omg almost done with httpx port to super smol http

2026-09-13 18:19:34 +00:00 · 2025-05-24 16:09:35 -03:00
parent 876f10f9d8
commit 095c4e1b57
3 changed files with 1034 additions and 692 deletions
@@ -0,0 +1,700 @@
+package httpx
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+var zeroTime time.Time
+
+var (
+	// cookieExpireDelete may be set on Cookie.Expire for expiring the given cookie.
+	cookieExpireDelete = time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+
+	// cookieExpireUnlimited indicates that the cookie doesn't expire.
+	cookieExpireUnlimited = zeroTime
+)
+
+// CookieSameSite is an enum for the mode in which the SameSite flag should be set for the given cookie.
+// See https://tools.ietf.org/html/draft-ietf-httpbis-cookie-same-site-00 for details.
+type CookieSameSite int
+
+const (
+	// CookieSameSiteDisabled removes the SameSite flag.
+	CookieSameSiteDisabled CookieSameSite = iota
+	// CookieSameSiteDefaultMode sets the SameSite flag.
+	CookieSameSiteDefaultMode
+	// CookieSameSiteLaxMode sets the SameSite flag with the "Lax" parameter.
+	CookieSameSiteLaxMode
+	// CookieSameSiteStrictMode sets the SameSite flag with the "Strict" parameter.
+	CookieSameSiteStrictMode
+	// CookieSameSiteNoneMode sets the SameSite flag with the "None" parameter.
+	// See https://tools.ietf.org/html/draft-west-cookie-incrementalism-00
+	CookieSameSiteNoneMode
+)
+
+// acquireCookie returns an empty Cookie object from the pool.
+//
+// The returned object may be returned back to the pool with ReleaseCookie.
+// This allows reducing GC load.
+func acquireCookie() *Cookie {
+	return cookiePool.Get().(*Cookie)
+}
+
+// releaseCookie returns the Cookie object acquired with AcquireCookie back
+// to the pool.
+//
+// Do not access released Cookie object, otherwise data races may occur.
+func releaseCookie(c *Cookie) {
+	c.Reset()
+	cookiePool.Put(c)
+}
+
+var cookiePool = &sync.Pool{
+	New: func() any {
+		return &Cookie{}
+	},
+}
+
+// Cookie represents HTTP response cookie.
+//
+// Do not copy Cookie objects. Create new object and use CopyTo instead.
+//
+// Cookie instance MUST NOT be used from concurrently running goroutines.
+type Cookie struct {
+	noCopy noCopy
+
+	key    []byte
+	value  []byte
+	expire time.Time
+	maxAge int
+	domain []byte
+	path   []byte
+
+	httpOnly bool
+	secure   bool
+	sameSite CookieSameSite
+
+	bufKV argsKV
+	buf   []byte
+}
+
+// CopyTo copies src cookie to c.
+func (c *Cookie) CopyTo(src *Cookie) {
+	c.Reset()
+	c.key = append(c.key, src.key...)
+	c.value = append(c.value, src.value...)
+	c.expire = src.expire
+	c.maxAge = src.maxAge
+	c.domain = append(c.domain, src.domain...)
+	c.path = append(c.path, src.path...)
+	c.httpOnly = src.httpOnly
+	c.secure = src.secure
+	c.sameSite = src.sameSite
+}
+
+// HTTPOnly returns true if the cookie is http only.
+func (c *Cookie) HTTPOnly() bool {
+	return c.httpOnly
+}
+
+// SetHTTPOnly sets cookie's httpOnly flag to the given value.
+func (c *Cookie) SetHTTPOnly(httpOnly bool) {
+	c.httpOnly = httpOnly
+}
+
+// Secure returns true if the cookie is secure.
+func (c *Cookie) Secure() bool {
+	return c.secure
+}
+
+// SetSecure sets cookie's secure flag to the given value.
+func (c *Cookie) SetSecure(secure bool) {
+	c.secure = secure
+}
+
+// SameSite returns the SameSite mode.
+func (c *Cookie) SameSite() CookieSameSite {
+	return c.sameSite
+}
+
+// SetSameSite sets the cookie's SameSite flag to the given value.
+// Set value CookieSameSiteNoneMode will set Secure to true also to avoid browser rejection.
