prometheus/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/mux.go

261 lines
9.6 KiB
Go

package runtime
import (
"fmt"
"net/http"
"net/textproto"
"strings"
"github.com/golang/protobuf/proto"
"golang.org/x/net/context"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/status"
)
// A HandlerFunc handles a specific pair of path pattern and HTTP method.
type HandlerFunc func(w http.ResponseWriter, r *http.Request, pathParams map[string]string)
// ServeMux is a request multiplexer for grpc-gateway.
// It matches http requests to patterns and invokes the corresponding handler.
type ServeMux struct {
// handlers maps HTTP method to a list of handlers.
handlers map[string][]handler
forwardResponseOptions []func(context.Context, http.ResponseWriter, proto.Message) error
marshalers marshalerRegistry
incomingHeaderMatcher HeaderMatcherFunc
outgoingHeaderMatcher HeaderMatcherFunc
metadataAnnotator func(context.Context, *http.Request) metadata.MD
protoErrorHandler ProtoErrorHandlerFunc
}
// ServeMuxOption is an option that can be given to a ServeMux on construction.
type ServeMuxOption func(*ServeMux)
// WithForwardResponseOption returns a ServeMuxOption representing the forwardResponseOption.
//
// forwardResponseOption is an option that will be called on the relevant context.Context,
// http.ResponseWriter, and proto.Message before every forwarded response.
//
// The message may be nil in the case where just a header is being sent.
func WithForwardResponseOption(forwardResponseOption func(context.Context, http.ResponseWriter, proto.Message) error) ServeMuxOption {
return func(serveMux *ServeMux) {
serveMux.forwardResponseOptions = append(serveMux.forwardResponseOptions, forwardResponseOption)
}
}
// HeaderMatcherFunc checks whether a header key should be forwarded to/from gRPC context.
type HeaderMatcherFunc func(string) (string, bool)
// DefaultHeaderMatcher is used to pass http request headers to/from gRPC context. This adds permanent HTTP header
// keys (as specified by the IANA) to gRPC context with grpcgateway- prefix. HTTP headers that start with
// 'Grpc-Metadata-' are mapped to gRPC metadata after removing prefix 'Grpc-Metadata-'.
func DefaultHeaderMatcher(key string) (string, bool) {
key = textproto.CanonicalMIMEHeaderKey(key)
if isPermanentHTTPHeader(key) {
return MetadataPrefix + key, true
} else if strings.HasPrefix(key, MetadataHeaderPrefix) {
return key[len(MetadataHeaderPrefix):], true
}
return "", false
}
// WithIncomingHeaderMatcher returns a ServeMuxOption representing a headerMatcher for incoming request to gateway.
//
// This matcher will be called with each header in http.Request. If matcher returns true, that header will be
// passed to gRPC context. To transform the header before passing to gRPC context, matcher should return modified header.
func WithIncomingHeaderMatcher(fn HeaderMatcherFunc) ServeMuxOption {
return func(mux *ServeMux) {
mux.incomingHeaderMatcher = fn
}
}
// WithOutgoingHeaderMatcher returns a ServeMuxOption representing a headerMatcher for outgoing response from gateway.
//
// This matcher will be called with each header in response header metadata. If matcher returns true, that header will be
// passed to http response returned from gateway. To transform the header before passing to response,
// matcher should return modified header.
func WithOutgoingHeaderMatcher(fn HeaderMatcherFunc) ServeMuxOption {
return func(mux *ServeMux) {
mux.outgoingHeaderMatcher = fn
}
}
// WithMetadata returns a ServeMuxOption for passing metadata to a gRPC context.
//
// This can be used by services that need to read from http.Request and modify gRPC context. A common use case
// is reading token from cookie and adding it in gRPC context.
func WithMetadata(annotator func(context.Context, *http.Request) metadata.MD) ServeMuxOption {
return func(serveMux *ServeMux) {
serveMux.metadataAnnotator = annotator
}
}
// WithProtoErrorHandler returns a ServeMuxOption for passing metadata to a gRPC context.
//
// This can be used to handle an error as general proto message defined by gRPC.
// The response including body and status is not backward compatible with the default error handler.
