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opentelemetry-go/propagation/http_trace_context_propagator.go
rghetia 15bfc5bb12
Namespace import path under "/otel" (#274)
Also fixes example module paths so that they use the vanity URL instead
of the github URL.

[Closes #184]
2019-11-01 11:40:29 -07:00

197 lines
5.4 KiB
Go

// Copyright 2019, 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 propagation
import (
"context"
"encoding/hex"
"fmt"
"net/url"
"regexp"
"strings"
"go.opentelemetry.io/otel/api/core"
dctx "go.opentelemetry.io/otel/api/distributedcontext"
"go.opentelemetry.io/otel/api/key"
apipropagation "go.opentelemetry.io/otel/api/propagation"
"go.opentelemetry.io/otel/api/trace"
)
const (
supportedVersion = 0
maxVersion = 254
TraceparentHeader = "Traceparent"
CorrelationContextHeader = "Correlation-Context"
)
// HTTPTraceContextPropagator propagates SpanContext in W3C TraceContext format.
type HTTPTraceContextPropagator struct{}
var _ apipropagation.TextFormatPropagator = HTTPTraceContextPropagator{}
var traceCtxRegExp = regexp.MustCompile("^[0-9a-f]{2}-[a-f0-9]{32}-[a-f0-9]{16}-[a-f0-9]{2}-?")
func (hp HTTPTraceContextPropagator) Inject(ctx context.Context, supplier apipropagation.Supplier) {
sc := trace.CurrentSpan(ctx).SpanContext()
if sc.IsValid() {
h := fmt.Sprintf("%.2x-%s-%.16x-%.2x",
supportedVersion,
sc.TraceIDString(),
sc.SpanID,
sc.TraceFlags&core.TraceFlagsSampled)
supplier.Set(TraceparentHeader, h)
}
correlationCtx := dctx.FromContext(ctx)
firstIter := true
var headerValueBuilder strings.Builder
correlationCtx.Foreach(func(kv core.KeyValue) bool {
if !firstIter {
headerValueBuilder.WriteRune(',')
}
firstIter = false
headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace((string)(kv.Key))))
headerValueBuilder.WriteRune('=')
headerValueBuilder.WriteString(url.QueryEscape(strings.TrimSpace(kv.Value.Emit())))
return true
})
if headerValueBuilder.Len() > 0 {
headerString := headerValueBuilder.String()
supplier.Set(CorrelationContextHeader, headerString)
}
}
func (hp HTTPTraceContextPropagator) Extract(
ctx context.Context, supplier apipropagation.Supplier,
) (core.SpanContext, dctx.Map) {
return hp.extractSpanContext(ctx, supplier), hp.extractCorrelationCtx(ctx, supplier)
}
func (hp HTTPTraceContextPropagator) extractSpanContext(
ctx context.Context, supplier apipropagation.Supplier,
) 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 (hp HTTPTraceContextPropagator) extractCorrelationCtx(ctx context.Context, supplier apipropagation.Supplier) dctx.Map {
correlationContext := supplier.Get(CorrelationContextHeader)
if correlationContext == "" {
return dctx.NewEmptyMap()
}
contextValues := strings.Split(correlationContext, ",")
keyValues := make([]core.KeyValue, 0, len(contextValues))
for _, contextValue := range contextValues {
valueAndProps := strings.Split(contextValue, ";")
if len(valueAndProps) < 1 {
continue
}
nameValue := strings.Split(valueAndProps[0], "=")
if len(nameValue) < 2 {
continue
}
name, err := url.QueryUnescape(nameValue[0])
if err != nil {
continue
}
trimmedName := strings.TrimSpace(name)
value, err := url.QueryUnescape(nameValue[1])
if err != nil {
continue
}
trimmedValue := strings.TrimSpace(value)
// TODO (skaris): properties defiend https://w3c.github.io/correlation-context/, are currently
// just put as part of the value.
var trimmedValueWithProps strings.Builder
trimmedValueWithProps.WriteString(trimmedValue)
for _, prop := range valueAndProps[1:] {
trimmedValueWithProps.WriteRune(';')
trimmedValueWithProps.WriteString(prop)
}
keyValues = append(keyValues, key.New(trimmedName).String(trimmedValueWithProps.String()))
}
return dctx.NewMap(dctx.MapUpdate{
MultiKV: keyValues,
})
}
func (hp HTTPTraceContextPropagator) GetAllKeys() []string {
return []string{TraceparentHeader, CorrelationContextHeader}
}