+func (c *Cookie) SetSameSite(mode CookieSameSite) {
+	c.sameSite = mode
+	if mode == CookieSameSiteNoneMode {
+		c.SetSecure(true)
+	}
+}
+
+// Path returns cookie path.
+func (c *Cookie) Path() []byte {
+	return c.path
+}
+
+// SetPath sets cookie path.
+func (c *Cookie) SetPath(path string) {
+	c.buf = append(c.buf[:0], path...)
+	c.path = normalizePath(c.path, b2s(c.buf))
+}
+
+// SetPathBytes sets cookie path.
+func (c *Cookie) SetPathBytes(path []byte) {
+	c.buf = append(c.buf[:0], path...)
+	c.path = normalizePath(c.path, b2s(c.buf))
+}
+
+// Domain returns cookie domain.
+//
+// The returned value is valid until the Cookie reused or released (ReleaseCookie).
+// Do not store references to the returned value. Make copies instead.
+func (c *Cookie) Domain() []byte {
+	return c.domain
+}
+
+// SetDomain sets cookie domain.
+func (c *Cookie) SetDomain(domain string) {
+	c.domain = append(c.domain[:0], domain...)
+}
+
+// SetDomainBytes sets cookie domain.
+func (c *Cookie) SetDomainBytes(domain []byte) {
+	c.domain = append(c.domain[:0], domain...)
+}
+
+// MaxAge returns the seconds until the cookie is meant to expire or 0
+// if no max age.
+func (c *Cookie) MaxAge() int {
+	return c.maxAge
+}
+
+// SetMaxAge sets cookie expiration time based on seconds. This takes precedence
+// over any absolute expiry set on the cookie.
+//
+// Set max age to 0 to unset.
+func (c *Cookie) SetMaxAge(seconds int) {
+	c.maxAge = seconds
+}
+
+// Expire returns cookie expiration time.
+//
+// CookieExpireUnlimited is returned if cookie doesn't expire.
+func (c *Cookie) Expire() time.Time {
+	expire := c.expire
+	if expire.IsZero() {
+		expire = cookieExpireUnlimited
+	}
+	return expire
+}
+
+// SetExpire sets cookie expiration time.
+//
+// Set expiration time to CookieExpireDelete for expiring (deleting)
+// the cookie on the client.
+//
+// By default cookie lifetime is limited by browser session.
+func (c *Cookie) SetExpire(expire time.Time) {
+	c.expire = expire
+}
+
+// Value returns cookie value.
+//
+// The returned value is valid until the Cookie reused or released (ReleaseCookie).
+// Do not store references to the returned value. Make copies instead.
+func (c *Cookie) Value() []byte {
+	return c.value
+}
+
+// SetValue sets cookie value.
+func (c *Cookie) SetValue(value string) {
+	c.value = append(c.value[:0], value...)
+}
+
+// SetValueBytes sets cookie value.
+func (c *Cookie) SetValueBytes(value []byte) {
+	c.value = append(c.value[:0], value...)
+}
+
+// Key returns cookie name.
+//
+// The returned value is valid until the Cookie reused or released (ReleaseCookie).
+// Do not store references to the returned value. Make copies instead.
+func (c *Cookie) Key() []byte {
+	return c.key
+}
+
+// SetKey sets cookie name.
+func (c *Cookie) SetKey(key string) {
+	c.key = append(c.key[:0], key...)
+}
+
+// SetKeyBytes sets cookie name.
+func (c *Cookie) SetKeyBytes(key []byte) {
+	c.key = append(c.key[:0], key...)
+}
+
+// Reset clears the cookie.
+func (c *Cookie) Reset() {
+	c.key = c.key[:0]
+	c.value = c.value[:0]
+	c.expire = zeroTime
+	c.maxAge = 0
+	c.domain = c.domain[:0]
+	c.path = c.path[:0]
+	c.httpOnly = false
+	c.secure = false
+	c.sameSite = CookieSameSiteDisabled
+}
+
+// AppendBytes appends cookie representation to dst and returns
+// the extended dst.
+func (c *Cookie) AppendBytes(dst []byte) []byte {
+	if len(c.key) > 0 {
+		dst = append(dst, c.key...)
+		dst = append(dst, '=')
+	}
+	dst = append(dst, c.value...)
