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rpc.go
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rpc.go
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// Package rpc is a go-micro rpc handler.
package rpc
import (
"encoding/json"
"io"
"io/ioutil"
"net/http"
"strconv"
"strings"
"github.com/joncalhoun/qson"
"github.com/focalsolution/micro-go-micro/api"
"github.com/focalsolution/micro-go-micro/api/handler"
proto "github.com/focalsolution/micro-go-micro/api/internal/proto"
"github.com/focalsolution/micro-go-micro/client"
"github.com/focalsolution/micro-go-micro/client/selector"
"github.com/focalsolution/micro-go-micro/codec"
"github.com/focalsolution/micro-go-micro/codec/jsonrpc"
"github.com/focalsolution/micro-go-micro/codec/protorpc"
"github.com/focalsolution/micro-go-micro/errors"
"github.com/focalsolution/micro-go-micro/registry"
"github.com/focalsolution/micro-go-micro/util/ctx"
)
const (
Handler = "rpc"
)
var (
// supported json codecs
jsonCodecs = []string{
"application/grpc+json",
"application/json",
"application/json-rpc",
}
// support proto codecs
protoCodecs = []string{
"application/grpc",
"application/grpc+proto",
"application/proto",
"application/protobuf",
"application/proto-rpc",
"application/octet-stream",
}
)
type rpcHandler struct {
opts handler.Options
s *api.Service
}
type buffer struct {
io.ReadCloser
}
func (b *buffer) Write(_ []byte) (int, error) {
return 0, nil
}
// strategy is a hack for selection
func strategy(services []*registry.Service) selector.Strategy {
return func(_ []*registry.Service) selector.Next {
// ignore input to this function, use services above
return selector.Random(services)
}
}
func (h *rpcHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
var service *api.Service
if h.s != nil {
// we were given the service
service = h.s
} else if h.opts.Router != nil {
// try get service from router
s, err := h.opts.Router.Route(r)
if err != nil {
writeError(w, r, errors.InternalServerError("go.micro.api", err.Error()))
return
}
service = s
} else {
// we have no way of routing the request
writeError(w, r, errors.InternalServerError("go.micro.api", "no route found"))
return
}
// only allow post when we have the router
if r.Method != "GET" && (h.opts.Router != nil && r.Method != "POST") {
http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
return
}
ct := r.Header.Get("Content-Type")
// Strip charset from Content-Type (like `application/json; charset=UTF-8`)
if idx := strings.IndexRune(ct, ';'); idx >= 0 {
ct = ct[:idx]
}
// micro client
c := h.opts.Service.Client()
// create strategy
so := selector.WithStrategy(strategy(service.Services))
// get payload
br, err := requestPayload(r)
if err != nil {
writeError(w, r, err)
return
}
// create context
cx := ctx.FromRequest(r)
var rsp []byte
switch {
// proto codecs
case hasCodec(ct, protoCodecs):
request := &proto.Message{}
// if the extracted payload isn't empty lets use it
if len(br) > 0 {
request = proto.NewMessage(br)
}
// create request/response
response := &proto.Message{}
req := c.NewRequest(
service.Name,
service.Endpoint.Name,
request,
client.WithContentType(ct),
)
// make the call
if err := c.Call(cx, req, response, client.WithSelectOption(so)); err != nil {
writeError(w, r, err)
return
}
// marshall response
rsp, _ = response.Marshal()
default:
// if json codec is not present set to json
if !hasCodec(ct, jsonCodecs) {
ct = "application/json"
}
// default to trying json
var request json.RawMessage
// if the extracted payload isn't empty lets use it
if len(br) > 0 {
request = json.RawMessage(br)
}
// create request/response
var response json.RawMessage
req := c.NewRequest(
service.Name,
service.Endpoint.Name,
&request,
client.WithContentType(ct),
)
// make the call
if err := c.Call(cx, req, &response, client.WithSelectOption(so)); err != nil {
writeError(w, r, err)
return
}
// marshall response
rsp, _ = response.MarshalJSON()
}
// write the response
writeResponse(w, r, rsp)
}
func (rh *rpcHandler) String() string {
return "rpc"
}
func hasCodec(ct string, codecs []string) bool {
for _, codec := range codecs {
if ct == codec {
return true
}
}
return false
}
// requestPayload takes a *http.Request.
// If the request is a GET the query string parameters are extracted and marshaled to JSON and the raw bytes are returned.
// If the request method is a POST the request body is read and returned
func requestPayload(r *http.Request) ([]byte, error) {
// we have to decode json-rpc and proto-rpc because we suck
// well actually because there's no proxy codec right now
switch r.Header.Get("Content-Type") {
case "application/json-rpc":
msg := codec.Message{
Type: codec.Request,
Header: make(map[string]string),
}
c := jsonrpc.NewCodec(&buffer{r.Body})
if err := c.ReadHeader(&msg, codec.Request); err != nil {
return nil, err
}
var raw json.RawMessage
if err := c.ReadBody(&raw); err != nil {
return nil, err
}
return ([]byte)(raw), nil
case "application/proto-rpc", "application/octet-stream":
msg := codec.Message{
Type: codec.Request,
Header: make(map[string]string),
}
c := protorpc.NewCodec(&buffer{r.Body})
if err := c.ReadHeader(&msg, codec.Request); err != nil {
return nil, err
}
var raw proto.Message
if err := c.ReadBody(&raw); err != nil {
return nil, err
}
b, _ := raw.Marshal()
return b, nil
}
// otherwise as per usual
switch r.Method {
case "GET":
if len(r.URL.RawQuery) > 0 {
return qson.ToJSON(r.URL.RawQuery)
}
case "PATCH", "POST":
return ioutil.ReadAll(r.Body)
}
return []byte{}, nil
}
func writeError(w http.ResponseWriter, r *http.Request, err error) {
ce := errors.Parse(err.Error())
switch ce.Code {
case 0:
// assuming it's totally screwed
ce.Code = 500
ce.Id = "go.micro.api"
ce.Status = http.StatusText(500)
ce.Detail = "error during request: " + ce.Detail
w.WriteHeader(500)
default:
w.WriteHeader(int(ce.Code))
}
// response content type
w.Header().Set("Content-Type", "application/json")
// Set trailers
if strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
w.Header().Set("Trailer", "grpc-status")
w.Header().Set("Trailer", "grpc-message")
w.Header().Set("grpc-status", "13")
w.Header().Set("grpc-message", ce.Detail)
}
w.Write([]byte(ce.Error()))
}
func writeResponse(w http.ResponseWriter, r *http.Request, rsp []byte) {
w.Header().Set("Content-Type", r.Header.Get("Content-Type"))
w.Header().Set("Content-Length", strconv.Itoa(len(rsp)))
// Set trailers
if strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
w.Header().Set("Trailer", "grpc-status")
w.Header().Set("Trailer", "grpc-message")
w.Header().Set("grpc-status", "0")
w.Header().Set("grpc-message", "")
}
// write response
w.Write(rsp)
}
func NewHandler(opts ...handler.Option) handler.Handler {
options := handler.NewOptions(opts...)
return &rpcHandler{
opts: options,
}
}
func WithService(s *api.Service, opts ...handler.Option) handler.Handler {
options := handler.NewOptions(opts...)
return &rpcHandler{
opts: options,
s: s,
}
}