Prevent duplicate nodes in repos

config/config.go

@@ -313,10 +313,12 @@ func Load(rd io.Reader, myID protocol.NodeID) (Configuration, error) {
 
 	// Ensure this node is present in all relevant places
 	// Ensure that any loose nodes are not present in the wrong places
+	// Ensure that there are no duplicate nodes
 	cfg.Nodes = ensureNodePresent(cfg.Nodes, myID)
 	for i := range cfg.Repositories {
 		cfg.Repositories[i].Nodes = ensureNodePresent(cfg.Repositories[i].Nodes, myID)
 		cfg.Repositories[i].Nodes = ensureExistingNodes(cfg.Repositories[i].Nodes, existingNodes)
+		cfg.Repositories[i].Nodes = ensureNoDuplicates(cfg.Repositories[i].Nodes)
 	}
 
 	// An empty address list is equivalent to a single "dynamic" entry
@@ -420,3 +422,25 @@ loop:
 
 	return nodes
 }
+
+func ensureNoDuplicates(nodes []NodeConfiguration) []NodeConfiguration {
+	count := len(nodes)
+	i := 0
+	seenNodes := make(map[protocol.NodeID]bool)
+loop:
+	for i < count {
+		id := nodes[i].NodeID
+		if _, ok := seenNodes[id]; ok {
+			nodes[i] = nodes[count-1]
+			count--
+			continue loop
+		}
+		seenNodes[id] = true
+		i++
+	}
+	nodes = nodes[0:count]
+
+	sort.Sort(NodeConfigurationList(nodes))
+
+	return nodes
+}

config/config_test.go

@@ -59,6 +59,12 @@ func TestNodeConfig(t *testing.T) {
         <node id="P56IOI7MZJNU2IQGDREYDM2MGTMGL3BXNPQ6W5BTBBZ4TJXZWICQ" name="node two">
             <address>b</address>
         </node>
+        <node id="AIR6LPZ7K4PTTUXQSMUUCPQ5YWOEDFIIQJUG7772YQXXR5YD6AWQ" name="node one">
+            <address>a</address>
+        </node>
+        <node id="P56IOI7MZJNU2IQGDREYDM2MGTMGL3BXNPQ6W5BTBBZ4TJXZWICQ" name="node two">
+            <address>b</address>
+        </node>
     </repository>
     <options>
         <readOnly>true</readOnly>
@@ -69,9 +75,12 @@ func TestNodeConfig(t *testing.T) {
 	v2data := []byte(`
 <configuration version="2">
     <repository id="test" directory="~/Sync" ro="true">
+        <node id="P56IOI7MZJNU2IQGDREYDM2MGTMGL3BXNPQ6W5BTBBZ4TJXZWICQ"/>
         <node id="AIR6LPZ7K4PTTUXQSMUUCPQ5YWOEDFIIQJUG7772YQXXR5YD6AWQ"/>
         <node id="C4YBIESWDUAIGU62GOSRXCRAAJDWVE3TKCPMURZE2LH5QHAF576A"/>
         <node id="P56IOI7MZJNU2IQGDREYDM2MGTMGL3BXNPQ6W5BTBBZ4TJXZWICQ"/>
+        <node id="AIR6LPZ7K4PTTUXQSMUUCPQ5YWOEDFIIQJUG7772YQXXR5YD6AWQ"/>
+        <node id="C4YBIESWDUAIGU62GOSRXCRAAJDWVE3TKCPMURZE2LH5QHAF576A"/>
     </repository>
     <node id="AIR6LPZ7K4PTTUXQSMUUCPQ5YWOEDFIIQJUG7772YQXXR5YD6AWQ" name="node one">
         <address>a</address>