Phase 2: Implement Execution Environment Abstraction (v0.3.0)

This commit implements Phase 2 of the CHORUS Task Execution Engine development plan, providing a comprehensive execution environment abstraction layer with Docker container sandboxing support. ## New Features ### Core Sandbox Interface - Comprehensive ExecutionSandbox interface with isolated task execution - Support for command execution, file I/O, environment management - Resource usage monitoring and sandbox lifecycle management - Standardized error handling with SandboxError types and categories ### Docker Container Sandbox Implementation - Full Docker API integration with secure container creation - Transparent repository mounting with configurable read/write access - Advanced security policies with capability dropping and privilege controls - Comprehensive resource limits (CPU, memory, disk, processes, file handles) - Support for tmpfs mounts, masked paths, and read-only bind mounts - Container lifecycle management with proper cleanup and health monitoring ### Security & Resource Management - Configurable security policies with SELinux, AppArmor, and Seccomp support - Fine-grained capability management with secure defaults - Network isolation options with configurable DNS and proxy settings - Resource monitoring with real-time CPU, memory, and network usage tracking - Comprehensive ulimits configuration for process and file handle limits ### Repository Integration - Seamless repository mounting from local paths to container workspaces - Git configuration support with user credentials and global settings - File inclusion/exclusion patterns for selective repository access - Configurable permissions and ownership for mounted repositories ### Testing Infrastructure - Comprehensive test suite with 60+ test cases covering all functionality - Docker integration tests with Alpine Linux containers (skipped in short mode) - Mock sandbox implementation for unit testing without Docker dependencies - Security policy validation tests with read-only filesystem enforcement - Resource usage monitoring and cleanup verification tests ## Technical Details ### Dependencies Added - github.com/docker/docker v28.4.0+incompatible - Docker API client - github.com/docker/go-connections v0.6.0 - Docker connection utilities - github.com/docker/go-units v0.5.0 - Docker units and formatting - Associated Docker API dependencies for complete container management ### Architecture - Interface-driven design enabling multiple sandbox implementations - Comprehensive configuration structures for all sandbox aspects - Resource usage tracking with detailed metrics collection - Error handling with retryable error classification - Proper cleanup and resource management throughout sandbox lifecycle ### Compatibility - Maintains backward compatibility with existing CHORUS architecture - Designed for future integration with Phase 3 Core Task Execution Engine - Extensible design supporting additional sandbox implementations (VM, process) This Phase 2 implementation provides the foundation for secure, isolated task execution that will be integrated with the AI model providers from Phase 1 in the upcoming Phase 3 development. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
2025-09-25 14:28:08 +10:00
parent d1252ade69
commit 8d9b62daf3
653 changed files with 88039 additions and 3766 deletions
--- a/vendor/go.opentelemetry.io/otel/baggage/baggage.go
+++ b/vendor/go.opentelemetry.io/otel/baggage/baggage.go
@@ -1,16 +1,5 @@
 // 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.
+// SPDX-License-Identifier: Apache-2.0

 package baggage // import "go.opentelemetry.io/otel/baggage"

@@ -18,8 +7,8 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
-	"regexp"
 	"strings"
+	"unicode/utf8"

 	"go.opentelemetry.io/otel/internal/baggage"
 )
@@ -32,16 +21,6 @@ const (
 	listDelimiter     = ","
 	keyValueDelimiter = "="
 	propertyDelimiter = ";"
-
-	keyDef      = `([\x21\x23-\x27\x2A\x2B\x2D\x2E\x30-\x39\x41-\x5a\x5e-\x7a\x7c\x7e]+)`
-	valueDef    = `([\x21\x23-\x2b\x2d-\x3a\x3c-\x5B\x5D-\x7e]*)`
-	keyValueDef = `\s*` + keyDef + `\s*` + keyValueDelimiter + `\s*` + valueDef + `\s*`
-)
-
-var (
-	keyRe      = regexp.MustCompile(`^` + keyDef + `$`)
-	valueRe    = regexp.MustCompile(`^` + valueDef + `$`)
-	propertyRe = regexp.MustCompile(`^(?:\s*` + keyDef + `\s*|` + keyValueDef + `)$`)
 )

 var (
@@ -61,33 +40,62 @@ type Property struct {
 	// hasValue indicates if a zero-value value means the property does not
 	// have a value or if it was the zero-value.
 	hasValue bool
-
-	// hasData indicates whether the created property contains data or not.
-	// Properties that do not contain data are invalid with no other check
-	// required.
-	hasData bool
 }

