wallet: add preimage to db.

We should be saving this, as it's our proof of payment.  Also, we return
it if they try to pay again.

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

lightningd/pay.c

@@ -68,7 +68,8 @@ void payment_succeeded(struct lightningd *ld, struct htlc_out *hout,
 		       const struct preimage *rval)
 {
 	assert(!hout->pay_command->rval);
-	wallet_payment_set_status(ld->wallet, &hout->payment_hash, PAYMENT_COMPLETE);
+	wallet_payment_set_status(ld->wallet, &hout->payment_hash,
+				  PAYMENT_COMPLETE, rval);
 	hout->pay_command->rval = tal_dup(hout->pay_command,
 					  struct preimage, rval);
 	json_pay_success(hout->pay_command->cmd, rval);
@@ -82,7 +83,8 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 	struct onionreply *reply;
 	enum onion_type failcode;
 
-	wallet_payment_set_status(ld->wallet, &hout->payment_hash, PAYMENT_FAILED);
+	wallet_payment_set_status(ld->wallet, &hout->payment_hash,
+				  PAYMENT_FAILED, NULL);
 
 	/* This gives more details than a generic failure message */
 	if (localfail) {
@@ -248,6 +250,7 @@ static bool send_payment(struct command *cmd,
 		payment->status = PAYMENT_PENDING;
 		payment->msatoshi = route[n_hops-1].amount;
 		payment->timestamp = time_now().ts.tv_sec;
+		payment->payment_preimage = NULL;
 	}
 	pc->cmd = cmd;
 	pc->rhash = *rhash;
@@ -514,6 +517,10 @@ static void json_listpayments(struct command *cmd, const char *buffer,
 			json_add_string(response, "status", "failed");
 			break;
 		}
+		if (t->payment_preimage)
+			json_add_hex(response, "payment_preimage",
+				     t->payment_preimage,
+				     sizeof(*t->payment_preimage));
 
 		json_object_end(response);
 	}

wallet/db.c

@@ -173,6 +173,8 @@ char *dbmigrations[] = {
     ");",
     "INSERT INTO payments SELECT id, timestamp, status, payment_hash, destination, msatoshi FROM temp_payments WHERE direction=1;",
     "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;",
     NULL,
 };
 

wallet/test/run-wallet.c

@@ -15,6 +15,7 @@ static void db_log_(struct log *log, enum log_level level, const char *fmt, ...)
 
 #include <ccan/mem/mem.h>
 #include <ccan/tal/str/str.h>
+#include <ccan/structeq/structeq.h>
 #include <common/memleak.h>
 #include <stdarg.h>
 #include <stddef.h>
@@ -557,6 +558,7 @@ static bool test_payment_crud(const tal_t *ctx)
 	t.id = 0;
 	t.msatoshi = 100;
 	t.status = PAYMENT_PENDING;
+	t.payment_preimage = NULL;
 	memset(&t.payment_hash, 1, sizeof(t.payment_hash));
 
 	db_begin_transaction(w->db);
@@ -568,15 +570,20 @@ static bool test_payment_crud(const tal_t *ctx)
 	CHECK(t2->status == t.status);
 	CHECK(pubkey_cmp(&t2->destination, &t.destination) == 0);
 	CHECK(t2->msatoshi == t.msatoshi);
+	CHECK(!t2->payment_preimage);
 
 	t.status = PAYMENT_COMPLETE;
-	wallet_payment_set_status(w, &t.payment_hash, t.status);
+	t.payment_preimage = tal(w, struct preimage);
+	memset(t.payment_preimage, 2, sizeof(*t.payment_preimage));
+	wallet_payment_set_status(w, &t.payment_hash, t.status,
+				  t.payment_preimage);
 	t2 = wallet_payment_by_hash(ctx, w, &t.payment_hash);
 	CHECK(t2 != NULL);
 	CHECK(t2->id == t.id);
 	CHECK(t2->status == t.status);
 	CHECK(pubkey_cmp(&t2->destination, &t.destination) == 0);
 	CHECK(t2->msatoshi == t.msatoshi);
+	CHECK(structeq(t.payment_preimage, t2->payment_preimage));
 
 	db_commit_transaction(w->db);
 	return true;

wallet/wallet.c

@@ -1284,6 +1284,11 @@ static struct wallet_payment *wallet_stmt2payment(const tal_t *ctx,
 	sqlite3_column_sha256(stmt, 4, &payment->payment_hash);
 
 	payment->timestamp = sqlite3_column_int(stmt, 5);
+	if (sqlite3_column_type(stmt, 6) != SQLITE_NULL) {
+		payment->payment_preimage = tal(payment, struct preimage);
+		sqlite3_column_preimage(stmt, 6, payment->payment_preimage);
+	} else
+		payment->payment_preimage = NULL;
 	return payment;
 }
 
@@ -1296,7 +1301,7 @@ wallet_payment_by_hash(const tal_t *ctx, struct wallet *wallet,
 
 	stmt = db_prepare(wallet->db,
 			  "SELECT id, status, destination,"
-			  "msatoshi, payment_hash, timestamp "
+			  "msatoshi, payment_hash, timestamp, payment_preimage "
 			  "FROM payments "
 			  "WHERE payment_hash = ?");
 
@@ -1310,7 +1315,8 @@ wallet_payment_by_hash(const tal_t *ctx, struct wallet *wallet,
 
 void wallet_payment_set_status(struct wallet *wallet,
 			       const struct sha256 *payment_hash,
-			       const enum wallet_payment_status newstatus)
+			       const enum wallet_payment_status newstatus,
+			       const struct preimage *preimage)
 {
 	sqlite3_stmt *stmt;
 
@@ -1321,6 +1327,16 @@ void wallet_payment_set_status(struct wallet *wallet,
 	sqlite3_bind_int(stmt, 1, newstatus);
 	sqlite3_bind_sha256(stmt, 2, payment_hash);
 	db_exec_prepared(wallet->db, stmt);
+
+	if (preimage) {
+		stmt = db_prepare(wallet->db,
+				  "UPDATE payments SET payment_preimage=? "
+				  "WHERE payment_hash=?");
+
+		sqlite3_bind_preimage(stmt, 1, preimage);
+		sqlite3_bind_sha256(stmt, 2, payment_hash);
+		db_exec_prepared(wallet->db, stmt);
+	}
 }
 
 const struct wallet_payment **wallet_payment_list(const tal_t *ctx,
@@ -1333,7 +1349,7 @@ const struct wallet_payment **wallet_payment_list(const tal_t *ctx,
 	stmt = db_prepare(
 		wallet->db,
 		"SELECT id, status, destination, "
-		"msatoshi , payment_hash, timestamp "
+		"msatoshi , payment_hash, timestamp, payment_preimage "
 		"FROM payments;");
 
 	for (int i = 0; sqlite3_step(stmt) == SQLITE_ROW; i++) {

wallet/wallet.h

@@ -88,6 +88,8 @@ struct wallet_payment {
 	enum wallet_payment_status status;
 	struct pubkey destination;
 	u64 msatoshi;
+	/* Iff PAYMENT_COMPLETE */
+	struct preimage *payment_preimage;
 };
 
 /**
@@ -551,7 +553,8 @@ wallet_payment_by_hash(const tal_t *ctx, struct wallet *wallet,
  */
 void wallet_payment_set_status(struct wallet *wallet,
 				const struct sha256 *payment_hash,
-				const enum wallet_payment_status newstatus);
+			        const enum wallet_payment_status newstatus,
+			        const struct preimage *preimage);
 
 /**
  * wallet_payment_list - Retrieve a list of payments