1 files changed, 14 insertions, 15 deletions

diff --git a/modules/upnp/upnp.cpp b/modules/upnp/upnp.cpp
index 5ef7575b0c..988bf3017d 100644
--- a/modules/upnp/upnp.cpp
+++ b/modules/upnp/upnp.cpp
@@ -44,9 +44,8 @@ bool UPNP::is_common_device(const String &dev) const {
 }
 
 int UPNP::discover(int timeout, int ttl, const String &device_filter) {
-	ERR_FAIL_COND_V(timeout < 0, UPNP_RESULT_INVALID_PARAM);
-	ERR_FAIL_COND_V(ttl < 0, UPNP_RESULT_INVALID_PARAM);
-	ERR_FAIL_COND_V(ttl > 255, UPNP_RESULT_INVALID_PARAM);
+	ERR_FAIL_COND_V_MSG(timeout < 0, UPNP_RESULT_INVALID_PARAM, "The response's wait time can't be negative.");
+	ERR_FAIL_COND_V_MSG(ttl < 0 || ttl > 255, UPNP_RESULT_INVALID_PARAM, "The time-to-live must be set between 0 and 255 (inclusive).");
 
 	devices.clear();
 
@@ -54,9 +53,9 @@ int UPNP::discover(int timeout, int ttl, const String &device_filter) {
 	struct UPNPDev *devlist;
 
 	if (is_common_device(device_filter)) {
-		devlist = upnpDiscover(timeout, discover_multicast_if.utf8().get_data(), NULL, discover_local_port, discover_ipv6, ttl, &error);
+		devlist = upnpDiscover(timeout, discover_multicast_if.utf8().get_data(), nullptr, discover_local_port, discover_ipv6, ttl, &error);
 	} else {
-		devlist = upnpDiscoverAll(timeout, discover_multicast_if.utf8().get_data(), NULL, discover_local_port, discover_ipv6, ttl, &error);
+		devlist = upnpDiscoverAll(timeout, discover_multicast_if.utf8().get_data(), nullptr, discover_local_port, discover_ipv6, ttl, &error);
 	}
 
 	if (error != UPNPDISCOVER_SUCCESS) {
@@ -133,7 +132,7 @@ void UPNP::parse_igd(Ref<UPNPDevice> dev, UPNPDev *devlist) {
 
 	parserootdesc(xml, size, &data);
 	free(xml);
-	xml = 0;
+	xml = nullptr;
 
 	GetUPNPUrls(urls, &data, dev->get_description_url().utf8().get_data(), 0);
 
@@ -235,20 +234,20 @@ int UPNP::get_device_count() const {
 }
 
 Ref<UPNPDevice> UPNP::get_device(int index) const {
-	ERR_FAIL_INDEX_V(index, devices.size(), NULL);
+	ERR_FAIL_INDEX_V(index, devices.size(), nullptr);
 
 	return devices.get(index);
 }
 
 void UPNP::add_device(Ref<UPNPDevice> device) {
-	ERR_FAIL_COND(device == NULL);
+	ERR_FAIL_COND(device == nullptr);
 
 	devices.push_back(device);
 }
 
 void UPNP::set_device(int index, Ref<UPNPDevice> device) {
 	ERR_FAIL_INDEX(index, devices.size());
-	ERR_FAIL_COND(device == NULL);
+	ERR_FAIL_COND(device == nullptr);
 
 	devices.set(index, device);
 }
@@ -264,17 +263,17 @@ void UPNP::clear_devices() {
 }
 
 Ref<UPNPDevice> UPNP::get_gateway() const {
-	ERR_FAIL_COND_V(devices.size() < 1, NULL);
+	ERR_FAIL_COND_V_MSG(devices.size() < 1, nullptr, "Couldn't find any UPNPDevices.");
 
 	for (int i = 0; i < devices.size(); i++) {
 		Ref<UPNPDevice> dev = get_device(i);
 
-		if (dev != NULL && dev->is_valid_gateway()) {
+		if (dev != nullptr && dev->is_valid_gateway()) {
 			return dev;
 		}
 	}
 
-	return NULL;
+	return nullptr;
 }
 
 void UPNP::set_discover_multicast_if(const String &m_if) {
@@ -304,7 +303,7 @@ bool UPNP::is_discover_ipv6() const {
 String UPNP::query_external_address() const {
 	Ref<UPNPDevice> dev = get_gateway();
 
-	if (dev == NULL) {
+	if (dev == nullptr) {
 		return "";
 	}
 
@@ -314,7 +313,7 @@ String UPNP::query_external_address() const {
 int UPNP::add_port_mapping(int port, int port_internal, String desc, String proto, int duration) const {
 	Ref<UPNPDevice> dev = get_gateway();
 
-	if (dev == NULL) {
+	if (dev == nullptr) {
 		return UPNP_RESULT_NO_GATEWAY;
 	}
 
@@ -326,7 +325,7 @@ int UPNP::add_port_mapping(int port, int port_internal, String desc, String prot
 int UPNP::delete_port_mapping(int port, String proto) const {
 	Ref<UPNPDevice> dev = get_gateway();
 
-	if (dev == NULL) {
+	if (dev == nullptr) {
 		return UPNP_RESULT_NO_GATEWAY;
 	}