From b2819f9f97882bdc328ec87469571b5dec52ec8a Mon Sep 17 00:00:00 2001
From: Christian Decker <decker.christian@gmail.com>
Date: Fri, 16 Feb 2018 17:55:33 +0100
Subject: [PATCH] wallet: Add check that wallet matches the network on startup

Adds a simple check that compares genesis-blockhashes from the
chainparams against the blockhash that the wallet was created
with. The wallet is network specific, so mixing is always a bad idea.

Signed-off-by: Christian Decker <decker.christian@gmail.com>
---
 lightningd/lightningd.c            |  3 +++
 lightningd/test/run-find_my_path.c |  4 ++++
 wallet/wallet.c                    | 31 ++++++++++++++++++++++++++++++
 wallet/wallet.h                    | 12 ++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/lightningd/lightningd.c b/lightningd/lightningd.c
index 836b1bbc3..10b722579 100644
--- a/lightningd/lightningd.c
+++ b/lightningd/lightningd.c
@@ -304,6 +304,9 @@ int main(int argc, char *argv[])
 	/* Everything is within a transaction. */
 	db_begin_transaction(ld->wallet->db);
 
+	if (!wallet_network_check(ld->wallet, get_chainparams(ld)))
+		errx(1, "Wallet network check failed.");
+
 	/* Initialize the transaction filter with our pubkeys. */
 	init_txfilter(ld->wallet, ld->owned_txfilter);
 
diff --git a/lightningd/test/run-find_my_path.c b/lightningd/test/run-find_my_path.c
index 9b16093c3..288836f3e 100644
--- a/lightningd/test/run-find_my_path.c
+++ b/lightningd/test/run-find_my_path.c
@@ -107,6 +107,10 @@ bool wallet_htlcs_reconnect(struct wallet *wallet UNNEEDED,
 /* Generated stub for wallet_invoice_load */
 bool wallet_invoice_load(struct wallet *wallet UNNEEDED)
 { fprintf(stderr, "wallet_invoice_load called!\n"); abort(); }
+/* Generated stub for wallet_network_check */
+bool wallet_network_check(struct wallet *w UNNEEDED,
+			  const struct chainparams *chainparams UNNEEDED)
+{ fprintf(stderr, "wallet_network_check called!\n"); abort(); }
 /* Generated stub for wallet_new */
 struct wallet *wallet_new(struct lightningd *ld UNNEEDED,
 			  struct log *log UNNEEDED, struct timers *timers UNNEEDED)
diff --git a/wallet/wallet.c b/wallet/wallet.c
index 6795ee7c1..1713825fa 100644
--- a/wallet/wallet.c
+++ b/wallet/wallet.c
@@ -1618,3 +1618,34 @@ void wallet_htlc_sigs_save(struct wallet *w, u64 channel_id,
 		db_exec_prepared(w->db, stmt);
 	}
 }
+
+bool wallet_network_check(struct wallet *w,
+			  const struct chainparams *chainparams)
+{
+	sqlite3_stmt *stmt = db_query(__func__, w->db,
+				      "SELECT val FROM vars WHERE name='genesis_hash'");
+	struct bitcoin_blkid chainhash;
+
+	if (stmt && sqlite3_step(stmt) == SQLITE_ROW) {
+		sqlite3_column_sha256_double(stmt, 0, &chainhash.shad);
+		sqlite3_finalize(stmt);
+		if (!structeq(&chainhash, &chainparams->genesis_blockhash)) {
+			log_broken(w->log, "Wallet blockchain hash does not "
+					   "match network blockchain hash: %s "
+					   "!= %s",
+				   type_to_string(w, struct bitcoin_blkid,
+						  &chainhash),
+				   type_to_string(w, struct bitcoin_blkid,
+						  &chainparams->genesis_blockhash));
+			return false;
+		}
+	} else {
+		/* Still a pristine wallet, claim it for the chain
+		 * that we are running */
+		sqlite3_finalize(stmt);
+		stmt = db_prepare(w->db, "INSERT INTO vars (name, val) VALUES ('genesis_hash', ?);");
+		sqlite3_bind_sha256_double(stmt, 1, &chainparams->genesis_blockhash.shad);
+		db_exec_prepared(w->db, stmt);
+	}
+	return true;
+}
diff --git a/wallet/wallet.h b/wallet/wallet.h
index f911065fe..de32f47ef 100644
--- a/wallet/wallet.h
+++ b/wallet/wallet.h
@@ -3,6 +3,7 @@
 
 #include "config.h"
 #include "db.h"
+#include <bitcoin/chainparams.h>
 #include <bitcoin/tx.h>
 #include <ccan/crypto/shachain/shachain.h>
 #include <ccan/list/list.h>
@@ -618,4 +619,15 @@ const struct wallet_payment **wallet_payment_list(const tal_t *ctx,
  */
 void wallet_htlc_sigs_save(struct wallet *w, u64 channel_id,
 			   secp256k1_ecdsa_signature *htlc_sigs);
+
+/**
+ * wallet_network_check - Check that the wallet is setup for this chain
+ *
+ * Ensure that the genesis_hash from the chainparams matches the
+ * genesis_hash with which the DB was initialized. Returns false if
+ * the check failed, i.e., if the genesis hashes do not match.
+ */
+bool wallet_network_check(struct wallet *w,
+			  const struct chainparams *chainparams);
+
 #endif /* WALLET_WALLET_H */