temp commit

vendor/go.opencensus.io/plugin/ochttp/propagation/b3/b3.go

@@ -0,0 +1,123 @@
+// Copyright 2018, OpenCensus 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 contains a propagation.HTTPFormat implementation
+// for B3 propagation. See https://github.com/openzipkin/b3-propagation
+// for more details.
+package b3 // import "go.opencensus.io/plugin/ochttp/propagation/b3"
+
+import (
+	"encoding/hex"
+	"net/http"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+)
+
+// B3 headers that OpenCensus understands.
+const (
+	TraceIDHeader = "X-B3-TraceId"
+	SpanIDHeader  = "X-B3-SpanId"
+	SampledHeader = "X-B3-Sampled"
+)
+
+// HTTPFormat implements propagation.HTTPFormat to propagate
+// traces in HTTP headers in B3 propagation format.
+// HTTPFormat skips the X-B3-ParentId and X-B3-Flags headers
+// because there are additional fields not represented in the
+// OpenCensus span context. Spans created from the incoming
+// header will be the direct children of the client-side span.
+// Similarly, receiver of the outgoing spans should use client-side
+// span created by OpenCensus as the parent.
+type HTTPFormat struct{}
+
+var _ propagation.HTTPFormat = (*HTTPFormat)(nil)
+
+// SpanContextFromRequest extracts a B3 span context from incoming requests.
+func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) {
+	tid, ok := ParseTraceID(req.Header.Get(TraceIDHeader))
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	sid, ok := ParseSpanID(req.Header.Get(SpanIDHeader))
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	sampled, _ := ParseSampled(req.Header.Get(SampledHeader))
+	return trace.SpanContext{
+		TraceID:      tid,
+		SpanID:       sid,
+		TraceOptions: sampled,
+	}, true
+}
+
+// ParseTraceID parses the value of the X-B3-TraceId header.
+func ParseTraceID(tid string) (trace.TraceID, bool) {
+	if tid == "" {
+		return trace.TraceID{}, false
+	}
+	b, err := hex.DecodeString(tid)
+	if err != nil {
+		return trace.TraceID{}, false
+	}
+	var traceID trace.TraceID
+	if len(b) <= 8 {
+		// The lower 64-bits.
+		start := 8 + (8 - len(b))
+		copy(traceID[start:], b)
+	} else {
+		start := 16 - len(b)
+		copy(traceID[start:], b)
+	}
+
+	return traceID, true
+}
+
+// ParseSpanID parses the value of the X-B3-SpanId or X-B3-ParentSpanId headers.
+func ParseSpanID(sid string) (spanID trace.SpanID, ok bool) {
+	if sid == "" {
+		return trace.SpanID{}, false
+	}
+	b, err := hex.DecodeString(sid)
+	if err != nil {
+		return trace.SpanID{}, false
+	}
+	start := 8 - len(b)
+	copy(spanID[start:], b)
+	return spanID, true
+}
+
+// ParseSampled parses the value of the X-B3-Sampled header.
+func ParseSampled(sampled string) (trace.TraceOptions, bool) {
+	switch sampled {
+	case "true", "1":
+		return trace.TraceOptions(1), true
+	default:
+		return trace.TraceOptions(0), false
+	}
+}
+
+// SpanContextToRequest modifies the given request to include B3 headers.
+func (f *HTTPFormat) SpanContextToRequest(sc trace.SpanContext, req *http.Request) {
+	req.Header.Set(TraceIDHeader, hex.EncodeToString(sc.TraceID[:]))
+	req.Header.Set(SpanIDHeader, hex.EncodeToString(sc.SpanID[:]))
+
+	var sampled string
+	if sc.IsSampled() {
+		sampled = "1"
+	} else {
+		sampled = "0"
+	}
+	req.Header.Set(SampledHeader, sampled)
+}

