vendor/google.golang.org/grpc/internal/transport/http_util.go - shac-project/shac - Git at Google

 /*
  *
  * Copyright 2014 gRPC 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 transport

 import (
 	"bufio"
 	"encoding/base64"
 	"errors"
 	"fmt"
 	"io"
 	"math"
 	"net"
 	"net/http"
 	"net/url"
 	"strconv"
 	"strings"
 	"sync"
 	"time"
 	"unicode/utf8"

 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/hpack"
 	"google.golang.org/grpc/codes"
 )

 const (
 	// http2MaxFrameLen specifies the max length of a HTTP2 frame.
 	http2MaxFrameLen = 16384 // 16KB frame
 	// https://httpwg.org/specs/rfc7540.html#SettingValues
 	http2InitHeaderTableSize = 4096
 )

 var (
 	clientPreface   = []byte(http2.ClientPreface)
 	http2ErrConvTab = map[http2.ErrCode]codes.Code{
 		http2.ErrCodeNo:                 codes.Internal,
 		http2.ErrCodeProtocol:           codes.Internal,
 		http2.ErrCodeInternal:           codes.Internal,
 		http2.ErrCodeFlowControl:        codes.ResourceExhausted,
 		http2.ErrCodeSettingsTimeout:    codes.Internal,
 		http2.ErrCodeStreamClosed:       codes.Internal,
 		http2.ErrCodeFrameSize:          codes.Internal,
 		http2.ErrCodeRefusedStream:      codes.Unavailable,
 		http2.ErrCodeCancel:             codes.Canceled,
 		http2.ErrCodeCompression:        codes.Internal,
 		http2.ErrCodeConnect:            codes.Internal,
 		http2.ErrCodeEnhanceYourCalm:    codes.ResourceExhausted,
 		http2.ErrCodeInadequateSecurity: codes.PermissionDenied,
 		http2.ErrCodeHTTP11Required:     codes.Internal,
 	}
 	// HTTPStatusConvTab is the HTTP status code to gRPC error code conversion table.
 	HTTPStatusConvTab = map[int]codes.Code{
 		// 400 Bad Request - INTERNAL.
 		http.StatusBadRequest: codes.Internal,
 		// 401 Unauthorized  - UNAUTHENTICATED.
 		http.StatusUnauthorized: codes.Unauthenticated,
 		// 403 Forbidden - PERMISSION_DENIED.
 		http.StatusForbidden: codes.PermissionDenied,
 		// 404 Not Found - UNIMPLEMENTED.
 		http.StatusNotFound: codes.Unimplemented,
 		// 429 Too Many Requests - UNAVAILABLE.
 		http.StatusTooManyRequests: codes.Unavailable,
 		// 502 Bad Gateway - UNAVAILABLE.
 		http.StatusBadGateway: codes.Unavailable,
 		// 503 Service Unavailable - UNAVAILABLE.
 		http.StatusServiceUnavailable: codes.Unavailable,
 		// 504 Gateway timeout - UNAVAILABLE.
 		http.StatusGatewayTimeout: codes.Unavailable,
 	}
 )

 var grpcStatusDetailsBinHeader = "grpc-status-details-bin"

 // isReservedHeader checks whether hdr belongs to HTTP2 headers
 // reserved by gRPC protocol. Any other headers are classified as the
 // user-specified metadata.
 func isReservedHeader(hdr string) bool {
 	if hdr != "" && hdr[0] == ':' {
 		return true
 	}
 	switch hdr {
 	case "content-type",
 		"user-agent",
 		"grpc-message-type",
 		"grpc-encoding",
 		"grpc-message",
 		"grpc-status",
 		"grpc-timeout",
 		// Intentionally exclude grpc-previous-rpc-attempts and
 		// grpc-retry-pushback-ms, which are "reserved", but their API
 		// intentionally works via metadata.
 		"te":
 		return true
 	default:
 		return false
 	}
 }

