path: root/rpc/codec/json.go

package codec

import (
    "encoding/json"
    "fmt"
    "net"
    "time"

    "github.com/ethereum/go-ethereum/rpc/shared"
)

const (
    READ_TIMEOUT      = 60 // in seconds
    MAX_REQUEST_SIZE  = 1024 * 1024
    MAX_RESPONSE_SIZE = 1024 * 1024
)

var (
    // No new requests in buffer
    EmptyRequestQueueError = fmt.Errorf("No incoming requests")
    // Next request in buffer isn't yet complete
    IncompleteRequestError = fmt.Errorf("Request incomplete")
)

// Json serialization support
type JsonCodec struct {
    c                net.Conn
    reqBuffer        []byte
    bytesInReqBuffer int
    reqLastPos       int
}

// Create new JSON coder instance
func NewJsonCoder(conn net.Conn) ApiCoder {
    return &JsonCodec{
        c:                conn,
        reqBuffer:        make([]byte, MAX_REQUEST_SIZE),
        bytesInReqBuffer: 0,
        reqLastPos:       0,
    }
}

// Indication if the next request in the buffer is a batch request
func (self *JsonCodec) isNextBatchReq() (bool, error) {
    for i := 0; i < self.bytesInReqBuffer; i++ {
        switch self.reqBuffer[i] {
        case 0x20, 0x09, 0x0a, 0x0d: // allow leading whitespace (JSON whitespace RFC4627)
            continue
        case 0x7b: // single req
            return false, nil
        case 0x5b: // batch req
            return true, nil
        default:
            return false, &json.InvalidUnmarshalError{}
        }
    }

    return false, EmptyRequestQueueError
}

// remove parsed request from buffer
func (self *JsonCodec) resetReqbuffer(pos int) {
    copy(self.reqBuffer, self.reqBuffer[pos:self.bytesInReqBuffer])
    self.reqLastPos = 0
    self.bytesInReqBuffer -= pos
}

// parse request in buffer
func (self *JsonCodec) nextRequest() (requests []*shared.Request, isBatch bool, err error) {
    if isBatch, err := self.isNextBatchReq(); err == nil {
        if isBatch {
            requests = make([]*shared.Request, 0)
            for ; self.reqLastPos <= self.bytesInReqBuffer; self.reqLastPos++ {
                if err = json.Unmarshal(self.reqBuffer[:self.reqLastPos], &requests); err == nil {
                    self.resetReqbuffer(self.reqLastPos)
                    return requests, true, nil
                }
            }
            return nil, true, IncompleteRequestError
        } else {
            request := shared.Request{}
            for ; self.reqLastPos <= self.bytesInReqBuffer; self.reqLastPos++ {
                if err = json.Unmarshal(self.reqBuffer[:self.reqLastPos], &request); err == nil {
                    requests := make([]*shared.Request, 1)
                    requests[0] = &request
                    self.resetReqbuffer(self.reqLastPos)
                    return requests, false, nil
                }
            }
            return nil, true, IncompleteRequestError
        }
    } else {
        return nil, false, err
    }
}

// Serialize obj to JSON and write it to conn
func (self *JsonCodec) ReadRequest() (requests []*shared.Request, isBatch bool, err error) {
    if self.bytesInReqBuffer != 0 {
        req, batch, err := self.nextRequest()
        if err == nil {
            return req, batch, err
        }

        if err != IncompleteRequestError {
            return nil, false, err
        }
    }

    // no/incomplete request in buffer -> read more data first
    deadline := time.Now().Add(READ_TIMEOUT * time.Second)
    if err := self.c.SetDeadline(deadline); err != nil {
        return nil, false, err
    }

    var retErr error
    for {
        n, err := self.c.Read(self.reqBuffer[self.bytesInReqBuffer:])
        if err != nil {
            retErr = err
            break
        }

        self.bytesInReqBuffer += n

        requests, isBatch, err := self.nextRequest()
        if err == nil {
            return requests, isBatch, nil
        }

        if err == IncompleteRequestError || err == EmptyRequestQueueError {
            continue // need more data
        }

        retErr = err
        break
    }

    self.c.Close()
    return nil, false, retErr
}

func (self *JsonCodec) ReadResponse() (interface{}, error) {
    bytesInBuffer := 0
    buf := make([]byte, MAX_RESPONSE_SIZE)

    deadline := time.Now().Add(READ_TIMEOUT * time.Second)
    if err := self.c.SetDeadline(deadline); err != nil {
        return nil, err
    }

    for {
        n, err := self.c.Read(buf[bytesInBuffer:])
        if err != nil {
            return nil, err
        }
        bytesInBuffer += n

        var success shared.SuccessResponse
        if err = json.Unmarshal(buf[:bytesInBuffer], &success); err == nil {
            return success, nil
        }

        var failure shared.ErrorResponse
        if err = json.Unmarshal(buf[:bytesInBuffer], &failure); err == nil && failure.Error != nil {
            return failure, nil
        }
    }

    self.c.Close()
    return nil, fmt.Errorf("Unable to read response")
}

// Decode data
func (self *JsonCodec) Decode(data []byte, msg interface{}) error {
    return json.Unmarshal(data, msg)
}

// Encode message
func (self *JsonCodec) Encode(msg interface{}) ([]byte, error) {
    return json.Marshal(msg)
}

// Parse JSON data from conn to obj
func (self *JsonCodec) WriteResponse(res interface{}) error {
    data, err := json.Marshal(res)
    if err != nil {
        self.c.Close()
        return err
    }

    bytesWritten := 0

    for bytesWritten < len(data) {
        n, err := self.c.Write(data[bytesWritten:])
        if err != nil {
            self.c.Close()
            return err
        }
        bytesWritten += n
    }

    return nil
}

// Close decoder and encoder
func (self *JsonCodec) Close() {
    self.c.Close()
}