mirror of https://github.com/minio/minio.git
95 lines
2.9 KiB
Go
95 lines
2.9 KiB
Go
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// Copyright 2018, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package propagation implement X-Cloud-Trace-Context header propagation used
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// by Google Cloud products.
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package propagation // import "contrib.go.opencensus.io/exporter/stackdriver/propagation"
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import (
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"go.opencensus.io/trace"
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"go.opencensus.io/trace/propagation"
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)
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const (
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httpHeaderMaxSize = 200
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httpHeader = `X-Cloud-Trace-Context`
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)
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var _ propagation.HTTPFormat = (*HTTPFormat)(nil)
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// HTTPFormat implements propagation.HTTPFormat to propagate
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// traces in HTTP headers for Google Cloud Platform and Stackdriver Trace.
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type HTTPFormat struct{}
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// SpanContextFromRequest extracts a Stackdriver Trace span context from incoming requests.
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func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) {
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h := req.Header.Get(httpHeader)
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// See https://cloud.google.com/trace/docs/faq for the header HTTPFormat.
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// Return if the header is empty or missing, or if the header is unreasonably
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// large, to avoid making unnecessary copies of a large string.
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if h == "" || len(h) > httpHeaderMaxSize {
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return trace.SpanContext{}, false
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}
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// Parse the trace id field.
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slash := strings.Index(h, `/`)
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if slash == -1 {
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return trace.SpanContext{}, false
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}
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tid, h := h[:slash], h[slash+1:]
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buf, err := hex.DecodeString(tid)
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if err != nil {
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return trace.SpanContext{}, false
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}
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copy(sc.TraceID[:], buf)
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// Parse the span id field.
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spanstr := h
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semicolon := strings.Index(h, `;`)
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if semicolon != -1 {
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spanstr, h = h[:semicolon], h[semicolon+1:]
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}
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sid, err := strconv.ParseUint(spanstr, 10, 64)
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if err != nil {
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return trace.SpanContext{}, false
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}
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binary.BigEndian.PutUint64(sc.SpanID[:], sid)
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// Parse the options field, options field is optional.
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if !strings.HasPrefix(h, "o=") {
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return sc, true
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}
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o, err := strconv.ParseUint(h[2:], 10, 64)
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if err != nil {
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return trace.SpanContext{}, false
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}
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sc.TraceOptions = trace.TraceOptions(o)
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return sc, true
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}
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// SpanContextToRequest modifies the given request to include a Stackdriver Trace header.
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func (f *HTTPFormat) SpanContextToRequest(sc trace.SpanContext, req *http.Request) {
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sid := binary.BigEndian.Uint64(sc.SpanID[:])
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header := fmt.Sprintf("%s/%d;o=%d", hex.EncodeToString(sc.TraceID[:]), sid, int64(sc.TraceOptions))
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req.Header.Set(httpHeader, header)
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}
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