 // isWhitelistedHeader checks whether hdr should be propagated into metadata
 // visible to users, even though it is classified as "reserved", above.
 func isWhitelistedHeader(hdr string) bool {
 	switch hdr {
 	case ":authority", "user-agent":
 		return true
 	default:
 		return false
 	}
 }

 const binHdrSuffix = "-bin"

 func encodeBinHeader(v []byte) string {
 	return base64.RawStdEncoding.EncodeToString(v)
 }

 func decodeBinHeader(v string) ([]byte, error) {
 	if len(v)%4 == 0 {
 		// Input was padded, or padding was not necessary.
 		return base64.StdEncoding.DecodeString(v)
 	}
 	return base64.RawStdEncoding.DecodeString(v)
 }

 func encodeMetadataHeader(k, v string) string {
 	if strings.HasSuffix(k, binHdrSuffix) {
 		return encodeBinHeader(([]byte)(v))
 	}
 	return v
 }

 func decodeMetadataHeader(k, v string) (string, error) {
 	if strings.HasSuffix(k, binHdrSuffix) {
 		b, err := decodeBinHeader(v)
 		return string(b), err
 	}
 	return v, nil
 }

 type timeoutUnit uint8

 const (
 	hour        timeoutUnit = 'H'
 	minute      timeoutUnit = 'M'
 	second      timeoutUnit = 'S'
 	millisecond timeoutUnit = 'm'
 	microsecond timeoutUnit = 'u'
 	nanosecond  timeoutUnit = 'n'
 )

 func timeoutUnitToDuration(u timeoutUnit) (d time.Duration, ok bool) {
 	switch u {
 	case hour:
 		return time.Hour, true
 	case minute:
 		return time.Minute, true
 	case second:
 		return time.Second, true
 	case millisecond:
 		return time.Millisecond, true
 	case microsecond:
 		return time.Microsecond, true
 	case nanosecond:
 		return time.Nanosecond, true
 	default:
 	}
 	return
 }

 func decodeTimeout(s string) (time.Duration, error) {
 	size := len(s)
 	if size < 2 {
 		return 0, fmt.Errorf("transport: timeout string is too short: %q", s)
 	}
 	if size > 9 {
 		// Spec allows for 8 digits plus the unit.
 		return 0, fmt.Errorf("transport: timeout string is too long: %q", s)
 	}
 	unit := timeoutUnit(s[size-1])
 	d, ok := timeoutUnitToDuration(unit)
 	if !ok {
 		return 0, fmt.Errorf("transport: timeout unit is not recognized: %q", s)
 	}
 	t, err := strconv.ParseInt(s[:size-1], 10, 64)
 	if err != nil {
 		return 0, err
 	}
 	const maxHours = math.MaxInt64 / int64(time.Hour)
 	if d == time.Hour && t > maxHours {
 		// This timeout would overflow math.MaxInt64; clamp it.
 		return time.Duration(math.MaxInt64), nil
 	}
 	return d * time.Duration(t), nil
 }

 const (
 	spaceByte   = ' '
 	tildeByte   = '~'
 	percentByte = '%'
 )

 // encodeGrpcMessage is used to encode status code in header field
 // "grpc-message". It does percent encoding and also replaces invalid utf-8
 // characters with Unicode replacement character.
 //
 // It checks to see if each individual byte in msg is an allowable byte, and
 // then either percent encoding or passing it through. When percent encoding,
 // the byte is converted into hexadecimal notation with a '%' prepended.
 func encodeGrpcMessage(msg string) string {
 	if msg == "" {
 		return ""
 	}
 	lenMsg := len(msg)
 	for i := 0; i < lenMsg; i++ {
 		c := msg[i]
 		if !(c >= spaceByte && c <= tildeByte && c != percentByte) {
 			return encodeGrpcMessageUnchecked(msg)
 		}
 	}
 	return msg
 }

 func encodeGrpcMessageUnchecked(msg string) string {
 	var sb strings.Builder
 	for len(msg) > 0 {
 		r, size := utf8.DecodeRuneInString(msg)
 		for _, b := range []byte(string(r)) {
 			if size > 1 {
 				// If size > 1, r is not ascii. Always do percent encoding.
 				fmt.Fprintf(&sb, "%%%02X", b)
 				continue
 			}

