mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 01:52:46 +00:00
160 lines
4.4 KiB
Go
160 lines
4.4 KiB
Go
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// Copyright The OpenTelemetry 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 // import "go.opentelemetry.io/otel/propagation"
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import (
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"context"
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"encoding/hex"
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"fmt"
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"regexp"
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"go.opentelemetry.io/otel/trace"
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)
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const (
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supportedVersion = 0
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maxVersion = 254
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traceparentHeader = "traceparent"
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tracestateHeader = "tracestate"
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)
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// TraceContext is a propagator that supports the W3C Trace Context format
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// (https://www.w3.org/TR/trace-context/)
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//
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// This propagator will propagate the traceparent and tracestate headers to
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// guarantee traces are not broken. It is up to the users of this propagator
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// to choose if they want to participate in a trace by modifying the
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// traceparent header and relevant parts of the tracestate header containing
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// their proprietary information.
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type TraceContext struct{}
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var _ TextMapPropagator = TraceContext{}
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var traceCtxRegExp = regexp.MustCompile("^(?P<version>[0-9a-f]{2})-(?P<traceID>[a-f0-9]{32})-(?P<spanID>[a-f0-9]{16})-(?P<traceFlags>[a-f0-9]{2})(?:-.*)?$")
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// Inject set tracecontext from the Context into the carrier.
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func (tc TraceContext) Inject(ctx context.Context, carrier TextMapCarrier) {
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sc := trace.SpanContextFromContext(ctx)
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if !sc.IsValid() {
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return
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}
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if ts := sc.TraceState().String(); ts != "" {
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carrier.Set(tracestateHeader, ts)
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}
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// Clear all flags other than the trace-context supported sampling bit.
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flags := sc.TraceFlags() & trace.FlagsSampled
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h := fmt.Sprintf("%.2x-%s-%s-%s",
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supportedVersion,
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sc.TraceID(),
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sc.SpanID(),
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flags)
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carrier.Set(traceparentHeader, h)
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}
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// Extract reads tracecontext from the carrier into a returned Context.
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//
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// The returned Context will be a copy of ctx and contain the extracted
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// tracecontext as the remote SpanContext. If the extracted tracecontext is
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// invalid, the passed ctx will be returned directly instead.
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func (tc TraceContext) Extract(ctx context.Context, carrier TextMapCarrier) context.Context {
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sc := tc.extract(carrier)
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if !sc.IsValid() {
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return ctx
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}
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return trace.ContextWithRemoteSpanContext(ctx, sc)
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}
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func (tc TraceContext) extract(carrier TextMapCarrier) trace.SpanContext {
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h := carrier.Get(traceparentHeader)
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if h == "" {
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return trace.SpanContext{}
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}
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matches := traceCtxRegExp.FindStringSubmatch(h)
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if len(matches) == 0 {
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return trace.SpanContext{}
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}
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if len(matches) < 5 { // four subgroups plus the overall match
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return trace.SpanContext{}
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}
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if len(matches[1]) != 2 {
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return trace.SpanContext{}
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}
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ver, err := hex.DecodeString(matches[1])
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if err != nil {
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return trace.SpanContext{}
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}
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version := int(ver[0])
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if version > maxVersion {
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return trace.SpanContext{}
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}
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if version == 0 && len(matches) != 5 { // four subgroups plus the overall match
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return trace.SpanContext{}
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}
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if len(matches[2]) != 32 {
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return trace.SpanContext{}
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}
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var scc trace.SpanContextConfig
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scc.TraceID, err = trace.TraceIDFromHex(matches[2][:32])
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if err != nil {
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return trace.SpanContext{}
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}
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if len(matches[3]) != 16 {
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return trace.SpanContext{}
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}
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scc.SpanID, err = trace.SpanIDFromHex(matches[3])
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if err != nil {
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return trace.SpanContext{}
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}
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if len(matches[4]) != 2 {
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return trace.SpanContext{}
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}
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opts, err := hex.DecodeString(matches[4])
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if err != nil || len(opts) < 1 || (version == 0 && opts[0] > 2) {
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return trace.SpanContext{}
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}
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// Clear all flags other than the trace-context supported sampling bit.
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scc.TraceFlags = trace.TraceFlags(opts[0]) & trace.FlagsSampled
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// Ignore the error returned here. Failure to parse tracestate MUST NOT
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// affect the parsing of traceparent according to the W3C tracecontext
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// specification.
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scc.TraceState, _ = trace.ParseTraceState(carrier.Get(tracestateHeader))
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scc.Remote = true
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sc := trace.NewSpanContext(scc)
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if !sc.IsValid() {
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return trace.SpanContext{}
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}
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return sc
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}
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// Fields returns the keys who's values are set with Inject.
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func (tc TraceContext) Fields() []string {
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return []string{traceparentHeader, tracestateHeader}
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}
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