khenaidoo | 59ce9dd | 2019-11-11 13:05:32 -0500 | [diff] [blame^] | 1 | package runtime |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "fmt" |
| 6 | "net/http" |
| 7 | "net/textproto" |
| 8 | "strings" |
| 9 | |
| 10 | "github.com/golang/protobuf/proto" |
| 11 | "google.golang.org/grpc/codes" |
| 12 | "google.golang.org/grpc/metadata" |
| 13 | "google.golang.org/grpc/status" |
| 14 | ) |
| 15 | |
| 16 | // A HandlerFunc handles a specific pair of path pattern and HTTP method. |
| 17 | type HandlerFunc func(w http.ResponseWriter, r *http.Request, pathParams map[string]string) |
| 18 | |
| 19 | // ErrUnknownURI is the error supplied to a custom ProtoErrorHandlerFunc when |
| 20 | // a request is received with a URI path that does not match any registered |
| 21 | // service method. |
| 22 | // |
| 23 | // Since gRPC servers return an "Unimplemented" code for requests with an |
| 24 | // unrecognized URI path, this error also has a gRPC "Unimplemented" code. |
| 25 | var ErrUnknownURI = status.Error(codes.Unimplemented, http.StatusText(http.StatusNotImplemented)) |
| 26 | |
| 27 | // ServeMux is a request multiplexer for grpc-gateway. |
| 28 | // It matches http requests to patterns and invokes the corresponding handler. |
| 29 | type ServeMux struct { |
| 30 | // handlers maps HTTP method to a list of handlers. |
| 31 | handlers map[string][]handler |
| 32 | forwardResponseOptions []func(context.Context, http.ResponseWriter, proto.Message) error |
| 33 | marshalers marshalerRegistry |
| 34 | incomingHeaderMatcher HeaderMatcherFunc |
| 35 | outgoingHeaderMatcher HeaderMatcherFunc |
| 36 | metadataAnnotators []func(context.Context, *http.Request) metadata.MD |
| 37 | streamErrorHandler StreamErrorHandlerFunc |
| 38 | protoErrorHandler ProtoErrorHandlerFunc |
| 39 | disablePathLengthFallback bool |
| 40 | lastMatchWins bool |
| 41 | } |
| 42 | |
| 43 | // ServeMuxOption is an option that can be given to a ServeMux on construction. |
| 44 | type ServeMuxOption func(*ServeMux) |
| 45 | |
| 46 | // WithForwardResponseOption returns a ServeMuxOption representing the forwardResponseOption. |
| 47 | // |
| 48 | // forwardResponseOption is an option that will be called on the relevant context.Context, |
| 49 | // http.ResponseWriter, and proto.Message before every forwarded response. |
| 50 | // |
| 51 | // The message may be nil in the case where just a header is being sent. |
| 52 | func WithForwardResponseOption(forwardResponseOption func(context.Context, http.ResponseWriter, proto.Message) error) ServeMuxOption { |
| 53 | return func(serveMux *ServeMux) { |
| 54 | serveMux.forwardResponseOptions = append(serveMux.forwardResponseOptions, forwardResponseOption) |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | // HeaderMatcherFunc checks whether a header key should be forwarded to/from gRPC context. |
| 59 | type HeaderMatcherFunc func(string) (string, bool) |
| 60 | |
| 61 | // DefaultHeaderMatcher is used to pass http request headers to/from gRPC context. This adds permanent HTTP header |
| 62 | // keys (as specified by the IANA) to gRPC context with grpcgateway- prefix. HTTP headers that start with |
| 63 | // 'Grpc-Metadata-' are mapped to gRPC metadata after removing prefix 'Grpc-Metadata-'. |
| 64 | func DefaultHeaderMatcher(key string) (string, bool) { |
| 65 | key = textproto.CanonicalMIMEHeaderKey(key) |
| 66 | if isPermanentHTTPHeader(key) { |
| 67 | return MetadataPrefix + key, true |
| 68 | } else if strings.HasPrefix(key, MetadataHeaderPrefix) { |
| 69 | return key[len(MetadataHeaderPrefix):], true |
| 70 | } |
| 71 | return "", false |
| 72 | } |
| 73 | |
| 74 | // WithIncomingHeaderMatcher returns a ServeMuxOption representing a headerMatcher for incoming request to gateway. |
| 75 | // |
| 76 | // This matcher will be called with each header in http.Request. If matcher returns true, that header will be |
| 77 | // passed to gRPC context. To transform the header before passing to gRPC context, matcher should return modified header. |
| 78 | func WithIncomingHeaderMatcher(fn HeaderMatcherFunc) ServeMuxOption { |
| 79 | return func(mux *ServeMux) { |
| 80 | mux.incomingHeaderMatcher = fn |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | // WithOutgoingHeaderMatcher returns a ServeMuxOption representing a headerMatcher for outgoing response from gateway. |
| 85 | // |
| 86 | // This matcher will be called with each header in response header metadata. If matcher returns true, that header will be |
| 87 | // passed to http response returned from gateway. To transform the header before passing to response, |
| 88 | // matcher should return modified header. |