+
+	if c.maxAge > 0 {
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieMaxAge...)
+		dst = append(dst, '=')
+		dst = appendUint(dst, c.maxAge)
+	} else if !c.expire.IsZero() {
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieExpires...)
+		dst = append(dst, '=')
+		dst = AppendHTTPDate(dst, c.expire)
+	}
+	if len(c.domain) > 0 {
+		dst = appendCookiePart(dst, strCookieDomain, b2s(c.domain))
+	}
+	if len(c.path) > 0 {
+		dst = appendCookiePart(dst, strCookiePath, b2s(c.path))
+	}
+	if c.httpOnly {
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieHTTPOnly...)
+	}
+	if c.secure {
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieSecure...)
+	}
+	switch c.sameSite {
+	case CookieSameSiteDefaultMode:
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieSameSite...)
+	case CookieSameSiteLaxMode:
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieSameSite...)
+		dst = append(dst, '=')
+		dst = append(dst, strCookieSameSiteLax...)
+	case CookieSameSiteStrictMode:
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieSameSite...)
+		dst = append(dst, '=')
+		dst = append(dst, strCookieSameSiteStrict...)
+	case CookieSameSiteNoneMode:
+		dst = append(dst, ';', ' ')
+		dst = append(dst, strCookieSameSite...)
+		dst = append(dst, '=')
+		dst = append(dst, strCookieSameSiteNone...)
+	}
+	return dst
+}
+
+// Cookie returns cookie representation.
+//
+// The returned value is valid until the Cookie reused or released (ReleaseCookie).
+// Do not store references to the returned value. Make copies instead.
+func (c *Cookie) Cookie() []byte {
+	c.buf = c.AppendBytes(c.buf[:0])
+	return c.buf
+}
+
+// String returns cookie representation.
+func (c *Cookie) String() string {
+	return string(c.Cookie())
+}
+
+// WriteTo writes cookie representation to w.
+//
+// WriteTo implements io.WriterTo interface.
+func (c *Cookie) WriteTo(w io.Writer) (int64, error) {
+	n, err := w.Write(c.Cookie())
+	return int64(n), err
+}
+
+var errNoCookies = errors.New("no cookies found")
+
+// Parse parses Set-Cookie header.
+func (c *Cookie) Parse(src string) error {
+	c.buf = append(c.buf[:0], src...)
+	return c.ParseBytes(c.buf)
+}
+
+// ParseBytes parses Set-Cookie header.
+func (c *Cookie) ParseBytes(src []byte) error {
+	c.Reset()
+	ntot := 0
+	for {
+		k, v, n := parseCookie(src)
+		if n == 0 {
+			break
+		} else if ntot == 0 {
+			c.key = append(c.key, k...)
+			c.value = append(c.value, v...)
+		}
+		key := b2s(k)
+		value := b2s(v)
+		ntot += n
+		src = src[n:]
+		if len(key) != 0 {
+			// Case insensitive switch on first char
+			switch key[0] | 0x20 {
+			case 'm':
+				if caseInsensitiveCompare(strCookieMaxAge, key) {
+					maxAge, err := strconv.ParseUint(value, 10, 32)
+					if err != nil {
+						return err
+					}
+					c.maxAge = int(maxAge)
+				}
+
+			case 'e': // "expires"
+				if caseInsensitiveCompare(strCookieExpires, key) {
+
+					// Try the same two formats as net/http
+					// See: https://github.com/golang/go/blob/00379be17e63a5b75b3237819392d2dc3b313a27/src/net/http/cookie.go#L133-L135
+					exptime, err := time.ParseInLocation(time.RFC1123, value, time.UTC)
+					if err != nil {
+						exptime, err = time.Parse("Mon, 02-Jan-2006 15:04:05 MST", value)
+						if err != nil {
+							return err
+						}
+					}
+					c.expire = exptime
+				}
+
+			case 'd': // "domain"
+				if caseInsensitiveCompare(strCookieDomain, key) {
+					c.domain = append(c.domain, value...)
+				}
+
+			case 'p': // "path"
+				if caseInsensitiveCompare(strCookiePath, key) {
+					c.path = append(c.path, value...)
