serialize.go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package serialize

import (
	"bytes"
	"errors"
	"fmt"
	"io/ioutil"

	"go.uber.org/yarpc/api/transport"
	"go.uber.org/yarpc/serialize/internal"

	"github.com/opentracing/opentracing-go"
	"go.uber.org/thriftrw/protocol"
	"go.uber.org/thriftrw/wire"
)

// version indicates which underlying serialization method will be used
// '0' indicates:
// 		thrift serialization (request) + jaeger.binary format (ctx/tracing)
const version = byte(0)

// ToBytes encodes an opentracing.SpanContext and transport.Request into bytes
func ToBytes(tracer opentracing.Tracer, spanContext opentracing.SpanContext, req *transport.Request) ([]byte, error) {
	spanBytes, err := spanContextToBytes(tracer, spanContext)
	if err != nil {
		return nil, err
	}

	body, err := ioutil.ReadAll(req.Body)
	if err != nil {
		return nil, err
	}

	rpc := internal.RPC{
		SpanContext: spanBytes,

		CallerName:      req.Caller,
		ServiceName:     req.Service,
		Encoding:        string(req.Encoding),
		Procedure:       req.Procedure,
		Headers:         req.Headers.Items(),
		ShardKey:        &req.ShardKey,
		RoutingKey:      &req.RoutingKey,
		RoutingDelegate: &req.RoutingDelegate,
		Body:            body,
	}

	wireValue, err := rpc.ToWire()
	if err != nil {
		return nil, err
	}

	var writer bytes.Buffer
	// use the first byte to version the serialization
	if err := writer.WriteByte(version); err != nil {
		return nil, err
	}
	err = protocol.Binary.Encode(wireValue, &writer)
	return writer.Bytes(), err
}

// FromBytes decodes bytes into a opentracing.SpanContext and transport.Request
func FromBytes(tracer opentracing.Tracer, request []byte) (opentracing.SpanContext, *transport.Request, error) {
	if len(request) <= 1 {
		return nil, nil, errors.New("cannot deserialize empty request")
	}

	// check valid thrift serialization byte
	if request[0] != 0 {
		return nil, nil,
			fmt.Errorf(
				"unsupported YARPC serialization version '%v' found during deserialization",
				request[0])
	}

	reader := bytes.NewReader(request[1:])
	wireValue, err := protocol.Binary.Decode(reader, wire.TStruct)
	if err != nil {
		return nil, nil, err
	}

	var rpc internal.RPC
	if err = rpc.FromWire(wireValue); err != nil {
		return nil, nil, err
	}

	req := transport.Request{
		Caller:    rpc.CallerName,
		Service:   rpc.ServiceName,
		Encoding:  transport.Encoding(rpc.Encoding),
		Procedure: rpc.Procedure,
		Headers:   transport.HeadersFromMap(rpc.Headers),
		Body:      bytes.NewBuffer(rpc.Body),
	}

	if rpc.ShardKey != nil {
		req.ShardKey = *rpc.ShardKey
	}
	if rpc.RoutingKey != nil {
		req.RoutingKey = *rpc.RoutingKey
	}
	if rpc.RoutingDelegate != nil {
		req.RoutingDelegate = *rpc.RoutingDelegate
	}

	spanContext, err := spanContextFromBytes(tracer, rpc.SpanContext)
	if err != nil {
		return nil, nil, err
	}

	return spanContext, &req, nil
}

func spanContextToBytes(tracer opentracing.Tracer, spanContext opentracing.SpanContext) ([]byte, error) {
	carrier := bytes.NewBuffer([]byte{})
	err := tracer.Inject(spanContext, opentracing.Binary, carrier)
	return carrier.Bytes(), err
}

func spanContextFromBytes(tracer opentracing.Tracer, spanContextBytes []byte) (opentracing.SpanContext, error) {
	carrier := bytes.NewBuffer(spanContextBytes)
	spanContext, err := tracer.Extract(opentracing.Binary, carrier)
	// If no SpanContext was given, we return nil instead of erroring
	// transport.ExtractOpenTracingSpan() safely accepts nil
	if err == opentracing.ErrSpanContextNotFound {
		return nil, nil
	}
	return spanContext, err
}