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"
    "reflect"
    "strings"
    "sync"

    "github.com/ethereum/go-ethereum/common/hexutil"
    "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
    typ           reflect.Type  // receiver type
    callbacks     callbacks     // registered handlers
    subscriptions subscriptions // available subscriptions/notifications
}

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

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

// Server represents a RPC server
type Server struct {
    services serviceRegistry

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

// rpcRequest represents a raw incoming RPC request
type rpcRequest struct {
    service  string
    method   string
    id       interface{}
    isPubSub bool
    params   interface{}
    err      Error // invalid batch element
}

// Error wraps RPC errors, which contain an error code in addition to the message.
type Error interface {
    Error() string  // returns the message
    ErrorCode() int // returns the code
}

// 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, Error)
    // Parse request argument to the given types
    ParseRequestArguments(argTypes []reflect.Type, params interface{}) ([]reflect.Value, Error)
    // Assemble success response, expects response id and payload
    CreateResponse(id interface{}, reply interface{}) interface{}
    // Assemble error response, expects response id and error
    CreateErrorResponse(id interface{}, err Error) interface{}
    // Assemble error response with extra information about the error through info
    CreateErrorResponseWithInfo(id interface{}, err Error, info interface{}) interface{}
    // Create notification response
    CreateNotification(id, namespace string, event interface{}) interface{}
    // Write msg to client.
    Write(msg interface{}) error
    // Close underlying data stream
    Close()
    // Closed when underlying connection is closed
    Closed() <-chan interface{}
}

type BlockNumber int64

const (
    PendingBlockNumber  = BlockNumber(-2)
    LatestBlockNumber   = BlockNumber(-1)
    EarliestBlockNumber = BlockNumber(0)
)

// UnmarshalJSON parses the given JSON fragment into a BlockNumber. It supports:
// - "latest", "earliest" or "pending" as string arguments
// - the block number
// Returned errors:
// - 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]
    }

    switch input {
    case "earliest":
        *bn = EarliestBlockNumber
        return nil
    case "latest":
        *bn = LatestBlockNumber
        return nil
    case "pending":
        *bn = PendingBlockNumber
        return nil
    }

    blckNum, err := hexutil.DecodeUint64(input)
    if err != nil {
        return err
    }
    if blckNum > math.MaxInt64 {
        return fmt.Errorf("Blocknumber too high")
    }

    *bn = BlockNumber(blckNum)
    return nil
}

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