示例#1
0
文件: scan.go 项目: zzmjohn/Sia
// threadedScan is an ongoing function which will query the full set of hosts
// every few hours to see who is online and available for uploading.
func (hdb *HostDB) threadedScan() {
	for {
		// Determine who to scan. At most 'MaxActiveHosts' will be scanned,
		// starting with the active hosts followed by a random selection of the
		// inactive hosts.
		func() {
			hdb.mu.Lock()
			defer hdb.mu.Unlock()

			// Scan all active hosts.
			for _, host := range hdb.activeHosts {
				hdb.scanHostEntry(host.hostEntry)
			}

			// Assemble all of the inactive hosts into a single array.
			var entries []*hostEntry
			for _, entry := range hdb.allHosts {
				entry2, exists := hdb.activeHosts[entry.NetAddress]
				if !exists {
					entries = append(entries, entry)
				} else if entry2.hostEntry != entry {
					build.Critical("allHosts + activeHosts mismatch!")
				}
			}

			// Generate a random ordering of up to InactiveHostCheckupQuantity
			// hosts.
			n := InactiveHostCheckupQuantity
			if n > len(entries) {
				n = len(entries)
			}
			hostOrder, err := crypto.Perm(n)
			if err != nil {
				hdb.log.Println("ERR: could not generate random permutation:", err)
			}

			// Scan each host.
			for _, randIndex := range hostOrder {
				hdb.scanHostEntry(entries[randIndex])
			}
		}()

		// Sleep for a random amount of time before doing another round of
		// scanning. The minimums and maximums keep the scan time reasonable,
		// while the randomness prevents the scanning from always happening at
		// the same time of day or week.
		maxBig := big.NewInt(int64(MaxScanSleep))
		minBig := big.NewInt(int64(MinScanSleep))
		randSleep, err := rand.Int(rand.Reader, maxBig.Sub(maxBig, minBig))
		if err != nil {
			build.Critical(err)
			// If there's an error, sleep for the default amount of time.
			defaultBig := big.NewInt(int64(DefaultScanSleep))
			randSleep = defaultBig.Sub(defaultBig, minBig)
		}
		hdb.sleeper.Sleep(time.Duration(randSleep.Int64()) + MinScanSleep) // this means the MaxScanSleep is actual Max+Min.
	}
}
示例#2
0
// RandomHosts will pull up to 'n' random hosts from the hostdb. There will be
// no repeats, but the length of the slice returned may be less than 'n', and
// may even be 0. The hosts that get returned first have the higher priority.
// Hosts specified in 'ignore' will not be considered; pass 'nil' if no
// blacklist is desired.
func (hdb *HostDB) RandomHosts(n int, ignore []modules.NetAddress) (hosts []modules.HostDBEntry) {
	hdb.mu.Lock()
	defer hdb.mu.Unlock()
	if hdb.isEmpty() {
		return
	}

	// These will be restored after selection is finished.
	var removedEntries []*hostEntry

	// Remove hosts that we want to ignore.
	for _, addr := range ignore {
		node, exists := hdb.activeHosts[addr]
		if !exists {
			continue
		}
		node.removeNode()
		delete(hdb.activeHosts, addr)
		removedEntries = append(removedEntries, node.hostEntry)
	}

	// Pick a host, remove it from the tree, and repeat until we have n hosts
	// or the tree is empty.
	for len(hosts) < n && !hdb.isEmpty() {
		randWeight, err := rand.Int(rand.Reader, hdb.hostTree.weight.Big())
		if err != nil {
			build.Critical("rand.Int is returning an error:", err)
			break
		}
		node, err := hdb.hostTree.nodeAtWeight(types.NewCurrency(randWeight))
		if err != nil {
			build.Critical("nodeAtWeight is returning and error:", err)
			break
		}
		// Only return the host if they are accepting contracts.
		if node.hostEntry.HostDBEntry.AcceptingContracts {
			hosts = append(hosts, node.hostEntry.HostDBEntry)
		}

		removedEntries = append(removedEntries, node.hostEntry)
		node.removeNode()
		delete(hdb.activeHosts, node.hostEntry.NetAddress)
	}