 			// The for loop is necessary even if size == 1. r could be
 			// utf8.RuneError.
 			//
 			// fmt.Sprintf("%%%02X", utf8.RuneError) gives "%FFFD".
 			if b >= spaceByte && b <= tildeByte && b != percentByte {
 				sb.WriteByte(b)
 			} else {
 				fmt.Fprintf(&sb, "%%%02X", b)
 			}
 		}
 		msg = msg[size:]
 	}
 	return sb.String()
 }

 // decodeGrpcMessage decodes the msg encoded by encodeGrpcMessage.
 func decodeGrpcMessage(msg string) string {
 	if msg == "" {
 		return ""
 	}
 	lenMsg := len(msg)
 	for i := 0; i < lenMsg; i++ {
 		if msg[i] == percentByte && i+2 < lenMsg {
 			return decodeGrpcMessageUnchecked(msg)
 		}
 	}
 	return msg
 }

 func decodeGrpcMessageUnchecked(msg string) string {
 	var sb strings.Builder
 	lenMsg := len(msg)
 	for i := 0; i < lenMsg; i++ {
 		c := msg[i]
 		if c == percentByte && i+2 < lenMsg {
 			parsed, err := strconv.ParseUint(msg[i+1:i+3], 16, 8)
 			if err != nil {
 				sb.WriteByte(c)
 			} else {
 				sb.WriteByte(byte(parsed))
 				i += 2
 			}
 		} else {
 			sb.WriteByte(c)
 		}
 	}
 	return sb.String()
 }

 type bufWriter struct {
 	pool      *sync.Pool
 	buf       []byte
 	offset    int
 	batchSize int
 	conn      net.Conn
 	err       error
 }

 func newBufWriter(conn net.Conn, batchSize int, pool *sync.Pool) *bufWriter {
 	w := &bufWriter{
 		batchSize: batchSize,
 		conn:      conn,
 		pool:      pool,
 	}
 	// this indicates that we should use non shared buf
 	if pool == nil {
 		w.buf = make([]byte, batchSize)
 	}
 	return w
 }

 func (w *bufWriter) Write(b []byte) (n int, err error) {
 	if w.err != nil {
 		return 0, w.err
 	}
 	if w.batchSize == 0 { // Buffer has been disabled.
 		n, err = w.conn.Write(b)
 		return n, toIOError(err)
 	}
 	if w.buf == nil {
 		b := w.pool.Get().(*[]byte)
 		w.buf = *b
 	}
 	for len(b) > 0 {
 		nn := copy(w.buf[w.offset:], b)
 		b = b[nn:]
 		w.offset += nn
 		n += nn
 		if w.offset >= w.batchSize {
 			err = w.flushKeepBuffer()
 		}
 	}
 	return n, err
 }

 func (w *bufWriter) Flush() error {
 	err := w.flushKeepBuffer()
 	// Only release the buffer if we are in a "shared" mode
 	if w.buf != nil && w.pool != nil {
 		b := w.buf
 		w.pool.Put(&b)
 		w.buf = nil
 	}
 	return err
 }

 func (w *bufWriter) flushKeepBuffer() error {
 	if w.err != nil {
 		return w.err
 	}
 	if w.offset == 0 {
 		return nil
 	}
 	_, w.err = w.conn.Write(w.buf[:w.offset])
 	w.err = toIOError(w.err)
 	w.offset = 0
 	return w.err
 }

 type ioError struct {
 	error
 }

 func (i ioError) Unwrap() error {
 	return i.error
 }

 func isIOError(err error) bool {
 	return errors.As(err, &ioError{})
 }

 func toIOError(err error) error {
 	if err == nil {
 		return nil
 	}
 	return ioError{error: err}
 }

