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