empty_service.twirp.go

// Code generated by protoc-gen-twirp v5.10.1, DO NOT EDIT.
// source: empty_service.proto

/*
Package empty_service is a generated twirp stub package.
This code was generated with github.com/twitchtv/twirp/protoc-gen-twirp v5.10.1.

It is generated from these files:
	empty_service.proto
*/
package empty_service

import bytes "bytes"
import context "context"
import fmt "fmt"
import ioutil "io/ioutil"
import http "net/http"
import strconv "strconv"

import jsonpb "github.com/golang/protobuf/jsonpb"
import proto "github.com/golang/protobuf/proto"
import twirp "github.com/twitchtv/twirp"
import ctxsetters "github.com/twitchtv/twirp/ctxsetters"

// Imports only used by utility functions:
import io "io"
import json "encoding/json"
import url "net/url"

// ===============
// Empty Interface
// ===============

type Empty interface {
}

// =====================
// Empty Protobuf Client
// =====================

type emptyProtobufClient struct {
	client HTTPClient
	urls   [0]string
	opts   twirp.ClientOptions
}

// NewEmptyProtobufClient creates a Protobuf client that implements the Empty interface.
// It communicates using Protobuf and can be configured with a custom HTTPClient.
func NewEmptyProtobufClient(addr string, client HTTPClient, opts ...twirp.ClientOption) Empty {
	if c, ok := client.(*http.Client); ok {
		client = withoutRedirects(c)
	}

	clientOpts := twirp.ClientOptions{}
	for _, o := range opts {
		o(&clientOpts)
	}

	urls := [0]string{}

	return &emptyProtobufClient{
		client: client,
		urls:   urls,
		opts:   clientOpts,
	}
}

// =================
// Empty JSON Client
// =================

type emptyJSONClient struct {
	client HTTPClient
	urls   [0]string
	opts   twirp.ClientOptions
}

// NewEmptyJSONClient creates a JSON client that implements the Empty interface.
// It communicates using JSON and can be configured with a custom HTTPClient.
func NewEmptyJSONClient(addr string, client HTTPClient, opts ...twirp.ClientOption) Empty {
	if c, ok := client.(*http.Client); ok {
		client = withoutRedirects(c)
	}

	clientOpts := twirp.ClientOptions{}
	for _, o := range opts {
		o(&clientOpts)
	}

	urls := [0]string{}

	return &emptyJSONClient{
		client: client,
		urls:   urls,
		opts:   clientOpts,
	}
}

// ====================
// Empty Server Handler
// ====================

type emptyServer struct {
	Empty
	hooks *twirp.ServerHooks
}

func NewEmptyServer(svc Empty, hooks *twirp.ServerHooks) TwirpServer {
	return &emptyServer{
		Empty: svc,
		hooks: hooks,
	}
}

// writeError writes an HTTP response with a valid Twirp error format, and triggers hooks.
// If err is not a twirp.Error, it will get wrapped with twirp.InternalErrorWith(err)
func (s *emptyServer) writeError(ctx context.Context, resp http.ResponseWriter, err error) {
	writeError(ctx, resp, err, s.hooks)
}

// EmptyPathPrefix is used for all URL paths on a twirp Empty server.
// Requests are always: POST EmptyPathPrefix/method
// It can be used in an HTTP mux to route twirp requests along with non-twirp requests on other routes.
const EmptyPathPrefix = "/twirp/twirp.internal.twirptest.emptyservice.Empty/"

func (s *emptyServer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
	ctx := req.Context()
	ctx = ctxsetters.WithPackageName(ctx, "twirp.internal.twirptest.emptyservice")
	ctx = ctxsetters.WithServiceName(ctx, "Empty")
	ctx = ctxsetters.WithResponseWriter(ctx, resp)

	var err error
	ctx, err = callRequestReceived(ctx, s.hooks)
	if err != nil {
		s.writeError(ctx, resp, err)
		return
	}

	if req.Method != "POST" {
		msg := fmt.Sprintf("unsupported method %q (only POST is allowed)", req.Method)
		err = badRouteError(msg, req.Method, req.URL.Path)
		s.writeError(ctx, resp, err)
		return
	}

	switch req.URL.Path {
	default:
		msg := fmt.Sprintf("no handler for path %q", req.URL.Path)
		err = badRouteError(msg, req.Method, req.URL.Path)
		s.writeError(ctx, resp, err)
		return
	}
}

func (s *emptyServer) ServiceDescriptor() ([]byte, int) {
	return twirpFileDescriptor0, 0
}

func (s *emptyServer) ProtocGenTwirpVersion() string {
	return "v5.10.1"
}

func (s *emptyServer) PathPrefix() string {
	return EmptyPathPrefix
}

// =====
// Utils
// =====

// HTTPClient is the interface used by generated clients to send HTTP requests.
// It is fulfilled by *(net/http).Client, which is sufficient for most users.
// Users can provide their own implementation for special retry policies.
//
// HTTPClient implementations should not follow redirects. Redirects are
// automatically disabled if *(net/http).Client is passed to client
// constructors. See the withoutRedirects function in this file for more
// details.
type HTTPClient interface {
	Do(req *http.Request) (*http.Response, error)
}