 // NewKeyProperty returns a new Property for key.
 //
+// The passed key must be valid, non-empty UTF-8 string.
 // If key is invalid, an error will be returned.
+// However, the specific Propagators that are used to transmit baggage entries across
+// component boundaries may impose their own restrictions on Property key.
+// For example, the W3C Baggage specification restricts the Property keys to strings that
+// satisfy the token definition from RFC7230, Section 3.2.6.
+// For maximum compatibility, alphanumeric value are strongly recommended to be used as Property key.
 func NewKeyProperty(key string) (Property, error) {
-	if !keyRe.MatchString(key) {
+	if !validateBaggageName(key) {
 		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidKey, key)
 	}

-	p := Property{key: key, hasData: true}
+	p := Property{key: key}
 	return p, nil
 }

 // NewKeyValueProperty returns a new Property for key with value.
 //
-// If key or value are invalid, an error will be returned.
+// The passed key must be compliant with W3C Baggage specification.
+// The passed value must be percent-encoded as defined in W3C Baggage specification.
+//
+// Notice: Consider using [NewKeyValuePropertyRaw] instead
+// that does not require percent-encoding of the value.
 func NewKeyValueProperty(key, value string) (Property, error) {
-	if !keyRe.MatchString(key) {
+	if !validateKey(key) {
 		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidKey, key)
 	}
-	if !valueRe.MatchString(value) {
+
+	if !validateValue(value) {
+		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidValue, value)
+	}
+	decodedValue, err := url.PathUnescape(value)
+	if err != nil {
+		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidValue, value)
+	}
+	return NewKeyValuePropertyRaw(key, decodedValue)
+}
+
+// NewKeyValuePropertyRaw returns a new Property for key with value.
+//
+// The passed key must be valid, non-empty UTF-8 string.
+// The passed value must be valid UTF-8 string.
+// However, the specific Propagators that are used to transmit baggage entries across
+// component boundaries may impose their own restrictions on Property key.
+// For example, the W3C Baggage specification restricts the Property keys to strings that
+// satisfy the token definition from RFC7230, Section 3.2.6.
+// For maximum compatibility, alphanumeric value are strongly recommended to be used as Property key.
+func NewKeyValuePropertyRaw(key, value string) (Property, error) {
+	if !validateBaggageName(key) {
+		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidKey, key)
+	}
+	if !validateBaggageValue(value) {
 		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidValue, value)
 	}

@@ -95,7 +103,6 @@ func NewKeyValueProperty(key, value string) (Property, error) {
 		key:      key,
 		value:    value,
 		hasValue: true,
-		hasData:  true,
 	}
 	return p, nil
 }
@@ -112,20 +119,11 @@ func parseProperty(property string) (Property, error) {
 		return newInvalidProperty(), nil
 	}

-	match := propertyRe.FindStringSubmatch(property)
-	if len(match) != 4 {
+	p, ok := parsePropertyInternal(property)
+	if !ok {
 		return newInvalidProperty(), fmt.Errorf("%w: %q", errInvalidProperty, property)
 	}

-	p := Property{hasData: true}
-	if match[1] != "" {
-		p.key = match[1]
-	} else {
-		p.key = match[2]
-		p.value = match[3]
-		p.hasValue = true
-	}
-
 	return p, nil
 }

@@ -136,19 +134,15 @@ func (p Property) validate() error {
 		return fmt.Errorf("invalid property: %w", err)
 	}

