`unexpected EOF` when gRPC inbound returns error with details

[asido]

Describe the bug Caller receives error unexpected EOF when gRPC outbound returns yarpc error with details. Doesn't happen with HTTP transport.

To Reproduce Is the issue reproducible?

• Yes

Steps to reproduce the behavior:

go.mod:

module yarpc-error

go 1.16

require go.uber.org/yarpc v1.58.0

main.go:

package main

import (
    "bytes"
    "context"
    "net"
    "time"

    "go.uber.org/yarpc"
    yarpctransport "go.uber.org/yarpc/api/transport"
    yarpcgrpc "go.uber.org/yarpc/transport/grpc"
    "go.uber.org/yarpc/yarpcerrors"
)

type UnaryHandlerFunc func(context.Context, *yarpctransport.Request, yarpctransport.ResponseWriter) error

func (f UnaryHandlerFunc) Handle(ctx context.Context, r *yarpctransport.Request, w yarpctransport.ResponseWriter) error {
    return f(ctx, r, w)
}

func main() {
    listener, err := net.Listen("tcp", "127.0.0.1:0")
    if err != nil {
        panic("unable to listen: " + err.Error())
    }

    ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(time.Minute))
    defer cancel()

    transport := yarpcgrpc.NewTransport()
    if err := transport.Start(); err != nil {
        panic("unable to start transport: " + err.Error())
    }

    router := yarpc.NewMapRouter("yarpc-error")
    router.Register([]yarpctransport.Procedure{
        {
            Name:    "some-procedure",
            Service: "some-service",
            HandlerSpec: yarpctransport.NewUnaryHandlerSpec(UnaryHandlerFunc(func(context.Context, *yarpctransport.Request, yarpctransport.ResponseWriter) error {
                return yarpcerrors.
                    Newf(yarpcerrors.CodeInvalidArgument, "some error").
                    WithDetails([]byte("kaboom")) // <-- TRIGGERS BUG
            })),
            Encoding:  "raw",
            Signature: "signature",
        },
    })

    inbound := transport.NewInbound(listener)
    inbound.SetRouter(router)
    if err := inbound.Start(); err != nil {
        panic("unable to start inbound: " + err.Error())
    }

    outbound := transport.NewSingleOutbound(inbound.Addr().String())
    if err := outbound.Start(); err != nil {
        panic("unable to start outbound: " + err.Error())
    }

    _, err = outbound.Call(ctx, &yarpctransport.Request{
        Caller:    "some-caller",
        Service:   "some-service",
        Encoding:  "raw",
        Procedure: "some-procedure",
        Body:      bytes.NewReader([]byte("some-payload")),
    })
    if err == nil {
        panic("unexpected call success")
    }
    println(err.Error())
}

$ go run .
code:unknown message:unexpected EOF

Expected behavior

$ go run .
code:invalid-argument message:some error

[gopalchouhan]

yarpcerrors.WithDetails() expects the details as a byte array so depending on the encoding scheme, the correct marshled byte array has to be provided here. In this case, string bytes were directly provided which can not be unmarshled through proto, hence we see the error from proto during unmarshling. Try passing a valid proto byte array and it should work fine. For example, I tried the following and works fine: WithDetails(types.StringValue{Value: "abc"}.XXX_unrecognized)

However, for a better readability I strongly recommend to use protobuf.WithErrorDetails() for protobuf error. Example:

HandlerSpec: yarpctransport.NewUnaryHandlerSpec(
    UnaryHandlerFunc(
        func(context.Context, *yarpctransport.Request, yarpctransport.ResponseWriter) error {
            return protobuf.NewError(yarpcerrors.CodeInvalidArgument,
                "some error",
                protobuf.WithErrorDetails(&types.StringValue{Value: "abc"}),
        )
}))

[gopalchouhan]

Spoke to @asido offline and agreed to close this issue.