vendor/go.opencensus.io/plugin/ochttp/propagation/tracecontext/propagation.go

@@ -0,0 +1,187 @@
+// Copyright 2018, OpenCensus 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 tracecontext contains HTTP propagator for TraceContext standard.
+// See https://github.com/w3c/distributed-tracing for more information.
+package tracecontext // import "go.opencensus.io/plugin/ochttp/propagation/tracecontext"
+
+import (
+	"encoding/hex"
+	"fmt"
+	"net/http"
+	"net/textproto"
+	"regexp"
+	"strings"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+	"go.opencensus.io/trace/tracestate"
+)
+
+const (
+	supportedVersion  = 0
+	maxVersion        = 254
+	maxTracestateLen  = 512
+	traceparentHeader = "traceparent"
+	tracestateHeader  = "tracestate"
+	trimOWSRegexFmt   = `^[\x09\x20]*(.*[^\x20\x09])[\x09\x20]*$`
+)
+
+var trimOWSRegExp = regexp.MustCompile(trimOWSRegexFmt)
+
+var _ propagation.HTTPFormat = (*HTTPFormat)(nil)
+
+// HTTPFormat implements the TraceContext trace propagation format.
+type HTTPFormat struct{}
+
+// SpanContextFromRequest extracts a span context from incoming requests.
+func (f *HTTPFormat) SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) {
+	h, ok := getRequestHeader(req, traceparentHeader, false)
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	sections := strings.Split(h, "-")
+	if len(sections) < 4 {
+		return trace.SpanContext{}, false
+	}
+
+	if len(sections[0]) != 2 {
+		return trace.SpanContext{}, false
+	}
+	ver, err := hex.DecodeString(sections[0])
+	if err != nil {
+		return trace.SpanContext{}, false
+	}
+	version := int(ver[0])
+	if version > maxVersion {
+		return trace.SpanContext{}, false
+	}
+
+	if version == 0 && len(sections) != 4 {
+		return trace.SpanContext{}, false
+	}
+
+	if len(sections[1]) != 32 {
+		return trace.SpanContext{}, false
+	}
+	tid, err := hex.DecodeString(sections[1])
+	if err != nil {
+		return trace.SpanContext{}, false
+	}
+	copy(sc.TraceID[:], tid)
+
+	if len(sections[2]) != 16 {
+		return trace.SpanContext{}, false
+	}
+	sid, err := hex.DecodeString(sections[2])
+	if err != nil {
+		return trace.SpanContext{}, false
+	}
+	copy(sc.SpanID[:], sid)
+
+	opts, err := hex.DecodeString(sections[3])
+	if err != nil || len(opts) < 1 {
+		return trace.SpanContext{}, false
+	}
+	sc.TraceOptions = trace.TraceOptions(opts[0])
+
+	// Don't allow all zero trace or span ID.
+	if sc.TraceID == [16]byte{} || sc.SpanID == [8]byte{} {
+		return trace.SpanContext{}, false
+	}
+
+	sc.Tracestate = tracestateFromRequest(req)
+	return sc, true
+}
+
+// getRequestHeader returns a combined header field according to RFC7230 section 3.2.2.
+// If commaSeparated is true, multiple header fields with the same field name using be
+// combined using ",".
+// If no header was found using the given name, "ok" would be false.
+// If more than one headers was found using the given name, while commaSeparated is false,
+// "ok" would be false.
+func getRequestHeader(req *http.Request, name string, commaSeparated bool) (hdr string, ok bool) {
+	v := req.Header[textproto.CanonicalMIMEHeaderKey(name)]
+	switch len(v) {
+	case 0:
+		return "", false
+	case 1:
+		return v[0], true
+	default:
+		return strings.Join(v, ","), commaSeparated
+	}
+}
+
+// TODO(rghetia): return an empty Tracestate when parsing tracestate header encounters an error.
+// Revisit to return additional boolean value to indicate parsing error when following issues
+// are resolved.
+// https://github.com/w3c/distributed-tracing/issues/172
+// https://github.com/w3c/distributed-tracing/issues/175
+func tracestateFromRequest(req *http.Request) *tracestate.Tracestate {
+	h, _ := getRequestHeader(req, tracestateHeader, true)
+	if h == "" {
+		return nil
+	}
+
+	var entries []tracestate.Entry
+	pairs := strings.Split(h, ",")
+	hdrLenWithoutOWS := len(pairs) - 1 // Number of commas
+	for _, pair := range pairs {
+		matches := trimOWSRegExp.FindStringSubmatch(pair)
+		if matches == nil {
+			return nil
+		}
+		pair = matches[1]
+		hdrLenWithoutOWS += len(pair)
+		if hdrLenWithoutOWS > maxTracestateLen {
+			return nil
+		}
+		kv := strings.Split(pair, "=")
+		if len(kv) != 2 {
+			return nil
+		}
+		entries = append(entries, tracestate.Entry{Key: kv[0], Value: kv[1]})
+	}
+	ts, err := tracestate.New(nil, entries...)
+	if err != nil {
+		return nil
+	}
+
+	return ts
+}
+
+func tracestateToRequest(sc trace.SpanContext, req *http.Request) {
+	var pairs = make([]string, 0, len(sc.Tracestate.Entries()))
+	if sc.Tracestate != nil {
+		for _, entry := range sc.Tracestate.Entries() {
+			pairs = append(pairs, strings.Join([]string{entry.Key, entry.Value}, "="))
+		}
+		h := strings.Join(pairs, ",")
+
+		if h != "" && len(h) <= maxTracestateLen {
+			req.Header.Set(tracestateHeader, h)
+		}
+	}
+}
+
+// SpanContextToRequest modifies the given request to include traceparent and tracestate headers.
+func (f *HTTPFormat) SpanContextToRequest(sc trace.SpanContext, req *http.Request) {
+	h := fmt.Sprintf("%x-%x-%x-%x",
+		[]byte{supportedVersion},
+		sc.TraceID[:],
+		sc.SpanID[:],
+		[]byte{byte(sc.TraceOptions)})
+	req.Header.Set(traceparentHeader, h)
+	tracestateToRequest(sc, req)
+}