// compile() takes the list of heartbeats and uses them to advance the state.
func (s *State) compile() {
// fetch a participant ordering
participantOrdering := s.participantOrdering()
// Lock down s.participants and s.heartbeats for editing
s.participantsLock.Lock()
s.heartbeatsLock.Lock()
// Read heartbeats, process them, then archive them.
for _, participant := range participantOrdering {
if s.participants[participant] == nil {
continue
}
// each participant must submit exactly 1 heartbeat
if len(s.heartbeats[participant]) != 1 {
s.tossParticipant(participant)
continue
}
// this is the only way I know to access the only element of a map;
// the key is unknown
for _, hb := range s.heartbeats[participant] {
s.processHeartbeat(hb, participant)
}
// archive heartbeats (unimplemented)
// clear heartbeat list for next block
s.heartbeats[participant] = make(map[crypto.TruncatedHash]*heartbeat)
}
// move UpcomingEntropy to CurrentEntropy
s.currentEntropy = s.upcomingEntropy
// generate a new heartbeat and add it to s.Heartbeats
hb, err := s.newHeartbeat()
if err != nil {
log.Fatalln(err)
}
hash, err := crypto.CalculateTruncatedHash(hb.marshal())
if err != nil {
log.Fatalln(err)
}
s.heartbeats[s.participantIndex][hash] = hb
// sign and annouce the heartbeat
shb, err := s.signHeartbeat(hb)
if err != nil {
log.Fatalln(err)
}
err = s.announceSignedHeartbeat(shb)
if err != nil {
log.Fatalln(err)
}
}
// compile() takes the list of heartbeats and uses them to advance the state.
func (s *State) compile() {
participantOrdering := s.participantOrdering()
// Read read heartbeats, process them, then archive them. Other functions
// concurrently access the heartbeats, so mutexes are needed.
for _, participant := range participantOrdering {
if s.participants[participant] == nil {
continue
}
// each participant must submit exactly 1 heartbeat
if len(s.heartbeats[participant]) != 1 {
s.tossParticipant(participant)
continue
}
for _, hb := range s.heartbeats[participant] {
s.processHeartbeat(hb, participant)
}
// archive heartbeats
// currently, archives are sent to /dev/null
s.heartbeats[participant] = make(map[crypto.TruncatedHash]*heartbeat)
}
// move UpcomingEntropy to CurrentEntropy
s.currentEntropy = s.upcomingEntropy
// generate a new heartbeat and add it to s.Heartbeats
hb, err := s.newHeartbeat()
if err != nil {
log.Fatalln(err)
}
hash, err := crypto.CalculateTruncatedHash(hb.marshal())
if err != nil {
log.Fatalln(err)
}
s.heartbeats[s.participantIndex][hash] = hb
// sign and annouce the heartbeat
shb, err := s.signHeartbeat(hb)
if err != nil {
log.Fatalln(err)
}
s.announceSignedHeartbeat(shb)
}
func (s *State) announceSignedHeartbeat(sh *signedHeartbeat) {
for i := range s.participants {
if s.participants[i] != nil {
payload, err := sh.marshal()
if err != nil {
log.Fatalln(err)
}
m := new(common.Message)
m.Payload = append([]byte{byte(1)}, payload...)
m.Destination = s.participants[i].Address
//time.Sleep(time.Millisecond) // prevents panics. No idea where original source of bug is.
err = s.messageSender.SendMessage(m)
if err != nil {
log.Fatalln("Error while sending message")
}
}
}
}
// participants are processed in a random order each block, determined by the
// entropy for the block. participantOrdering() deterministically picks that
// order, using entropy from the state.
func (s *State) participantOrdering() (participantOrdering [common.QuorumSize]byte) {
// create an in-order list of participants
for i := range participantOrdering {
participantOrdering[i] = byte(i)
}
// shuffle the list of participants
for i := range participantOrdering {
newIndex, err := s.randInt(i, common.QuorumSize)
if err != nil {
log.Fatalln(err)
}
tmp := participantOrdering[newIndex]
participantOrdering[newIndex] = participantOrdering[i]
participantOrdering[i] = tmp
}
return
}
// Update the state according to the information presented in the heartbeat
// processHeartbeat uses return codes for testing purposes
func (s *State) processHeartbeat(hb *heartbeat, i participantIndex) int {
// compare EntropyStage2 to the hash from the previous heartbeat
expectedHash, err := crypto.CalculateTruncatedHash(hb.entropyStage2[:])
if err != nil {
log.Fatalln(err)
}
if expectedHash != s.previousEntropyStage1[i] {
s.tossParticipant(i)
return 1
}
// Add the EntropyStage2 to UpcomingEntropy
th, err := crypto.CalculateTruncatedHash(append(s.upcomingEntropy[:], hb.entropyStage2[:]...))
