forked from open-telemetry/opentelemetry-go
/
trace_context_propagator.go
132 lines (110 loc) · 3.19 KB
/
trace_context_propagator.go
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// 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 trace
import (
"context"
"encoding/hex"
"fmt"
"regexp"
"strings"
"github.com/InVisionApp/opentelemetry-go/api/core"
"github.com/InVisionApp/opentelemetry-go/api/propagation"
)
const (
supportedVersion = 0
maxVersion = 254
traceparentHeader = "Traceparent"
)
// TraceContext propagates SpanContext in W3C TraceContext format.
//nolint:golint
type TraceContext struct{}
var _ propagation.HTTPPropagator = TraceContext{}
var traceCtxRegExp = regexp.MustCompile("^[0-9a-f]{2}-[a-f0-9]{32}-[a-f0-9]{16}-[a-f0-9]{2}-?")
// DefaultHTTPPropagator returns the default trace HTTP propagator.
func DefaultHTTPPropagator() propagation.HTTPPropagator {
return TraceContext{}
}
func (TraceContext) Inject(ctx context.Context, supplier propagation.HTTPSupplier) {
sc := SpanFromContext(ctx).SpanContext()
if !sc.IsValid() {
return
}
h := fmt.Sprintf("%.2x-%s-%s-%.2x",
supportedVersion,
sc.TraceID,
sc.SpanID,
sc.TraceFlags&core.TraceFlagsSampled)
supplier.Set(traceparentHeader, h)
}
func (tc TraceContext) Extract(ctx context.Context, supplier propagation.HTTPSupplier) context.Context {
return ContextWithRemoteSpanContext(ctx, tc.extract(supplier))
}
func (TraceContext) extract(supplier propagation.HTTPSupplier) core.SpanContext {
h := supplier.Get(traceparentHeader)
if h == "" {
return core.EmptySpanContext()
}
h = strings.Trim(h, "-")
if !traceCtxRegExp.MatchString(h) {
return core.EmptySpanContext()
}
sections := strings.Split(h, "-")
if len(sections) < 4 {
return core.EmptySpanContext()
}
if len(sections[0]) != 2 {
return core.EmptySpanContext()
}
ver, err := hex.DecodeString(sections[0])
if err != nil {
return core.EmptySpanContext()
}
version := int(ver[0])
if version > maxVersion {
return core.EmptySpanContext()
}
if version == 0 && len(sections) != 4 {
return core.EmptySpanContext()
}
if len(sections[1]) != 32 {
return core.EmptySpanContext()
}
var sc core.SpanContext
sc.TraceID, err = core.TraceIDFromHex(sections[1][:32])
if err != nil {
return core.EmptySpanContext()
}
if len(sections[2]) != 16 {
return core.EmptySpanContext()
}
sc.SpanID, err = core.SpanIDFromHex(sections[2])
if err != nil {
return core.EmptySpanContext()
}
if len(sections[3]) != 2 {
return core.EmptySpanContext()
}
opts, err := hex.DecodeString(sections[3])
if err != nil || len(opts) < 1 || (version == 0 && opts[0] > 2) {
return core.EmptySpanContext()
}
sc.TraceFlags = opts[0] &^ core.TraceFlagsUnused
if !sc.IsValid() {
return core.EmptySpanContext()
}
return sc
}
func (TraceContext) GetAllKeys() []string {
return []string{traceparentHeader}
}