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/* Code to talk to bitcoind to watch for various events.
*
* Here's what we want to know:
*
* - An anchor tx:
* - Reached given depth
* - Times out.
* - Is unspent after reaching given depth.
*
* - Our own commitment tx:
* - Reached a given depth.
*
* - HTLC spend tx:
* - Reached a given depth.
*
* - Anchor tx output:
* - Is spent by their current tx.
* - Is spent by a revoked tx.
*
* - Commitment tx HTLC outputs:
* - HTLC timed out
* - HTLC spent
*
* We do this by adding the P2SH address to the wallet, and then querying
* that using listtransactions.
*
* WE ASSUME NO MALLEABILITY! This requires segregated witness.
*/
#include <bitcoin/script.h>
#include <bitcoin/tx.h>
#include <ccan/crypto/siphash24/siphash24.h>
#include <ccan/ptrint/ptrint.h>
#include <ccan/structeq/structeq.h>
#include <common/pseudorand.h>
#include <common/timeout.h>
#include <lightningd/bitcoind.h>
#include <lightningd/chaintopology.h>
#include <lightningd/lightningd.h>
#include <lightningd/log.h>
#include <lightningd/peer_control.h>
#include <lightningd/watch.h>
/* Watching an output */
struct txowatch {
struct chain_topology *topo;
/* Channel who owns us. */
struct channel *channel;
/* Output to watch. */
struct txwatch_output out;
/* A new tx. */
enum watch_result (*cb)(struct channel *channel,
const struct bitcoin_tx *tx,
size_t input_num,
const struct block *block);
};
struct txwatch {
struct chain_topology *topo;
/* Channel who owns us. */
struct channel *channel;
/* Transaction to watch. */
struct bitcoin_txid txid;
unsigned int depth;
/* A new depth (0 if kicked out, otherwise 1 = tip, etc.) */
enum watch_result (*cb)(struct channel *channel,
const struct bitcoin_tx *tx,
unsigned int depth);
};
const struct txwatch_output *txowatch_keyof(const struct txowatch *w)
{
return &w->out;
}
size_t txo_hash(const struct txwatch_output *out)
{
/* This hash-in-one-go trick only works if they're consecutive. */
BUILD_ASSERT(offsetof(struct txwatch_output, index)
== sizeof(((struct txwatch_output *)NULL)->txid));
return siphash24(siphash_seed(), &out->txid,
sizeof(out->txid) + sizeof(out->index));
}
bool txowatch_eq(const struct txowatch *w, const struct txwatch_output *out)
{
return structeq(&w->out.txid, &out->txid)
&& w->out.index == out->index;
}
static void destroy_txowatch(struct txowatch *w)
{
txowatch_hash_del(&w->topo->txowatches, w);
}
const struct bitcoin_txid *txwatch_keyof(const struct txwatch *w)
{
return &w->txid;
}
size_t txid_hash(const struct bitcoin_txid *txid)
{
return siphash24(siphash_seed(),
txid->shad.sha.u.u8, sizeof(txid->shad.sha.u.u8));
}
bool txwatch_eq(const struct txwatch *w, const struct bitcoin_txid *txid)
{
return structeq(&w->txid, txid);
}
static void destroy_txwatch(struct txwatch *w)
{
txwatch_hash_del(&w->topo->txwatches, w);
}
struct txwatch *watch_txid(const tal_t *ctx,
struct chain_topology *topo,
struct channel *channel,
const struct bitcoin_txid *txid,
enum watch_result (*cb)(struct channel *channel,
const struct bitcoin_tx *,
unsigned int depth))
{
struct txwatch *w;
w = tal(ctx, struct txwatch);
w->topo = topo;
w->depth = 0;
w->txid = *txid;
w->channel = channel;
w->cb = cb;
txwatch_hash_add(&w->topo->txwatches, w);
tal_add_destructor(w, destroy_txwatch);
return w;
}
