core-lightning/wallet/wallet.c

#include "wallet.h"

#include <bitcoin/script.h>
#include <ccan/str/hex/hex.h>
#include <lightningd/lightningd.h>

struct wallet *wallet_new(const tal_t *ctx, struct log *log)
{
	struct wallet *wallet = tal(ctx, struct wallet);
	wallet->db = db_setup(wallet);
	wallet->log = log;
	wallet->bip32_base = NULL;
	if (!wallet->db) {
		fatal("Unable to setup the wallet database");
	}
	return wallet;
}

bool wallet_add_utxo(struct wallet *w, struct utxo *utxo,
		     enum wallet_output_type type)
{
	tal_t *tmpctx = tal_tmpctx(w);
	char *hextxid = tal_hexstr(tmpctx, &utxo->txid, 32);
	bool result = db_exec(
	    __func__, w->db,
	    "INSERT INTO outputs (prev_out_tx, prev_out_index, value, type, "
	    "status, keyindex) VALUES ('%s', %d, %zu, %d, %d, %d);",
	    hextxid, utxo->outnum, utxo->amount, type, output_state_available,
	    utxo->keyindex);
	tal_free(tmpctx);
	return result;
}

/**
 * wallet_stmt2output - Extract data from stmt and fill a utxo
 *
 * Returns true on success.
 */
static bool wallet_stmt2output(sqlite3_stmt *stmt, struct utxo *utxo)
{
	const unsigned char *hextxid = sqlite3_column_text(stmt, 0);
	hex_decode((const char*)hextxid, sizeof(utxo->txid) * 2, &utxo->txid, sizeof(utxo->txid));
	utxo->outnum = sqlite3_column_int(stmt, 1);
	utxo->amount = sqlite3_column_int(stmt, 2);
	utxo->is_p2sh = sqlite3_column_int(stmt, 3) == p2sh_wpkh;
	utxo->status = sqlite3_column_int(stmt, 4);
	utxo->keyindex = sqlite3_column_int(stmt, 5);
	return true;
}

bool wallet_update_output_status(struct wallet *w,
				 const struct sha256_double *txid,
				 const u32 outnum, enum output_status oldstatus,
				 enum output_status newstatus)
{
	tal_t *tmpctx = tal_tmpctx(w);
	char *hextxid = tal_hexstr(tmpctx, txid, sizeof(*txid));
	if (oldstatus != output_state_any) {
		db_exec(__func__, w->db,
			"UPDATE outputs SET status=%d WHERE status=%d "
			"AND prev_out_tx = '%s' AND prev_out_index = "
			"%d;",
			newstatus, oldstatus, hextxid, outnum);
	} else {
		db_exec(__func__, w->db,
			"UPDATE outputs SET status=%d WHERE "
			"AND prev_out_tx = '%s' AND prev_out_index = "
			"%d;",
			newstatus, hextxid, outnum);
	}
	tal_free(tmpctx);
	return sqlite3_changes(w->db->sql) > 0;
}

struct utxo **wallet_get_utxos(const tal_t *ctx, struct wallet *w, const enum output_status state)
{
	struct utxo **results;
	int i;
	sqlite3_stmt *stmt =
	    db_query(__func__, w->db, "SELECT prev_out_tx, prev_out_index, "
				      "value, type, status, keyindex FROM "
				      "outputs WHERE status=%d OR %d=255",
		     state, state);

	if (!stmt)
		return NULL;

	results = tal_arr(ctx, struct utxo*, 0);
	for (i=0; sqlite3_step(stmt) == SQLITE_ROW; i++) {
		tal_resize(&results, i+1);
		results[i] = tal(results, struct utxo);
		wallet_stmt2output(stmt, results[i]);
	}
	sqlite3_finalize(stmt);

	return results;
}

/**
 * unreserve_utxo - Mark a reserved UTXO as available again
 */
static void unreserve_utxo(struct wallet *w, const struct utxo *unres)
{
	if (!wallet_update_output_status(w, &unres->txid, unres->outnum,
					 output_state_reserved,
					 output_state_available)) {
		fatal("Unable to unreserve output: %s", w->db->err);
	}
}

