core

package
v1.9.2 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Aug 13, 2019 License: GPL-3.0 Imports: 34 Imported by: 0

Documentation

Index

Constants

View Source 
const (

	// ExternalAPIVersion -- see extapi_changelog.md
	ExternalAPIVersion = "6.0.0"
	// InternalAPIVersion -- see intapi_changelog.md
	InternalAPIVersion = "7.0.0"
)
View Source 
const (
	WARN = "WARNING"
	CRIT = "CRITICAL"
	INFO = "Info"
)

Variables

View Source 
var (
	IntendedValidator = SigFormat{
		accounts.MimetypeDataWithValidator,
		0x00,
	}
	DataTyped = SigFormat{
		accounts.MimetypeTypedData,
		0x01,
	}
	ApplicationClique = SigFormat{
		accounts.MimetypeClique,
		0x02,
	}
	TextPlain = SigFormat{
		accounts.MimetypeTextPlain,
		0x45,
	}
)
View Source 
var ErrRequestDenied = errors.New("Request denied")

Functions

func SignTextValidator added in v1.9.0 

func SignTextValidator(validatorData ValidatorData) (hexutil.Bytes, string)

SignTextWithValidator signs the given message which can be further recovered with the given validator. hash = keccak256("\x19\x00"${address}${data}).

func StartClefAccountManager added in v1.9.0 

func StartClefAccountManager(ksLocation string, nousb, lightKDF bool, scpath string) *accounts.Manager

func ValidatePasswordFormat added in v1.8.17 

func ValidatePasswordFormat(password string) error

ValidatePasswordFormat returns an error if the password is too short, or consists of characters outside the range of the printable 7bit ascii set

Types

type AuditLogger 

type AuditLogger struct {
	// contains filtered or unexported fields
}

func NewAuditLogger 

func NewAuditLogger(path string, api ExternalAPI) (*AuditLogger, error)

func (*AuditLogger) EcRecover 

func (l *AuditLogger) EcRecover(ctx context.Context, data hexutil.Bytes, sig hexutil.Bytes) (common.Address, error)

func (*AuditLogger) List 

func (l *AuditLogger) List(ctx context.Context) ([]common.Address, error)

func (*AuditLogger) New 

func (l *AuditLogger) New(ctx context.Context) (common.Address, error)

func (*AuditLogger) SignData added in v1.9.0 

func (l *AuditLogger) SignData(ctx context.Context, contentType string, addr common.MixedcaseAddress, data interface{}) (hexutil.Bytes, error)

func (*AuditLogger) SignTransaction 

func (l *AuditLogger) SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error)

func (*AuditLogger) SignTypedData added in v1.9.0 

func (l *AuditLogger) SignTypedData(ctx context.Context, addr common.MixedcaseAddress, data TypedData) (hexutil.Bytes, error)

func (*AuditLogger) Version added in v1.9.0 

func (l *AuditLogger) Version(ctx context.Context) (string, error)

type CommandlineUI 

type CommandlineUI struct {
	// contains filtered or unexported fields
}

func NewCommandlineUI 

func NewCommandlineUI() *CommandlineUI

func (*CommandlineUI) ApproveListing 

func (ui *CommandlineUI) ApproveListing(request *ListRequest) (ListResponse, error)

ApproveListing prompt the user for confirmation to list accounts the list of accounts to list can be modified by the UI

func (*CommandlineUI) ApproveNewAccount 

func (ui *CommandlineUI) ApproveNewAccount(request *NewAccountRequest) (NewAccountResponse, error)

ApproveNewAccount prompt the user for confirmation to create new Account, and reveal to caller

func (*CommandlineUI) ApproveSignData 

func (ui *CommandlineUI) ApproveSignData(request *SignDataRequest) (SignDataResponse, error)

ApproveSignData prompt the user for confirmation to request to sign data

func (*CommandlineUI) ApproveTx 

func (ui *CommandlineUI) ApproveTx(request *SignTxRequest) (SignTxResponse, error)

