Added --no-dns command line parameter

docs/COMMAND_LINE.MD

@@ -24,6 +24,7 @@
 --no-autodiff        Disable automatic difficulty adjustment for miners connected to stratum
 --rpc-login          Specify username[:password] required for Monero RPC server
 --socks5             Specify IP:port of a SOCKS5 proxy to use for outgoing connections
+--no-dns             disable DNS queries, use only IP addresses to connect to peers (seed node DNS will be unavailable too)
 ```
 
 ### Example command line

src/main.cpp

@@ -49,6 +49,7 @@ void p2pool_usage()
 		"--no-autodiff        Disable automatic difficulty adjustment for miners connected to stratum\n"
 		"--rpc-login          Specify username[:password] required for Monero RPC server\n"
 		"--socks5             Specify IP:port of a SOCKS5 proxy to use for outgoing connections\n"
+		"--no-dns             disable DNS queries, use only IP addresses to connect to peers (seed node DNS will be unavailable too)\n"
 		"--help               Show this help message\n\n"
 		"Example command line:\n\n"
 		"%s --host 127.0.0.1 --rpc-port 18081 --zmq-port 18083 --wallet YOUR_WALLET_ADDRESS --stratum 0.0.0.0:%d --p2p 0.0.0.0:%d\n\n",

src/p2p_server.cpp

@@ -246,7 +246,7 @@ void P2PServer::connect_to_peers(const std::string& peer_list)
 	parse_address_list(peer_list,
 		[this](bool is_v6, const std::string& /*address*/, std::string ip, int port)
 		{
-			if (!m_socks5Proxy.empty() || resolve_host(ip, is_v6)) {
+			if (!m_pool->params().m_dns || resolve_host(ip, is_v6)) {
 				connect_to_peer(is_v6, ip.c_str(), port);
 			}
 		});
@@ -356,7 +356,7 @@ void P2PServer::update_peer_connections()
 		peer_list.pop_back();
 	}
 
-	if (!has_good_peers && ((m_timerCounter % 30) == 0)) {
+	if (!has_good_peers && ((m_timerCounter % 10) == 0)) {
 		LOGERR(1, "no connections to other p2pool nodes, check your monerod/p2pool/network/firewall setup!!!");
 		load_peer_list();
 		if (m_peerListMonero.empty()) {
@@ -536,12 +536,14 @@ void P2PServer::load_peer_list()
 		}
 	};
 
+	if (m_pool->params().m_dns) {
 		if (m_pool->side_chain().is_default()) {
 			load_from_seed_nodes(seed_nodes, DEFAULT_P2P_PORT);
 		}
 		else if (m_pool->side_chain().is_mini()) {
 			load_from_seed_nodes(seed_nodes_mini, DEFAULT_P2P_PORT_MINI);
 		}
+	}
 
 	// Finally load peers from p2pool_peers.txt
 	std::ifstream f(saved_peer_list_file_name);

src/p2pool.cpp

@@ -64,11 +64,19 @@ p2pool::p2pool(int argc, char* argv[])
 		throw std::exception();
 	}
 
+	if (m_params->m_socks5Proxy.empty()) {
+		if (m_params->m_dns) {
 			bool is_v6;
-	if (m_params->m_socks5Proxy.empty() && !resolve_host(m_params->m_host, is_v6)) {
+			if (!resolve_host(m_params->m_host, is_v6)) {
 				LOGERR(1, "resolve_host failed for " << m_params->m_host);
 				throw std::exception();
 			}
+		}
+		else if (m_params->m_host.find_first_not_of("0123456789.:") != std::string::npos) {
+			LOGERR(1, "Can't resolve hostname " << m_params->m_host << " with DNS disabled");
+			throw std::exception();
+		}
+	}
 
 	hash pub, sec, eph_public_key;
 	generate_keys(pub, sec);

src/params.cpp

@@ -140,6 +140,12 @@ Params::Params(int argc, char* argv[])
 			ok = true;
 		}
 
+		if (strcmp(argv[i], "--no-dns") == 0) {
+			m_dns = false;
+			disable_resolve_host = true;
+			ok = true;
+		}
+
 		if (!ok) {
 			fprintf(stderr, "Unknown command line parameter %s\n\n", argv[i]);
 			p2pool_usage();

src/params.h

@@ -51,6 +51,7 @@ struct Params
 	bool m_autoDiff = true;
 	std::string m_rpcLogin;
 	std::string m_socks5Proxy;
+	bool m_dns = true;
 };
 
 } // namespace p2pool

src/util.cpp

@@ -353,8 +353,15 @@ static thread_local bool main_thread = false;
 void set_main_thread() { main_thread = true; }
 bool is_main_thread() { return main_thread; }
 
+bool disable_resolve_host = false;
+
 bool resolve_host(std::string& host, bool& is_v6)
 {
+	if (disable_resolve_host) {
+		LOGERR(1, "resolve_host was called with DNS disabled for host " << host);
+		return false;
+	}
+
 	addrinfo hints{};
 	hints.ai_family = AF_UNSPEC;
 	hints.ai_socktype = SOCK_STREAM;

src/util.h

@@ -171,6 +171,7 @@ extern BackgroundJobTracker bkg_jobs_tracker;
 void set_main_thread();
 bool is_main_thread();
 
+extern bool disable_resolve_host;
 bool resolve_host(std::string& host, bool& is_v6);
 
 template <typename Key, typename T>