// TwirpServer is the interface generated server structs will support: they're
// HTTP handlers with additional methods for accessing metadata about the
// service. Those accessors are a low-level API for building reflection tools.
// Most people can think of TwirpServers as just http.Handlers.
type TwirpServer interface {
	http.Handler
	// ServiceDescriptor returns gzipped bytes describing the .proto file that
	// this service was generated from. Once unzipped, the bytes can be
	// unmarshalled as a
	// github.com/golang/protobuf/protoc-gen-go/descriptor.FileDescriptorProto.
	//
	// The returned integer is the index of this particular service within that
	// FileDescriptorProto's 'Service' slice of ServiceDescriptorProtos. This is a
	// low-level field, expected to be used for reflection.
	ServiceDescriptor() ([]byte, int)
	// ProtocGenTwirpVersion is the semantic version string of the version of
	// twirp used to generate this file.
	ProtocGenTwirpVersion() string
	// PathPrefix returns the HTTP URL path prefix for all methods handled by this
	// service. This can be used with an HTTP mux to route twirp requests
	// alongside non-twirp requests on one HTTP listener.
	PathPrefix() string
}

// WriteError writes an HTTP response with a valid Twirp error format (code, msg, meta).
// Useful outside of the Twirp server (e.g. http middleware), but does not trigger hooks.
// If err is not a twirp.Error, it will get wrapped with twirp.InternalErrorWith(err)
func WriteError(resp http.ResponseWriter, err error) {
	writeError(context.Background(), resp, err, nil)
}

// writeError writes Twirp errors in the response and triggers hooks.
func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks *twirp.ServerHooks) {
	// Non-twirp errors are wrapped as Internal (default)
	twerr, ok := err.(twirp.Error)
	if !ok {
		twerr = twirp.InternalErrorWith(err)
	}

	statusCode := twirp.ServerHTTPStatusFromErrorCode(twerr.Code())
	ctx = ctxsetters.WithStatusCode(ctx, statusCode)
	ctx = callError(ctx, hooks, twerr)

	respBody := marshalErrorToJSON(twerr)

	resp.Header().Set("Content-Type", "application/json") // Error responses are always JSON
	resp.Header().Set("Content-Length", strconv.Itoa(len(respBody)))
	resp.WriteHeader(statusCode) // set HTTP status code and send response

	_, writeErr := resp.Write(respBody)
	if writeErr != nil {
		// We have three options here. We could log the error, call the Error
		// hook, or just silently ignore the error.
		//
		// Logging is unacceptable because we don't have a user-controlled
		// logger; writing out to stderr without permission is too rude.
		//
		// Calling the Error hook would confuse users: it would mean the Error
		// hook got called twice for one request, which is likely to lead to
		// duplicated log messages and metrics, no matter how well we document
		// the behavior.
		//
		// Silently ignoring the error is our least-bad option. It's highly
		// likely that the connection is broken and the original 'err' says
		// so anyway.
		_ = writeErr
	}

	callResponseSent(ctx, hooks)
}

// urlBase helps ensure that addr specifies a scheme. If it is unparsable
// as a URL, it returns addr unchanged.
func urlBase(addr string) string {
	// If the addr specifies a scheme, use it. If not, default to
	// http. If url.Parse fails on it, return it unchanged.
	url, err := url.Parse(addr)
	if err != nil {
		return addr
	}
	if url.Scheme == "" {
		url.Scheme = "http"
	}
	return url.String()
}

// getCustomHTTPReqHeaders retrieves a copy of any headers that are set in
// a context through the twirp.WithHTTPRequestHeaders function.
// If there are no headers set, or if they have the wrong type, nil is returned.
func getCustomHTTPReqHeaders(ctx context.Context) http.Header {
	header, ok := twirp.HTTPRequestHeaders(ctx)
	if !ok || header == nil {
		return nil
	}
	copied := make(http.Header)
	for k, vv := range header {
		if vv == nil {
			copied[k] = nil
			continue
		}
		copied[k] = make([]string, len(vv))
		copy(copied[k], vv)
	}
	return copied
}