ApproveTx prompt the user for confirmation to request to sign Transaction

func (*CommandlineUI) OnApprovedTx 

func (ui *CommandlineUI) OnApprovedTx(tx ethapi.SignTransactionResult)

func (*CommandlineUI) OnInputRequired added in v1.8.17 

func (ui *CommandlineUI) OnInputRequired(info UserInputRequest) (UserInputResponse, error)

func (*CommandlineUI) OnSignerStartup 

func (ui *CommandlineUI) OnSignerStartup(info StartupInfo)

func (*CommandlineUI) RegisterUIServer added in v1.9.0 

func (ui *CommandlineUI) RegisterUIServer(api *UIServerAPI)

func (*CommandlineUI) ShowError 

func (ui *CommandlineUI) ShowError(message string)

ShowError displays error message to user

func (*CommandlineUI) ShowInfo 

func (ui *CommandlineUI) ShowInfo(message string)

ShowInfo displays info message to user

type ExternalAPI 

type ExternalAPI interface {
	// List available accounts
	List(ctx context.Context) ([]common.Address, error)
	// New request to create a new account
	New(ctx context.Context) (common.Address, error)
	// SignTransaction request to sign the specified transaction
	SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error)
	// SignData - request to sign the given data (plus prefix)
	SignData(ctx context.Context, contentType string, addr common.MixedcaseAddress, data interface{}) (hexutil.Bytes, error)
	// SignTypedData - request to sign the given structured data (plus prefix)
	SignTypedData(ctx context.Context, addr common.MixedcaseAddress, data TypedData) (hexutil.Bytes, error)
	// EcRecover - recover public key from given message and signature
	EcRecover(ctx context.Context, data hexutil.Bytes, sig hexutil.Bytes) (common.Address, error)
	// Version info about the APIs
	Version(ctx context.Context) (string, error)
}

ExternalAPI defines the external API through which signing requests are made.

type ListRequest 

type ListRequest struct {
	Accounts []accounts.Account `json:"accounts"`
	Meta     Metadata           `json:"meta"`
}

types for the requests/response types between signer and UI

type ListResponse 

type ListResponse struct {
	Accounts []accounts.Account `json:"accounts"`
}

types for the requests/response types between signer and UI

type Message 

type Message struct {
	Text string `json:"text"`
}

types for the requests/response types between signer and UI

type Metadata 

type Metadata struct {
	Remote    string `json:"remote"`
	Local     string `json:"local"`
	Scheme    string `json:"scheme"`
	UserAgent string `json:"User-Agent"`
	Origin    string `json:"Origin"`
}

Metadata about a request

func MetadataFromContext 

func MetadataFromContext(ctx context.Context) Metadata

MetadataFromContext extracts Metadata from a given context.Context

func (Metadata) String 

func (m Metadata) String() string

String implements Stringer interface

type NameValueType added in v1.9.0 

type NameValueType struct {
	Name  string      `json:"name"`
	Value interface{} `json:"value"`
	Typ   string      `json:"type"`
}

NameValueType is a very simple struct with Name, Value and Type. It's meant for simple json structures used to communicate signing-info about typed data with the UI

func (*NameValueType) Pprint added in v1.9.0 

func (nvt *NameValueType) Pprint(depth int) string

Pprint returns a pretty-printed version of nvt

type NewAccountRequest 

type NewAccountRequest struct {
	Meta Metadata `json:"meta"`
}

types for the requests/response types between signer and UI

type NewAccountResponse 

type NewAccountResponse struct {
	Approved bool `json:"approved"`
}

types for the requests/response types between signer and UI

type SendTxArgs 

type SendTxArgs struct {
	From     common.MixedcaseAddress  `json:"from"`
	To       *common.MixedcaseAddress `json:"to"`
	Gas      hexutil.Uint64           `json:"gas"`
	GasPrice hexutil.Big              `json:"gasPrice"`
	Value    hexutil.Big              `json:"value"`
	Nonce    hexutil.Uint64           `json:"nonce"`
	// We accept "data" and "input" for backwards-compatibility reasons.
	Data  *hexutil.Bytes `json:"data"`
	Input *hexutil.Bytes `json:"input,omitempty"`
}