-	if !p.hasData {
-		return errFunc(fmt.Errorf("%w: %q", errInvalidProperty, p))
-	}
-
-	if !keyRe.MatchString(p.key) {
+	if !validateBaggageName(p.key) {
 		return errFunc(fmt.Errorf("%w: %q", errInvalidKey, p.key))
 	}
-	if p.hasValue && !valueRe.MatchString(p.value) {
-		return errFunc(fmt.Errorf("%w: %q", errInvalidValue, p.value))
-	}
 	if !p.hasValue && p.value != "" {
 		return errFunc(errors.New("inconsistent value"))
 	}
+	if p.hasValue && !validateBaggageValue(p.value) {
+		return errFunc(fmt.Errorf("%w: %q", errInvalidValue, p.value))
+	}
 	return nil
 }

@@ -164,11 +158,19 @@ func (p Property) Value() (string, bool) {
 	return p.value, p.hasValue
 }

-// String encodes Property into a string compliant with the W3C Baggage
+// String encodes Property into a header string compliant with the W3C Baggage
 // specification.
+// It would return empty string if the key is invalid with the W3C Baggage
+// specification. This could happen for a UTF-8 key, as it may contain
+// invalid characters.
 func (p Property) String() string {
+	//  W3C Baggage specification does not allow percent-encoded keys.
+	if !validateKey(p.key) {
+		return ""
+	}
+
 	if p.hasValue {
-		return fmt.Sprintf("%s%s%v", p.key, keyValueDelimiter, p.value)
+		return fmt.Sprintf("%s%s%v", p.key, keyValueDelimiter, valueEscape(p.value))
 	}
 	return p.key
 }
@@ -228,12 +230,17 @@ func (p properties) validate() error {
 	return nil
 }

-// String encodes properties into a string compliant with the W3C Baggage
+// String encodes properties into a header string compliant with the W3C Baggage
 // specification.
 func (p properties) String() string {
-	props := make([]string, len(p))
-	for i, prop := range p {
-		props[i] = prop.String()
+	props := make([]string, 0, len(p))
+	for _, prop := range p {
+		s := prop.String()
+
+		// Ignored empty properties.
+		if s != "" {
+			props = append(props, s)
+		}
 	}
 	return strings.Join(props, propertyDelimiter)
 }
@@ -250,11 +257,38 @@ type Member struct {
 	hasData bool
 }

-// NewMember returns a new Member from the passed arguments. The key will be
-// used directly while the value will be url decoded after validation. An error
-// is returned if the created Member would be invalid according to the W3C
-// Baggage specification.
+// NewMember returns a new Member from the passed arguments.
+//
+// The passed key must be compliant with W3C Baggage specification.
+// The passed value must be percent-encoded as defined in W3C Baggage specification.
+//
+// Notice: Consider using [NewMemberRaw] instead
+// that does not require percent-encoding of the value.
 func NewMember(key, value string, props ...Property) (Member, error) {
+	if !validateKey(key) {
+		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidKey, key)
+	}
+
+	if !validateValue(value) {
+		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidValue, value)
+	}
+	decodedValue, err := url.PathUnescape(value)
+	if err != nil {
+		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidValue, value)
+	}
+	return NewMemberRaw(key, decodedValue, props...)
+}
+
+// NewMemberRaw returns a new Member from the passed arguments.
+//
+// The passed key must be valid, non-empty UTF-8 string.
+// The passed value must be valid UTF-8 string.
+// However, the specific Propagators that are used to transmit baggage entries across
+// component boundaries may impose their own restrictions on baggage key.
+// For example, the W3C Baggage specification restricts the baggage keys to strings that
+// satisfy the token definition from RFC7230, Section 3.2.6.
+// For maximum compatibility, alphanumeric value are strongly recommended to be used as baggage key.
+func NewMemberRaw(key, value string, props ...Property) (Member, error) {
 	m := Member{
 		key:        key,
 		value:      value,
@@ -264,11 +298,6 @@ func NewMember(key, value string, props ...Property) (Member, error) {
 	if err := m.validate(); err != nil {
 		return newInvalidMember(), err
 	}
-	decodedValue, err := url.QueryUnescape(value)
-	if err != nil {
-		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidValue, value)
-	}
-	m.value = decodedValue
 	return m, nil
 }