// When this option is used, HTTPError and OtherErrorHandler are overwritten on initialization.
func WithProtoErrorHandler(fn ProtoErrorHandlerFunc) ServeMuxOption {
return func(serveMux *ServeMux) {
serveMux.protoErrorHandler = fn
}
}
// NewServeMux returns a new ServeMux whose internal mapping is empty.
func NewServeMux(opts ...ServeMuxOption) *ServeMux {
serveMux := &ServeMux{
handlers: make(map[string][]handler),
forwardResponseOptions: make([]func(context.Context, http.ResponseWriter, proto.Message) error, 0),
marshalers: makeMarshalerMIMERegistry(),
}
for _, opt := range opts {
opt(serveMux)
}
if serveMux.protoErrorHandler != nil {
HTTPError = serveMux.protoErrorHandler
// OtherErrorHandler is no longer used when protoErrorHandler is set.
// Overwritten by a special error handler to return Unknown.
OtherErrorHandler = func(w http.ResponseWriter, r *http.Request, _ string, _ int) {
ctx := context.Background()
_, outboundMarshaler := MarshalerForRequest(serveMux, r)
sterr := status.Error(codes.Unknown, "unexpected use of OtherErrorHandler")
serveMux.protoErrorHandler(ctx, serveMux, outboundMarshaler, w, r, sterr)
}
}
if serveMux.incomingHeaderMatcher == nil {
serveMux.incomingHeaderMatcher = DefaultHeaderMatcher
}
if serveMux.outgoingHeaderMatcher == nil {
serveMux.outgoingHeaderMatcher = func(key string) (string, bool) {
return fmt.Sprintf("%s%s", MetadataHeaderPrefix, key), true
}
}
return serveMux
}
// Handle associates "h" to the pair of HTTP method and path pattern.
func (s *ServeMux) Handle(meth string, pat Pattern, h HandlerFunc) {
s.handlers[meth] = append(s.handlers[meth], handler{pat: pat, h: h})
}
// ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.Path.
func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
path := r.URL.Path
if !strings.HasPrefix(path, "/") {
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.InvalidArgument, http.StatusText(http.StatusBadRequest))
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
}
return
}
components := strings.Split(path[1:], "/")
l := len(components)
var verb string
if idx := strings.LastIndex(components[l-1], ":"); idx == 0 {
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.Unimplemented, http.StatusText(http.StatusNotImplemented))
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound)
}
return
} else if idx > 0 {
c := components[l-1]
components[l-1], verb = c[:idx], c[idx+1:]
}
if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && isPathLengthFallback(r) {
r.Method = strings.ToUpper(override)
if err := r.ParseForm(); err != nil {
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.InvalidArgument, err.Error())
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest)
}
return
}
}
for _, h := range s.handlers[r.Method] {
pathParams, err := h.pat.Match(components, verb)
if err != nil {
continue
}
h.h(w, r, pathParams)
return
}
// lookup other methods to handle fallback from GET to POST and
// to determine if it is MethodNotAllowed or NotFound.
for m, handlers := range s.handlers {
if m == r.Method {
continue
}
for _, h := range handlers {
pathParams, err := h.pat.Match(components, verb)
if err != nil {
continue
}
// X-HTTP-Method-Override is optional. Always allow fallback to POST.
if isPathLengthFallback(r) {
if err := r.ParseForm(); err != nil {
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.InvalidArgument, err.Error())
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest)
}
return
}
h.h(w, r, pathParams)
return
}
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.Unimplemented, http.StatusText(http.StatusMethodNotAllowed))
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
}
return
}
}
if s.protoErrorHandler != nil {
_, outboundMarshaler := MarshalerForRequest(s, r)
sterr := status.Error(codes.Unimplemented, http.StatusText(http.StatusNotImplemented))
s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr)
} else {
OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound)
}
}
// GetForwardResponseOptions returns the ForwardResponseOptions associated with this ServeMux.
func (s *ServeMux) GetForwardResponseOptions() []func(context.Context, http.ResponseWriter, proto.Message) error {
return s.forwardResponseOptions
}
func isPathLengthFallback(r *http.Request) bool {
return r.Method == "POST" && r.Header.Get("Content-Type") == "application/x-www-form-urlencoded"
}
type handler struct {
pat Pattern
h HandlerFunc
}