func (a *SellActivity) HandleWork(log bitwrk.Logger, workFile cafs.File, buyerSecret bitwrk.Thash) (io.ReadCloser, error) {
// Wait for buyer to establish
active := true
var workHash, workSecretHash *bitwrk.Thash
log.Printf("Watching transaction state...")
a.waitWhile(func() bool {
active = a.tx.State == bitwrk.StateActive
workHash, workSecretHash = a.tx.WorkHash, a.tx.WorkSecretHash
log.Printf(" state: %v phase: %v", a.tx.State, a.tx.Phase)
return active && a.tx.Phase != bitwrk.PhaseTransmitting
})
if !active {
return nil, fmt.Errorf("Transaction timed out waiting for buyer to establish")
}
// Verify work hash
if *workHash != bitwrk.Thash(workFile.Key()) {
return nil, fmt.Errorf("WorkHash and received data do not match")
}
if err := verifyBuyerSecret(workHash, workSecretHash, &buyerSecret); err != nil {
return nil, err
}
log.Println("Got valid work data. Publishing buyer's secret.")
if err := SendTxMessagePublishBuyerSecret(a.txId, a.identity, &buyerSecret); err != nil {
return nil, fmt.Errorf("Error publishing buyer's secret: %v", err)
}
log.Println("Starting to work...")
r, err := a.dispatchWork(log, workFile)
if err != nil {
log.Printf("Rejecting work because of error '%v'", err)
if err := SendTxMessageRejectWork(a.txId, a.identity); err != nil {
log.Printf("Rejecting work failed: %v", err)
}
}
return r, err
}
func (a *BuyActivity) doPerformBuy(log bitwrk.Logger, interrupt <-chan bool) (cafs.File, error) {
if err := a.beginTrade(log, interrupt); err != nil {
return nil, err
}
// draw random bytes for buyer's secret
var secret bitwrk.Thash
if _, err := rand.Reader.Read(secret[:]); err != nil {
return nil, err
}
a.execSync(func() { a.buyerSecret = &secret })
log.Printf("Computed buyer's secret.")
// Get work hash
var workHash, workSecretHash bitwrk.Thash
workHash = bitwrk.Thash(a.workFile.Key())
// compute workSecretHash = hash(workHash | secret)
hash := sha256.New()
hash.Write(workHash[:])
hash.Write(secret[:])
hash.Sum(workSecretHash[:0])
// Start polling for transaction state changes in background
abortPolling := make(chan bool)
defer func() {
abortPolling <- true // Stop polling when sell has ended
}()
go func() {
a.pollTransaction(log, abortPolling)
}()
if err := SendTxMessageEstablishBuyer(a.txId, a.identity, workHash, workSecretHash); err != nil {
return nil, fmt.Errorf("Error establishing buyer: %v", err)
}
if err := a.waitForTransactionPhase(log.New("establishing"), bitwrk.PhaseTransmitting, bitwrk.PhaseEstablishing, bitwrk.PhaseSellerEstablished, bitwrk.PhaseBuyerEstablished); err != nil {
return nil, fmt.Errorf("Error awaiting TRANSMITTING phase: %v", err)
}
var sellerErr error
if err := a.interactWithSeller(log.New("transmitting")); err != nil {
sellerErr = fmt.Errorf("Error transmitting work and receiving encrypted result: %v", err)
}
var phaseErr error
if err := a.waitForTransactionPhase(log, bitwrk.PhaseUnverified, bitwrk.PhaseTransmitting, bitwrk.PhaseWorking); err != nil {
phaseErr = fmt.Errorf("Error awaiting UNVERIFIED phase: %v", err)
}
if sellerErr == nil && phaseErr == nil {
// Everythong went fine, continue
} else if sellerErr == nil {
return nil, phaseErr
} else if phaseErr == nil {
return nil, sellerErr
} else {
return nil, fmt.Errorf("%v. Additionally: %v", phaseErr, sellerErr)
}
a.execSync(func() { a.encResultKey = a.tx.ResultDecryptionKey })
if err := a.decryptResult(); err != nil {
return nil, fmt.Errorf("Error decrypting result: %v", err)
}
// In normal buys (without verifying), we can leave the rest as homework
// for a goroutine and exit here.
go func() {
if err := a.finishBuy(log); err != nil {
log.Printf("Error finishing buy: %v", err)
}
}()
return a.resultFile, nil
}