s.upcomingEntropy = common.Entropy(th)
// store entropyStage1 to compare with next heartbeat from this participant
s.previousEntropyStage1[i] = hb.entropyStage1
return 0
}
// HandleSignedHeartbeat takes the payload of an incoming message of type
// 'incomingSignedHeartbeat' and verifies it according to the specification
//
// What sort of input error checking is needed for this function?
func (s *State) HandleSignedHeartbeat(sh SignedHeartbeat, arb *struct{}) error {
// Check that the slices of signatures and signatories are of the same length
if len(sh.signatures) != len(sh.signatories) {
return hsherrMismatchedSignatures
}
// check that there are not too many signatures and signatories
if len(sh.signatories) > common.QuorumSize {
return hsherrOversigned
}
s.stepLock.Lock() // prevents a benign race condition; is here to follow best practices
currentStep := s.currentStep
s.stepLock.Unlock()
// s.CurrentStep must be less than or equal to len(sh.Signatories), unless
// there is a new block and s.CurrentStep is common.QuorumSize
if currentStep > len(sh.signatories) {
if currentStep == common.QuorumSize && len(sh.signatories) == 1 {
// by waiting common.StepDuration, the new block will be compiled
time.Sleep(common.StepDuration)
// now continue to rest of function
} else {
return hsherrNoSync
}
}
// Check bounds on first signatory
if int(sh.signatories[0]) >= common.QuorumSize {
return hsherrBounds
}
// we are starting to read from memory, initiate locks
s.participantsLock.RLock()
s.heartbeatsLock.Lock()
defer s.participantsLock.RUnlock()
defer s.heartbeatsLock.Unlock()
// check that first signatory is a participant
if s.participants[sh.signatories[0]] == nil {
return hsherrNonParticipant
}
// Check if we have already received this heartbeat
_, exists := s.heartbeats[sh.signatories[0]][sh.heartbeatHash]
if exists {
return hsherrHaveHeartbeat
}
// Check if we already have two heartbeats from this host
if len(s.heartbeats[sh.signatories[0]]) >= 2 {
return hsherrManyHeartbeats
}
// iterate through the signatures and make sure each is legal
var signedMessage crypto.SignedMessage // grows each iteration
signedMessage.Message = sh.heartbeatHash[:]
previousSignatories := make(map[byte]bool) // which signatories have already signed
for i, signatory := range sh.signatories {
// Check bounds on the signatory
if int(signatory) >= common.QuorumSize {
return hsherrBounds
}
// Verify that the signatory is a participant in the quorum
if s.participants[signatory] == nil {
return hsherrNonParticipant
}
// Verify that the signatory has only been seen once in the current SignedHeartbeat
if previousSignatories[signatory] {
return hsherrDoubleSigned
}
// record that we've seen this signatory in the current SignedHeartbeat
previousSignatories[signatory] = true
// verify the signature
signedMessage.Signature = sh.signatures[i]
verification := s.participants[signatory].publicKey.Verify(&signedMessage)
// check status of verification
if !verification {
return hsherrInvalidSignature
}
// throwing the signature into the message here makes code cleaner in the loop
// and after we sign it to send it to everyone else
newMessage, err := signedMessage.CombinedMessage()
signedMessage.Message = newMessage
if err != nil {
return err
}
}
// Add heartbeat to list of seen heartbeats
s.heartbeats[sh.signatories[0]][sh.heartbeatHash] = sh.heartbeat
// Sign the stack of signatures and send it to all hosts
signedMessage, err := s.secretKey.Sign(signedMessage.Message)
if err != nil {
log.Fatalln(err)
}
// add our signature to the signedHeartbeat
sh.signatures = append(sh.signatures, signedMessage.Signature)
sh.signatories = append(sh.signatories, s.self.index)
// broadcast the message to the quorum
err = s.announceSignedHeartbeat(&sh)
if err != nil {
log.Fatalln(err)
return err
}
return nil
}
// handleSignedHeartbeat takes the payload of an incoming message of type
// 'incomingSignedHeartbeat' and verifies it according to rules established by
// the specification.