// newRequest makes an http.Request from a client, adding common headers.
func newRequest(ctx context.Context, url string, reqBody io.Reader, contentType string) (*http.Request, error) {
	req, err := http.NewRequest("POST", url, reqBody)
	if err != nil {
		return nil, err
	}
	req = req.WithContext(ctx)
	if customHeader := getCustomHTTPReqHeaders(ctx); customHeader != nil {
		req.Header = customHeader
	}
	req.Header.Set("Accept", contentType)
	req.Header.Set("Content-Type", contentType)
	req.Header.Set("Twirp-Version", "v5.10.1")
	return req, nil
}

// JSON serialization for errors
type twerrJSON struct {
	Code string            `json:"code"`
	Msg  string            `json:"msg"`
	Meta map[string]string `json:"meta,omitempty"`
}

// marshalErrorToJSON returns JSON from a twirp.Error, that can be used as HTTP error response body.
// If serialization fails, it will use a descriptive Internal error instead.
func marshalErrorToJSON(twerr twirp.Error) []byte {
	// make sure that msg is not too large
	msg := twerr.Msg()
	if len(msg) > 1e6 {
		msg = msg[:1e6]
	}

	tj := twerrJSON{
		Code: string(twerr.Code()),
		Msg:  msg,
		Meta: twerr.MetaMap(),
	}

	buf, err := json.Marshal(&tj)
	if err != nil {
		buf = []byte("{\"type\": \"" + twirp.Internal + "\", \"msg\": \"There was an error but it could not be serialized into JSON\"}") // fallback
	}

	return buf
}

// errorFromResponse builds a twirp.Error from a non-200 HTTP response.
// If the response has a valid serialized Twirp error, then it's returned.
// If not, the response status code is used to generate a similar twirp
// error. See twirpErrorFromIntermediary for more info on intermediary errors.
func errorFromResponse(resp *http.Response) twirp.Error {
	statusCode := resp.StatusCode
	statusText := http.StatusText(statusCode)

	if isHTTPRedirect(statusCode) {
		// Unexpected redirect: it must be an error from an intermediary.
		// Twirp clients don't follow redirects automatically, Twirp only handles
		// POST requests, redirects should only happen on GET and HEAD requests.
		location := resp.Header.Get("Location")
		msg := fmt.Sprintf("unexpected HTTP status code %d %q received, Location=%q", statusCode, statusText, location)
		return twirpErrorFromIntermediary(statusCode, msg, location)
	}

	respBodyBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return wrapInternal(err, "failed to read server error response body")
	}

	var tj twerrJSON
	dec := json.NewDecoder(bytes.NewReader(respBodyBytes))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&tj); err != nil || tj.Code == "" {
		// Invalid JSON response; it must be an error from an intermediary.
		msg := fmt.Sprintf("Error from intermediary with HTTP status code %d %q", statusCode, statusText)
		return twirpErrorFromIntermediary(statusCode, msg, string(respBodyBytes))
	}

	errorCode := twirp.ErrorCode(tj.Code)
	if !twirp.IsValidErrorCode(errorCode) {
		msg := "invalid type returned from server error response: " + tj.Code
		return twirp.InternalError(msg)
	}

	twerr := twirp.NewError(errorCode, tj.Msg)
	for k, v := range tj.Meta {
		twerr = twerr.WithMeta(k, v)
	}
	return twerr
}

// twirpErrorFromIntermediary maps HTTP errors from non-twirp sources to twirp errors.
// The mapping is similar to gRPC: https://github.com/grpc/grpc/blob/master/doc/http-grpc-status-mapping.md.
// Returned twirp Errors have some additional metadata for inspection.
func twirpErrorFromIntermediary(status int, msg string, bodyOrLocation string) twirp.Error {
	var code twirp.ErrorCode
	if isHTTPRedirect(status) { // 3xx
		code = twirp.Internal
	} else {
		switch status {
		case 400: // Bad Request
			code = twirp.Internal
		case 401: // Unauthorized
			code = twirp.Unauthenticated
		case 403: // Forbidden
			code = twirp.PermissionDenied
		case 404: // Not Found
			code = twirp.BadRoute
		case 429, 502, 503, 504: // Too Many Requests, Bad Gateway, Service Unavailable, Gateway Timeout
			code = twirp.Unavailable
		default: // All other codes
			code = twirp.Unknown
		}
	}

