lightningd: check bitcoind version when setup_topology

lightningd/bitcoind.c

@@ -783,6 +783,66 @@ void bitcoind_gettxout(struct bitcoind *bitcoind,
 			  NULL);
 }
 
+static bool extract_numeric_version(struct bitcoin_cli *bcli,
+			    const char *output, size_t output_bytes,
+			    u64 *version)
+{
+	const jsmntok_t *tokens, *versiontok;
+	bool valid;
+
+	tokens = json_parse_input(output, output, output_bytes, &valid);
+	if (!tokens)
+		fatal("%s: %s response",
+		      bcli_args(tmpctx, bcli),
+		      valid ? "partial" : "invalid");
+
+	if (tokens[0].type != JSMN_OBJECT) {
+		log_unusual(bcli->bitcoind->log,
+			    "%s: gave non-object (%.*s)?",
+			    bcli_args(tmpctx, bcli),
+			    (int)output_bytes, output);
+		return false;
+	}
+
+	versiontok = json_get_member(output, tokens, "version");
+	if (!versiontok)
+		return false;
+
+	return json_to_u64(output, versiontok, version);
+}
+
+static bool process_getclientversion(struct bitcoin_cli *bcli)
+{
+	u64 version;
+	u64 min_version = bcli->bitcoind->chainparams->cli_min_supported_version;
+
+	if (!extract_numeric_version(bcli, bcli->output,
+				     bcli->output_bytes,
+				     &version)) {
+		fatal("%s: Unable to getclientversion (%.*s)",
+		      bcli_args(tmpctx, bcli),
+		      (int)bcli->output_bytes,
+		      bcli->output);
+	}
+
+	if (version < min_version)
+		fatal("Unsupported bitcoind version? bitcoind version: %"PRIu64","
+		      " supported minimum version: %"PRIu64"",
+		      version, min_version);
+
+	return true;
+}
+
+void bitcoind_getclientversion(struct bitcoind *bitcoind)
+{
+	/* `getnetworkinfo` was added in v0.14.0. The older version would
+	 * return non-zero exitstatus. */
+	start_bitcoin_cli(bitcoind, NULL, process_getclientversion, false,
+			  BITCOIND_HIGH_PRIO,
+			  NULL, NULL,
+			  "getnetworkinfo", NULL);
+}
+
 static void destroy_bitcoind(struct bitcoind *bitcoind)
 {
 	/* Suppresses the callbacks from bcli_finished as we free conns. */

lightningd/bitcoind.h

@@ -168,4 +168,6 @@ void bitcoind_gettxout(struct bitcoind *bitcoind,
 				  void *arg),
 		       void *arg);
 
+void bitcoind_getclientversion(struct bitcoind *bitcoind);
+
 #endif /* LIGHTNING_LIGHTNINGD_BITCOIND_H */

lightningd/chaintopology.c

@@ -912,6 +912,8 @@ void setup_topology(struct chain_topology *topo,
 	/* Make sure bitcoind is started, and ready */
 	wait_for_bitcoind(topo->bitcoind);
 
+	bitcoind_getclientversion(topo->bitcoind);
+
 	bitcoind_getblockcount(topo->bitcoind, get_init_blockhash, topo);
 
 	tal_add_destructor(topo, destroy_chain_topology);