	// Add back all of the entries that got removed.
	for i := range removedEntries {
		hdb.insertNode(removedEntries[i])
	}
	return hosts
}
示例#3
0
文件: log.go 项目: zzmjohn/Sia
// Write takes the input data and writes it to the file.
func (cf *closeableFile) Write(b []byte) (int, error) {
	// Sanity check - close should not have been called yet.
	if cf.closed {
		build.Critical("cannot write to the file after it has been closed")
	}
	return cf.File.Write(b)
}
示例#4
0
// nodeAtWeight grabs an element in the tree that appears at the given weight.
// Though the tree has an arbitrary sorting, a sufficiently random weight will
// pull a random element. The tree is searched through in a post-ordered way.
func (hn *hostNode) nodeAtWeight(weight types.Currency) (*hostNode, error) {
	// Sanity check - weight must be less than the total weight of the tree.
	if weight.Cmp(hn.weight) > 0 {
		return nil, errOverweight
	}

	// Check if the left or right child should be returned.
	if hn.left != nil {
		if weight.Cmp(hn.left.weight) < 0 {
			return hn.left.nodeAtWeight(weight)
		}
		weight = weight.Sub(hn.left.weight) // Search from 0th index of right side.
	}
	if hn.right != nil && weight.Cmp(hn.right.weight) < 0 {
		return hn.right.nodeAtWeight(weight)
	}

	// Sanity check
	if build.DEBUG && !hn.taken {
		build.Critical("nodeAtWeight should not be returning a nil entry")
	}

	// Return the root entry.
	return hn, nil
}
示例#5
0
文件: files.go 项目: zzmjohn/Sia
// redundancy returns the redundancy of the least redundant chunk. A file
// becomes available when this redundancy is >= 1. Assumes that every piece is
// unique within a file contract. -1 is returned if the file has size 0.
func (f *file) redundancy() float64 {
	if f.size == 0 {
		return math.NaN()
	}
	piecesPerChunk := make([]int, f.numChunks())
	// If the file has non-0 size then the number of chunks should also be
	// non-0. Therefore the f.size == 0 conditional block above must appear
	// before this check.
	if len(piecesPerChunk) == 0 {
		build.Critical("cannot get redundancy of a file with 0 chunks")
		return math.NaN()
	}
	for _, fc := range f.contracts {
		for _, p := range fc.Pieces {
			piecesPerChunk[p.Chunk]++
		}
	}
	minPieces := piecesPerChunk[0]
	for _, numPieces := range piecesPerChunk {
		if numPieces < minPieces {
			minPieces = numPieces
		}
	}
	return float64(minPieces) / float64(f.erasureCode.MinPieces())
}
示例#6
0
// isSane checks that required assumptions about the storage obligation are
// correct.
func (so storageObligation) isSane() error {
	// There should be an origin transaction set.
	if len(so.OriginTransactionSet) == 0 {
		build.Critical("origin transaction set is empty")
		return errInsaneOriginSetSize
	}

	// The final transaction of the origin transaction set should have one file
	// contract.
	final := len(so.OriginTransactionSet) - 1
	fcCount := len(so.OriginTransactionSet[final].FileContracts)
	if fcCount != 1 {
		build.Critical("wrong number of file contracts associated with storage obligation:", fcCount)
		return errInsaneOriginSetFileContract
	}

	// The file contract in the final transaction of the origin transaction set
	// should have two valid proof outputs and two missed proof outputs.
	lenVPOs := len(so.OriginTransactionSet[final].FileContracts[0].ValidProofOutputs)
	lenMPOs := len(so.OriginTransactionSet[final].FileContracts[0].MissedProofOutputs)
	if lenVPOs != 2 || lenMPOs != 2 {
		build.Critical("file contract has wrong number of VPOs and MPOs, expecting 2 each:", lenVPOs, lenMPOs)
		return errInsaneFileContractOutputCounts
	}

	// If there is a revision transaction set, there should be one file
	// contract revision in the final transaction.
	if len(so.RevisionTransactionSet) > 0 {
		final = len(so.OriginTransactionSet) - 1
		fcrCount := len(so.OriginTransactionSet[final].FileContractRevisions)
		if fcrCount != 1 {
			build.Critical("wrong number of file contract revisions in final transaction of revision transaction set:", fcrCount)
			return errInsaneRevisionSetRevisionCount
		}

