Added Duplicate-item PoM checking to Gossiper

CTng/gossip/gossip_object.go

@@ -29,7 +29,7 @@ func (g Gossip_object) GetID(period_interval int64) Gossip_object_ID {
 	}
 }
 
-// This function is highly associated with this type, so I think it belongs here.
+// GetCurrentTimestamp returns the current UTC timestamp in RFC3339 format
 func GetCurrentTimestamp() string {
 	return time.Now().UTC().Format(time.RFC3339)
 }

CTng/gossip/gossiper.go

@@ -29,7 +29,7 @@ func Accuse(c *GossiperContext, url string) {
 
 // Sends a gossip object to all connected gossipers.
 // This function assumes you are passing valid data. ALWAYS CHECK BEFORE CALLING THIS FUNCTION.
-func gossipData(c *GossiperContext, gossip_obj Gossip_object) error {
+func GossipData(c *GossiperContext, gossip_obj Gossip_object) error {
 	// Convert gossip object to JSON
 	msg, err := json.Marshal(gossip_obj)
 	if err != nil {
@@ -64,7 +64,7 @@ func gossipData(c *GossiperContext, gossip_obj Gossip_object) error {
 }
 
 // Sends a gossip object to the owner of the object.
-func sendToOwner(c *GossiperContext, obj Gossip_object) {
+func SendToOwner(c *GossiperContext, obj Gossip_object) {
 	// Convert gossip object to JSON
 	msg, err := json.Marshal(obj)
 	if err != nil {

CTng/gossip/process_object.go

@@ -2,6 +2,7 @@ package gossip
 
 import (
 	"CTng/util"
+	"errors"
 	"fmt"
 )
 
@@ -15,25 +16,25 @@ func ProcessValidObject(c *GossiperContext, obj Gossip_object) {
 	var err error = nil
 	switch obj.Type {
 	case STH:
-		sendToOwner(c, obj)
-		err = gossipData(c, obj)
+		SendToOwner(c, obj)
+		err = GossipData(c, obj)
 	case REVOCATION:
-		sendToOwner(c, obj)
-		err = gossipData(c, obj)
+		SendToOwner(c, obj)
+		err = GossipData(c, obj)
 	case STH_FRAG:
-		sendToOwner(c, obj)
-		err = gossipData(c, obj)
+		SendToOwner(c, obj)
+		err = GossipData(c, obj)
 	case GOSSIP_POM:
-		sendToOwner(c, obj)
-		err = gossipData(c, obj)
+		SendToOwner(c, obj)
+		err = GossipData(c, obj)
 	case REVOCATION_FRAG:
-		err = gossipData(c, obj)
+		err = GossipData(c, obj)
 	case ACCUSATION_FRAG:
 		ProcessAccusation(c, obj)
-		err = gossipData(c, obj)
+		err = GossipData(c, obj)
 	case APPLICATION_POM:
-		sendToOwner(c, obj)
-		err = gossipData(c, obj)
+		SendToOwner(c, obj)
+		err = GossipData(c, obj)
 	default:
 		fmt.Println("Recieved unsupported object type.")
 	}
@@ -42,10 +43,34 @@ func ProcessValidObject(c *GossiperContext, obj Gossip_object) {
 	}
 }
 
+// Process a valid gossip object which is a duplicate to another one.
+// If the signature/payload is identical, then we can safely ignore the duplicate.
+// Otherwise, we generate a PoM for two objects sent in the same period.
+func ProcessDuplicateObject(c *GossiperContext, obj Gossip_object, dup Gossip_object) err {
+	if obj.Signature == dup.Signature &&
+		obj.Payload == dup.Payload {
+		return nil
+	} else {
+		// Generate PoM
+		pom := Gossip_object{
+			Application: obj.Application,
+			Type:        GOSSIP_POM,
+			Signer:      obj.Signer,
+			Signature:   [2]string{obj.Signature[0], dup.Signature[0]},
+			Payload:     [2]string{obj.Payload[0], dup.Payload[0]},
+			Timestamp:   GetCurrentTimestamp(),
+		}
+		c.StoreObject(pom)
+		c.HasPom[obj.Payload[0]] = true
+		// Currently, we don't send PoMs. but if we did, we could do it here.
+		SendToOwner(c, pom)
+		return errors.New("Proof of Misbhevior Generated")
+	}
+}
+
 func ProcessInvalidObject(obj Gossip_object, e error) {
 	// TODO:
 	// 	Determine Conflict/misbehavior
-	//  Log error
 	//  Send neccessary accusations
 }
 
@@ -57,13 +82,13 @@ func ProcessAccusation(c *GossiperContext, acc Gossip_object) {
 		fmt.Println(util.YELLOW+"Processed accusation against", acc.Payload[0], util.RESET)
 	}
 	if shouldGossip {
-		gossipData(c, acc)
+		GossipData(c, acc)
 	}
 	if pom != nil {
 		fmt.Println(util.RED+"Generated POM for", acc.Payload[0], util.RESET)
 		c.StoreObject(*pom)
 		c.HasPom[acc.Payload[0]] = true
 		// We do not currently gossip PoMs.
-		sendToOwner(c, *pom)
+		SendToOwner(c, *pom)
 	}
 }

CTng/server/Gossiper_server.go

@@ -127,12 +127,17 @@ func handleGossip(c *gossip.GossiperContext, w http.ResponseWriter, r *http.Requ
 		return
 	}
 	// Check for duplicate object.
-	_, found := c.GetObject(gossip_obj.GetID(c.Config.Public.Period_interval))
+	stored_obj, found := c.GetObject(gossip_obj.GetID(c.Config.Public.Period_interval))
 	if found {
 		// If the object is already stored, still return OK.{
 		fmt.Println("Duplicate:", gossip_obj.Type, getSenderURL(r)+".")
-		http.Error(w, "Gossip object already stored.", http.StatusOK)
-		// gossip.ProcessDuplicateObject(c, gossip_obj, stored_obj)
+		err := gossip.ProcessDuplicateObject(c, gossip_obj, stored_obj)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusOK)
+		} else {
+			http.Error(w, "Duplicate object.", http.StatusOK)
+		}
+		http.Error(w, "Recieved Duplicate Object.", http.StatusOK)
 		return
 	} else {
 		fmt.Println(util.GREEN+"Recieved new, valid", gossip_obj.Type, "from "+getSenderURL(r)+".", util.RESET)
@@ -165,12 +170,16 @@ func handleOwnerGossip(c *gossip.GossiperContext, w http.ResponseWriter, r *http
 		fmt.Println(util.RED+"Owner sent invalid object.", util.RESET)
 		http.Error(w, err.Error(), http.StatusBadRequest)
 	}
-	_, found := c.GetObject(gossip_obj.GetID(c.Config.Public.Period_interval))
+	stored_obj, found := c.GetObject(gossip_obj.GetID(c.Config.Public.Period_interval))
 	if found {
 		// If the object is already stored, still return OK.{
 		fmt.Println("Recieved duplicate object from Owner.")
-		http.Error(w, "Gossip object already stored.", http.StatusOK)
-		// gossip.ProcessDuplicateObject(c, gossip_obj, stored_obj)
+		err := gossip.ProcessDuplicateObject(c, gossip_obj, stored_obj)
+		if err != nil {
+			http.Error(w, "Duplicate Object recieved!", http.StatusOK)
+		} else {
+			http.Error(w, err.Error(), http.StatusOK)
+		}
 		return
 	} else {
 		// Prints the body of the post request to the server console