SendTxArgs represents the arguments to submit a transaction

func (SendTxArgs) String 

func (args SendTxArgs) String() string

type SigFormat added in v1.9.0 

type SigFormat struct {
	Mime        string
	ByteVersion byte
}

type SignDataRequest 

type SignDataRequest struct {
	ContentType string                  `json:"content_type"`
	Address     common.MixedcaseAddress `json:"address"`
	Rawdata     []byte                  `json:"raw_data"`
	Messages    []*NameValueType        `json:"messages"`
	Hash        hexutil.Bytes           `json:"hash"`
	Meta        Metadata                `json:"meta"`
}

types for the requests/response types between signer and UI

type SignDataResponse 

type SignDataResponse struct {
	Approved bool `json:"approved"`
}

types for the requests/response types between signer and UI

type SignTxRequest 

type SignTxRequest struct {
	Transaction SendTxArgs       `json:"transaction"`
	Callinfo    []ValidationInfo `json:"call_info"`
	Meta        Metadata         `json:"meta"`
}

SignTxRequest contains info about a Transaction to sign

type SignTxResponse 

type SignTxResponse struct {
	//The UI may make changes to the TX
	Transaction SendTxArgs `json:"transaction"`
	Approved    bool       `json:"approved"`
}

SignTxResponse result from SignTxRequest

type SignerAPI 

type SignerAPI struct {
	UI UIClientAPI
	// contains filtered or unexported fields
}

SignerAPI defines the actual implementation of ExternalAPI

func NewSignerAPI 

func NewSignerAPI(am *accounts.Manager, chainID int64, noUSB bool, ui UIClientAPI, validator Validator, advancedMode bool, credentials storage.Storage) *SignerAPI

NewSignerAPI creates a new API that can be used for Account management. ksLocation specifies the directory where to store the password protected private key that is generated when a new Account is created. noUSB disables USB support that is required to support hardware devices such as ledger and trezor.

func (*SignerAPI) EcRecover 

func (api *SignerAPI) EcRecover(ctx context.Context, data hexutil.Bytes, sig hexutil.Bytes) (common.Address, error)

EcRecover recovers the address associated with the given sig. Only compatible with `text/plain`

func (*SignerAPI) List 

func (api *SignerAPI) List(ctx context.Context) ([]common.Address, error)

List returns the set of wallet this signer manages. Each wallet can contain multiple accounts.

func (*SignerAPI) New 

func (api *SignerAPI) New(ctx context.Context) (common.Address, error)

New creates a new password protected Account. The private key is protected with the given password. Users are responsible to backup the private key that is stored in the keystore location thas was specified when this API was created.

func (*SignerAPI) SignData added in v1.9.0 

func (api *SignerAPI) SignData(ctx context.Context, contentType string, addr common.MixedcaseAddress, data interface{}) (hexutil.Bytes, error)

SignData signs the hash of the provided data, but does so differently depending on the content-type specified.

Different types of validation occur.

func (*SignerAPI) SignTransaction 

func (api *SignerAPI) SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error)

SignTransaction signs the given Transaction and returns it both as json and rlp-encoded form

func (*SignerAPI) SignTypedData added in v1.9.0 

func (api *SignerAPI) SignTypedData(ctx context.Context, addr common.MixedcaseAddress, typedData TypedData) (hexutil.Bytes, error)

SignTypedData signs EIP-712 conformant typed data hash = keccak256("\x19${byteVersion}${domainSeparator}${hashStruct(message)}")

func (*SignerAPI) Version added in v1.9.0 

func (api *SignerAPI) Version(ctx context.Context) (string, error)

Returns the external api version. This method does not require user acceptance. Available methods are available via enumeration anyway, and this info does not contain user-specific data

type StartupInfo 

type StartupInfo struct {
	Info map[string]interface{} `json:"info"`
}

types for the requests/response types between signer and UI

type StdIOUI 

type StdIOUI struct {
	// contains filtered or unexported fields
}

func NewStdIOUI 

func NewStdIOUI() *StdIOUI

func (*StdIOUI) ApproveListing 

func (ui *StdIOUI) ApproveListing(request *ListRequest) (ListResponse, error)

func (*StdIOUI) ApproveNewAccount 

func (ui *StdIOUI) ApproveNewAccount(request *NewAccountRequest) (NewAccountResponse, error)

func (*StdIOUI) ApproveSignData 

func (ui *StdIOUI) ApproveSignData(request *SignDataRequest) (SignDataResponse, error)