+				}
+
+			case 's': // "samesite"
+				if caseInsensitiveCompare(strCookieSameSite, key) {
+					if len(value) > 0 {
+						// Case insensitive switch on first char
+						switch value[0] | 0x20 {
+						case 'l': // "lax"
+							if caseInsensitiveCompare(strCookieSameSiteLax, value) {
+								c.sameSite = CookieSameSiteLaxMode
+							}
+						case 's': // "strict"
+							if caseInsensitiveCompare(strCookieSameSiteStrict, value) {
+								c.sameSite = CookieSameSiteStrictMode
+							}
+						case 'n': // "none"
+							if caseInsensitiveCompare(strCookieSameSiteNone, value) {
+								c.sameSite = CookieSameSiteNoneMode
+							}
+						}
+					}
+				}
+			}
+		} else if len(value) != 0 {
+			// Case insensitive switch on first char
+			switch value[0] | 0x20 {
+			case 'h': // "httponly"
+				if caseInsensitiveCompare(strCookieHTTPOnly, value) {
+					c.httpOnly = true
+				}
+
+			case 's': // "secure"
+				if caseInsensitiveCompare(strCookieSecure, value) {
+					c.secure = true
+				} else if caseInsensitiveCompare(strCookieSameSite, value) {
+					c.sameSite = CookieSameSiteDefaultMode
+				}
+			}
+		} // else empty or no match
+	}
+	if len(c.key) == 0 && len(c.value) == 0 {
+		return errNoCookies
+	}
+	return nil
+}
+
+func appendCookiePart(dst []byte, key, value string) []byte {
+	dst = append(dst, ';', ' ')
+	dst = append(dst, key...)
+	dst = append(dst, '=')
+	return append(dst, value...)
+}
+
+func (hb *headerBuf) appendRequestCookieBytes(dst []byte) []byte {
+	n := len(hb.cookies)
+	for i := 0; i < n; i++ {
+		kv := hb.cookies[i]
+		if !kv.isValid() {
+			continue
+		} else if kv.key.len > 0 {
+			dst = append(dst, hb.musttoken(kv.key)...)
+			dst = append(dst, '=')
+		}
+		dst = append(dst, hb.musttoken(kv.value)...)
+		if i+1 < n {
+			dst = append(dst, ';', ' ')
+		}
+	}
+	return dst
+}
+func (hb *headerBuf) appendResponseCookieBytes(dst []byte) []byte {
+	n := len(hb.cookies)
+	for i := 0; i < n; i++ {
+		kv := hb.cookies[i]
+		if !kv.isValid() {
+			continue
+		}
+		dst = append(dst, hb.musttoken(kv.value)...)
+		if i+1 < n {
+			dst = append(dst, ';', ' ')
+		}
+	}
+	return dst
+}
+
+type cookieScanner struct {
+	b []byte
+}
+
+// parseCookie parses a cookie inside cookie buffer and adds it to cookie buffer..
+//
+//	Cookie: <cookie>\r\n
+func parseCookie(cookie []byte) (key, value []byte, cookieEnd int) {
+	if len(cookie) == 0 {
+		return nil, nil, 0
+	}
+	eqIdx := bytes.IndexByte(cookie, '=')
+	semiIdx := bytes.IndexByte(cookie, ';')
+	if eqIdx > 0 && eqIdx < semiIdx {
+		// cookies has form key=value;
+		key = trimCookie(cookie[:eqIdx], false)
+	} else {
+		// cookie has no key.
+		eqIdx = -1 // ensure is -1.
+	}
+	if semiIdx > 0 {
+		// found ';'
+		value = trimCookie(cookie[eqIdx+1:semiIdx], true)
+	} else {
+		value = trimCookie(cookie[eqIdx+1:], true)
+	}
+	return key, value, max(len(cookie), semiIdx+1)
+}
+
+func trimCookie(src []byte, trimQuotes bool) []byte {
+	for len(src) > 0 && src[0] == ' ' {
+		src = src[1:] // skip leading whitespace.
+	}
+	for len(src) > 0 && src[len(src)-1] == ' ' {
+		src = src[:len(src)-1] // skip trailing whitespace
+	}
+	if trimQuotes {
+		if len(src) > 1 && src[0] == '"' && src[len(src)-1] == '"' {
+			src = src[1 : len(src)-1] // Trim leading+trailing quotes.