		// The file contract revision in the final transaction of the revision
		// transaction set should have two valid proof outputs and two missed
		// proof outputs.
		lenVPOs = len(so.RevisionTransactionSet[final].FileContractRevisions[0].NewValidProofOutputs)
		lenMPOs = len(so.RevisionTransactionSet[final].FileContractRevisions[0].NewMissedProofOutputs)
		if lenVPOs != 2 || lenMPOs != 2 {
			build.Critical("file contract has wrong number of VPOs and MPOs, expecting 2 each:", lenVPOs, lenMPOs)
			return errInsaneFileContractRevisionOutputCounts
		}
	}
	return nil
}
示例#7
0
文件: scan.go 项目: robvanmieghem/Sia
// threadedScan is an ongoing function which will query the full set of hosts
// every few hours to see who is online and available for uploading.
func (hdb *HostDB) threadedScan() {
	defer hdb.threadGroup.Done()
	for {
		// Determine who to scan. At most 'maxActiveHosts' will be scanned,
		// starting with the active hosts followed by a random selection of the
		// inactive hosts.
		func() {
			hdb.mu.Lock()
			defer hdb.mu.Unlock()

			// Scan all active hosts.
			for _, host := range hdb.activeHosts {
				hdb.scanHostEntry(host.hostEntry)
			}

			// Assemble all of the inactive hosts into a single array.
			var entries []*hostEntry
			for _, entry := range hdb.allHosts {
				_, exists := hdb.activeHosts[entry.NetAddress]
				if !exists {
					entries = append(entries, entry)
				}
			}

			// Generate a random ordering of up to inactiveHostCheckupQuantity
			// hosts.
			hostOrder, err := crypto.Perm(len(entries))
			if err != nil {
				hdb.log.Println("ERR: could not generate random permutation:", err)
			}

			// Scan each host.
			for i := 0; i < len(hostOrder) && i < inactiveHostCheckupQuantity; i++ {
				hdb.scanHostEntry(entries[hostOrder[i]])
			}
		}()

		// Sleep for a random amount of time before doing another round of
		// scanning. The minimums and maximums keep the scan time reasonable,
		// while the randomness prevents the scanning from always happening at
		// the same time of day or week.
		maxBig := big.NewInt(int64(maxScanSleep))
		minBig := big.NewInt(int64(minScanSleep))
		randSleep, err := rand.Int(rand.Reader, maxBig.Sub(maxBig, minBig))
		if err != nil {
			build.Critical(err)
			// If there's an error, sleep for the default amount of time.
			defaultBig := big.NewInt(int64(defaultScanSleep))
			randSleep = defaultBig.Sub(defaultBig, minBig)
		}

