fix: update lego.

vendor/go.opencensus.io/trace/propagation/propagation.go

@@ -0,0 +1,108 @@
+// Copyright 2017, 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 propagation implements the binary trace context format.
+package propagation // import "go.opencensus.io/trace/propagation"
+
+// TODO: link to external spec document.
+
+// BinaryFormat format:
+//
+// Binary value: <version_id><version_format>
+// version_id: 1 byte representing the version id.
+//
+// For version_id = 0:
+//
+// version_format: <field><field>
+// field_format: <field_id><field_format>
+//
+// Fields:
+//
+// TraceId: (field_id = 0, len = 16, default = "0000000000000000") - 16-byte array representing the trace_id.
+// SpanId: (field_id = 1, len = 8, default = "00000000") - 8-byte array representing the span_id.
+// TraceOptions: (field_id = 2, len = 1, default = "0") - 1-byte array representing the trace_options.
+//
+// Fields MUST be encoded using the field id order (smaller to higher).
+//
+// Valid value example:
+//
+// {0, 0, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 1, 97,
+// 98, 99, 100, 101, 102, 103, 104, 2, 1}
+//
+// version_id = 0;
+// trace_id = {64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79}
+// span_id = {97, 98, 99, 100, 101, 102, 103, 104};
+// trace_options = {1};
+
+import (
+	"net/http"
+
+	"go.opencensus.io/trace"
+)
+
+// Binary returns the binary format representation of a SpanContext.
+//
+// If sc is the zero value, Binary returns nil.
+func Binary(sc trace.SpanContext) []byte {
+	if sc == (trace.SpanContext{}) {
+		return nil
+	}
+	var b [29]byte
+	copy(b[2:18], sc.TraceID[:])
+	b[18] = 1
+	copy(b[19:27], sc.SpanID[:])
+	b[27] = 2
+	b[28] = uint8(sc.TraceOptions)
+	return b[:]
+}
+
+// FromBinary returns the SpanContext represented by b.
+//
+// If b has an unsupported version ID or contains no TraceID, FromBinary
+// returns with ok==false.
+func FromBinary(b []byte) (sc trace.SpanContext, ok bool) {
+	if len(b) == 0 || b[0] != 0 {
+		return trace.SpanContext{}, false
+	}
+	b = b[1:]
+	if len(b) >= 17 && b[0] == 0 {
+		copy(sc.TraceID[:], b[1:17])
+		b = b[17:]
+	} else {
+		return trace.SpanContext{}, false
+	}
+	if len(b) >= 9 && b[0] == 1 {
+		copy(sc.SpanID[:], b[1:9])
+		b = b[9:]
+	}
+	if len(b) >= 2 && b[0] == 2 {
+		sc.TraceOptions = trace.TraceOptions(b[1])
+	}
+	return sc, true
+}
+
+// HTTPFormat implementations propagate span contexts
+// in HTTP requests.
+//
+// SpanContextFromRequest extracts a span context from incoming
+// requests.
+//
+// SpanContextToRequest modifies the given request to include the given
+// span context.
+type HTTPFormat interface {
+	SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool)
+	SpanContextToRequest(sc trace.SpanContext, req *http.Request)
+}
+
+// TODO(jbd): Find a more representative but short name for HTTPFormat.