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minio/pkg/rpc/server.go

320 lines
9.6 KiB

// Copyright 2009 The Go Authors. All rights reserved.
// Copyright 2012 The Gorilla Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Copyright 2020 MinIO, Inc. All rights reserved.
// forked from https://github.com/gorilla/rpc/v2
// modified to be used with MinIO under Apache
// 2.0 license that can be found in the LICENSE file.
package rpc
import (
"fmt"
"net/http"
"reflect"
"strings"
)
var nilErrorValue = reflect.Zero(reflect.TypeOf((*error)(nil)).Elem())
// ----------------------------------------------------------------------------
// Codec
// ----------------------------------------------------------------------------
// Codec creates a CodecRequest to process each request.
type Codec interface {
NewRequest(*http.Request) CodecRequest
}
// CodecRequest decodes a request and encodes a response using a specific
// serialization scheme.
type CodecRequest interface {
// Reads the request and returns the RPC method name.
Method() (string, error)
// Reads the request filling the RPC method args.
ReadRequest(interface{}) error
// Writes the response using the RPC method reply.
WriteResponse(http.ResponseWriter, interface{})
// Writes an error produced by the server.
WriteError(w http.ResponseWriter, status int, err error)
}
// ----------------------------------------------------------------------------
// Server
// ----------------------------------------------------------------------------
// NewServer returns a new RPC server.
func NewServer() *Server {
return &Server{
codecs: make(map[string]Codec),
services: new(serviceMap),
}
}
// RequestInfo contains all the information we pass to before/after functions
type RequestInfo struct {
Args reflect.Value
Method string
Error error
ResponseWriter http.ResponseWriter
Request *http.Request
StatusCode int
}
// Server serves registered RPC services using registered codecs.
type Server struct {
codecs map[string]Codec
services *serviceMap
interceptFunc func(i *RequestInfo) *http.Request
beforeFunc func(i *RequestInfo)
afterFunc func(i *RequestInfo)
validateFunc reflect.Value
}
// RegisterCodec adds a new codec to the server.
//
// Codecs are defined to process a given serialization scheme, e.g., JSON or
// XML. A codec is chosen based on the "Content-Type" header from the request,
// excluding the charset definition.
func (s *Server) RegisterCodec(codec Codec, contentType string) {
s.codecs[strings.ToLower(contentType)] = codec
}
// RegisterInterceptFunc registers the specified function as the function
// that will be called before every request. The function is allowed to intercept
// the request e.g. add values to the context.
//
// Note: Only one function can be registered, subsequent calls to this
// method will overwrite all the previous functions.
func (s *Server) RegisterInterceptFunc(f func(i *RequestInfo) *http.Request) {
s.interceptFunc = f
}
// RegisterBeforeFunc registers the specified function as the function
// that will be called before every request.
//
// Note: Only one function can be registered, subsequent calls to this
// method will overwrite all the previous functions.
func (s *Server) RegisterBeforeFunc(f func(i *RequestInfo)) {
s.beforeFunc = f
}
// RegisterValidateRequestFunc registers the specified function as the function
// that will be called after the BeforeFunc (if registered) and before invoking
// the actual Service method. If this function returns a non-nil error, the method
// won't be invoked and this error will be considered as the method result.
// The first argument is information about the request, useful for accessing to http.Request.Context()
// The second argument of this function is the already-unmarshalled *args parameter of the method.
func (s *Server) RegisterValidateRequestFunc(f func(r *RequestInfo, i interface{}) error) {
s.validateFunc = reflect.ValueOf(f)
}
// RegisterAfterFunc registers the specified function as the function
// that will be called after every request
//
// Note: Only one function can be registered, subsequent calls to this
// method will overwrite all the previous functions.
func (s *Server) RegisterAfterFunc(f func(i *RequestInfo)) {
s.afterFunc = f
}
// RegisterService adds a new service to the server.
//
// The name parameter is optional: if empty it will be inferred from
// the receiver type name.
//
// Methods from the receiver will be extracted if these rules are satisfied:
//
// - The receiver is exported (begins with an upper case letter) or local
// (defined in the package registering the service).
// - The method name is exported.
// - The method has three arguments: *http.Request, *args, *reply.
// - All three arguments are pointers.
// - The second and third arguments are exported or local.
// - The method has return type error.
