path: root/rpc/types.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package rpc

import (
    "fmt"
    "math"
    "math/big"
    "reflect"
    "strings"
    "sync"

    "github.com/ethereum/go-ethereum/event"
    "gopkg.in/fatih/set.v0"
)

// API describes the set of methods offered over the RPC interface
type API struct {
    Namespace string      // namespace under which the rpc methods of Service are exposed
    Version   string      // api version for DApp's
    Service   interface{} // receiver instance which holds the methods
    Public    bool        // indication if the methods must be considered safe for public use
}

// callback is a method callback which was registered in the server
type callback struct {
    rcvr        reflect.Value  // receiver of method
    method      reflect.Method // callback
    argTypes    []reflect.Type // input argument types
    hasCtx      bool           // method's first argument is a context (not included in argTypes)
    errPos      int            // err return idx, of -1 when method cannot return error
    isSubscribe bool           // indication if the callback is a subscription
}

// service represents a registered object
type service struct {
    name          string        // name for service
    rcvr          reflect.Value // receiver of methods for the service
    typ           reflect.Type  // receiver type
    callbacks     callbacks     // registered handlers
    subscriptions subscriptions // available subscriptions/notifications
}

// serverRequest is an incoming request
type serverRequest struct {
    id            int64
    svcname       string
    rcvr          reflect.Value
    callb         *callback
    args          []reflect.Value
    isUnsubscribe bool
    err           RPCError
}

type serviceRegistry map[string]*service          // collection of services
type callbacks map[string]*callback               // collection of RPC callbacks
type subscriptions map[string]*callback           // collection of subscription callbacks
type subscriptionRegistry map[string]Subscription // collection of subscriptions

// Server represents a RPC server
type Server struct {
    services       serviceRegistry
    muSubcriptions sync.Mutex // protects subscriptions
    subscriptions  subscriptionRegistry

    run      int32
    codecsMu sync.Mutex
    codecs   *set.Set
}

// rpcRequest represents a raw incoming RPC request
type rpcRequest struct {
    service  string
    method   string
    id       int64
    isPubSub bool
    params   interface{}
}

// RPCError implements RPC error, is add support for error codec over regular go errors
type RPCError interface {
    // RPC error code
    Code() int
    // Error message
    Error() string
}

// ServerCodec implements reading, parsing and writing RPC messages for the server side of
// a RPC session. Implementations must be go-routine safe since the codec can be called in
// multiple go-routines concurrently.
type ServerCodec interface {
    // Read next request
    ReadRequestHeaders() ([]rpcRequest, bool, RPCError)
    // Parse request argument to the given types
    ParseRequestArguments([]reflect.Type, interface{}) ([]reflect.Value, RPCError)
    // Assemble success response
    CreateResponse(int64, interface{}) interface{}
    // Assemble error response
    CreateErrorResponse(*int64, RPCError) interface{}
    // Assemble error response with extra information about the error through info
    CreateErrorResponseWithInfo(id *int64, err RPCError, info interface{}) interface{}
    // Create notification response
    CreateNotification(string, interface{}) interface{}
    // Write msg to client.
    Write(interface{}) error
    // Close underlying data stream
    Close()
    // Closed when underlying connection is closed
    Closed() <-chan interface{}
}

// SubscriptionMatcher returns true if the given value matches the criteria specified by the user
type SubscriptionMatcher func(interface{}) bool

// SubscriptionOutputFormat accepts event data and has the ability to format the data before it is send to the client
type SubscriptionOutputFormat func(interface{}) interface{}

// defaultSubscriptionOutputFormatter returns data and is used as default output format for notifications
func defaultSubscriptionOutputFormatter(data interface{}) interface{} {
    return data
}

// Subscription is used by the server to send notifications to the client
type Subscription struct {
    sub    event.Subscription
    match  SubscriptionMatcher
    format SubscriptionOutputFormat
}

// NewSubscription create a new RPC subscription
func NewSubscription(sub event.Subscription) Subscription {
    return Subscription{sub, nil, defaultSubscriptionOutputFormatter}
}

// NewSubscriptionWithOutputFormat create a new RPC subscription which a custom notification output format
func NewSubscriptionWithOutputFormat(sub event.Subscription, formatter SubscriptionOutputFormat) Subscription {
    return Subscription{sub, nil, formatter}
}

// NewSubscriptionFiltered will create a new subscription. For each raised event the given matcher is
// called. If it returns true the event is send as notification to the client, otherwise it is ignored.
func NewSubscriptionFiltered(sub event.Subscription, match SubscriptionMatcher) Subscription {
    return Subscription{sub, match, defaultSubscriptionOutputFormatter}
}

// Chan returns the channel where new events will be published. It's up the user to call the matcher to
// determine if the events are interesting for the client.
func (s *Subscription) Chan() <-chan *event.Event {
    return s.sub.Chan()
}

// Unsubscribe will end the subscription and closes the event channel
func (s *Subscription) Unsubscribe() {
    s.sub.Unsubscribe()
}

// HexNumber serializes a number to hex format using the "%#x" format
type HexNumber big.Int

