From b5f4637b5cceac4630fda0ad4df53be2059c6253 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Sun, 2 Dec 2018 23:20:11 +0000
Subject: [PATCH] Enforce min 4MB switch queue total size

---
 src/yggdrasil/admin.go  | 2 +-
 src/yggdrasil/core.go   | 8 +++++---
 src/yggdrasil/switch.go | 8 ++++++--
 yggdrasil.go            | 2 +-
 4 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/yggdrasil/admin.go b/src/yggdrasil/admin.go
index 7784ea4..2b5bc64 100644
--- a/src/yggdrasil/admin.go
+++ b/src/yggdrasil/admin.go
@@ -638,7 +638,7 @@ func (a *admin) getData_getSwitchQueues() admin_nodeInfo {
 			{"queues_size", switchTable.queues.size},
 			{"highest_queues_count", switchTable.queues.maxbufs},
 			{"highest_queues_size", switchTable.queues.maxsize},
-			{"maximum_queues_size", switchTable.queuetotalmaxsize},
+			{"maximum_queues_size", switchTable.queueTotalMaxSize},
 		}
 	}
 	a.core.switchTable.doAdmin(getSwitchQueues)
diff --git a/src/yggdrasil/core.go b/src/yggdrasil/core.go
index 67a50c9..224945e 100644
--- a/src/yggdrasil/core.go
+++ b/src/yggdrasil/core.go
@@ -105,9 +105,11 @@ func (c *Core) Start(nc *config.NodeConfig, log *log.Logger) error {
 		return err
 	}
 
-	c.switchTable.doAdmin(func() {
-		c.switchTable.queuetotalmaxsize = nc.SwitchOptions.MaxTotalQueueSize
-	})
+	if nc.SwitchOptions.MaxTotalQueueSize >= SwitchQueueTotalMinSize {
+		c.switchTable.doAdmin(func() {
+			c.switchTable.queueTotalMaxSize = nc.SwitchOptions.MaxTotalQueueSize
+		})
+	}
 
 	c.sessions.setSessionFirewallState(nc.SessionFirewall.Enable)
 	c.sessions.setSessionFirewallDefaults(
diff --git a/src/yggdrasil/switch.go b/src/yggdrasil/switch.go
index 5dede5b..adb624a 100644
--- a/src/yggdrasil/switch.go
+++ b/src/yggdrasil/switch.go
@@ -169,9 +169,12 @@ type switchTable struct {
 	idleIn            chan switchPort     // Incoming idle notifications from peer links
 	admin             chan func()         // Pass a lambda for the admin socket to query stuff
 	queues            switch_buffers      // Queues - not atomic so ONLY use through admin chan
-	queuetotalmaxsize uint64              // Maximum combined size of queues
+	queueTotalMaxSize uint64              // Maximum combined size of queues
 }
 
+// Minimum allowed total size of switch queues.
+const SwitchQueueTotalMinSize = 4 * 1024 * 1024
+
 // Initializes the switchTable struct.
 func (t *switchTable) init(core *Core, key sigPubKey) {
 	now := time.Now()
@@ -186,6 +189,7 @@ func (t *switchTable) init(core *Core, key sigPubKey) {
 	t.packetIn = make(chan []byte, 1024)
 	t.idleIn = make(chan switchPort, 1024)
 	t.admin = make(chan func())
+	t.queueTotalMaxSize = SwitchQueueTotalMinSize
 }
 
 // Safely gets a copy of this node's locator.
@@ -649,7 +653,7 @@ func (b *switch_buffers) cleanup(t *switchTable) {
 		}
 	}
 
-	for b.size > b.switchTable.queuetotalmaxsize {
+	for b.size > b.switchTable.queueTotalMaxSize {
 		// Drop a random queue
 		target := rand.Uint64() % b.size
 		var size uint64 // running total
diff --git a/yggdrasil.go b/yggdrasil.go
index c3df805..8536fa1 100644
--- a/yggdrasil.go
+++ b/yggdrasil.go
@@ -69,7 +69,7 @@ func generateConfig(isAutoconf bool) *nodeConfig {
 	cfg.SessionFirewall.Enable = false
 	cfg.SessionFirewall.AllowFromDirect = true
 	cfg.SessionFirewall.AllowFromRemote = true
-	cfg.SwitchOptions.MaxTotalQueueSize = 4 * 1048576
+	cfg.SwitchOptions.MaxTotalQueueSize = yggdrasil.SwitchQueueTotalMinSize
 
 	return &cfg
 }