//
// All other methods are ignored.
func (s *Server) RegisterService(receiver interface{}, name string) error {
return s.services.register(receiver, name)
}
// HasMethod returns true if the given method is registered.
//
// The method uses a dotted notation as in "Service.Method".
func (s *Server) HasMethod(method string) bool {
if _, _, err := s.services.get(method); err == nil {
return true
}
return false
}
// ServeHTTP
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
err := fmt.Errorf("rpc: POST method required, received %s", r.Method)
WriteError(w, http.StatusMethodNotAllowed, err.Error())
// Call the registered After Function
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
ResponseWriter: w,
Request: r,
Method: "Unknown." + r.Method,
StatusCode: http.StatusMethodNotAllowed,
})
}
return
}
contentType := r.Header.Get("Content-Type")
idx := strings.Index(contentType, ";")
if idx != -1 {
contentType = contentType[:idx]
}
var codec Codec
if contentType == "" && len(s.codecs) == 1 {
// If Content-Type is not set and only one codec has been registered,
// then default to that codec.
for _, c := range s.codecs {
codec = c
}
} else if codec = s.codecs[strings.ToLower(contentType)]; codec == nil {
err := fmt.Errorf("rpc: unrecognized Content-Type: %s", contentType)
WriteError(w, http.StatusUnsupportedMediaType, err.Error())
// Call the registered After Function
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
ResponseWriter: w,
Request: r,
Method: "Unknown." + r.Method,
Error: err,
StatusCode: http.StatusUnsupportedMediaType,
})
}
return
}
// Create a new codec request.
codecReq := codec.NewRequest(r)
// Get service method to be called.
method, errMethod := codecReq.Method()
if errMethod != nil {
codecReq.WriteError(w, http.StatusBadRequest, errMethod)
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
ResponseWriter: w,
Request: r,
Method: "Unknown." + r.Method,
Error: errMethod,
StatusCode: http.StatusBadRequest,
})
}
return
}
serviceSpec, methodSpec, errGet := s.services.get(method)
if errGet != nil {
codecReq.WriteError(w, http.StatusBadRequest, errGet)
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
ResponseWriter: w,
Request: r,
Method: method,
Error: errGet,
StatusCode: http.StatusBadRequest,
})
}
return
}
// Decode the args.
args := reflect.New(methodSpec.argsType)
if errRead := codecReq.ReadRequest(args.Interface()); errRead != nil {
codecReq.WriteError(w, http.StatusBadRequest, errRead)
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
ResponseWriter: w,
Request: r,
Method: method,
Error: errRead,
StatusCode: http.StatusBadRequest,
})
}
return
}
// Call the registered Intercept Function
if s.interceptFunc != nil {
req := s.interceptFunc(&RequestInfo{
Request: r,
Method: method,
})
if req != nil {
r = req
}
}
requestInfo := &RequestInfo{
Request: r,
Method: method,
}
// Call the registered Before Function
if s.beforeFunc != nil {
s.beforeFunc(requestInfo)
}
// Prepare the reply, we need it even if validation fails
reply := reflect.New(methodSpec.replyType)
errValue := []reflect.Value{nilErrorValue}
// Call the registered Validator Function
if s.validateFunc.IsValid() {
errValue = s.validateFunc.Call([]reflect.Value{reflect.ValueOf(requestInfo), args})
}
// If still no errors after validation, call the method
if errValue[0].IsNil() {
errValue = methodSpec.method.Func.Call([]reflect.Value{
serviceSpec.rcvr,
reflect.ValueOf(r),
args,
reply,
})
}
// Extract the result to error if needed.
var errResult error
statusCode := http.StatusOK
errInter := errValue[0].Interface()
if errInter != nil {
statusCode = http.StatusBadRequest
errResult = errInter.(error)
}
// Prevents Internet Explorer from MIME-sniffing a response away
// from the declared content-type
w.Header().Set("x-content-type-options", "nosniff")
// Encode the response.
if errResult == nil {
codecReq.WriteResponse(w, reply.Interface())
} else {
codecReq.WriteError(w, statusCode, errResult)
}
// Call the registered After Function
if s.afterFunc != nil {
s.afterFunc(&RequestInfo{
Args: args,
ResponseWriter: w,
Request: r,
Method: method,
Error: errResult,
StatusCode: statusCode,
})
}
}
func WriteError(w http.ResponseWriter, status int, msg string) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
w.WriteHeader(status)
fmt.Fprint(w, msg)
}