// NewHexNumber creates a new hex number instance which will serialize the given val with `%#x` on marshal.
func NewHexNumber(val interface{}) *HexNumber {
    if val == nil {
        return nil
    }

    if v, ok := val.(*big.Int); ok && v != nil {
        hn := new(big.Int).Set(v)
        return (*HexNumber)(hn)
    }

    rval := reflect.ValueOf(val)

    var unsigned uint64
    utype := reflect.TypeOf(unsigned)
    if t := rval.Type(); t.ConvertibleTo(utype) {
        hn := new(big.Int).SetUint64(rval.Convert(utype).Uint())
        return (*HexNumber)(hn)
    }

    var signed int64
    stype := reflect.TypeOf(signed)
    if t := rval.Type(); t.ConvertibleTo(stype) {
        hn := new(big.Int).SetInt64(rval.Convert(stype).Int())
        return (*HexNumber)(hn)
    }

    return nil
}

func (h *HexNumber) UnmarshalJSON(input []byte) error {
    length := len(input)
    if length >= 2 && input[0] == '"' && input[length-1] == '"' {
        input = input[1 : length-1]
    }

    hn := (*big.Int)(h)
    if _, ok := hn.SetString(string(input), 0); ok {
        return nil
    }

    return fmt.Errorf("Unable to parse number")
}

// MarshalJSON serialize the hex number instance to a hex representation.
func (h *HexNumber) MarshalJSON() ([]byte, error) {
    if h != nil {
        hn := (*big.Int)(h)
        if hn.BitLen() == 0 {
            return []byte(`"0x0"`), nil
        }
        return []byte(fmt.Sprintf(`"0x%x"`, hn)), nil
    }
    return nil, nil
}

func (h *HexNumber) Int() int {
    hn := (*big.Int)(h)
    return int(hn.Int64())
}

func (h *HexNumber) Int64() int64 {
    hn := (*big.Int)(h)
    return hn.Int64()
}

func (h *HexNumber) Uint() uint {
    hn := (*big.Int)(h)
    return uint(hn.Uint64())
}

func (h *HexNumber) Uint64() uint64 {
    hn := (*big.Int)(h)
    return hn.Uint64()
}

func (h *HexNumber) BigInt() *big.Int {
    return (*big.Int)(h)
}

type Number int64

func (n *Number) UnmarshalJSON(data []byte) error {
    input := strings.TrimSpace(string(data))

    if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
        input = input[1 : len(input)-1]
    }

    if len(input) == 0 {
        *n = Number(latestBlockNumber.Int64())
        return nil
    }

    in := new(big.Int)
    _, ok := in.SetString(input, 0)

    if !ok { // test if user supplied string tag
        return fmt.Errorf(`invalid number %s`, data)
    }

    if in.Cmp(earliestBlockNumber) >= 0 && in.Cmp(maxBlockNumber) <= 0 {
        *n = Number(in.Int64())
        return nil
    }

    return fmt.Errorf("blocknumber not in range [%d, %d]", earliestBlockNumber, maxBlockNumber)
}

func (n *Number) Int64() int64 {
    return *(*int64)(n)
}

func (n *Number) BigInt() *big.Int {
    return big.NewInt(n.Int64())
}

var (
    pendingBlockNumber  = big.NewInt(-2)
    latestBlockNumber   = big.NewInt(-1)
    earliestBlockNumber = big.NewInt(0)
    maxBlockNumber      = big.NewInt(math.MaxInt64)
)

type BlockNumber int64

const (
    PendingBlockNumber = BlockNumber(-2)
    LatestBlockNumber  = BlockNumber(-1)
)

// UnmarshalJSON parses the given JSON fragement into a BlockNumber. It supports:
// - "latest" or "earliest" as string arguments
// - the block number
// Returned errors:
// - an unsupported error when "pending" is specified (not yet implemented)
// - an invalid block number error when the given argument isn't a known strings
// - an out of range error when the given block number is either too little or too large
func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
    input := strings.TrimSpace(string(data))

    if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
        input = input[1 : len(input)-1]
    }

    if len(input) == 0 {
        *bn = BlockNumber(latestBlockNumber.Int64())
        return nil
    }

    in := new(big.Int)
    _, ok := in.SetString(input, 0)

    if !ok { // test if user supplied string tag
        strBlockNumber := input
        if strBlockNumber == "latest" {
            *bn = BlockNumber(latestBlockNumber.Int64())
            return nil
        }

        if strBlockNumber == "earliest" {
            *bn = BlockNumber(earliestBlockNumber.Int64())
            return nil
        }

        if strBlockNumber == "pending" {
            *bn = BlockNumber(pendingBlockNumber.Int64())
            return nil
        }

        return fmt.Errorf(`invalid blocknumber %s`, data)
    }

    if in.Cmp(earliestBlockNumber) >= 0 && in.Cmp(maxBlockNumber) <= 0 {
        *bn = BlockNumber(in.Int64())
        return nil
    }

    return fmt.Errorf("blocknumber not in range [%d, %d]", earliestBlockNumber, maxBlockNumber)
}

func (bn *BlockNumber) Int64() int64 {
    return (int64)(*bn)
}

// Client defines the interface for go client that wants to connect to a geth RPC endpoint
type Client interface {
    // SupportedModules returns the collection of API's the server offers
    SupportedModules() (map[string]string, error)

    Send(req interface{}) error
    Recv(msg interface{}) error

    Close()
}