func (*StdIOUI) ApproveTx 

func (ui *StdIOUI) ApproveTx(request *SignTxRequest) (SignTxResponse, error)

func (*StdIOUI) OnApprovedTx 

func (ui *StdIOUI) OnApprovedTx(tx ethapi.SignTransactionResult)

func (*StdIOUI) OnInputRequired added in v1.8.17 

func (ui *StdIOUI) OnInputRequired(info UserInputRequest) (UserInputResponse, error)

func (*StdIOUI) OnSignerStartup 

func (ui *StdIOUI) OnSignerStartup(info StartupInfo)

func (*StdIOUI) RegisterUIServer added in v1.9.0 

func (ui *StdIOUI) RegisterUIServer(api *UIServerAPI)

func (*StdIOUI) ShowError 

func (ui *StdIOUI) ShowError(message string)

func (*StdIOUI) ShowInfo 

func (ui *StdIOUI) ShowInfo(message string)

type Type added in v1.9.0 

type Type struct {
	Name string `json:"name"`
	Type string `json:"type"`
}

type TypePriority added in v1.9.0 

type TypePriority struct {
	Type  string
	Value uint
}

type TypedData added in v1.9.0 

type TypedData struct {
	Types       Types            `json:"types"`
	PrimaryType string           `json:"primaryType"`
	Domain      TypedDataDomain  `json:"domain"`
	Message     TypedDataMessage `json:"message"`
}

func (*TypedData) Dependencies added in v1.9.0 

func (typedData *TypedData) Dependencies(primaryType string, found []string) []string

Dependencies returns an array of custom types ordered by their hierarchical reference tree

func (*TypedData) EncodeData added in v1.9.0 

func (typedData *TypedData) EncodeData(primaryType string, data map[string]interface{}, depth int) (hexutil.Bytes, error)

EncodeData generates the following encoding: `enc(value₁) ‖ enc(value₂) ‖ … ‖ enc(valueₙ)`

each encoded member is 32-byte long

func (*TypedData) EncodePrimitiveValue added in v1.9.0 

func (typedData *TypedData) EncodePrimitiveValue(encType string, encValue interface{}, depth int) ([]byte, error)

EncodePrimitiveValue deals with the primitive values found while searching through the typed data

func (*TypedData) EncodeType added in v1.9.0 

func (typedData *TypedData) EncodeType(primaryType string) hexutil.Bytes

EncodeType generates the following encoding: `name ‖ "(" ‖ member₁ ‖ "," ‖ member₂ ‖ "," ‖ … ‖ memberₙ ")"`

each member is written as `type ‖ " " ‖ name` encodings cascade down and are sorted by name

func (*TypedData) Format added in v1.9.0 

func (typedData *TypedData) Format() ([]*NameValueType, error)

Format returns a representation of typedData, which can be easily displayed by a user-interface without in-depth knowledge about 712 rules

func (*TypedData) HashStruct added in v1.9.0 

func (typedData *TypedData) HashStruct(primaryType string, data TypedDataMessage) (hexutil.Bytes, error)

HashStruct generates a keccak256 hash of the encoding of the provided data

func (*TypedData) Map added in v1.9.0 

func (typedData *TypedData) Map() map[string]interface{}

Map generates a map version of the typed data

func (*TypedData) TypeHash added in v1.9.0 

func (typedData *TypedData) TypeHash(primaryType string) hexutil.Bytes

TypeHash creates the keccak256 hash of the data

type TypedDataDomain added in v1.9.0 

type TypedDataDomain struct {
	Name              string                `json:"name"`
	Version           string                `json:"version"`
	ChainId           *math.HexOrDecimal256 `json:"chainId"`
	VerifyingContract string                `json:"verifyingContract"`
	Salt              string                `json:"salt"`
}