	twerr := twirp.NewError(code, msg)
	twerr = twerr.WithMeta("http_error_from_intermediary", "true") // to easily know if this error was from intermediary
	twerr = twerr.WithMeta("status_code", strconv.Itoa(status))
	if isHTTPRedirect(status) {
		twerr = twerr.WithMeta("location", bodyOrLocation)
	} else {
		twerr = twerr.WithMeta("body", bodyOrLocation)
	}
	return twerr
}

func isHTTPRedirect(status int) bool {
	return status >= 300 && status <= 399
}

// wrapInternal wraps an error with a prefix as an Internal error.
// The original error cause is accessible by github.com/pkg/errors.Cause.
func wrapInternal(err error, prefix string) twirp.Error {
	return twirp.InternalErrorWith(&wrappedError{prefix: prefix, cause: err})
}

type wrappedError struct {
	prefix string
	cause  error
}

func (e *wrappedError) Cause() error  { return e.cause }
func (e *wrappedError) Error() string { return e.prefix + ": " + e.cause.Error() }

// ensurePanicResponses makes sure that rpc methods causing a panic still result in a Twirp Internal
// error response (status 500), and error hooks are properly called with the panic wrapped as an error.
// The panic is re-raised so it can be handled normally with middleware.
func ensurePanicResponses(ctx context.Context, resp http.ResponseWriter, hooks *twirp.ServerHooks) {
	if r := recover(); r != nil {
		// Wrap the panic as an error so it can be passed to error hooks.
		// The original error is accessible from error hooks, but not visible in the response.
		err := errFromPanic(r)
		twerr := &internalWithCause{msg: "Internal service panic", cause: err}
		// Actually write the error
		writeError(ctx, resp, twerr, hooks)
		// If possible, flush the error to the wire.
		f, ok := resp.(http.Flusher)
		if ok {
			f.Flush()
		}

		panic(r)
	}
}

// errFromPanic returns the typed error if the recovered panic is an error, otherwise formats as error.
func errFromPanic(p interface{}) error {
	if err, ok := p.(error); ok {
		return err
	}
	return fmt.Errorf("panic: %v", p)
}

// internalWithCause is a Twirp Internal error wrapping an original error cause, accessible
// by github.com/pkg/errors.Cause, but the original error message is not exposed on Msg().
type internalWithCause struct {
	msg   string
	cause error
}

func (e *internalWithCause) Cause() error                                { return e.cause }
func (e *internalWithCause) Error() string                               { return e.msg + ": " + e.cause.Error() }
func (e *internalWithCause) Code() twirp.ErrorCode                       { return twirp.Internal }
func (e *internalWithCause) Msg() string                                 { return e.msg }
func (e *internalWithCause) Meta(key string) string                      { return "" }
func (e *internalWithCause) MetaMap() map[string]string                  { return nil }
func (e *internalWithCause) WithMeta(key string, val string) twirp.Error { return e }

// malformedRequestError is used when the twirp server cannot unmarshal a request
func malformedRequestError(msg string) twirp.Error {
	return twirp.NewError(twirp.Malformed, msg)
}

// badRouteError is used when the twirp server cannot route a request
func badRouteError(msg string, method, url string) twirp.Error {
	err := twirp.NewError(twirp.BadRoute, msg)
	err = err.WithMeta("twirp_invalid_route", method+" "+url)
	return err
}

// withoutRedirects makes sure that the POST request can not be redirected.
// The standard library will, by default, redirect requests (including POSTs) if it gets a 302 or
// 303 response, and also 301s in go1.8. It redirects by making a second request, changing the
// method to GET and removing the body. This produces very confusing error messages, so instead we
// set a redirect policy that always errors. This stops Go from executing the redirect.
//
// We have to be a little careful in case the user-provided http.Client has its own CheckRedirect
// policy - if so, we'll run through that policy first.
//
// Because this requires modifying the http.Client, we make a new copy of the client and return it.
func withoutRedirects(in *http.Client) *http.Client {
	copy := *in
	copy.CheckRedirect = func(req *http.Request, via []*http.Request) error {
		if in.CheckRedirect != nil {
			// Run the input's redirect if it exists, in case it has side effects, but ignore any error it
			// returns, since we want to use ErrUseLastResponse.
			err := in.CheckRedirect(req, via)
			_ = err // Silly, but this makes sure generated code passes errcheck -blank, which some people use.
		}
		return http.ErrUseLastResponse
	}
	return &copy
}