+		}
+	}
+	return src
+}
+
+// caseInsensitiveCompare does a case insensitive equality comparison of
+// two []byte. Assumes only letters need to be matched.
+func caseInsensitiveCompare(a, b string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := 0; i < len(a); i++ {
+		if a[i]|0x20 != b[i]|0x20 {
+			return false
+		}
+	}
+	return true
+}
+
+func normalizePath(dst []byte, src string) []byte {
+	dst = dst[:0]
+	dst = addLeadingSlash(dst, src)
+	dst = decodeArgAppendNoPlus(dst, src)
+
+	// remove duplicate slashes
+	b := dst
+	bSize := len(b)
+	for {
+		n := strings.Index(b2s(b), strSlashSlash)
+		if n < 0 {
+			break
+		}
+		b = b[n:]
+		copy(b, b[1:])
+		b = b[:len(b)-1]
+		bSize--
+	}
+	dst = dst[:bSize]
+
+	// remove /./ parts
+	b = dst
+	for {
+		n := strings.Index(b2s(b), strSlashDotSlash)
+		if n < 0 {
+			break
+		}
+		nn := n + len(strSlashDotSlash) - 1
+		copy(b[n:], b[nn:])
+		b = b[:len(b)-nn+n]
+	}
+
+	// remove /foo/../ parts
+	for {
+		n := strings.Index(b2s(b), strSlashDotDotSlash)
+		if n < 0 {
+			break
+		}
+		nn := strings.LastIndexByte(b2s(b[:n]), slashChar)
+		if nn < 0 {
+			nn = 0
+		}
+		n += len(strSlashDotDotSlash) - 1
+		copy(b[nn:], b[n:])
+		b = b[:len(b)-n+nn]
+	}
+
+	// remove trailing /foo/..
+	n := strings.LastIndex(b2s(b), strSlashDotDot)
+	if n >= 0 && n+len(strSlashDotDot) == len(b) {
+		nn := strings.LastIndexByte(b2s(b[:n]), slashChar)
+		if nn < 0 {
+			return append(dst[:0], slashChar)
+		}
+		b = b[:nn+1]
+	}
+
+	if filepath.Separator == '\\' {
+		// remove \.\ parts
+		for {
+			n := strings.Index(b2s(b), strBackSlashDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := n + len(strSlashDotSlash) - 1
+			copy(b[n:], b[nn:])
+			b = b[:len(b)-nn+n]
+		}
+
+		// remove /foo/..\ parts
+		for {
+			n := strings.Index(b2s(b), strSlashDotDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := strings.LastIndexByte(b2s(b[:n]), slashChar)
+			if nn < 0 {
+				nn = 0
+			}
+			nn++
+			n += len(strSlashDotDotBackSlash)
+			copy(b[nn:], b[n:])
+			b = b[:len(b)-n+nn]
+		}
+
+		// remove /foo\..\ parts
+		for {
+			n := strings.Index(b2s(b), strBackSlashDotDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := strings.LastIndexByte(b2s(b[:n]), slashChar)
+			if nn < 0 {
+				nn = 0
+			}
+			n += len(strBackSlashDotDotBackSlash) - 1
+			copy(b[nn:], b[n:])
+			b = b[:len(b)-n+nn]
+		}
+
+		// remove trailing \foo\..
+		n := strings.LastIndex(b2s(b), strBackSlashDotDot)
+		if n >= 0 && n+len(strSlashDotDot) == len(b) {
+			nn := strings.LastIndexByte(b2s(b[:n]), slashChar)
+			if nn < 0 {
+				return append(dst[:0], slashChar)
+			}
+			b = b[:nn+1]
+		}
+	}
+
+	return b
+}
+
+func addLeadingSlash(dst []byte, src string) []byte {
+	// add leading slash for unix paths
+	if len(src) == 0 || src[0] != slashChar {
+		dst = append(dst, slashChar)
+	}
+
+	return dst
+}
+
+// decodeArgAppendNoPlus is almost identical to decodeArgAppend, but it doesn't
+// substitute '+' with ' '.
+//
+// The function is copy-pasted from decodeArgAppend due to the performance
+// reasons only.