func (*TypedDataDomain) Map added in v1.9.0 

func (domain *TypedDataDomain) Map() map[string]interface{}

Map is a helper function to generate a map version of the domain

type TypedDataMessage added in v1.9.0 

type TypedDataMessage = map[string]interface{}

type Types added in v1.9.0 

type Types map[string][]Type

type UIClientAPI added in v1.9.0 

type UIClientAPI interface {
	// ApproveTx prompt the user for confirmation to request to sign Transaction
	ApproveTx(request *SignTxRequest) (SignTxResponse, error)
	// ApproveSignData prompt the user for confirmation to request to sign data
	ApproveSignData(request *SignDataRequest) (SignDataResponse, error)
	// ApproveListing prompt the user for confirmation to list accounts
	// the list of accounts to list can be modified by the UI
	ApproveListing(request *ListRequest) (ListResponse, error)
	// ApproveNewAccount prompt the user for confirmation to create new Account, and reveal to caller
	ApproveNewAccount(request *NewAccountRequest) (NewAccountResponse, error)
	// ShowError displays error message to user
	ShowError(message string)
	// ShowInfo displays info message to user
	ShowInfo(message string)
	// OnApprovedTx notifies the UI about a transaction having been successfully signed.
	// This method can be used by a UI to keep track of e.g. how much has been sent to a particular recipient.
	OnApprovedTx(tx ethapi.SignTransactionResult)
	// OnSignerStartup is invoked when the signer boots, and tells the UI info about external API location and version
	// information
	OnSignerStartup(info StartupInfo)
	// OnInputRequired is invoked when clef requires user input, for example master password or
	// pin-code for unlocking hardware wallets
	OnInputRequired(info UserInputRequest) (UserInputResponse, error)
	// RegisterUIServer tells the UI to use the given UIServerAPI for ui->clef communication
	RegisterUIServer(api *UIServerAPI)
}

UIClientAPI specifies what method a UI needs to implement to be able to be used as a UI for the signer

type UIServerAPI added in v1.9.0 

type UIServerAPI struct {
	// contains filtered or unexported fields
}

SignerUIAPI implements methods Clef provides for a UI to query, in the bidirectional communication channel. This API is considered secure, since a request can only ever arrive from the UI -- and the UI is capable of approving any action, thus we can consider these requests pre-approved. NB: It's very important that these methods are not ever exposed on the external service registry.

func NewUIServerAPI added in v1.9.0 

func NewUIServerAPI(extapi *SignerAPI) *UIServerAPI

NewUIServerAPI creates a new UIServerAPI

func (*UIServerAPI) ChainId added in v1.9.0 

func (s *UIServerAPI) ChainId() math.HexOrDecimal64

ChainId returns the chainid in use for Eip-155 replay protection Example call {"jsonrpc":"2.0","method":"clef_chainId","params":[], "id":8}

func (*UIServerAPI) DeriveAccount added in v1.9.0 

func (s *UIServerAPI) DeriveAccount(url string, path string, pin *bool) (accounts.Account, error)

DeriveAccount requests a HD wallet to derive a new account, optionally pinning it for later reuse. Example call {"jsonrpc":"2.0","method":"clef_deriveAccount","params":["ledger://","m/44'/60'/0'", false], "id":6}

func (*UIServerAPI) Export added in v1.9.0 

func (s *UIServerAPI) Export(ctx context.Context, addr common.Address) (json.RawMessage, error)

Export returns encrypted private key associated with the given address in web3 keystore format. Example {"jsonrpc":"2.0","method":"clef_export","params":["0x19e7e376e7c213b7e7e7e46cc70a5dd086daff2a"], "id":4}

func (*UIServerAPI) Import added in v1.9.0 

func (api *UIServerAPI) Import(ctx context.Context, keyJSON json.RawMessage, oldPassphrase, newPassphrase string) (accounts.Account, error)

Import tries to import the given keyJSON in the local keystore. The keyJSON data is expected to be in web3 keystore format. It will decrypt the keyJSON with the given passphrase and on successful decryption it will encrypt the key with the given newPassphrase and store it in the keystore. Example (the address in question has privkey `11...11`): {"jsonrpc":"2.0","method":"clef_import","params":[{"address":"19e7e376e7c213b7e7e7e46cc70a5dd086daff2a","crypto":{"cipher":"aes-128-ctr","ciphertext":"33e4cd3756091d037862bb7295e9552424a391a6e003272180a455ca2a9fb332","cipherparams":{"iv":"b54b263e8f89c42bb219b6279fba5cce"},"kdf":"scrypt","kdfparams":{"dklen":32,"n":262144,"p":1,"r":8,"salt":"e4ca94644fd30569c1b1afbbc851729953c92637b7fe4bb9840bbb31ffbc64a5"},"mac":"f4092a445c2b21c0ef34f17c9cd0d873702b2869ec5df4439a0c2505823217e7"},"id":"216c7eac-e8c1-49af-a215-fa0036f29141","version":3},"test","yaddayadda"], "id":4}

func (*UIServerAPI) ImportRawKey added in v1.9.0 

func (s *UIServerAPI) ImportRawKey(privkey string, password string) (accounts.Account, error)

