host

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 Go to latest Published: Feb 19, 2020 License: MIT Imports: 35 Imported by: 0

README

Host

The host takes local disk storage and makes it available to the Sia network. It will do so by announcing itself, and its settings, to the network. Renters transact with the host through a number of RPC calls.

In order for data to be uploaded and stored, the renter and host must agree on a file contract. Once they have negotiated the terms of the file contract, it is signed and put on chain. Any further action related to the data is reflected in the file contract by means of contract revisions that get signed by both parties. The host is responsible for managing these contracts, and making sure the data is safely stored. The host proves that it is storing the data by providing a segment of the file and a list of hashes from the file's merkletree.

Aside from storage, the host offers another service called ephemeral accounts. These accounts serve as an alternative payment method to file contracts. Users can deposit money into them and then later use those funds to transact with the host. The most common transactions are uploading and downloading data, however any RPC that requires payment will support receiving payment from an ephemeral account.

Submodules

ContractManager

The ContractManager is responsible for managing contracts that the host has with renters, including storing the data, submitting storage proofs, and deleting the data when a contract is complete.

Subsystems

The Host has the following subsystems that help carry out its responsibilities.

AccountManager Subsystem

Key Files

The AccountManager subsystem manages all of the ephemeral accounts on the host.

Ephemeral accounts are a service offered by hosts that allow users to connect a balance to a pubkey. Users can deposit funds into an ephemeral account with a host and then later use the funds to transact with the host.

The account owner fully entrusts the money with the host, they have no recourse at all if the host decides to steal the funds. For this reason, users should only keep tiny balances in ephemeral accounts and users should refill the ephemeral accounts frequently, even on the order of multiple times per minute.

To increase performance, the host will allow a user to withdraw from an ephemeral account without requiring the user to wait until the host has persisted the withdrawal to complete a transaction. This allows the user to perform actions such as downloading with significantly less latency. This also means that if the host loses power at that exact moment, the host will forget that the user has spent money and the user will be able to spend that money again. The host can configure the amount of money it is willing to risk due to this asynchronous persist model through the maxephemeralaccountrisk setting.

Ephemeral accounts that have been inactive for a long period of time will be pruned from the account list. This will effectively expire the account, along with all the money that was associated to it. The host can configure this period through the ephemeralaccountexpiry setting. The default is set to a period of 7 days.

AccountsPersister Subsystem

Key Files

The AccountsPersister subsystem will persist all ephemeral account data to disk. This data consists of two parts, the account balance and the fingerprints. Fingerprints are derived from the withdrawal message the user used to perform a withdrawal. They ensure that the same withdrawal can not be withdrawn twice, thus preventing a replay attack on the host.

The account balances together with the corresponding publickey are persisted in a single accounts file. The fingerprints are persisted across two files, the current and the next fingerprint bucket. The expiry blockheight of the withdrawal message decide if the fingerprint belongs to either the current or the next bucket.

Documentation

Overview

Package host is an implementation of the host module, and is responsible for participating in the storage ecosystem, turning available disk space an internet bandwidth into profit for the user.

Index

Constants

View Source 
const (
	// AlertMSGHostInsufficientCollateral indicates that a host has insufficient
	// collateral budget remaining
	AlertMSGHostInsufficientCollateral = "host has insufficient collateral budget"
)

Constants related to the host's alerts.

Variables

View Source 
var (
	// ErrAccountPersist occurs when an ephemeral account could not be persisted
	// to disk.
	ErrAccountPersist = errors.New("ephemeral account could not be persisted to disk")

	// ErrAccountExpired occurs when a blocked action can not complete because
	// the account has expired in the meantime.
	ErrAccountExpired = errors.New("ephemeral account expired")

	// ErrBalanceInsufficient occurs when a withdrawal could not be successfully
	// completed because the account balance was insufficient.
	ErrBalanceInsufficient = errors.New("ephemeral account balance was insufficient")

	// ErrBalanceMaxExceeded occurs when a deposit would push the account's
	// balance over the maximum allowed ephemeral account balance.
	ErrBalanceMaxExceeded = errors.New("ephemeral account maximam balance exceeded")

	// ErrDepositCancelled occurs when the host was willingly or unwillingly
	// stopped in the midst of a deposit process.
	ErrDepositCancelled = errors.New("ephemeral account deposit cancelled due to a shutdown")

	// ErrWithdrawalCancelled occurs when the host was willingly or unwillingly
	// stopped in the midst of a withdrawal process.
	ErrWithdrawalCancelled = errors.New("ephemeral account withdrawal cancelled due to a shutdown")

	// ErrWithdrawalSpent occurs when a withdrawal is requested using a
	// withdrawal message that has been spent already.
	ErrWithdrawalSpent = errors.New("withdrawal message was already spent")
)

Functions

This section is empty.