 type framer struct {
 	writer *bufWriter
 	fr     *http2.Framer
 }

 var writeBufferPoolMap map[int]*sync.Pool = make(map[int]*sync.Pool)
 var writeBufferMutex sync.Mutex

 func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, sharedWriteBuffer bool, maxHeaderListSize uint32) *framer {
 	if writeBufferSize < 0 {
 		writeBufferSize = 0
 	}
 	var r io.Reader = conn
 	if readBufferSize > 0 {
 		r = bufio.NewReaderSize(r, readBufferSize)
 	}
 	var pool *sync.Pool
 	if sharedWriteBuffer {
 		pool = getWriteBufferPool(writeBufferSize)
 	}
 	w := newBufWriter(conn, writeBufferSize, pool)
 	f := &framer{
 		writer: w,
 		fr:     http2.NewFramer(w, r),
 	}
 	f.fr.SetMaxReadFrameSize(http2MaxFrameLen)
 	// Opt-in to Frame reuse API on framer to reduce garbage.
 	// Frames aren't safe to read from after a subsequent call to ReadFrame.
 	f.fr.SetReuseFrames()
 	f.fr.MaxHeaderListSize = maxHeaderListSize
 	f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
 	return f
 }

 func getWriteBufferPool(writeBufferSize int) *sync.Pool {
 	writeBufferMutex.Lock()
 	defer writeBufferMutex.Unlock()
 	size := writeBufferSize * 2
 	pool, ok := writeBufferPoolMap[size]
 	if ok {
 		return pool
 	}
 	pool = &sync.Pool{
 		New: func() any {
 			b := make([]byte, size)
 			return &b
 		},
 	}
 	writeBufferPoolMap[size] = pool
 	return pool
 }

 // parseDialTarget returns the network and address to pass to dialer.
 func parseDialTarget(target string) (string, string) {
 	net := "tcp"
 	m1 := strings.Index(target, ":")
 	m2 := strings.Index(target, ":/")
 	// handle unix:addr which will fail with url.Parse
 	if m1 >= 0 && m2 < 0 {
 		if n := target[0:m1]; n == "unix" {
 			return n, target[m1+1:]
 		}
 	}
 	if m2 >= 0 {
 		t, err := url.Parse(target)
 		if err != nil {
 			return net, target
 		}
 		scheme := t.Scheme
 		addr := t.Path
 		if scheme == "unix" {
 			if addr == "" {
 				addr = t.Host
 			}
 			return scheme, addr
 		}
 	}
 	return net, target
 }
	/*
	*
	* Copyright 2014 gRPC 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 transport

	import (
	"bufio"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"math"
	"net"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"sync"
	"time"
	"unicode/utf8"

	"golang.org/x/net/http2"
	"golang.org/x/net/http2/hpack"
	"google.golang.org/grpc/codes"
	)

	const (
	// http2MaxFrameLen specifies the max length of a HTTP2 frame.
	http2MaxFrameLen = 16384 // 16KB frame
	// https://httpwg.org/specs/rfc7540.html#SettingValues
	http2InitHeaderTableSize = 4096
	)

