1 files changed, 212 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/trace/tracestate.go b/vendor/go.opentelemetry.io/otel/trace/tracestate.go
new file mode 100644
index 000000000..ca68a82e5
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/trace/tracestate.go
@@ -0,0 +1,212 @@
+// Copyright The 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 trace // import "go.opentelemetry.io/otel/trace"
+
+import (
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+const (
+	maxListMembers = 32
+
+	listDelimiter = ","
+
+	// based on the W3C Trace Context specification, see
+	// https://www.w3.org/TR/trace-context-1/#tracestate-header
+	noTenantKeyFormat   = `[a-z][_0-9a-z\-\*\/]{0,255}`
+	withTenantKeyFormat = `[a-z0-9][_0-9a-z\-\*\/]{0,240}@[a-z][_0-9a-z\-\*\/]{0,13}`
+	valueFormat         = `[\x20-\x2b\x2d-\x3c\x3e-\x7e]{0,255}[\x21-\x2b\x2d-\x3c\x3e-\x7e]`
+
+	errInvalidKey    errorConst = "invalid tracestate key"
+	errInvalidValue  errorConst = "invalid tracestate value"
+	errInvalidMember errorConst = "invalid tracestate list-member"
+	errMemberNumber  errorConst = "too many list-members in tracestate"
+	errDuplicate     errorConst = "duplicate list-member in tracestate"
+)
+
+var (
+	keyRe    = regexp.MustCompile(`^((` + noTenantKeyFormat + `)|(` + withTenantKeyFormat + `))$`)
+	valueRe  = regexp.MustCompile(`^(` + valueFormat + `)$`)
+	memberRe = regexp.MustCompile(`^\s*((` + noTenantKeyFormat + `)|(` + withTenantKeyFormat + `))=(` + valueFormat + `)\s*$`)
+)
+
+type member struct {
+	Key   string
+	Value string
+}
+
+func newMember(key, value string) (member, error) {
+	if !keyRe.MatchString(key) {
+		return member{}, fmt.Errorf("%w: %s", errInvalidKey, key)
+	}
+	if !valueRe.MatchString(value) {
+		return member{}, fmt.Errorf("%w: %s", errInvalidValue, value)
+	}
+	return member{Key: key, Value: value}, nil
+}
+
+func parseMember(m string) (member, error) {
+	matches := memberRe.FindStringSubmatch(m)
+	if len(matches) != 5 {
+		return member{}, fmt.Errorf("%w: %s", errInvalidMember, m)
+	}
+
+	return member{
+		Key:   matches[1],
+		Value: matches[4],
+	}, nil
+}
+
+// String encodes member into a string compliant with the W3C Trace Context
+// specification.
+func (m member) String() string {
+	return fmt.Sprintf("%s=%s", m.Key, m.Value)
+}
+
+// TraceState provides additional vendor-specific trace identification
+// information across different distributed tracing systems. It represents an
+// immutable list consisting of key/value pairs, each pair is referred to as a
+// list-member.
+//
+// TraceState conforms to the W3C Trace Context specification
+// (https://www.w3.org/TR/trace-context-1). All operations that create or copy
+// a TraceState do so by validating all input and will only produce TraceState
+// that conform to the specification. Specifically, this means that all
+// list-member's key/value pairs are valid, no duplicate list-members exist,
+// and the maximum number of list-members (32) is not exceeded.
+type TraceState struct { //nolint:revive // revive complains about stutter of `trace.TraceState`
+	// list is the members in order.
+	list []member
+}
+
+var _ json.Marshaler = TraceState{}
+
+// ParseTraceState attempts to decode a TraceState from the passed
+// string. It returns an error if the input is invalid according to the W3C
+// Trace Context specification.
+func ParseTraceState(tracestate string) (TraceState, error) {
+	if tracestate == "" {
+		return TraceState{}, nil
+	}
+
+	wrapErr := func(err error) error {
+		return fmt.Errorf("failed to parse tracestate: %w", err)
+	}
+
+	var members []member
+	found := make(map[string]struct{})
+	for _, memberStr := range strings.Split(tracestate, listDelimiter) {
+		if len(memberStr) == 0 {
+			continue
+		}
+
+		m, err := parseMember(memberStr)
+		if err != nil {
+			return TraceState{}, wrapErr(err)
+		}
+
+		if _, ok := found[m.Key]; ok {
+			return TraceState{}, wrapErr(errDuplicate)
+		}
+		found[m.Key] = struct{}{}
+
+		members = append(members, m)
+		if n := len(members); n > maxListMembers {
+			return TraceState{}, wrapErr(errMemberNumber)
+		}
+	}
+
+	return TraceState{list: members}, nil
+}
+
+// MarshalJSON marshals the TraceState into JSON.
+func (ts TraceState) MarshalJSON() ([]byte, error) {
+	return json.Marshal(ts.String())
+}
+
+// String encodes the TraceState into a string compliant with the W3C
+// Trace Context specification. The returned string will be invalid if the
+// TraceState contains any invalid members.
+func (ts TraceState) String() string {
+	members := make([]string, len(ts.list))
+	for i, m := range ts.list {
+		members[i] = m.String()
+	}
+	return strings.Join(members, listDelimiter)
+}
+
+// Get returns the value paired with key from the corresponding TraceState
+// list-member if it exists, otherwise an empty string is returned.
+func (ts TraceState) Get(key string) string {
+	for _, member := range ts.list {
+		if member.Key == key {
+			return member.Value
+		}
+	}
+
+	return ""
+}
+
+// Insert adds a new list-member defined by the key/value pair to the
+// TraceState. If a list-member already exists for the given key, that
+// list-member's value is updated. The new or updated list-member is always
+// moved to the beginning of the TraceState as specified by the W3C Trace
+// Context specification.
+//
+// If key or value are invalid according to the W3C Trace Context
+// specification an error is returned with the original TraceState.
+//
+// If adding a new list-member means the TraceState would have more members
+// then is allowed, the new list-member will be inserted and the right-most
+// list-member will be dropped in the returned TraceState.
+func (ts TraceState) Insert(key, value string) (TraceState, error) {
+	m, err := newMember(key, value)
+	if err != nil {
+		return ts, err
+	}
+
+	cTS := ts.Delete(key)
+	if cTS.Len()+1 <= maxListMembers {
+		cTS.list = append(cTS.list, member{})
+	}
+	// When the number of members exceeds capacity, drop the "right-most".
+	copy(cTS.list[1:], cTS.list)
+	cTS.list[0] = m
+
+	return cTS, nil
+}
+
+// Delete returns a copy of the TraceState with the list-member identified by
+// key removed.
+func (ts TraceState) Delete(key string) TraceState {
+	members := make([]member, ts.Len())
+	copy(members, ts.list)
+	for i, member := range ts.list {
+		if member.Key == key {
+			members = append(members[:i], members[i+1:]...)
+			// TraceState should contain no duplicate members.
+			break
+		}
+	}
+	return TraceState{list: members}
+}
+
+// Len returns the number of list-members in the TraceState.
+func (ts TraceState) Len() int {
+	return len(ts.list)
+}