//
// The return code is currently purely for the testing suite, the numbers
// have been chosen arbitrarily
func (s *State) handleSignedHeartbeat(payload []byte) (returnCode int) {
// covert payload to SignedHeartbeat
sh, err := unmarshalSignedHeartbeat(payload)
if err != nil {
log.Infoln("Received bad message SignedHeartbeat: ", err)
returnCode = 11
return
}
// Check that the slices of signatures and signatories are of the same length
if len(sh.signatures) != len(sh.signatories) {
log.Infoln("SignedHeartbeat has mismatched signatures")
returnCode = 1
return
}
// check that there are not too many signatures and signatories
if len(sh.signatories) > common.QuorumSize {
log.Infoln("Received an over-signed signedHeartbeat")
returnCode = 12
return
}
s.stepLock.Lock() // prevents a benign race condition; is here to follow best practices
// s.CurrentStep must be less than or equal to len(sh.Signatories), unless
// there is a new block and s.CurrentStep is common.QuorumSize
if s.currentStep > len(sh.signatories) {
if s.currentStep == common.QuorumSize && len(sh.signatories) == 1 {
// by waiting common.StepDuration, the new block will be compiled
time.Sleep(common.StepDuration)
// now continue to rest of function
} else {
log.Infoln("Received an out-of-sync SignedHeartbeat")
returnCode = 2
return
}
}
s.stepLock.Unlock()
// Check bounds on first signatory
if int(sh.signatories[0]) >= common.QuorumSize {
log.Infoln("Received an out of bounds index")
returnCode = 9
return
}
// we are starting to read from memory, initiate locks
s.participantsLock.RLock()
s.heartbeatsLock.Lock()
// check that first sigatory is a participant
if s.participants[sh.signatories[0]] == nil {
log.Infoln("Received heartbeat from non-participant")
returnCode = 10
return
}
// Check if we have already received this heartbeat
_, exists := s.heartbeats[sh.signatories[0]][sh.heartbeatHash]
if exists {
returnCode = 8
return
}
// Check if we already have two heartbeats from this host
if len(s.heartbeats[sh.signatories[0]]) >= 2 {
log.Infoln("Received many invalid heartbeats from one host")
returnCode = 13
return
}
// iterate through the signatures and make sure each is legal
var signedMessage crypto.SignedMessage // grows each iteration
signedMessage.Message = string(sh.heartbeatHash[:])
previousSignatories := make(map[participantIndex]bool) // which signatories have already signed
for i, signatory := range sh.signatories {
// Check bounds on the signatory
if int(signatory) >= common.QuorumSize {
log.Infoln("Received an out of bounds index")
returnCode = 9
return
}
// Verify that the signatory is a participant in the quorum
if s.participants[signatory] == nil {
log.Infoln("Received a heartbeat signed by an invalid signatory")
returnCode = 4
return
}
// Verify that the signatory has only been seen once in the current SignedHeartbeat
if previousSignatories[signatory] {
log.Infoln("Received a double-signed heartbeat")
returnCode = 5
return
}
// record that we've seen this signatory in the current SignedHeartbeat
previousSignatories[signatory] = true
// verify the signature
signedMessage.Signature = sh.signatures[i]
verification, err := crypto.Verify(s.participants[signatory].publicKey, signedMessage)
if err != nil {
log.Fatalln(err)
return
}
// check status of verification
if !verification {
log.Infoln("Received invalid signature in SignedHeartbeat")
returnCode = 6
return
}
// throwing the signature into the message here makes code cleaner in the loop
// and after we sign it to send it to everyone else
signedMessage.Message = signedMessage.CombinedMessage()
}
// Add heartbeat to list of seen heartbeats
s.heartbeats[sh.signatories[0]][sh.heartbeatHash] = sh.heartbeat
// Sign the stack of signatures and send it to all hosts
signedMessage, err = crypto.Sign(s.secretKey, signedMessage.Message)
if err != nil {
log.Fatalln(err)
}
// add our signature to the signedHeartbeat
sh.signatures = append(sh.signatures, signedMessage.Signature)
sh.signatories = append(sh.signatories, s.participantIndex)
// broadcast the message to the quorum
err = s.announceSignedHeartbeat(sh)
if err != nil {
log.Fatalln(err)
}
returnCode = 0
return
}
// HandleSignedHeartbeat takes a heartbeat that has been signed
// as a part of the concensus algorithm, and follows all the rules
// that are necessary to ensure that all honest hosts arrive at
// the same conclusions about the actions of their peers.