struct txwatch *find_txwatch(struct chain_topology *topo,
const struct bitcoin_txid *txid,
const struct channel *channel)
{
struct txwatch_hash_iter i;
struct txwatch *w;
/* We could have more than one channel watching same txid, though we
* don't for onchaind. */
for (w = txwatch_hash_getfirst(&topo->txwatches, txid, &i);
w;
w = txwatch_hash_getnext(&topo->txwatches, txid, &i)) {
if (w->channel == channel)
break;
}
return w;
}
bool watching_txid(const struct chain_topology *topo,
const struct bitcoin_txid *txid)
{
return txwatch_hash_get(&topo->txwatches, txid) != NULL;
}
struct txwatch *watch_tx(const tal_t *ctx,
struct chain_topology *topo,
struct channel *channel,
const struct bitcoin_tx *tx,
enum watch_result (*cb)(struct channel *channel,
const struct bitcoin_tx *,
unsigned int depth))
{
struct bitcoin_txid txid;
bitcoin_txid(tx, &txid);
return watch_txid(ctx, topo, channel, &txid, cb);
}
struct txowatch *watch_txo(const tal_t *ctx,
struct chain_topology *topo,
struct channel *channel,
const struct bitcoin_txid *txid,
unsigned int output,
enum watch_result (*cb)(struct channel *channel,
const struct bitcoin_tx *tx,
size_t input_num,
const struct block *block))
{
struct txowatch *w = tal(ctx, struct txowatch);
w->topo = topo;
w->out.txid = *txid;
w->out.index = output;
w->channel = channel;
w->cb = cb;
txowatch_hash_add(&w->topo->txowatches, w);
tal_add_destructor(w, destroy_txowatch);
return w;
}
/* Returns true if we fired a callback */
static bool txw_fire(struct txwatch *txw,
const struct bitcoin_tx *tx,
unsigned int depth)
{
enum watch_result r;
if (depth == txw->depth)
return false;
log_debug(txw->channel->log,
"Got depth change %u->%u for %s",
txw->depth, depth,
type_to_string(ltmp, struct bitcoin_txid, &txw->txid));
txw->depth = depth;
r = txw->cb(txw->channel, tx, txw->depth);
switch (r) {
case DELETE_WATCH:
tal_free(txw);
return true;
case KEEP_WATCHING:
return true;
}
fatal("txwatch callback %p returned %i\n", txw->cb, r);
}
void txwatch_fire(struct chain_topology *topo,
const struct bitcoin_tx *tx,
unsigned int depth)
{
struct bitcoin_txid txid;
struct txwatch *txw;
bitcoin_txid(tx, &txid);
txw = txwatch_hash_get(&topo->txwatches, &txid);
if (txw)
txw_fire(txw, tx, depth);
}
void txowatch_fire(const struct txowatch *txow,
const struct bitcoin_tx *tx,
size_t input_num,
const struct block *block)
{
struct bitcoin_txid txid;
enum watch_result r;
bitcoin_txid(tx, &txid);
log_debug(txow->channel->log,
"Got UTXO spend for %s:%u: %s",
type_to_string(ltmp, struct bitcoin_txid, &txow->out.txid),
txow->out.index,
type_to_string(ltmp, struct bitcoin_txid, &txid));
r = txow->cb(txow->channel, tx, input_num, block);
switch (r) {
case DELETE_WATCH:
tal_free(txow);
return;
case KEEP_WATCHING:
return;
}
fatal("txowatch callback %p returned %i", txow->cb, r);
}
void watch_topology_changed(struct chain_topology *topo)
{
struct txwatch_hash_iter i;
struct txwatch *w;
bool needs_rerun;
again:
/* Iterating a htable during deletes is safe, but might skip entries. */
needs_rerun = false;
for (w = txwatch_hash_first(&topo->txwatches, &i);
w;
w = txwatch_hash_next(&topo->txwatches, &i)) {
u32 depth;
const struct bitcoin_tx *tx;
depth = get_tx_depth(topo, &w->txid, &tx);
if (depth)
needs_rerun |= txw_fire(w, tx, depth);
}
if (needs_rerun)
goto again;
}