		select {
		// awaken and exit if hostdb is closing
		case <-hdb.closeChan:
			return
		case <-time.After(time.Duration(randSleep.Int64()) + minScanSleep):
		}
	}
}
示例#8
0
文件: currency.go 项目: zzmjohn/Sia
// NewCurrency creates a Currency value from a big.Int. Undefined behavior
// occurs if a negative input is used.
func NewCurrency(b *big.Int) (c Currency) {
	if b.Sign() < 0 {
		build.Critical(ErrNegativeCurrency)
	} else {
		c.i = *b
	}
	return
}
示例#9
0
文件: rpc.go 项目: CSSZiegler/Sia
// RegisterConnectCall registers a name and RPCFunc to be called on a peer
// upon connecting.
func (g *Gateway) RegisterConnectCall(name string, fn modules.RPCFunc) {
	g.mu.Lock()
	defer g.mu.Unlock()
	if _, ok := g.initRPCs[name]; ok {
		build.Critical("ConnectCall already registered: " + name)
	}
	g.initRPCs[name] = fn
}
示例#10
0
文件: rpc.go 项目: CSSZiegler/Sia
// UnregisterRPC unregisters an RPC and removes the corresponding RPCFunc from
// g.handlers. Future calls to the RPC by peers will fail.
func (g *Gateway) UnregisterRPC(name string) {
	g.mu.Lock()
	defer g.mu.Unlock()
	if _, ok := g.handlers[handlerName(name)]; !ok {
		build.Critical("RPC not registered: " + name)
	}
	delete(g.handlers, handlerName(name))
}
示例#11
0
文件: rpc.go 项目: CSSZiegler/Sia
// RegisterRPC registers an RPCFunc as a handler for a given identifier. To
// call an RPC, use gateway.RPC, supplying the same identifier given to
// RegisterRPC. Identifiers should always use PascalCase. The first 8
// characters of an identifier should be unique, as the identifier used
// internally is truncated to 8 bytes.
func (g *Gateway) RegisterRPC(name string, fn modules.RPCFunc) {
	g.mu.Lock()
	defer g.mu.Unlock()
	if _, ok := g.handlers[handlerName(name)]; ok {
		build.Critical("RPC already registered: " + name)
	}
	g.handlers[handlerName(name)] = fn
}
示例#12
0
文件: rpc.go 项目: CSSZiegler/Sia
// UnregisterConnectCall unregisters an on-connect call and removes the
// corresponding RPCFunc from g.initRPCs. Future connections to peers will not
// trigger the RPC to be called on them.
func (g *Gateway) UnregisterConnectCall(name string) {
	g.mu.Lock()
	defer g.mu.Unlock()
	if _, ok := g.initRPCs[name]; !ok {
		build.Critical("ConnectCall not registered: " + name)
	}
	delete(g.initRPCs, name)
}
示例#13
0
// init runs a series of sanity checks to verify that the constants have sane
// values.
func init() {
	// The revision submission buffer should be greater than the resubmission
	// timeout, because there should be time to perform resubmission if the
	// first attempt to submit the revision fails.
	if revisionSubmissionBuffer < resubmissionTimeout {
		build.Critical("revision submission buffer needs to be larger than or equal to the resubmission timeout")
	}
}
示例#14
0
文件: currency.go 项目: zzmjohn/Sia
// Sub returns a new Currency value c = x - y. Behavior is undefined when
// x < y.
func (x Currency) Sub(y Currency) (c Currency) {
	if x.Cmp(y) < 0 {
		c = x
		build.Critical(ErrNegativeCurrency)
	} else {
		c.i.Sub(&x.i, &y.i)
	}
	return
}
示例#15
0
文件: currency.go 项目: zzmjohn/Sia
// MulRat returns a new Currency value c = x * y, where y is a big.Rat.
func (x Currency) MulRat(y *big.Rat) (c Currency) {
	if y.Sign() < 0 {
		build.Critical(ErrNegativeCurrency)
	} else {
		c.i.Mul(&x.i, y.Num())
		c.i.Div(&c.i, y.Denom())
	}
	return
}
示例#16
0
文件: host.go 项目: robvanmieghem/Sia
// ExternalSettings returns the hosts external settings. These values cannot be
// set by the user (host is configured through InternalSettings), and are the
// values that get displayed to other hosts on the network.
func (h *Host) ExternalSettings() modules.HostExternalSettings {
	h.mu.RLock()
	defer h.mu.RUnlock()
	err := h.tg.Add()
	if err != nil {
		build.Critical("Call to ExternalSettings after close")
	}
	defer h.tg.Done()
	return h.externalSettings()
}
示例#17
0
文件: host.go 项目: robvanmieghem/Sia
// FinancialMetrics returns information about the financial commitments,
// rewards, and activities of the host.
func (h *Host) FinancialMetrics() modules.HostFinancialMetrics {
	h.mu.RLock()
	defer h.mu.RUnlock()
	err := h.tg.Add()
	if err != nil {
		build.Critical("Call to FinancialMetrics after close")
	}
	defer h.tg.Done()
	return h.financialMetrics
}
示例#18
0
// CPUMining indicates whether the cpu miner is running.
func (m *Miner) CPUMining() bool {
	if err := m.tg.Add(); err != nil {
		build.Critical(err)
	}
	defer m.tg.Done()

	m.mu.Lock()
	defer m.mu.Unlock()
	return m.miningOn
}
示例#19
0
// CPUHashrate returns an estimated cpu hashrate.
func (m *Miner) CPUHashrate() int {
	if err := m.tg.Add(); err != nil {
		build.Critical(err)
	}
	defer m.tg.Done()

	m.mu.Lock()
	defer m.mu.Unlock()
	return int(m.hashRate)
}
示例#20
0
// StopCPUMining will stop the cpu miner. If the cpu miner is already stopped,
// nothing will happen.
func (m *Miner) StopCPUMining() {
	if err := m.tg.Add(); err != nil {
		build.Critical(err)
	}
	defer m.tg.Done()

	m.mu.Lock()
	defer m.mu.Unlock()
	m.hashRate = 0
	m.miningOn = false
}
示例#21
0
// StartCPUMining will start a single threaded cpu miner. If the miner is
// already running, nothing will happen.
func (m *Miner) StartCPUMining() {
	if err := m.tg.Add(); err != nil {
		build.Critical(err)
	}
	defer m.tg.Done()

