// alterPublication will maliciously alter a publications information.
// It returns true if the publication was altered.
// It takes as input the publication.
func (b *Broker) alterPublication(pub *pb.Publication) pb.Publication {
tempPub := pb.Publication{
PubType: pub.PubType,
PublisherID: pub.PublisherID,
PublicationID: pub.PublicationID,
TopicID: pub.TopicID,
BrokerID: pub.BrokerID,
}
for i := range pub.Contents {
tempPub.Contents = append(tempPub.Contents, pub.Contents[i])
}
for i := range pub.ChainMACs {
tempPub.ChainMACs = append(tempPub.ChainMACs, pub.ChainMACs[i])
}
r := b.random.Intn(101)
if r <= b.maliciousPercent {
var alterType int
if len(tempPub.ChainMACs) > 0 {
alterType = r % 6
} else {
alterType = r % 5
}
switch alterType {
case 0:
tempPub.PublicationID = tempPub.PublicationID + 1
case 1:
tempPub.PublisherID = tempPub.PublisherID + 1
case 2:
tempPub.BrokerID = tempPub.BrokerID + 1
case 3:
tempPub.TopicID = tempPub.TopicID + 1
case 4:
if len(tempPub.Contents) > 0 {
tempPub.Contents[0] = badMessage
}
case 5:
tempPub.ChainMACs = nil
}
}
return tempPub
}
// addMACsRecursive adds MACs to the chain of MACs. Some older MACs may need to be kept depending
// on the number of generations in the chain.
// It takes as input the new publication,
// the old publication,
// the current node ID string in the tree (should start with the local node's children),
// and the number of generations to add.
func (b *Broker) addMACsRecursive(pub *pb.Publication, oldPub *pb.Publication, currentStr string, generations uint64) {
// Add any old chain MACs that add going to the child node
for _, oldChainMAC := range oldPub.ChainMACs {
if oldChainMAC.To == currentStr {
pub.ChainMACs = append(pub.ChainMACs, oldChainMAC)
}
}
if generations > 1 {
// Add MACs for all the broker children
for _, childStr := range b.chainNodes[currentStr].children {
addMAC := true
// Check if the subscriber is subscribed to this topic
if strings.HasPrefix(childStr, "S") {
childID, _ := strconv.ParseUint(childStr[1:], 10, 64)
b.subscribersMutex.RLock()
if b.subscribers[childID].topics[pub.TopicID] == false {
// Don't add the MAC is the subscriber isn't interested in this topic
addMAC = false
}
b.subscribersMutex.RUnlock()
}
if addMAC {
chainMAC := pb.ChainMAC{
From: b.localStr,
To: childStr,
MAC: common.CreatePublicationMAC(pub, b.chainNodes[childStr].key),
}
pub.ChainMACs = append(pub.ChainMACs, &chainMAC)
// Recursively add child macs for next generation
b.addMACsRecursive(pub, oldPub, childStr, generations-1)
}
}
}
}
// addMACsRecursive adds MACs to the chain of MACs.
// It takes as input the publication,
// the current node ID string in the tree (should start with the local node's children),
// and the number of generations to add.
func (p *Publisher) addMACs(pub *pb.Publication, currentStr string, generations uint64) {
if generations > 1 {
// Add MACs for all the children
for _, childStr := range p.chainNodes[currentStr].children {
chainMAC := pb.ChainMAC{
From: p.localStr,
To: childStr,
MAC: common.CreatePublicationMAC(pub, p.chainNodes[childStr].key),
}
pub.ChainMACs = append(pub.ChainMACs, &chainMAC)
// Recursively add child macs for next generation
p.addMACs(pub, childStr, generations-1)
}
}
}