@@ -284,11 +313,7 @@ func parseMember(member string) (Member, error) {
 		return newInvalidMember(), fmt.Errorf("%w: %d", errMemberBytes, n)
 	}

-	var (
-		key, value string
-		props      properties
-	)
-
+	var props properties
 	keyValue, properties, found := strings.Cut(member, propertyDelimiter)
 	if found {
 		// Parse the member properties.
@@ -309,34 +334,61 @@ func parseMember(member string) (Member, error) {
 	}
 	// "Leading and trailing whitespaces are allowed but MUST be trimmed
 	// when converting the header into a data structure."
-	key = strings.TrimSpace(k)
-	var err error
-	value, err = url.QueryUnescape(strings.TrimSpace(v))
-	if err != nil {
-		return newInvalidMember(), fmt.Errorf("%w: %q", err, value)
-	}
-	if !keyRe.MatchString(key) {
+	key := strings.TrimSpace(k)
+	if !validateKey(key) {
 		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidKey, key)
 	}
-	if !valueRe.MatchString(value) {
-		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidValue, value)
+
+	rawVal := strings.TrimSpace(v)
+	if !validateValue(rawVal) {
+		return newInvalidMember(), fmt.Errorf("%w: %q", errInvalidValue, v)
 	}

+	// Decode a percent-encoded value.
+	unescapeVal, err := url.PathUnescape(rawVal)
+	if err != nil {
+		return newInvalidMember(), fmt.Errorf("%w: %w", errInvalidValue, err)
+	}
+
+	value := replaceInvalidUTF8Sequences(len(rawVal), unescapeVal)
 	return Member{key: key, value: value, properties: props, hasData: true}, nil
 }

+// replaceInvalidUTF8Sequences replaces invalid UTF-8 sequences with '<27>'.
+func replaceInvalidUTF8Sequences(c int, unescapeVal string) string {
+	if utf8.ValidString(unescapeVal) {
+		return unescapeVal
+	}
+	// W3C baggage spec:
+	// https://github.com/w3c/baggage/blob/8c215efbeebd3fa4b1aceb937a747e56444f22f3/baggage/HTTP_HEADER_FORMAT.md?plain=1#L69
+
+	var b strings.Builder
+	b.Grow(c)
+	for i := 0; i < len(unescapeVal); {
+		r, size := utf8.DecodeRuneInString(unescapeVal[i:])
+		if r == utf8.RuneError && size == 1 {
+			// Invalid UTF-8 sequence found, replace it with '<27>'
+			_, _ = b.WriteString("<22>")
+		} else {
+			_, _ = b.WriteRune(r)
+		}
+		i += size
+	}
+
+	return b.String()
+}
+
 // validate ensures m conforms to the W3C Baggage specification.
-// A key is just an ASCII string, but a value must be URL encoded UTF-8,
-// returning an error otherwise.
+// A key must be an ASCII string, returning an error otherwise.
 func (m Member) validate() error {
 	if !m.hasData {
 		return fmt.Errorf("%w: %q", errInvalidMember, m)
 	}

-	if !keyRe.MatchString(m.key) {
+	if !validateBaggageName(m.key) {
 		return fmt.Errorf("%w: %q", errInvalidKey, m.key)
 	}
-	if !valueRe.MatchString(m.value) {
+	if !validateBaggageValue(m.value) {
 		return fmt.Errorf("%w: %q", errInvalidValue, m.value)
 	}
 	return m.properties.validate()
@@ -351,13 +403,20 @@ func (m Member) Value() string { return m.value }
 // Properties returns a copy of the Member properties.
 func (m Member) Properties() []Property { return m.properties.Copy() }

