diff options
Diffstat (limited to 'vendor/google.golang.org/api/transport/http/internal/propagation/http.go')
-rw-r--r-- | vendor/google.golang.org/api/transport/http/internal/propagation/http.go | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/vendor/google.golang.org/api/transport/http/internal/propagation/http.go b/vendor/google.golang.org/api/transport/http/internal/propagation/http.go new file mode 100644 index 000000000..24b4f0d29 --- /dev/null +++ b/vendor/google.golang.org/api/transport/http/internal/propagation/http.go @@ -0,0 +1,96 @@ +// Copyright 2018 Google LLC +// +// 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. + +// +build go1.8 + +// Package propagation implements X-Cloud-Trace-Context header propagation used +// by Google Cloud products. +package propagation + +import ( + "encoding/binary" + "encoding/hex" + "fmt" + "net/http" + "strconv" + "strings" + + "go.opencensus.io/trace" + "go.opencensus.io/trace/propagation" +) + +const ( + httpHeaderMaxSize = 200 + httpHeader = `X-Cloud-Trace-Context` +) + +var _ propagation.HTTPFormat = (*HTTPFormat)(nil) + +// HTTPFormat implements propagation.HTTPFormat to propagate +// traces in HTTP headers for Google Cloud Platform and Stackdriver Trace. +type HTTPFormat struct{} + +// SpanContextFromRequest extracts a Stackdriver Trace span context from incoming requests. +func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) { + h := req.Header.Get(httpHeader) + // See https://cloud.google.com/trace/docs/faq for the header HTTPFormat. + // Return if the header is empty or missing, or if the header is unreasonably + // large, to avoid making unnecessary copies of a large string. + if h == "" || len(h) > httpHeaderMaxSize { + return trace.SpanContext{}, false + } + + // Parse the trace id field. + slash := strings.Index(h, `/`) + if slash == -1 { + return trace.SpanContext{}, false + } + tid, h := h[:slash], h[slash+1:] + + buf, err := hex.DecodeString(tid) + if err != nil { + return trace.SpanContext{}, false + } + copy(sc.TraceID[:], buf) + + // Parse the span id field. + spanstr := h + semicolon := strings.Index(h, `;`) + if semicolon != -1 { + spanstr, h = h[:semicolon], h[semicolon+1:] + } + sid, err := strconv.ParseUint(spanstr, 10, 64) + if err != nil { + return trace.SpanContext{}, false + } + binary.BigEndian.PutUint64(sc.SpanID[:], sid) + + // Parse the options field, options field is optional. + if !strings.HasPrefix(h, "o=") { + return sc, true + } + o, err := strconv.ParseUint(h[2:], 10, 64) + if err != nil { + return trace.SpanContext{}, false + } + sc.TraceOptions = trace.TraceOptions(o) + return sc, true +} + +// SpanContextToRequest modifies the given request to include a Stackdriver Trace header. +func (f *HTTPFormat) SpanContextToRequest(sc trace.SpanContext, req *http.Request) { + sid := binary.BigEndian.Uint64(sc.SpanID[:]) + header := fmt.Sprintf("%s/%d;o=%d", hex.EncodeToString(sc.TraceID[:]), sid, int64(sc.TraceOptions)) + req.Header.Set(httpHeader, header) +} |