[no squash] Networking improvements / hardening

src/clientiface.cpp

@@ -33,21 +33,31 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/srp.h"
 #include "face_position_cache.h"
 
+static std::string string_sanitize_ascii(const std::string &s, u32 max_length)
+{
+	std::string out;
+	for (char c : s) {
+		if (out.size() >= max_length)
+			break;
+		if (c > 32 && c < 127)
+			out.push_back(c);
+	}
+	return out;
+}
+
 const char *ClientInterface::statenames[] = {
 	"Invalid",
 	"Disconnecting",
 	"Denied",
 	"Created",
-	"AwaitingInit2",
 	"HelloSent",
+	"AwaitingInit2",
 	"InitDone",
 	"DefinitionsSent",
 	"Active",
 	"SudoMode",
 };
 
-
-
 std::string ClientInterface::state2Name(ClientState state)
 {
 	return statenames[state];
@@ -639,16 +649,23 @@ void RemoteClient::resetChosenMech()
 	chosen_mech = AUTH_MECHANISM_NONE;
 }
 
-u64 RemoteClient::uptime() const
+void RemoteClient::setVersionInfo(u8 major, u8 minor, u8 patch, const std::string &full)
 {
-	return porting::getTimeS() - m_connection_time;
+	m_version_major = major;
+	m_version_minor = minor;
+	m_version_patch = patch;
+	m_full_version = string_sanitize_ascii(full, 64);
+}
+
+void RemoteClient::setLangCode(const std::string &code)
+{
+	m_lang_code = string_sanitize_ascii(code, 12);
 }
 
 ClientInterface::ClientInterface(const std::shared_ptr<con::Connection> & con)
 :
 	m_con(con),
-	m_env(NULL),
-	m_print_info_timer(0.0f)
+	m_env(nullptr)
 {
 
 }
@@ -706,6 +723,34 @@ void ClientInterface::step(float dtime)
 		m_print_info_timer = 0.0f;
 		UpdatePlayerList();
 	}
+
+	m_check_linger_timer += dtime;
+	if (m_check_linger_timer < 1.0f)
+		return;
+	m_check_linger_timer = 0;
+
+	RecursiveMutexAutoLock clientslock(m_clients_mutex);
+	for (const auto &it : m_clients) {
+		auto state = it.second->getState();
+		if (state >= CS_HelloSent)
+			continue;
+		if (it.second->uptime() <= LINGER_TIMEOUT)
+			continue;
+		// CS_Created means nobody has even noticed the client is there
+		//            (this is before on_prejoinplayer runs)
+		// CS_Invalid should not happen
+		// -> log those as warning, the rest as info
+		std::ostream &os = state == CS_Created || state == CS_Invalid ?
+			warningstream : infostream;
+		try {
+			Address addr = m_con->GetPeerAddress(it.second->peer_id);
+			os << "Disconnecting lingering client from "
+				<< addr.serializeString() << " (state="
+				<< state2Name(state) << ")" << std::endl;
+			m_con->DisconnectPeer(it.second->peer_id);
+		} catch (con::PeerNotFoundException &e) {
+		}
+	}
 }
 
 void ClientInterface::UpdatePlayerList()

src/clientiface.h

@@ -181,8 +181,8 @@ enum ClientState
 	CS_Disconnecting,
 	CS_Denied,
 	CS_Created,
-	CS_AwaitingInit2,
 	CS_HelloSent,
+	CS_AwaitingInit2,
 	CS_InitDone,
 	CS_DefinitionsSent,
 	CS_Active,
@@ -329,24 +329,18 @@ class RemoteClient
 		{ serialization_version = m_pending_serialization_version; }
 
 	/* get uptime */
-	u64 uptime() const;
+	u64 uptime() const { return porting::getTimeS() - m_connection_time; }
 
 	/* set version information */
-	void setVersionInfo(u8 major, u8 minor, u8 patch, const std::string &full)
-	{
-		m_version_major = major;
-		m_version_minor = minor;
-		m_version_patch = patch;
-		m_full_version = full;
-	}
+	void setVersionInfo(u8 major, u8 minor, u8 patch, const std::string &full);
 
 	/* read version information */
 	u8 getMajor() const { return m_version_major; }
 	u8 getMinor() const { return m_version_minor; }
 	u8 getPatch() const { return m_version_patch; }
 	const std::string &getFullVer() const { return m_full_version; }
 
-	void setLangCode(const std::string &code) { m_lang_code = code; }
+	void setLangCode(const std::string &code);
 	const std::string &getLangCode() const { return m_lang_code; }
 
 	void setCachedAddress(const Address &addr) { m_addr = addr; }
@@ -550,7 +544,10 @@ class ClientInterface {
 	// Environment
 	ServerEnvironment *m_env;
 
-	float m_print_info_timer;
+	float m_print_info_timer = 0;
+	float m_check_linger_timer = 0;
 
 	static const char *statenames[];
+
+	static constexpr int LINGER_TIMEOUT = 10;
 };

src/constants.h

@@ -42,11 +42,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #define CONNECTION_TIMEOUT 30
 
-#define RESEND_TIMEOUT_MIN 0.1
-#define RESEND_TIMEOUT_MAX 3.0
-// resend_timeout = avg_rtt * this
-#define RESEND_TIMEOUT_FACTOR 4
-
 /*
     Server
 */