Allow UTF-8 string in baggage key

baggage/baggage.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/url"
 	"strings"
+	"unicode/utf8"
 
 	"go.opentelemetry.io/otel/internal/baggage"
 )
@@ -241,7 +242,12 @@ func NewMember(key, value string, props ...Property) (Member, error) {
 
 // NewMemberRaw returns a new Member from the passed arguments.
 //
-// The passed key must be compliant with W3C Baggage specification.
+// The passed key and 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, alpha-numeric value are strongly recommended to be used as baggage key.
 func NewMemberRaw(key, value string, props ...Property) (Member, error) {
 	m := Member{
 		key:        key,
@@ -313,9 +319,12 @@ func (m Member) validate() error {
 		return fmt.Errorf("%w: %q", errInvalidMember, m)
 	}
 
-	if !validateKey(m.key) {
+	if !validateBaggageName(m.key) {
 		return fmt.Errorf("%w: %q", errInvalidKey, m.key)
 	}
+	if !validateBaggageValue(m.value) {
+		return fmt.Errorf("%w: %q", errInvalidValue, m.value)
+	}
 	return m.properties.validate()
 }
 
@@ -630,6 +639,23 @@ func skipSpace(s string, offset int) int {
 	return i
 }
 
+// validateBaggageName checks if the string is a valid OpenTelemetry Baggage name.
+// Baggage name is a valid UTF-8 string.
+func validateBaggageName(s string) bool {
+	if len(s) == 0 {
+		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.
+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 len(s) == 0 {
 		return false
@@ -658,6 +684,7 @@ func validateKeyChar(c int32) bool {
 		c == 0x7e
 }
 
+// validateValue checks if the string is a valid W3C Baggage value.
 func validateValue(s string) bool {
 	for _, c := range s {
 		if !validateValueChar(c) {

baggage/baggage_test.go

@@ -140,6 +140,11 @@ func TestNewKeyValueProperty(t *testing.T) {
 	assert.ErrorIs(t, err, errInvalidValue)
 	assert.Equal(t, Property{}, p)
 
+	// wrong value with wrong decoding
+	p, err = NewKeyValueProperty("key", "%zzzzz")
+	assert.ErrorIs(t, err, errInvalidValue)
+	assert.Equal(t, Property{}, p)
+
 	p, err = NewKeyValueProperty("key", "value")
 	assert.NoError(t, err)
 	assert.Equal(t, Property{key: "key", value: "value", hasValue: true}, p)
@@ -409,6 +414,15 @@ func TestBaggageParse(t *testing.T) {
 				"foo": {Value: "ąść"},
 			},
 		},
+		{
+			name: "encoded UTF-8 string in key",
+			in:   "a=b,%C4%85%C5%9B%C4%87=%C4%85%C5%9B%C4%87",
+			want: baggage.List{
+				"a": {Value: "b"},
+				// The percent-encoded key won't be decoded.
+				"%C4%85%C5%9B%C4%87": {Value: "ąść"},
+			},
+		},
 		{
 			name: "invalid member: empty",
 			in:   "foo=,,bar=",
@@ -861,6 +875,10 @@ func TestMemberValidation(t *testing.T) {
 	m.hasData = true
 	assert.ErrorIs(t, m.validate(), errInvalidKey)
 
+	// Invalid UTF-8 in value
+	m.key, m.value = "k", string([]byte{255})
+	assert.ErrorIs(t, m.validate(), errInvalidValue)
+
 	m.key, m.value = "k", "\\"
 	assert.NoError(t, m.validate())
 }
@@ -882,6 +900,11 @@ func TestNewMember(t *testing.T) {
 	}
 	assert.Equal(t, expected, m)
 
+	// wrong value with invalid token
+	val = ";"
+	_, err = NewMember(key, val, p)
+	assert.ErrorIs(t, err, errInvalidValue)
+
 	// wrong value with wrong decoding
 	val = "%zzzzz"
 	_, err = NewMember(key, val, p)
@@ -926,6 +949,31 @@ func TestNewMemberRaw(t *testing.T) {
 	assert.Equal(t, expected, m)
 }
 
+func TestBaggageUTF8(t *testing.T) {
+	testCases := map[string]string{
+		"ąść": "B% 💼",
+
+		// Case sensitive
+		"a": "a",
+		"A": "A",
+	}
+
+	var members []Member
+	for k, v := range testCases {
+		m, err := NewMemberRaw(k, v)
+		require.NoError(t, err)
+
+		members = append(members, m)
+	}
+
+	b, err := New(members...)
+	require.NoError(t, err)
+
+	for k, v := range testCases {
+		assert.Equal(t, v, b.Member(k).Value())
+	}
+}
+
 func TestPropertiesValidate(t *testing.T) {
 	p := properties{{}}
 	assert.ErrorIs(t, p.validate(), errInvalidKey)