| 89 | func WithOutgoingHeaderMatcher(fn HeaderMatcherFunc) ServeMuxOption { |
| 90 | return func(mux *ServeMux) { |
| 91 | mux.outgoingHeaderMatcher = fn |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | // WithMetadata returns a ServeMuxOption for passing metadata to a gRPC context. |
| 96 | // |
| 97 | // This can be used by services that need to read from http.Request and modify gRPC context. A common use case |
| 98 | // is reading token from cookie and adding it in gRPC context. |
| 99 | func WithMetadata(annotator func(context.Context, *http.Request) metadata.MD) ServeMuxOption { |
| 100 | return func(serveMux *ServeMux) { |
| 101 | serveMux.metadataAnnotators = append(serveMux.metadataAnnotators, annotator) |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | // WithProtoErrorHandler returns a ServeMuxOption for passing metadata to a gRPC context. |
| 106 | // |
| 107 | // This can be used to handle an error as general proto message defined by gRPC. |
| 108 | // The response including body and status is not backward compatible with the default error handler. |
| 109 | // When this option is used, HTTPError and OtherErrorHandler are overwritten on initialization. |
| 110 | func WithProtoErrorHandler(fn ProtoErrorHandlerFunc) ServeMuxOption { |
| 111 | return func(serveMux *ServeMux) { |
| 112 | serveMux.protoErrorHandler = fn |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | // WithDisablePathLengthFallback returns a ServeMuxOption for disable path length fallback. |
| 117 | func WithDisablePathLengthFallback() ServeMuxOption { |
| 118 | return func(serveMux *ServeMux) { |
| 119 | serveMux.disablePathLengthFallback = true |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | // WithStreamErrorHandler returns a ServeMuxOption that will use the given custom stream |
| 124 | // error handler, which allows for customizing the error trailer for server-streaming |
| 125 | // calls. |
| 126 | // |
| 127 | // For stream errors that occur before any response has been written, the mux's |
| 128 | // ProtoErrorHandler will be invoked. However, once data has been written, the errors must |
| 129 | // be handled differently: they must be included in the response body. The response body's |
| 130 | // final message will include the error details returned by the stream error handler. |
| 131 | func WithStreamErrorHandler(fn StreamErrorHandlerFunc) ServeMuxOption { |
| 132 | return func(serveMux *ServeMux) { |
| 133 | serveMux.streamErrorHandler = fn |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | // WithLastMatchWins returns a ServeMuxOption that will enable "last |
| 138 | // match wins" behavior, where if multiple path patterns match a |
| 139 | // request path, the last one defined in the .proto file will be used. |
| 140 | func WithLastMatchWins() ServeMuxOption { |
| 141 | return func(serveMux *ServeMux) { |
| 142 | serveMux.lastMatchWins = true |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | // NewServeMux returns a new ServeMux whose internal mapping is empty. |
| 147 | func NewServeMux(opts ...ServeMuxOption) *ServeMux { |
| 148 | serveMux := &ServeMux{ |
| 149 | handlers: make(map[string][]handler), |
| 150 | forwardResponseOptions: make([]func(context.Context, http.ResponseWriter, proto.Message) error, 0), |
| 151 | marshalers: makeMarshalerMIMERegistry(), |
| 152 | streamErrorHandler: DefaultHTTPStreamErrorHandler, |
| 153 | } |
| 154 | |
| 155 | for _, opt := range opts { |
| 156 | opt(serveMux) |
| 157 | } |
| 158 | |
| 159 | if serveMux.protoErrorHandler != nil { |
| 160 | HTTPError = serveMux.protoErrorHandler |
| 161 | // OtherErrorHandler is no longer used when protoErrorHandler is set. |
| 162 | // Overwritten by a special error handler to return Unknown. |
| 163 | OtherErrorHandler = func(w http.ResponseWriter, r *http.Request, _ string, _ int) { |
| 164 | ctx := context.Background() |
| 165 | _, outboundMarshaler := MarshalerForRequest(serveMux, r) |
| 166 | sterr := status.Error(codes.Unknown, "unexpected use of OtherErrorHandler") |
| 167 | serveMux.protoErrorHandler(ctx, serveMux, outboundMarshaler, w, r, sterr) |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | if serveMux.incomingHeaderMatcher == nil { |
| 172 | serveMux.incomingHeaderMatcher = DefaultHeaderMatcher |
| 173 | } |
| 174 | |
| 175 | if serveMux.outgoingHeaderMatcher == nil { |
| 176 | serveMux.outgoingHeaderMatcher = func(key string) (string, bool) { |
| 177 | return fmt.Sprintf("%s%s", MetadataHeaderPrefix, key), true |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | return serveMux |
| 182 | } |
| 183 | |
| 184 | // Handle associates "h" to the pair of HTTP method and path pattern. |
