MTU support in controller.

controller/EmbeddedNetworkController.cpp

@@ -809,6 +809,7 @@ unsigned int EmbeddedNetworkController::handleControlPlaneHttpPOST(
 					if (b.count("enableBroadcast")) network["enableBroadcast"] = OSUtils::jsonBool(b["enableBroadcast"],false);
 					if (b.count("allowPassiveBridging")) network["allowPassiveBridging"] = OSUtils::jsonBool(b["allowPassiveBridging"],false);
 					if (b.count("multicastLimit")) network["multicastLimit"] = OSUtils::jsonInt(b["multicastLimit"],32ULL);
+					if (b.count("mtu")) network["mtu"] = std::max(std::min((unsigned int)OSUtils::jsonInt(b["mtu"],ZT_DEFAULT_MTU),(unsigned int)ZT_MAX_MTU),(unsigned int)ZT_MIN_MTU);
 
 					if (b.count("v4AssignMode")) {
 						json nv4m;
@@ -1424,6 +1425,7 @@ void EmbeddedNetworkController::_request(
 	if (OSUtils::jsonBool(network["enableBroadcast"],true)) nc->flags |= ZT_NETWORKCONFIG_FLAG_ENABLE_BROADCAST;
 	if (OSUtils::jsonBool(network["allowPassiveBridging"],false)) nc->flags |= ZT_NETWORKCONFIG_FLAG_ALLOW_PASSIVE_BRIDGING;
 	Utils::scopy(nc->name,sizeof(nc->name),OSUtils::jsonString(network["name"],"").c_str());
+	nc->mtu = std::max(std::min((unsigned int)OSUtils::jsonInt(network["mtu"],ZT_DEFAULT_MTU),(unsigned int)ZT_MAX_MTU),(unsigned int)ZT_MIN_MTU);
 	nc->multicastLimit = (unsigned int)OSUtils::jsonInt(network["multicastLimit"],32ULL);
 
 	for(std::vector<Address>::const_iterator ab(ns.activeBridges.begin());ab!=ns.activeBridges.end();++ab)

controller/EmbeddedNetworkController.hpp

@@ -162,6 +162,7 @@ private:
 		if (!network.count("tags")) network["tags"] = nlohmann::json::array();
 		if (!network.count("routes")) network["routes"] = nlohmann::json::array();
 		if (!network.count("ipAssignmentPools")) network["ipAssignmentPools"] = nlohmann::json::array();
+		if (!network.count("mtu")) network["mtu"] = ZT_DEFAULT_MTU;
 		if (!network.count("rules")) {
 			// If unspecified, rules are set to allow anything and behave like a flat L2 segment
 			network["rules"] = {{

include/ZeroTierOne.h

@@ -59,6 +59,11 @@ extern "C" {
  */
 #define ZT_DEFAULT_PORT 9993
 
+/**
+ * Minimum MTU, which is the minimum allowed by IPv6 and several specs
+ */
+#define ZT_MIN_MTU 1280
+
 /**
  * Maximum MTU for ZeroTier virtual networks
  */