	var (
	clientPreface = []byte(http2.ClientPreface)
	http2ErrConvTab = map[http2.ErrCode]codes.Code{
	http2.ErrCodeNo: codes.Internal,
	http2.ErrCodeProtocol: codes.Internal,
	http2.ErrCodeInternal: codes.Internal,
	http2.ErrCodeFlowControl: codes.ResourceExhausted,
	http2.ErrCodeSettingsTimeout: codes.Internal,
	http2.ErrCodeStreamClosed: codes.Internal,
	http2.ErrCodeFrameSize: codes.Internal,
	http2.ErrCodeRefusedStream: codes.Unavailable,
	http2.ErrCodeCancel: codes.Canceled,
	http2.ErrCodeCompression: codes.Internal,
	http2.ErrCodeConnect: codes.Internal,
	http2.ErrCodeEnhanceYourCalm: codes.ResourceExhausted,
	http2.ErrCodeInadequateSecurity: codes.PermissionDenied,
	http2.ErrCodeHTTP11Required: codes.Internal,
	}
	// HTTPStatusConvTab is the HTTP status code to gRPC error code conversion table.
	HTTPStatusConvTab = map[int]codes.Code{
	// 400 Bad Request - INTERNAL.
	http.StatusBadRequest: codes.Internal,
	// 401 Unauthorized - UNAUTHENTICATED.
	http.StatusUnauthorized: codes.Unauthenticated,
	// 403 Forbidden - PERMISSION_DENIED.
	http.StatusForbidden: codes.PermissionDenied,
	// 404 Not Found - UNIMPLEMENTED.
	http.StatusNotFound: codes.Unimplemented,
	// 429 Too Many Requests - UNAVAILABLE.
	http.StatusTooManyRequests: codes.Unavailable,
	// 502 Bad Gateway - UNAVAILABLE.
	http.StatusBadGateway: codes.Unavailable,
	// 503 Service Unavailable - UNAVAILABLE.
	http.StatusServiceUnavailable: codes.Unavailable,
	// 504 Gateway timeout - UNAVAILABLE.
	http.StatusGatewayTimeout: codes.Unavailable,
	}
	)

	var grpcStatusDetailsBinHeader = "grpc-status-details-bin"

	// isReservedHeader checks whether hdr belongs to HTTP2 headers
	// reserved by gRPC protocol. Any other headers are classified as the
	// user-specified metadata.
	func isReservedHeader(hdr string) bool {
	if hdr != "" && hdr[0] == ':' {
	return true
	}
	switch hdr {
	case "content-type",
	"user-agent",
	"grpc-message-type",
	"grpc-encoding",
	"grpc-message",
	"grpc-status",
	"grpc-timeout",
	// Intentionally exclude grpc-previous-rpc-attempts and
	// grpc-retry-pushback-ms, which are "reserved", but their API
	// intentionally works via metadata.
	"te":
	return true
	default:
	return false
	}
	}

	// isWhitelistedHeader checks whether hdr should be propagated into metadata
	// visible to users, even though it is classified as "reserved", above.
	func isWhitelistedHeader(hdr string) bool {
	switch hdr {
	case ":authority", "user-agent":
	return true
	default:
	return false
	}
	}

	const binHdrSuffix = "-bin"

	func encodeBinHeader(v []byte) string {
	return base64.RawStdEncoding.EncodeToString(v)
	}

	func decodeBinHeader(v string) ([]byte, error) {
	if len(v)%4 == 0 {
	// Input was padded, or padding was not necessary.
	return base64.StdEncoding.DecodeString(v)
	}
	return base64.RawStdEncoding.DecodeString(v)
	}

	func encodeMetadataHeader(k, v string) string {
	if strings.HasSuffix(k, binHdrSuffix) {
	return encodeBinHeader(([]byte)(v))
	}
	return v
	}

	func decodeMetadataHeader(k, v string) (string, error) {
	if strings.HasSuffix(k, binHdrSuffix) {
	b, err := decodeBinHeader(v)
	return string(b), err
	}
	return v, nil
	}

	type timeoutUnit uint8

	const (
	hour timeoutUnit = 'H'
	minute timeoutUnit = 'M'
	second timeoutUnit = 'S'
	millisecond timeoutUnit = 'm'
	microsecond timeoutUnit = 'u'
	nanosecond timeoutUnit = 'n'
	)

	func timeoutUnitToDuration(u timeoutUnit) (d time.Duration, ok bool) {
	switch u {
	case hour:
	return time.Hour, true
	case minute:
	return time.Minute, true
	case second:
	return time.Second, true
	case millisecond:
	return time.Millisecond, true
	case microsecond:
	return time.Microsecond, true
	case nanosecond:
	return time.Nanosecond, true
	default:
	}
	return
	}