| 185 | func (s *ServeMux) Handle(meth string, pat Pattern, h HandlerFunc) { |
| 186 | if s.lastMatchWins { |
| 187 | s.handlers[meth] = append([]handler{handler{pat: pat, h: h}}, s.handlers[meth]...) |
| 188 | } else { |
| 189 | s.handlers[meth] = append(s.handlers[meth], handler{pat: pat, h: h}) |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | // ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.Path. |
| 194 | func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) { |
| 195 | ctx := r.Context() |
| 196 | |
| 197 | path := r.URL.Path |
| 198 | if !strings.HasPrefix(path, "/") { |
| 199 | if s.protoErrorHandler != nil { |
| 200 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 201 | sterr := status.Error(codes.InvalidArgument, http.StatusText(http.StatusBadRequest)) |
| 202 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr) |
| 203 | } else { |
| 204 | OtherErrorHandler(w, r, http.StatusText(http.StatusBadRequest), http.StatusBadRequest) |
| 205 | } |
| 206 | return |
| 207 | } |
| 208 | |
| 209 | components := strings.Split(path[1:], "/") |
| 210 | l := len(components) |
| 211 | var verb string |
| 212 | if idx := strings.LastIndex(components[l-1], ":"); idx == 0 { |
| 213 | if s.protoErrorHandler != nil { |
| 214 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 215 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, ErrUnknownURI) |
| 216 | } else { |
| 217 | OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound) |
| 218 | } |
| 219 | return |
| 220 | } else if idx > 0 { |
| 221 | c := components[l-1] |
| 222 | components[l-1], verb = c[:idx], c[idx+1:] |
| 223 | } |
| 224 | |
| 225 | if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && s.isPathLengthFallback(r) { |
| 226 | r.Method = strings.ToUpper(override) |
| 227 | if err := r.ParseForm(); err != nil { |
| 228 | if s.protoErrorHandler != nil { |
| 229 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 230 | sterr := status.Error(codes.InvalidArgument, err.Error()) |
| 231 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr) |
| 232 | } else { |
| 233 | OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest) |
| 234 | } |
| 235 | return |
| 236 | } |
| 237 | } |
| 238 | for _, h := range s.handlers[r.Method] { |
| 239 | pathParams, err := h.pat.Match(components, verb) |
| 240 | if err != nil { |
| 241 | continue |
| 242 | } |
| 243 | h.h(w, r, pathParams) |
| 244 | return |
| 245 | } |
| 246 | |
| 247 | // lookup other methods to handle fallback from GET to POST and |
| 248 | // to determine if it is MethodNotAllowed or NotFound. |
| 249 | for m, handlers := range s.handlers { |
| 250 | if m == r.Method { |
| 251 | continue |
| 252 | } |
| 253 | for _, h := range handlers { |
| 254 | pathParams, err := h.pat.Match(components, verb) |
| 255 | if err != nil { |
| 256 | continue |
| 257 | } |
| 258 | // X-HTTP-Method-Override is optional. Always allow fallback to POST. |
| 259 | if s.isPathLengthFallback(r) { |
| 260 | if err := r.ParseForm(); err != nil { |
| 261 | if s.protoErrorHandler != nil { |
| 262 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 263 | sterr := status.Error(codes.InvalidArgument, err.Error()) |
| 264 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, sterr) |
| 265 | } else { |
| 266 | OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest) |
| 267 | } |
| 268 | return |
| 269 | } |
| 270 | h.h(w, r, pathParams) |
| 271 | return |
| 272 | } |
| 273 | if s.protoErrorHandler != nil { |
| 274 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 275 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, ErrUnknownURI) |
| 276 | } else { |
| 277 | OtherErrorHandler(w, r, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed) |
| 278 | } |
| 279 | return |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | if s.protoErrorHandler != nil { |
| 284 | _, outboundMarshaler := MarshalerForRequest(s, r) |
| 285 | s.protoErrorHandler(ctx, s, outboundMarshaler, w, r, ErrUnknownURI) |
| 286 | } else { |
| 287 | OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound) |
| 288 | } |
| 289 | } |
| 290 | |
| 291 | // GetForwardResponseOptions returns the ForwardResponseOptions associated with this ServeMux. |
| 292 | func (s *ServeMux) GetForwardResponseOptions() []func(context.Context, http.ResponseWriter, proto.Message) error { |
| 293 | return s.forwardResponseOptions |
| 294 | } |
| 295 | |
| 296 | func (s *ServeMux) isPathLengthFallback(r *http.Request) bool { |
| 297 | return !s.disablePathLengthFallback && r.Method == "POST" && r.Header.Get("Content-Type") == "application/x-www-form-urlencoded" |
| 298 | } |
| 299 | |
| 300 | type handler struct { |
| 301 | pat Pattern |
| 302 | h HandlerFunc |
| 303 | } |