	m.mu.Lock()
	defer m.mu.Unlock()
	m.miningOn = true
	go m.threadedMine()
}
示例#22
0
文件: pool.go 项目: robvanmieghem/Sia
// remove disconnects from a host and adds it to the blacklist.
func (p *hostPool) remove(addr modules.NetAddress) {
	for i, h := range p.hosts {
		if h.Address() == addr {
			h.Close()
			p.hosts = append(p.hosts[:i], p.hosts[i+1:]...)
			p.blacklist = append(p.blacklist, addr)
			return
		}
	}
	build.Critical("could not remove host from pool: no record of host", addr)
}
示例#23
0
文件: currency.go 项目: zzmjohn/Sia
// COMPATv0.4.0 - until the first 10e3 blocks have been archived, MulFloat is
// needed while verifying the first set of blocks.
//
// MulFloat returns a new Currency value y = c * x, where x is a float64.
// Behavior is undefined when x is negative.
func (x Currency) MulFloat(y float64) (c Currency) {
	if y < 0 {
		build.Critical(ErrNegativeCurrency)
	} else {
		cRat := new(big.Rat).Mul(
			new(big.Rat).SetInt(&x.i),
			new(big.Rat).SetFloat64(y),
		)
		c.i.Div(cRat.Num(), cRat.Denom())
	}
	return
}
示例#24
0
文件: log.go 项目: zzmjohn/Sia
// Close closes the file and sets the closed flag.
func (cf *closeableFile) Close() error {
	// Sanity check - close should not have been called yet.
	if cf.closed {
		build.Critical("cannot close the file; already closed")
	}
	// Ensure that all data has actually hit the disk.
	if err := cf.Sync(); err != nil {
		return err
	}
	cf.closed = true
	return cf.File.Close()
}
示例#25
0
文件: update.go 项目: zzmjohn/Sia
// ProcessConsensusDigest will update the miner's most recent block.
func (m *Miner) ProcessConsensusChange(cc modules.ConsensusChange) {
	m.mu.Lock()
	defer m.mu.Unlock()

	// Adjust the height of the miner. The miner height is initialized to zero,
	// but the genesis block is actually height zero. For the genesis block
	// only, the height will be left at zero.
	//
	// Checking the height here eliminates the need to initialize the miner to
	// an underflowed types.BlockHeight, which was deemed the worse of the two
	// evils.
	if m.persist.Height != 0 || cc.AppliedBlocks[len(cc.AppliedBlocks)-1].ID() != types.GenesisBlock.ID() {
		m.persist.Height -= types.BlockHeight(len(cc.RevertedBlocks))
		m.persist.Height += types.BlockHeight(len(cc.AppliedBlocks))
	}

	// Update the unsolved block.
	var exists1, exists2 bool
	m.persist.UnsolvedBlock.ParentID = cc.AppliedBlocks[len(cc.AppliedBlocks)-1].ID()
	m.persist.Target, exists1 = m.cs.ChildTarget(m.persist.UnsolvedBlock.ParentID)
	m.persist.UnsolvedBlock.Timestamp, exists2 = m.cs.MinimumValidChildTimestamp(m.persist.UnsolvedBlock.ParentID)
	if !exists1 {
		build.Critical("miner was unable to find parent id of an unsolved block in the consensus set")
	}
	if !exists2 {
		build.Critical("miner was unable to find child timestamp of an unsovled block in the consensus set")
	}

	// There is a new parent block, the source block should be updated to keep
	// the stale rate as low as possible.
	m.newSourceBlock()
	m.persist.RecentChange = cc.ID