	func decodeTimeout(s string) (time.Duration, error) {
	size := len(s)
	if size < 2 {
	return 0, fmt.Errorf("transport: timeout string is too short: %q", s)
	}
	if size > 9 {
	// Spec allows for 8 digits plus the unit.
	return 0, fmt.Errorf("transport: timeout string is too long: %q", s)
	}
	unit := timeoutUnit(s[size-1])
	d, ok := timeoutUnitToDuration(unit)
	if !ok {
	return 0, fmt.Errorf("transport: timeout unit is not recognized: %q", s)
	}
	t, err := strconv.ParseInt(s[:size-1], 10, 64)
	if err != nil {
	return 0, err
	}
	const maxHours = math.MaxInt64 / int64(time.Hour)
	if d == time.Hour && t > maxHours {
	// This timeout would overflow math.MaxInt64; clamp it.
	return time.Duration(math.MaxInt64), nil
	}
	return d * time.Duration(t), nil
	}

	const (
	spaceByte = ' '
	tildeByte = '~'
	percentByte = '%'
	)

	// encodeGrpcMessage is used to encode status code in header field
	// "grpc-message". It does percent encoding and also replaces invalid utf-8
	// characters with Unicode replacement character.
	//
	// It checks to see if each individual byte in msg is an allowable byte, and
	// then either percent encoding or passing it through. When percent encoding,
	// the byte is converted into hexadecimal notation with a '%' prepended.
	func encodeGrpcMessage(msg string) string {
	if msg == "" {
	return ""
	}
	lenMsg := len(msg)
	for i := 0; i < lenMsg; i++ {
	c := msg[i]
	if !(c >= spaceByte && c <= tildeByte && c != percentByte) {
	return encodeGrpcMessageUnchecked(msg)
	}
	}
	return msg
	}

	func encodeGrpcMessageUnchecked(msg string) string {
	var sb strings.Builder
	for len(msg) > 0 {
	r, size := utf8.DecodeRuneInString(msg)
	for _, b := range []byte(string(r)) {
	if size > 1 {
	// If size > 1, r is not ascii. Always do percent encoding.
	fmt.Fprintf(&sb, "%%%02X", b)
	continue
	}

	// The for loop is necessary even if size == 1. r could be
	// utf8.RuneError.
	//
	// fmt.Sprintf("%%%02X", utf8.RuneError) gives "%FFFD".
	if b >= spaceByte && b <= tildeByte && b != percentByte {
	sb.WriteByte(b)
	} else {
	fmt.Fprintf(&sb, "%%%02X", b)
	}
	}
	msg = msg[size:]
	}
	return sb.String()
	}

	// decodeGrpcMessage decodes the msg encoded by encodeGrpcMessage.
	func decodeGrpcMessage(msg string) string {
	if msg == "" {
	return ""
	}
	lenMsg := len(msg)
	for i := 0; i < lenMsg; i++ {
	if msg[i] == percentByte && i+2 < lenMsg {
	return decodeGrpcMessageUnchecked(msg)
	}
	}
	return msg
	}

	func decodeGrpcMessageUnchecked(msg string) string {
	var sb strings.Builder
	lenMsg := len(msg)
	for i := 0; i < lenMsg; i++ {
	c := msg[i]
	if c == percentByte && i+2 < lenMsg {
	parsed, err := strconv.ParseUint(msg[i+1:i+3], 16, 8)
	if err != nil {
	sb.WriteByte(c)
	} else {
	sb.WriteByte(byte(parsed))
	i += 2
	}
	} else {
	sb.WriteByte(c)
	}
	}
	return sb.String()
	}

	type bufWriter struct {
	pool *sync.Pool
	buf []byte
	offset int
	batchSize int
	conn net.Conn
	err error
	}

	func newBufWriter(conn net.Conn, batchSize int, pool sync.Pool) bufWriter {
	w := &bufWriter{
	batchSize: batchSize,
	conn: conn,
	pool: pool,
	}
	// this indicates that we should use non shared buf
	if pool == nil {
	w.buf = make([]byte, batchSize)
	}
	return w
	}

