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 0000000..24b4f0d
--- /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)
+}