-// String encodes Member into a string compliant with the W3C Baggage
+// String encodes Member into a header string compliant with the W3C Baggage
 // specification.
+// It would return empty string if the key is invalid with the W3C Baggage
+// specification. This could happen for a UTF-8 key, as it may contain
+// invalid characters.
 func (m Member) String() string {
-	// A key is just an ASCII string, but a value is URL encoded UTF-8.
-	s := fmt.Sprintf("%s%s%s", m.key, keyValueDelimiter, url.QueryEscape(m.value))
+	//  W3C Baggage specification does not allow percent-encoded keys.
+	if !validateKey(m.key) {
+		return ""
+	}
+
+	s := m.key + keyValueDelimiter + valueEscape(m.value)
 	if len(m.properties) > 0 {
-		s = fmt.Sprintf("%s%s%s", s, propertyDelimiter, m.properties.String())
+		s += propertyDelimiter + m.properties.String()
 	}
 	return s
 }
@@ -468,7 +527,7 @@ func (b Baggage) Member(key string) Member {
 }

 // Members returns all the baggage list-members.
-// The order of the returned list-members does not have significance.
+// The order of the returned list-members is not significant.
 //
 // The returned members are not validated, as we assume the validation happened
 // when they were added to the Baggage.
@@ -489,8 +548,8 @@ func (b Baggage) Members() []Member {
 	return members
 }

-// SetMember returns a copy the Baggage with the member included. If the
-// baggage contains a Member with the same key the existing Member is
+// SetMember returns a copy of the Baggage with the member included. If the
+// baggage contains a Member with the same key, the existing Member is
 // replaced.
 //
 // If member is invalid according to the W3C Baggage specification, an error
@@ -546,17 +605,414 @@ func (b Baggage) Len() int {
 	return len(b.list)
 }