//
// See the paper 'The Byzantine Generals Problem' for more insight
// on the algorithms used here. Paper can be found in
// doc/The Byzantine Generals Problem
//
// This function is called concurrently, mutexes will be needed when
// accessing or altering the State
//
// It is assumed that when this function is called, the Heartbeat in
// question will already be in memory, and was correctly signed by the
// first signatory, the the first signatory is a participant, and that
// it matches its hash. And that the first signatory is used to store
// the heartbeat
//
// The return code is purely for the testing suite. The numbers are chosen
// arbitrarily
func (s *State) handleSignedHeartbeat(message []byte) (returnCode int) {
// covert message to SignedHeartbeat
sh, err := unmarshalSignedHeartbeat(message)
if err != nil {
log.Infoln("Received bad message SignedHeartbeat: ", err)
return
}
// Check that the slices of signatures and signatories are of the same length
if len(sh.signatures) != len(sh.signatories) {
log.Infoln("SignedHeartbeat has mismatched signatures")
returnCode = 1
return
}
// s.CurrentStep must be less than or equal to len(sh.Signatories), unless the
// current step is common.QuorumSize and len(sh.Signatories) == 1
if s.currentStep > len(sh.signatories) {
if s.currentStep == common.QuorumSize && len(sh.signatories) == 1 {
// sleep long enough to pass the first requirement
time.Sleep(common.StepDuration)
// now continue to rest of function
} else {
log.Infoln("Received an out-of-sync SignedHeartbeat")
returnCode = 2
return
}
}
// Check bounds on first signatory
if int(sh.signatories[0]) >= common.QuorumSize {
log.Infoln("Received an out of bounds index")
returnCode = 9
return
}
// Check existence of first signatory
if s.participants[sh.signatories[0]] == nil {
log.Infoln("Received heartbeat from non-participant")
returnCode = 10
return
}
// Check if we have already received this heartbeat
_, exists := s.heartbeats[sh.signatories[0]][sh.heartbeatHash]
if exists {
returnCode = 8
return
}
// while processing signatures, signedMessage will keep growing
var signedMessage crypto.SignedMessage
signedMessage.Message = string(sh.heartbeatHash[:])
// keep a map of which signatories have already been confirmed
previousSignatories := make(map[participantIndex]bool)
for i, signatory := range sh.signatories {
// Check bounds on the signatory
if int(signatory) >= common.QuorumSize {
log.Infoln("Received an out of bounds index")
returnCode = 9
return
}
// Verify that the signatory is a participant in the quorum
if s.participants[signatory] == nil {
log.Infoln("Received a heartbeat signed by an invalid signatory")
returnCode = 4
return
}
// Verify that the signatory has only been seen once in the current SignedHeartbeat
if previousSignatories[signatory] {
log.Infoln("Received a double-signed heartbeat")
returnCode = 5
return
}
// record that we've seen this signatory in the current SignedHeartbeat
previousSignatories[signatory] = true
// verify the signature
signedMessage.Signature = sh.signatures[i]
verification, err := crypto.Verify(s.participants[signatory].PublicKey, signedMessage)
if err != nil {
log.Fatalln(err)
return
}
// check status of verification
if !verification {
log.Infoln("Received invalid signature in SignedHeartbeat")
returnCode = 6
return
}
// throwing the signature into the message here makes code cleaner in the loop
// and after we sign it to send it to everyone else
signedMessage.Message = signedMessage.CombinedMessage()
}
// Add heartbeat to list of seen heartbeats
// Don't check if heartbeat is valid, that's for compile()
s.heartbeats[sh.signatories[0]][sh.heartbeatHash] = sh.heartbeat
// Sign the stack of signatures and send it to all hosts
_, err = crypto.Sign(s.secretKey, signedMessage.Message)
if err != nil {
log.Fatalln(err)
}
// Send the new message to everybody
returnCode = 0
return
}