+func decodeArgAppendNoPlus(dst []byte, src string) []byte {
+	idx := strings.IndexByte(src, '%')
+	if idx < 0 {
+		// fast path: src doesn't contain encoded chars
+		return append(dst, src...)
+	}
+	dst = append(dst, src[:idx]...)
+
+	// slow path
+	for i := idx; i < len(src); i++ {
+		c := src[i]
+		if c == '%' {
+			if i+2 >= len(src) {
+				return append(dst, src[i:]...)
+			}
+			x2 := hex2intTable[src[i+2]]
+			x1 := hex2intTable[src[i+1]]
+			if x1 == 16 || x2 == 16 {
+				dst = append(dst, '%')
+			} else {
+				dst = append(dst, x1<<4|x2)
+				i += 2
+			}
+		} else {
+			dst = append(dst, c)
+		}
+	}
+	return dst
+}
+
+// AppendHTTPDate appends HTTP-compliant (RFC1123) representation of date
+// to dst and returns the extended dst.
+func AppendHTTPDate(dst []byte, date time.Time) []byte {
+	dst = date.In(time.UTC).AppendFormat(dst, time.RFC1123)
+	copy(dst[len(dst)-3:], strGMT)
+	return dst
+}
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"slices"
 	"strings"
 	"unsafe"
 )
@@ -17,49 +18,37 @@ var (
 	errNonNumericChars = errors.New("non-numeric chars found")
 )

-type headerScanner struct {
-	b     []byte
-	key   []byte
-	value []byte
-	err   error
-
-	// hLen stores header subslice len
-	hLen int
-
-	disableNormalizing bool
-
-	// by checking whether the next line contains a colon or not to tell
-	// it's a header entry or a multi line value of current header entry.
-	// the side effect of this operation is that we know the index of the
-	// next colon and new line, so this can be used during next iteration,
-	// instead of find them again.
-	nextColon   int
-	nextNewLine int
-
-	initialized bool
+func (hb *headerBuf) readFromBytes(b []byte) {
+	hb.buf = append(hb.buf, b...)
 }

-type headerValueScanner struct {
-	b     string
-	value string
+func (hb *headerBuf) free() int { return cap(hb.buf) - len(hb.buf) }
+
+func (hb *headerBuf) readFrom(r io.Reader) error {
+	buf := hb.buf
+	free := hb.free()
+	if free == 0 {
+		return errSmallBuffer
+	}
+	n, err := r.Read(buf[len(buf):cap(buf)])
+	hb.buf = buf[:len(buf)+n]
+	return err
 }

-func (h *header) parse(buf []byte) (int, error) {
-	m, err := h.parseFirstLine(buf)
+func (h *header) parse() (err error) {
+	hb := &h.hbuf
+	hb.off = 0 // start parsing from 0.
+	h.method, h.requestURI, h.proto, h.flags, err = hb.parseFirstLine(h.flags)
 	if err != nil {
-		return 0, err
+		return err
 	}

-	h.rawHeaders, _, err = readRawHeaders(h.rawHeaders[:0], b2s(buf[m:]))
+	var ss scannerState
+	err = h.parseHeaders(&ss)
 	if err != nil {
-		return 0, err
+		return err
 	}
-	var n int
-	n, err = h.parseHeaders(buf[m:])
-	if err != nil {
-		return 0, err
-	}
-	return m + n, nil
+	return nil
 }

 func (hb *headerBuf) offBuf() []byte {
@@ -87,13 +76,14 @@ func (hb *headerBuf) scanUntilByte(c byte) []byte {
 	return buf
 }

-func (hb *headerBuf) parseFirstLine() (method, uri, proto headerSlice, flags flags, err error) {
+func (hb *headerBuf) parseFirstLine(initFlags flags) (method, uri, proto headerSlice, flags flags, err error) {
 	var b []byte
 	for len(b) == 0 {
 		b = hb.scanLine()
 	}
+	flags = initFlags
 	if len(b) < 5 {
-		return method, uri, proto, 0, errors.New("too short first HTTP line")
+		return method, uri, proto, flags, errors.New("too short first HTTP line")
 	}

 	methodEnd := max(0, bytes.IndexByte(b, ' '))
@@ -115,6 +105,143 @@ func (hb *headerBuf) parseFirstLine() (method, uri, proto headerSlice, flags fla
 	return method, uri, proto, flags, nil
 }

+type scannerState struct {
+	err error
+
+	// hLen stores header subslice len
+	hLen int
+
+	disableNormalizing bool
+
+	// by checking whether the next line contains a colon or not to tell
+	// it's a header entry or a multi line value of current header entry.