-// String encodes Baggage into a string compliant with the W3C Baggage
-// specification. The returned string will be invalid if the Baggage contains
-// any invalid list-members.
+// String encodes Baggage into a header string compliant with the W3C Baggage
+// specification.
+// It would ignore members where the member key is invalid with the W3C Baggage
+// specification. This could happen for a UTF-8 key, as it may contain
+// invalid characters.
 func (b Baggage) String() string {
 	members := make([]string, 0, len(b.list))
 	for k, v := range b.list {
-		members = append(members, Member{
+		s := Member{
 			key:        k,
 			value:      v.Value,
 			properties: fromInternalProperties(v.Properties),
-		}.String())
+		}.String()
+
+		// Ignored empty members.
+		if s != "" {
+			members = append(members, s)
+		}
 	}
 	return strings.Join(members, listDelimiter)
 }
+
+// parsePropertyInternal attempts to decode a Property from the passed string.
+// It follows the spec at https://www.w3.org/TR/baggage/#definition.
+func parsePropertyInternal(s string) (p Property, ok bool) {
+	// For the entire function we will use "   key    =    value  " as an example.
+	// Attempting to parse the key.
+	// First skip spaces at the beginning "<   >key    =    value  " (they could be empty).
+	index := skipSpace(s, 0)
+
+	// Parse the key: "   <key>    =    value  ".
+	keyStart := index
+	keyEnd := index
+	for _, c := range s[keyStart:] {
+		if !validateKeyChar(c) {
+			break
+		}
+		keyEnd++
+	}
+
+	// If we couldn't find any valid key character,
+	// it means the key is either empty or invalid.
+	if keyStart == keyEnd {
+		return
+	}
+
+	// Skip spaces after the key: "   key<    >=    value  ".
+	index = skipSpace(s, keyEnd)
+
+	if index == len(s) {
+		// A key can have no value, like: "   key    ".
+		ok = true
+		p.key = s[keyStart:keyEnd]
+		return
+	}
+
+	// If we have not reached the end and we can't find the '=' delimiter,
+	// it means the property is invalid.
+	if s[index] != keyValueDelimiter[0] {
+		return
+	}
+
+	// Attempting to parse the value.
+	// Match: "   key    =<    >value  ".
+	index = skipSpace(s, index+1)
+
+	// Match the value string: "   key    =    <value>  ".
+	// A valid property can be: "   key    =".
+	// Therefore, we don't have to check if the value is empty.
+	valueStart := index
+	valueEnd := index
+	for _, c := range s[valueStart:] {
+		if !validateValueChar(c) {
+			break
+		}
+		valueEnd++
+	}
+
+	// Skip all trailing whitespaces: "   key    =    value<  >".
+	index = skipSpace(s, valueEnd)
+
+	// If after looking for the value and skipping whitespaces
+	// we have not reached the end, it means the property is
+	// invalid, something like: "   key    =    value  value1".
+	if index != len(s) {
+		return
+	}
+
+	// Decode a percent-encoded value.
+	rawVal := s[valueStart:valueEnd]
+	unescapeVal, err := url.PathUnescape(rawVal)
+	if err != nil {
+		return
+	}
+	value := replaceInvalidUTF8Sequences(len(rawVal), unescapeVal)
+
+	ok = true
+	p.key = s[keyStart:keyEnd]
+	p.hasValue = true
+
+	p.value = value
+	return
+}
+
+func skipSpace(s string, offset int) int {
+	i := offset
+	for ; i < len(s); i++ {
+		c := s[i]
+		if c != ' ' && c != '\t' {
+			break
+		}
+	}
+	return i
+}
+
+var safeKeyCharset = [utf8.RuneSelf]bool{
+	// 0x23 to 0x27
+	'#':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+
+	// 0x30 to 0x39
+	'0': true,
+	'1': true,
+	'2': true,
+	'3': true,
+	'4': true,
+	'5': true,
+	'6': true,
+	'7': true,
+	'8': true,
+	'9': true,
+
+	// 0x41 to 0x5a
+	'A': true,
+	'B': true,
+	'C': true,
+	'D': true,
+	'E': true,
+	'F': true,
+	'G': true,
+	'H': true,
+	'I': true,
+	'J': true,
+	'K': true,
+	'L': true,
+	'M': true,
+	'N': true,
+	'O': true,
+	'P': true,
+	'Q': true,
+	'R': true,
+	'S': true,
+	'T': true,
+	'U': true,
+	'V': true,
+	'W': true,
+	'X': true,
+	'Y': true,
+	'Z': true,
+
+	// 0x5e to 0x7a
+	'^': true,
+	'_': true,
+	'`': true,
+	'a': true,
+	'b': true,
+	'c': true,
+	'd': true,
+	'e': true,
+	'f': true,
+	'g': true,
+	'h': true,
+	'i': true,
+	'j': true,
+	'k': true,
+	'l': true,
+	'm': true,
+	'n': true,
+	'o': true,
+	'p': true,
+	'q': true,
+	'r': true,
+	's': true,
+	't': true,
+	'u': true,
+	'v': true,
+	'w': true,
+	'x': true,
+	'y': true,
+	'z': true,
+
+	// remainder
+	'!': true,