	// Save the new consensus information.
	err := m.save()
	if err != nil {
		m.log.Println("ERROR: could not save during ProcessConsensusChange:", err)
	}
}
示例#26
0
文件: info.go 项目: robvanmieghem/Sia
// LatestBlockFacts returns a set of statistics about the blockchain as they appeared
// at the latest block height in the explorer's consensus set.
func (e *Explorer) LatestBlockFacts() modules.BlockFacts {
	var bf blockFacts
	err := e.db.View(func(tx *bolt.Tx) error {
		var height types.BlockHeight
		err := dbGetInternal(internalBlockHeight, &height)(tx)
		if err != nil {
			return err
		}
		return e.dbGetBlockFacts(height, &bf)(tx)
	})
	if err != nil {
		build.Critical(err)
	}
	return bf.BlockFacts
}
示例#27
0
// contractEndHeight returns the height at which the Contractor's contracts
// end. If there are no contracts, it returns zero.
func (c *Contractor) contractEndHeight() types.BlockHeight {
	var endHeight types.BlockHeight
	for _, contract := range c.contracts {
		endHeight = contract.EndHeight()
		break
	}
	// sanity check: all contracts should have same EndHeight
	if build.DEBUG {
		for _, contract := range c.contracts {
			if contract.EndHeight() != endHeight {
				build.Critical("all contracts should have EndHeight", endHeight, "-- got", contract.EndHeight())
			}
		}
	}
	return endHeight
}
示例#28
0
// SubmitHeader accepts a block header.
func (m *Miner) SubmitHeader(bh types.BlockHeader) error {
	// Because a call to managedSubmitBlock is required at the end of this
	// function, the first part needs to be wrapped in an anonymous function
	// for lock safety.
	var b types.Block
	err := func() error {
		m.mu.Lock()
		defer m.mu.Unlock()

		// Lookup the block that corresponds to the provided header.
		nonce := bh.Nonce
		bh.Nonce = [8]byte{}
		bPointer, bExists := m.blockMem[bh]
		arbData, arbExists := m.arbDataMem[bh]
		if !bExists || !arbExists {
			return errLateHeader
		}

		// Block is going to be passed to external memory, but the memory pointed
		// to by the transactions slice is still being modified - needs to be
		// copied. Same with the memory being pointed to by the arb data slice.
		b = *bPointer
		txns := make([]types.Transaction, len(b.Transactions))
		copy(txns, b.Transactions)
		b.Transactions = txns
		b.Transactions[0].ArbitraryData = [][]byte{arbData[:]}
		b.Nonce = nonce

		// Sanity check - block should have same id as header.
		bh.Nonce = nonce
		if types.BlockID(crypto.HashObject(bh)) != b.ID() {
			build.Critical("block reconstruction failed")
		}
		return nil
	}()
	if err != nil {
		m.log.Println("ERROR during call to SubmitHeader, pre SubmitBlock:", err)
		return err
	}
	err = m.managedSubmitBlock(b)
	if err != nil {
		m.log.Println("ERROR returned by managedSubmitBlock:", err)
		return err
	}
	return nil
}
示例#29
0
// BlocksMined returns the number of good blocks and stale blocks that have
// been mined by the miner.
func (m *Miner) BlocksMined() (goodBlocks, staleBlocks int) {
	if err := m.tg.Add(); err != nil {
		build.Critical(err)
	}
	defer m.tg.Done()

	m.mu.Lock()
	defer m.mu.Unlock()

	for _, blockID := range m.persist.BlocksFound {
		if m.cs.InCurrentPath(blockID) {
			goodBlocks++
		} else {
			staleBlocks++
		}
	}
	return
}
示例#30
0
// verifySettings reads a signed HostSettings object from conn, validates the
// signature, and checks for discrepancies between the known settings and the
// received settings. If there is a discrepancy, the hostDB is notified. The
// received settings are returned.
func verifySettings(conn net.Conn, host modules.HostDBEntry) (modules.HostDBEntry, error) {
	// convert host key (types.SiaPublicKey) to a crypto.PublicKey
	if host.PublicKey.Algorithm != types.SignatureEd25519 || len(host.PublicKey.Key) != crypto.PublicKeySize {
		build.Critical("hostdb did not filter out host with wrong signature algorithm:", host.PublicKey.Algorithm)
		return modules.HostDBEntry{}, errors.New("host used unsupported signature algorithm")
	}
	var pk crypto.PublicKey
	copy(pk[:], host.PublicKey.Key)

	// read signed host settings
	var recvSettings modules.HostExternalSettings
	if err := crypto.ReadSignedObject(conn, &recvSettings, modules.NegotiateMaxHostExternalSettingsLen, pk); err != nil {
		return modules.HostDBEntry{}, errors.New("couldn't read host's settings: " + err.Error())
	}
	// TODO: check recvSettings against host.HostExternalSettings. If there is
	// a discrepancy, write the error to conn.
	if recvSettings.NetAddress != host.NetAddress {
		// for now, just overwrite the NetAddress, since we know that
		// host.NetAddress works (it was the one we dialed to get conn)
		recvSettings.NetAddress = host.NetAddress
	}
	host.HostExternalSettings = recvSettings
	return host, nil
}