	func (w *bufWriter) Write(b []byte) (n int, err error) {
	if w.err != nil {
	return 0, w.err
	}
	if w.batchSize == 0 { // Buffer has been disabled.
	n, err = w.conn.Write(b)
	return n, toIOError(err)
	}
	if w.buf == nil {
	b := w.pool.Get().(*[]byte)
	w.buf = *b
	}
	for len(b) > 0 {
	nn := copy(w.buf[w.offset:], b)
	b = b[nn:]
	w.offset += nn
	n += nn
	if w.offset >= w.batchSize {
	err = w.flushKeepBuffer()
	}
	}
	return n, err
	}

	func (w *bufWriter) Flush() error {
	err := w.flushKeepBuffer()
	// Only release the buffer if we are in a "shared" mode
	if w.buf != nil && w.pool != nil {
	b := w.buf
	w.pool.Put(&b)
	w.buf = nil
	}
	return err
	}

	func (w *bufWriter) flushKeepBuffer() error {
	if w.err != nil {
	return w.err
	}
	if w.offset == 0 {
	return nil
	}
	_, w.err = w.conn.Write(w.buf[:w.offset])
	w.err = toIOError(w.err)
	w.offset = 0
	return w.err
	}

	type ioError struct {
	error
	}

	func (i ioError) Unwrap() error {
	return i.error
	}

	func isIOError(err error) bool {
	return errors.As(err, &ioError{})
	}

	func toIOError(err error) error {
	if err == nil {
	return nil
	}
	return ioError{error: err}
	}

	type framer struct {
	writer *bufWriter
	fr *http2.Framer
	}

	var writeBufferPoolMap map[int]sync.Pool = make(map[int]sync.Pool)
	var writeBufferMutex sync.Mutex

	func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, sharedWriteBuffer bool, maxHeaderListSize uint32) *framer {
	if writeBufferSize < 0 {
	writeBufferSize = 0
	}
	var r io.Reader = conn
	if readBufferSize > 0 {
	r = bufio.NewReaderSize(r, readBufferSize)
	}
	var pool *sync.Pool
	if sharedWriteBuffer {
	pool = getWriteBufferPool(writeBufferSize)
	}
	w := newBufWriter(conn, writeBufferSize, pool)
	f := &framer{
	writer: w,
	fr: http2.NewFramer(w, r),
	}
	f.fr.SetMaxReadFrameSize(http2MaxFrameLen)
	// Opt-in to Frame reuse API on framer to reduce garbage.
	// Frames aren't safe to read from after a subsequent call to ReadFrame.
	f.fr.SetReuseFrames()
	f.fr.MaxHeaderListSize = maxHeaderListSize
	f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
	return f
	}

	func getWriteBufferPool(writeBufferSize int) *sync.Pool {
	writeBufferMutex.Lock()
	defer writeBufferMutex.Unlock()
	size := writeBufferSize * 2
	pool, ok := writeBufferPoolMap[size]
	if ok {
	return pool
	}
	pool = &sync.Pool{
	New: func() any {
	b := make([]byte, size)
	return &b
	},
	}
	writeBufferPoolMap[size] = pool
	return pool
	}

	// parseDialTarget returns the network and address to pass to dialer.
	func parseDialTarget(target string) (string, string) {
	net := "tcp"
	m1 := strings.Index(target, ":")
	m2 := strings.Index(target, ":/")
	// handle unix:addr which will fail with url.Parse
	if m1 >= 0 && m2 < 0 {
	if n := target[0:m1]; n == "unix" {
	return n, target[m1+1:]
	}
	}
	if m2 >= 0 {
	t, err := url.Parse(target)
	if err != nil {
	return net, target
	}
	scheme := t.Scheme
	addr := t.Path
	if scheme == "unix" {
	if addr == "" {
	addr = t.Host
	}
	return scheme, addr
	}
	}
	return net, target
	}