+	'*': true,
+	'+': true,
+	'-': true,
+	'.': true,
+	'|': true,
+	'~': true,
+}
+
+// validateBaggageName checks if the string is a valid OpenTelemetry Baggage name.
+// Baggage name is a valid, non-empty UTF-8 string.
+func validateBaggageName(s string) bool {
+	if s == "" {
+		return false
+	}
+
+	return utf8.ValidString(s)
+}
+
+// validateBaggageValue checks if the string is a valid OpenTelemetry Baggage value.
+// Baggage value is a valid UTF-8 strings.
+// Empty string is also a valid UTF-8 string.
+func validateBaggageValue(s string) bool {
+	return utf8.ValidString(s)
+}
+
+// validateKey checks if the string is a valid W3C Baggage key.
+func validateKey(s string) bool {
+	if s == "" {
+		return false
+	}
+
+	for _, c := range s {
+		if !validateKeyChar(c) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func validateKeyChar(c int32) bool {
+	return c >= 0 && c < int32(utf8.RuneSelf) && safeKeyCharset[c]
+}
+
+// validateValue checks if the string is a valid W3C Baggage value.
+func validateValue(s string) bool {
+	for _, c := range s {
+		if !validateValueChar(c) {
+			return false
+		}
+	}
+
+	return true
+}
+
+var safeValueCharset = [utf8.RuneSelf]bool{
+	'!': true, // 0x21
+
+	// 0x23 to 0x2b
+	'#':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+	'(':  true,
+	')':  true,
+	'*':  true,
+	'+':  true,
+
+	// 0x2d to 0x3a
+	'-': true,
+	'.': true,
+	'/': true,
+	'0': true,
+	'1': true,
+	'2': true,
+	'3': true,
+	'4': true,
+	'5': true,
+	'6': true,
+	'7': true,
+	'8': true,
+	'9': true,
+	':': true,
+
+	// 0x3c to 0x5b
+	'<': true, // 0x3C
+	'=': true, // 0x3D
+	'>': true, // 0x3E
+	'?': true, // 0x3F
+	'@': true, // 0x40
+	'A': true, // 0x41
+	'B': true, // 0x42
+	'C': true, // 0x43
+	'D': true, // 0x44
+	'E': true, // 0x45
+	'F': true, // 0x46
+	'G': true, // 0x47
+	'H': true, // 0x48
+	'I': true, // 0x49
+	'J': true, // 0x4A
+	'K': true, // 0x4B
+	'L': true, // 0x4C
+	'M': true, // 0x4D
+	'N': true, // 0x4E
+	'O': true, // 0x4F
+	'P': true, // 0x50
+	'Q': true, // 0x51
+	'R': true, // 0x52
+	'S': true, // 0x53
+	'T': true, // 0x54
+	'U': true, // 0x55
+	'V': true, // 0x56
+	'W': true, // 0x57
+	'X': true, // 0x58
+	'Y': true, // 0x59
+	'Z': true, // 0x5A
+	'[': true, // 0x5B
+
+	// 0x5d to 0x7e
+	']': true, // 0x5D
+	'^': true, // 0x5E
+	'_': true, // 0x5F
+	'`': true, // 0x60
+	'a': true, // 0x61
+	'b': true, // 0x62
+	'c': true, // 0x63
+	'd': true, // 0x64
+	'e': true, // 0x65
+	'f': true, // 0x66
+	'g': true, // 0x67
+	'h': true, // 0x68
+	'i': true, // 0x69
+	'j': true, // 0x6A
+	'k': true, // 0x6B
+	'l': true, // 0x6C
+	'm': true, // 0x6D
+	'n': true, // 0x6E
+	'o': true, // 0x6F
+	'p': true, // 0x70
+	'q': true, // 0x71
+	'r': true, // 0x72
+	's': true, // 0x73
+	't': true, // 0x74
+	'u': true, // 0x75
+	'v': true, // 0x76
+	'w': true, // 0x77
+	'x': true, // 0x78
+	'y': true, // 0x79
+	'z': true, // 0x7A
+	'{': true, // 0x7B
+	'|': true, // 0x7C
+	'}': true, // 0x7D
+	'~': true, // 0x7E
+}
+
+func validateValueChar(c int32) bool {
+	return c >= 0 && c < int32(utf8.RuneSelf) && safeValueCharset[c]
+}
+
+// valueEscape escapes the string so it can be safely placed inside a baggage value,
+// replacing special characters with %XX sequences as needed.
+//
+// The implementation is based on:
+// https://github.com/golang/go/blob/f6509cf5cdbb5787061b784973782933c47f1782/src/net/url/url.go#L285.
+func valueEscape(s string) string {
+	hexCount := 0
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if shouldEscape(c) {
+			hexCount++
+		}
+	}
+
+	if hexCount == 0 {
+		return s
+	}
+
+	var buf [64]byte
+	var t []byte
+
+	required := len(s) + 2*hexCount
+	if required <= len(buf) {
+		t = buf[:required]
+	} else {
+		t = make([]byte, required)
+	}
+
+	j := 0
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if shouldEscape(s[i]) {
+			const upperhex = "0123456789ABCDEF"
+			t[j] = '%'
+			t[j+1] = upperhex[c>>4]
+			t[j+2] = upperhex[c&15]
+			j += 3
+		} else {
+			t[j] = c
+			j++
+		}
+	}
+
+	return string(t)
+}
+
+// shouldEscape returns true if the specified byte should be escaped when
+// appearing in a baggage value string.
+func shouldEscape(c byte) bool {
+	if c == '%' {
+		// The percent character must be encoded so that percent-encoding can work.
+		return true
+	}
+	return !validateValueChar(int32(c))
+}