ImportRawKey stores the given hex encoded ECDSA key into the key directory, encrypting it with the passphrase. Example call (should fail on password too short) {"jsonrpc":"2.0","method":"clef_importRawKey","params":["1111111111111111111111111111111111111111111111111111111111111111","test"], "id":6}

func (*UIServerAPI) ListAccounts added in v1.9.0 

func (s *UIServerAPI) ListAccounts(ctx context.Context) ([]accounts.Account, error)

List available accounts. As opposed to the external API definition, this method delivers the full Account object and not only Address. Example call {"jsonrpc":"2.0","method":"clef_listAccounts","params":[], "id":4}

func (*UIServerAPI) ListWallets added in v1.9.0 

func (s *UIServerAPI) ListWallets() []rawWallet

ListWallets will return a list of wallets that clef manages Example call {"jsonrpc":"2.0","method":"clef_listWallets","params":[], "id":5}

func (*UIServerAPI) OpenWallet added in v1.9.0 

func (s *UIServerAPI) OpenWallet(url string, passphrase *string) error

OpenWallet initiates a hardware wallet opening procedure, establishing a USB connection and attempting to authenticate via the provided passphrase. Note, the method may return an extra challenge requiring a second open (e.g. the Trezor PIN matrix challenge). Example {"jsonrpc":"2.0","method":"clef_openWallet","params":["ledger://",""], "id":6}

func (*UIServerAPI) SetChainId added in v1.9.0 

func (s *UIServerAPI) SetChainId(id math.HexOrDecimal64) math.HexOrDecimal64

SetChainId sets the chain id to use when signing transactions. Example call to set Ropsten: {"jsonrpc":"2.0","method":"clef_setChainId","params":["3"], "id":8}

type UserInputRequest added in v1.8.17 

type UserInputRequest struct {
	Title      string `json:"title"`
	Prompt     string `json:"prompt"`
	IsPassword bool   `json:"isPassword"`
}

types for the requests/response types between signer and UI

type UserInputResponse added in v1.8.17 

type UserInputResponse struct {
	Text string `json:"text"`
}

types for the requests/response types between signer and UI

type ValidationInfo 

type ValidationInfo struct {
	Typ     string `json:"type"`
	Message string `json:"message"`
}

type ValidationMessages 

type ValidationMessages struct {
	Messages []ValidationInfo
}

func (*ValidationMessages) Crit added in v1.9.0 

func (vs *ValidationMessages) Crit(msg string)

func (*ValidationMessages) Info added in v1.9.0 

func (vs *ValidationMessages) Info(msg string)

func (*ValidationMessages) Warn added in v1.9.0 

func (vs *ValidationMessages) Warn(msg string)

type Validator 

type Validator interface {
	// ValidateTransaction does a number of checks on the supplied transaction, and
	// returns either a list of warnings, or an error (indicating that the transaction
	// should be immediately rejected).
	ValidateTransaction(selector *string, tx *SendTxArgs) (*ValidationMessages, error)
}

Validator defines the methods required to validate a transaction against some sanity defaults as well as any underlying 4byte method database.

Use fourbyte.Database as an implementation. It is separated out of this package to allow pieces of the signer package to be used without having to load the 7MB embedded 4byte dump.

type ValidatorData added in v1.9.0 

type ValidatorData struct {
	Address common.Address
	Message hexutil.Bytes
}

func UnmarshalValidatorData added in v1.9.0 

func UnmarshalValidatorData(data interface{}) (ValidatorData, error)

UnmarshalValidatorData converts the bytes input to typed data

Source Files

View all Source files

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.