dns_client: fix crash issue.

src/dns_client.c

@@ -3444,7 +3444,7 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
 	}
 
 	int num  = atomic_dec_return(&query->dns_request_sent);
-	if (num == 0) {
+	if (num == 0 && send_count > 0) {
 		_dns_client_query_remove(query);
 	}
 

test/cases/test-server.cc

@@ -0,0 +1,68 @@
+/*************************************************************************
+ *
+ * Copyright (C) 2018-2023 Ruilin Peng (Nick) <[email protected]>.
+ *
+ * smartdns is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * smartdns is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "client.h"
+#include "dns.h"
+#include "include/utils.h"
+#include "server.h"
+#include "gtest/gtest.h"
+
+class Server : public ::testing::Test
+{
+  protected:
+	virtual void SetUp() {}
+	virtual void TearDown() {}
+};
+
+TEST_F(Server, all_unreach)
+{
+	smartdns::MockServer server_upstream;
+	smartdns::Server server;
+
+	server_upstream.Start("udp://0.0.0.0:61053", [](struct smartdns::ServerRequestContext *request) {
+		if (request->qtype != DNS_T_A) {
+			return smartdns::SERVER_REQUEST_SOA;
+		}
+
+		smartdns::MockServer::AddIP(request, request->domain.c_str(), "1.2.3.4", 611);
+		EXPECT_EQ(request->domain, "e.com");
+		return smartdns::SERVER_REQUEST_OK;
+	});
+
+    server.MockPing(PING_TYPE_ICMP, "2001::", 128, 10000);
+	server.Start(R"""(bind [::]:60053
+bind-tcp [::]:60053
+server tls://255.255.255.255
+server https://255.255.255.255
+server tcp://255.255.255.255
+log-num 0
+log-console yes
+log-level debug
+cache-persist no)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("a.com", 60053));
+	std::cout << client.GetResult() << std::endl;
+	EXPECT_EQ(client.GetStatus(), "SERVFAIL");
+    EXPECT_EQ(client.GetAnswerNum(), 0);
+
+    /* server should not crash */
+    ASSERT_TRUE(client.Query("a.com +tcp", 60053));
+	std::cout << client.GetResult() << std::endl;
+	EXPECT_EQ(client.GetStatus(), "SERVFAIL");
+    EXPECT_EQ(client.GetAnswerNum(), 0);
+}