Types

type ErrorCommunication 

type ErrorCommunication string

ErrorCommunication errors are meant to be returned if the host and the renter seem to be miscommunicating. For example, if the renter attempts to pay an insufficient price, there has been a communication error.

func (ErrorCommunication) Error 

func (ec ErrorCommunication) Error() string

Error satisfies the Error interface for the ErrorCommunication type.

type ErrorConnection 

type ErrorConnection string

ErrorConnection is meant to be used on errors where the network is returning unexpected errors. For example, sudden disconnects or connection write failures.

func (ErrorConnection) Error 

func (ec ErrorConnection) Error() string

Error satisfies the Error interface for the ErrorConnection type.

type ErrorConsensus 

type ErrorConsensus string

ErrorConsensus errors are meant to be used when there are problems related to consensus, such as an inability to submit a storage proof to the blockchain, or an inability to get a file contract revision on to the blockchain.

func (ErrorConsensus) Error 

func (ec ErrorConsensus) Error() string

Error satisfies the Error interface for the ErrorConsensus type.

type ErrorInternal 

type ErrorInternal string

ErrorInternal errors are meant to be used if an internal process in the host is malfunctioning, for example if the disk is failing.

func (ErrorInternal) Error 

func (ec ErrorInternal) Error() string

Error satisfies the Error interface for the ErrorInternal type.

type Host 

type Host struct {
	modules.StorageManager
	// contains filtered or unexported fields
}

A Host contains all the fields necessary for storing files for clients and performing the storage proofs on the received files.

func New 

func New(cs modules.ConsensusSet, g modules.Gateway, tpool modules.TransactionPool, wallet modules.Wallet, mux *siamux.SiaMux, address string, persistDir string) (*Host, error)

New returns an initialized Host.

func NewCustomHost 

func NewCustomHost(deps modules.Dependencies, cs modules.ConsensusSet, g modules.Gateway, tpool modules.TransactionPool, wallet modules.Wallet, mux *siamux.SiaMux, address string, persistDir string) (*Host, error)

NewCustomHost returns an initialized Host using the provided dependencies.

func NewCustomTestHost 

func NewCustomTestHost(deps modules.Dependencies, smDeps modules.Dependencies, cs modules.ConsensusSet, g modules.Gateway, tpool modules.TransactionPool, wallet modules.Wallet, mux *siamux.SiaMux, address string, persistDir string) (*Host, error)

NewCustomTestHost allows passing in both host dependencies and storage manager dependencies. Used solely for testing purposes, to allow dependency injection into the host's submodules.

func (*Host) Alerts 

func (h *Host) Alerts() []modules.Alert

Alerts implements the modules.Alerter interface for the host.

func (*Host) Announce 

func (h *Host) Announce() error

Announce creates a host announcement transaction.

func (*Host) AnnounceAddress 

func (h *Host) AnnounceAddress(addr modules.NetAddress) error

AnnounceAddress submits a host announcement to the blockchain to announce a specific address. If there is no error, the host's address will be updated to the supplied address.

func (*Host) BandwidthCounters 

func (h *Host) BandwidthCounters() (uint64, uint64, time.Time, error)

BandwidthCounters returns the Hosts's upload and download bandwidth

func (*Host) BlockHeight 

func (h *Host) BlockHeight() types.BlockHeight

BlockHeight returns the host's current blockheight.

func (*Host) Close 

func (h *Host) Close() error

Close shuts down the host.

func (*Host) ConnectabilityStatus 

func (h *Host) ConnectabilityStatus() modules.HostConnectabilityStatus

ConnectabilityStatus returns the connectability state of the host, whether the host can connect to itself on its configured netaddress.

func (*Host) ExternalSettings 

func (h *Host) ExternalSettings() modules.HostExternalSettings

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 (*Host) FinancialMetrics 

func (h *Host) FinancialMetrics() modules.HostFinancialMetrics

FinancialMetrics returns information about the financial commitments, rewards, and activities of the host.

func (*Host) InternalSettings 

func (h *Host) InternalSettings() modules.HostInternalSettings

InternalSettings returns the settings of a host.

func (*Host) NetAddress 

func (h *Host) NetAddress() modules.NetAddress

NetAddress returns the address at which the host can be reached.

func (*Host) NetworkMetrics 

func (h *Host) NetworkMetrics() modules.HostNetworkMetrics

NetworkMetrics returns information about the types of rpc calls that have been made to the host.

func (*Host) ProcessConsensusChange 

func (h *Host) ProcessConsensusChange(cc modules.ConsensusChange)

ProcessConsensusChange will be called by the consensus set every time there is a change to the blockchain.

func (*Host) PruneStaleStorageObligations 

func (h *Host) PruneStaleStorageObligations() error

PruneStaleStorageObligations will delete storage obligations from the host that, for whatever reason, did not make it on the block chain. As these stale storage obligations have an impact on the host financial metrics, this method updates the host financial metrics to show the correct values.

func (*Host) PublicKey 

func (h *Host) PublicKey() types.SiaPublicKey

PublicKey returns the public key of the host that is used to facilitate relationships between the host and renter.

func (*Host) SetInternalSettings 

func (h *Host) SetInternalSettings(settings modules.HostInternalSettings) error

SetInternalSettings updates the host's internal HostInternalSettings object.

func (*Host) StorageObligations 

func (h *Host) StorageObligations() (sos []modules.StorageObligation)

StorageObligations fetches the set of storage obligations in the host and returns metadata on them.

func (*Host) TryUnregisterInsufficientCollateralBudgetAlert 

func (h *Host) TryUnregisterInsufficientCollateralBudgetAlert()

TryUnregisterInsufficientCollateralBudgetAlert will be called when the host updates his collateral budget setting or when the locked storage collateral gets updated (in a way the updated storage collateral is lower).

func (*Host) WorkingStatus 

func (h *Host) WorkingStatus() modules.HostWorkingStatus

WorkingStatus returns the working state of the host, where working is defined as having received more than workingStatusThreshold settings calls over the period of workingStatusFrequency.

Source Files

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Directories

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