wallet: add path_secrets to payment table.

We need these to decode any returned errors.

We remove it from struct pay_command too, and load directly from db
when we need it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/pay.c

@@ -28,9 +28,6 @@ struct pay_command {
 	/* Preimage if this succeeded. */
 	const struct preimage *rval;
 	struct command *cmd;
-
-	/* Remember all shared secrets, so we can unwrap an eventual failure */
-	struct secret *path_secrets;
 };
 
 static void json_pay_success(struct command *cmd, const struct preimage *rval)
@@ -82,6 +79,8 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 	struct pay_command *pc = hout->pay_command;
 	struct onionreply *reply;
 	enum onion_type failcode;
+	struct secret *path_secrets;
+	const tal_t *tmpctx = tal_tmpctx(ld);
 
 	wallet_payment_set_status(ld->wallet, &hout->payment_hash,
 				  PAYMENT_FAILED, NULL);
@@ -89,13 +88,15 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 	/* This gives more details than a generic failure message */
 	if (localfail) {
 		json_pay_failed(pc, NULL, hout->failcode, localfail);
+		tal_free(tmpctx);
 		return;
 	}
 
 	/* Must be remote fail. */
 	assert(!hout->failcode);
-	reply = unwrap_onionreply(pc, pc->path_secrets,
+	path_secrets = wallet_payment_get_secrets(tmpctx, ld->wallet,
-				  tal_count(pc->path_secrets),
+						  &hout->payment_hash);
+	reply = unwrap_onionreply(pc, path_secrets, tal_count(path_secrets),
 				  hout->failuremsg);
 	if (!reply) {
 		log_info(hout->key.peer->log,
@@ -118,6 +119,7 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 	/* check_for_routing_failure(i, sender, failure_code); */
 
 	json_pay_failed(pc, NULL, failcode, "reply from remote");
+	tal_free(tmpctx);
 }
 
 /* When JSON RPC goes away, cmd is freed: detach from any running paycommand */
@@ -237,7 +239,6 @@ static bool send_payment(struct command *cmd,
 
 	if (pc) {
 		pc->ids = tal_free(pc->ids);
-		pc->path_secrets = tal_free(pc->path_secrets);
 	} else {
 		pc = tal(cmd->ld, struct pay_command);
 		list_add_tail(&cmd->ld->pay_commands, &pc->list);
@@ -251,13 +252,13 @@ static bool send_payment(struct command *cmd,
 		payment->msatoshi = route[n_hops-1].amount;
 		payment->timestamp = time_now().ts.tv_sec;
 		payment->payment_preimage = NULL;
+		payment->path_secrets = tal_steal(payment, path_secrets);
 	}
 	pc->cmd = cmd;
 	pc->rhash = *rhash;
 	pc->rval = NULL;
 	pc->ids = tal_steal(pc, ids);
 	pc->msatoshi = route[n_hops-1].amount;
-	pc->path_secrets = tal_steal(pc, path_secrets);
 	pc->out = NULL;
 
 	log_info(cmd->ld->log, "Sending %u over %zu hops to deliver %"PRIu64,

wallet/db.c

@@ -175,6 +175,8 @@ char *dbmigrations[] = {
     "DROP TABLE temp_payments;",
     /* We need to keep the preimage in case they ask to pay again. */
     "ALTER TABLE payments ADD COLUMN payment_preimage BLOB;",
+    /* We need to keep the shared secrets to decode error returns. */
+    "ALTER TABLE payments ADD COLUMN path_secrets BLOB;",
     NULL,
 };
 
@@ -533,6 +535,8 @@ struct secret *sqlite3_column_secrets(const tal_t *ctx,
 
 	/* Must fit exactly */
 	assert(n * sizeof(struct secret) == sqlite3_column_bytes(stmt, col));
+	if (n == 0)
+		return NULL;
 	secrets = tal_arr(ctx, struct secret, n);
 	return memcpy(secrets, sqlite3_column_blob(stmt, col), tal_len(secrets));
 }

wallet/wallet.c

@@ -1289,6 +1289,9 @@ static struct wallet_payment *wallet_stmt2payment(const tal_t *ctx,
 		sqlite3_column_preimage(stmt, 6, payment->payment_preimage);
 	} else
 		payment->payment_preimage = NULL;
+
+	/* Can be NULL for old db! */
+	payment->path_secrets = sqlite3_column_secrets(payment, stmt, 7);
 	return payment;
 }
 
@@ -1301,7 +1304,8 @@ wallet_payment_by_hash(const tal_t *ctx, struct wallet *wallet,
 
 	stmt = db_prepare(wallet->db,
 			  "SELECT id, status, destination,"
-			  "msatoshi, payment_hash, timestamp, payment_preimage "
+			  "msatoshi, payment_hash, timestamp, payment_preimage, "
+			  "path_secrets "
 			  "FROM payments "
 			  "WHERE payment_hash = ?");
 
@@ -1313,6 +1317,26 @@ wallet_payment_by_hash(const tal_t *ctx, struct wallet *wallet,
 	return payment;
 }
 
+struct secret *wallet_payment_get_secrets(const tal_t *ctx,
+					  struct wallet *wallet,
+					  const struct sha256 *payment_hash)
+{
+	sqlite3_stmt *stmt;
+	struct secret *path_secrets = NULL;
+
+	stmt = db_prepare(wallet->db,
+			  "SELECT path_secrets "
+			  "FROM payments "
+			  "WHERE payment_hash = ?");
+
+	sqlite3_bind_sha256(stmt, 1, payment_hash);
+	if (sqlite3_step(stmt) == SQLITE_ROW) {
+		path_secrets = sqlite3_column_secrets(ctx, stmt, 0);
+	}
+	sqlite3_finalize(stmt);
+	return path_secrets;
+}
+
 void wallet_payment_set_status(struct wallet *wallet,
 			       const struct sha256 *payment_hash,
 			       const enum wallet_payment_status newstatus,
@@ -1349,7 +1373,8 @@ const struct wallet_payment **wallet_payment_list(const tal_t *ctx,
 	stmt = db_prepare(
 		wallet->db,
 		"SELECT id, status, destination, "
-		"msatoshi , payment_hash, timestamp, payment_preimage "
+		"msatoshi, payment_hash, timestamp, payment_preimage, "
+		"path_secrets "
 		"FROM payments;");
 
 	for (int i = 0; sqlite3_step(stmt) == SQLITE_ROW; i++) {

wallet/wallet.h

@@ -90,6 +90,7 @@ struct wallet_payment {
 	u64 msatoshi;
 	/* Iff PAYMENT_COMPLETE */
 	struct preimage *payment_preimage;
+	struct secret *path_secrets;
 };
 
 /**
@@ -556,6 +557,15 @@ void wallet_payment_set_status(struct wallet *wallet,
 			        const enum wallet_payment_status newstatus,
 			        const struct preimage *preimage);
 
+/**
+ * wallet_payment_get_secrets - Get the secrets array for a given `payment_hash`
+ *
+ * Returns a tal_array: can return NULL for old dbs.
+ */
+struct secret *wallet_payment_get_secrets(const tal_t *ctx,
+					  struct wallet *wallet,
+					  const struct sha256 *payment_hash);
+
 /**
  * wallet_payment_list - Retrieve a list of payments
  */