// doProtobufRequest makes a Protobuf request to the remote Twirp service.
func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.ClientHooks, url string, in, out proto.Message) (err error) {
	reqBodyBytes, err := proto.Marshal(in)
	if err != nil {
		return wrapInternal(err, "failed to marshal proto request")
	}
	reqBody := bytes.NewBuffer(reqBodyBytes)
	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}

	req, err := newRequest(ctx, url, reqBody, "application/protobuf")
	if err != nil {
		return wrapInternal(err, "could not build request")
	}
	ctx, err = callClientRequestPrepared(ctx, hooks, req)
	if err != nil {
		return err
	}

	req = req.WithContext(ctx)
	resp, err := client.Do(req)
	if err != nil {
		return wrapInternal(err, "failed to do request")
	}

	defer func() {
		cerr := resp.Body.Close()
		if err == nil && cerr != nil {
			err = wrapInternal(cerr, "failed to close response body")
		}
	}()

	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}

	if resp.StatusCode != 200 {
		return errorFromResponse(resp)
	}

	respBodyBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return wrapInternal(err, "failed to read response body")
	}
	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}

	if err = proto.Unmarshal(respBodyBytes, out); err != nil {
		return wrapInternal(err, "failed to unmarshal proto response")
	}
	return nil
}

// doJSONRequest makes a JSON request to the remote Twirp service.
func doJSONRequest(ctx context.Context, client HTTPClient, hooks *twirp.ClientHooks, url string, in, out proto.Message) (err error) {
	reqBody := bytes.NewBuffer(nil)
	marshaler := &jsonpb.Marshaler{OrigName: true}
	if err = marshaler.Marshal(reqBody, in); err != nil {
		return wrapInternal(err, "failed to marshal json request")
	}
	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}

	req, err := newRequest(ctx, url, reqBody, "application/json")
	if err != nil {
		return wrapInternal(err, "could not build request")
	}
	ctx, err = callClientRequestPrepared(ctx, hooks, req)
	if err != nil {
		return err
	}

	req = req.WithContext(ctx)
	resp, err := client.Do(req)
	if err != nil {
		return wrapInternal(err, "failed to do request")
	}

	defer func() {
		cerr := resp.Body.Close()
		if err == nil && cerr != nil {
			err = wrapInternal(cerr, "failed to close response body")
		}
	}()

	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}

	if resp.StatusCode != 200 {
		return errorFromResponse(resp)
	}

	unmarshaler := jsonpb.Unmarshaler{AllowUnknownFields: true}
	if err = unmarshaler.Unmarshal(resp.Body, out); err != nil {
		return wrapInternal(err, "failed to unmarshal json response")
	}
	if err = ctx.Err(); err != nil {
		return wrapInternal(err, "aborted because context was done")
	}
	return nil
}

// Call twirp.ServerHooks.RequestReceived if the hook is available
func callRequestReceived(ctx context.Context, h *twirp.ServerHooks) (context.Context, error) {
	if h == nil || h.RequestReceived == nil {
		return ctx, nil
	}
	return h.RequestReceived(ctx)
}

// Call twirp.ServerHooks.RequestRouted if the hook is available
func callRequestRouted(ctx context.Context, h *twirp.ServerHooks) (context.Context, error) {
	if h == nil || h.RequestRouted == nil {
		return ctx, nil
	}
	return h.RequestRouted(ctx)
}

// Call twirp.ServerHooks.ResponsePrepared if the hook is available
func callResponsePrepared(ctx context.Context, h *twirp.ServerHooks) context.Context {
	if h == nil || h.ResponsePrepared == nil {
		return ctx
	}
	return h.ResponsePrepared(ctx)
}

// Call twirp.ServerHooks.ResponseSent if the hook is available
func callResponseSent(ctx context.Context, h *twirp.ServerHooks) {
	if h == nil || h.ResponseSent == nil {
		return
	}
	h.ResponseSent(ctx)
}

// Call twirp.ServerHooks.Error if the hook is available
func callError(ctx context.Context, h *twirp.ServerHooks, err twirp.Error) context.Context {
	if h == nil || h.Error == nil {
		return ctx
	}
	return h.Error(ctx, err)
}

func callClientResponseReceived(ctx context.Context, h *twirp.ClientHooks) {
	if h == nil || h.ResponseReceived == nil {
		return
	}
	h.ResponseReceived(ctx)
}

func callClientRequestPrepared(ctx context.Context, h *twirp.ClientHooks, req *http.Request) (context.Context, error) {
	if h == nil || h.RequestPrepared == nil {
		return ctx, nil
	}
	return h.RequestPrepared(ctx, req)
}

func callClientError(ctx context.Context, h *twirp.ClientHooks, err twirp.Error) {
	if h == nil || h.Error == nil {
		return
	}
	h.Error(ctx, err)
}

var twirpFileDescriptor0 = []byte{
	// 91 bytes of a gzipped FileDescriptorProto
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}