void set_state(enum peer_state state) { wire_sync_write(REQ_FD, take(towire_onchain_init_reply(NULL, state))); } static void handle_mutual_close(const struct bitcoin_tx *tx, const struct bitcoin_txid *txid, struct tracked_output **outs) { set_state(ONCHAIND_MUTUAL); /* 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, <ime)) 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, <ime, 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); 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: * * 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: * * 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: * * */ 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); 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 sha256 *shaseed, 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); 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; if (argc == 2 && streq(argv[1], "--version")) { printf("%s\n", version()); exit(0); } subdaemon_debug(argc, argv); /* We handle write returning errors! */ signal(SIGCHLD, SIG_IGN); secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY | SECP256K1_CONTEXT_SIGN); status_setup_sync(REQ_FD); missing_htlc_msgs = tal_arr(ctx, u8 *, 0); msg = wire_sync_read(ctx, REQ_FD); tx = tal(ctx, struct bitcoin_tx); if (!fromwire_onchain_init(ctx, msg, NULL, &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, NULL, &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(tx, &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, &shaseed, &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, &shaseed, &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; }