/**
 * destroy_utxos - Destructor for an array of pointers to utxo
 */
static void destroy_utxos(const struct utxo **utxos, struct wallet *w)
{
	for (size_t i = 0; i < tal_count(utxos); i++)
		unreserve_utxo(w, utxos[i]);
}

void wallet_confirm_utxos(struct wallet *w, const struct utxo **utxos)
{
	tal_del_destructor2(utxos, destroy_utxos, w);
	for (size_t i = 0; i < tal_count(utxos); i++) {
		if (!wallet_update_output_status(
			w, &utxos[i]->txid, utxos[i]->outnum,
			output_state_reserved, output_state_spent)) {
			fatal("Unable to mark output as spent: %s", w->db->err);
		}
	}
}

const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
					const u64 value,
					const u32 feerate_per_kw,
					u64 *fee_estimate, u64 *changesatoshi)
{
	size_t i = 0;
	struct utxo **available;
	const struct utxo **utxos = tal_arr(ctx, const struct utxo *, 0);
	*fee_estimate = 0;

	/* We assume two outputs for the weight. */
	u64 satoshi_in = 0, weight = (4 + (8 + 22) * 2 + 4) * 4;
	tal_add_destructor2(utxos, destroy_utxos, w);

	if (!db_begin_transaction(w->db)) {
		fatal("Unable to begin transaction: %s", w->db->err);
	}
	available = wallet_get_utxos(ctx, w, output_state_available);

	for (i = 0; i < tal_count(available); i++) {
		tal_resize(&utxos, i + 1);
		utxos[i] = tal_steal(utxos, available[i]);

		if (!wallet_update_output_status(
			w, &available[i]->txid, available[i]->outnum,
			output_state_available, output_state_reserved))
			fatal("Unable to reserve output: %s", w->db->err);

		weight += (32 + 4 + 4) * 4;
		if (utxos[i]->is_p2sh)
			weight += 22 * 4;

		/* Account for witness (1 byte count + sig + key */
		weight += 1 + (1 + 73 + 1 + 33);
		*fee_estimate = weight * feerate_per_kw / 1000;
		satoshi_in += utxos[i]->amount;
		if (satoshi_in >= *fee_estimate + value)
			break;
	}
	tal_free(available);

	if (satoshi_in < *fee_estimate + value) {
		/* Could not collect enough inputs, cleanup and bail */
		utxos = tal_free(utxos);
		db_rollback_transaction(w->db);
	} else {
		/* Commit the db transaction to persist markings */
		db_commit_transaction(w->db);
		*changesatoshi = satoshi_in - value - *fee_estimate;

	}
	return utxos;
}

bool wallet_can_spend(struct wallet *w, const u8 *script,
		      u32 *index, bool *output_is_p2sh)
{
	struct ext_key ext;
	u64 bip32_max_index = db_get_intvar(w->db, "bip32_max_index", 0);
	u32 i;

	/* If not one of these, can't be for us. */
	if (is_p2sh(script))
		*output_is_p2sh = true;
	else if (is_p2wpkh(script))
		*output_is_p2sh = false;
	else
		return false;

	for (i = 0; i <= bip32_max_index; i++) {
		u8 *s;

		if (bip32_key_from_parent(w->bip32_base, i,
					  BIP32_FLAG_KEY_PUBLIC, &ext)
		    != WALLY_OK) {
			abort();
		}
		s = scriptpubkey_p2wpkh_derkey(w, ext.pub_key);
		if (*output_is_p2sh) {
			u8 *p2sh = scriptpubkey_p2sh(w, s);
			tal_free(s);
			s = p2sh;
		}
		if (scripteq(s, script)) {
			tal_free(s);
			*index = i;
			return true;
		}
		tal_free(s);
	}
	return false;
}

s64 wallet_get_newindex(struct lightningd *ld)
{
	u64 newidx = db_get_intvar(ld->wallet->db, "bip32_max_index", 0) + 1;

	if (newidx == BIP32_INITIAL_HARDENED_CHILD)
		return -1;

	db_set_intvar(ld->wallet->db, "bip32_max_index", newidx);
	return newidx;
}