| // Copyright The OpenTelemetry Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package otelhttp // import "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp" |
| |
| import ( |
| "context" |
| "io" |
| "net/http" |
| |
| "go.opentelemetry.io/otel/propagation" |
| ) |
| |
| var _ io.ReadCloser = &bodyWrapper{} |
| |
| // bodyWrapper wraps a http.Request.Body (an io.ReadCloser) to track the number |
| // of bytes read and the last error. |
| type bodyWrapper struct { |
| io.ReadCloser |
| record func(n int64) // must not be nil |
| |
| read int64 |
| err error |
| } |
| |
| func (w *bodyWrapper) Read(b []byte) (int, error) { |
| n, err := w.ReadCloser.Read(b) |
| n1 := int64(n) |
| w.read += n1 |
| w.err = err |
| w.record(n1) |
| return n, err |
| } |
| |
| func (w *bodyWrapper) Close() error { |
| return w.ReadCloser.Close() |
| } |
| |
| var _ http.ResponseWriter = &respWriterWrapper{} |
| |
| // respWriterWrapper wraps a http.ResponseWriter in order to track the number of |
| // bytes written, the last error, and to catch the first written statusCode. |
| // TODO: The wrapped http.ResponseWriter doesn't implement any of the optional |
| // types (http.Hijacker, http.Pusher, http.CloseNotifier, http.Flusher, etc) |
| // that may be useful when using it in real life situations. |
| type respWriterWrapper struct { |
| http.ResponseWriter |
| record func(n int64) // must not be nil |
| |
| // used to inject the header |
| ctx context.Context |
| |
| props propagation.TextMapPropagator |
| |
| written int64 |
| statusCode int |
| err error |
| wroteHeader bool |
| } |
| |
| func (w *respWriterWrapper) Header() http.Header { |
| return w.ResponseWriter.Header() |
| } |
| |
| func (w *respWriterWrapper) Write(p []byte) (int, error) { |
| if !w.wroteHeader { |
| w.WriteHeader(http.StatusOK) |
| } |
| n, err := w.ResponseWriter.Write(p) |
| n1 := int64(n) |
| w.record(n1) |
| w.written += n1 |
| w.err = err |
| return n, err |
| } |
| |
| // WriteHeader persists initial statusCode for span attribution. |
| // All calls to WriteHeader will be propagated to the underlying ResponseWriter |
| // and will persist the statusCode from the first call. |
| // Blocking consecutive calls to WriteHeader alters expected behavior and will |
| // remove warning logs from net/http where developers will notice incorrect handler implementations. |
| func (w *respWriterWrapper) WriteHeader(statusCode int) { |
| if !w.wroteHeader { |
| w.wroteHeader = true |
| w.statusCode = statusCode |
| } |
| w.ResponseWriter.WriteHeader(statusCode) |
| } |