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// Copyright 2022 The OpenZipkin 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 b3
import (
"net/http"
"github.com/openzipkin/zipkin-go/model"
"github.com/openzipkin/zipkin-go/propagation"
)
// InjectOption provides functional option handler type.
type InjectOption func(opts *InjectOptions)
// InjectOptions provides the available functional options.
type InjectOptions struct {
shouldInjectSingleHeader bool
shouldInjectMultiHeader bool
}
// WithSingleAndMultiHeader allows to include both single and multiple
// headers in the context injection
func WithSingleAndMultiHeader() InjectOption {
return func(opts *InjectOptions) {
opts.shouldInjectSingleHeader = true
opts.shouldInjectMultiHeader = true
}
}
// WithSingleHeaderOnly allows to include only single header in the context
// injection
func WithSingleHeaderOnly() InjectOption {
return func(opts *InjectOptions) {
opts.shouldInjectSingleHeader = true
opts.shouldInjectMultiHeader = false
}
}
// ExtractHTTP will extract a span.Context from the HTTP Request if found in
// B3 header format.
func ExtractHTTP(r *http.Request) propagation.Extractor {
return func() (*model.SpanContext, error) {
var (
traceIDHeader = r.Header.Get(TraceID)
spanIDHeader = r.Header.Get(SpanID)
parentSpanIDHeader = r.Header.Get(ParentSpanID)
sampledHeader = r.Header.Get(Sampled)
flagsHeader = r.Header.Get(Flags)
singleHeader = r.Header.Get(Context)
)
var (
sc *model.SpanContext
sErr error
mErr error
)
if singleHeader != "" {
sc, sErr = ParseSingleHeader(singleHeader)
if sErr == nil {
return sc, nil
}
}
sc, mErr = ParseHeaders(
traceIDHeader, spanIDHeader, parentSpanIDHeader,
sampledHeader, flagsHeader,
)
if mErr != nil && sErr != nil {
return nil, sErr
}
return sc, mErr
}
}
// InjectHTTP will inject a span.Context into a HTTP Request
func InjectHTTP(r *http.Request, opts ...InjectOption) propagation.Injector {
options := InjectOptions{shouldInjectMultiHeader: true}
for _, opt := range opts {
opt(&options)
}
return func(sc model.SpanContext) error {
if (model.SpanContext{}) == sc {
return ErrEmptyContext
}
if options.shouldInjectMultiHeader {
if sc.Debug {
r.Header.Set(Flags, "1")
} else if sc.Sampled != nil {
// Debug is encoded as X-B3-Flags: 1. Since Debug implies Sampled,
// so don't also send "X-B3-Sampled: 1".
if *sc.Sampled {
r.Header.Set(Sampled, "1")
} else {
r.Header.Set(Sampled, "0")
}
}
if !sc.TraceID.Empty() && sc.ID > 0 {
r.Header.Set(TraceID, sc.TraceID.String())
r.Header.Set(SpanID, sc.ID.String())
if sc.ParentID != nil {
r.Header.Set(ParentSpanID, sc.ParentID.String())
}
}
}
if options.shouldInjectSingleHeader {
r.Header.Set(Context, BuildSingleHeader(sc))
}
return nil
}
}
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