+	// the side effect of this operation is that we know the index of the
+	// next colon and new line, so this can be used during next iteration,
+	// instead of find them again.
+	nextColon   int
+	nextNewLine int
+
+	initialized bool
+}
+
+func (h *header) parseHeaders(ss *scannerState) (err error) {
+	hb := &h.hbuf
+	h.contentLength = -2
+
+	for kv := hb.nextKV(ss); kv.isValid(); kv = hb.nextKV(ss) {
+		if h.flags.hasAny(disableSpecialHeader) {
+			h.hbuf.headers = append(h.hbuf.headers, kv)
+			continue
+		}
+	}
+	if ss.err != nil && err == nil {
+		err = ss.err
+	}
+	if err != nil {
+		h.flags |= connectionClose
+		return err
+	}
+
+	// if h.contentLength < 0 {
+	// 	h.contentLengthBytes = hb.noKV().value
+	// }
+	if h.flags.hasAny(noHTTP11) && !h.flags.hasAny(connectionClose) {
+		// close connection for non-http/1.1 request unless 'Connection: keep-alive' is set.
+		if !h.hasHeaderValue(strConnection, strKeepAlive) {
+			h.flags |= connectionClose
+		}
+	}
+	return nil
+}
+
+func (h *header) hasHeaderValue(key, value string) bool {
+	kv := h.peekHeader(key)
+	return kv.isValid() && b2s(h.hbuf.musttoken(kv.value)) == value
+}
+
+func (h *header) peekHeaderBytes(key string) []byte {
+	kv := h.peekHeader(key)
+	if kv.isValid() {
+		return h.hbuf.musttoken(kv.value)
+	}
+	return nil
+}
+
+// peekHeader returns header key-value for the given key.
+//
+// The returned value is valid until the request is released,
+// either though ReleaseRequest or your request handler returning.
+// Do not store references to returned value. Make copies instead.
+func (h *header) peekHeader(key string) argsKV {
+	hb := &h.hbuf
+	for i := 0; i < len(h.hbuf.headers); i++ {
+		if b2s(hb.musttoken(h.hbuf.headers[i].key)) == key {
+			return h.hbuf.headers[i]
+		}
+	}
+	return hb.noKV()
+}
+
+func (h *header) peekPtrHeader(key string) *argsKV {
+	hb := &h.hbuf
+	for i := 0; i < len(h.hbuf.headers); i++ {
+		if b2s(hb.musttoken(h.hbuf.headers[i].key)) == key {
+			return &h.hbuf.headers[i]
+		}
+	}
+	return nil
+}
+
+func (hb *headerBuf) mustAppendSlice(value string) headerSlice {
+	L := len(hb.buf)
+	copy(hb.buf[L:L+len(value)], value)
+	hb.buf = hb.buf[:L+len(value)]
+	return hb.slice(hb.buf[L : L+len(value)])
+}
+
+func (h *header) reuseOrAppend(tok headerSlice, value string) headerSlice {
+	if tok.len > tokint(len(value)) {
+		copy(h.hbuf.musttoken(tok), value)
+		tok.len = tokint(len(value))
+		return tok
+	}
+	return h.appendSlice(value)
+}
+
+func (h *header) appendSlice(value string) headerSlice {
+	free := h.hbuf.free()
+	if len(value) > free {
+		if h.flags.hasAny(flagNoBufferGrow) {
+			h.flags |= flagOOMReached
+			return headerSlice{}
+		}
+		h.hbuf.buf = slices.Grow(h.hbuf.buf, len(value))
+	}
+	return h.hbuf.mustAppendSlice(value)
+}
+
+func (h *header) appendHeader(key, value string) {
+	hb := &h.hbuf
+	free := hb.free()
+	buf := h.hbuf.buf
+
+	if len(key)+len(value) > free {
+		if h.flags.hasAny(flagNoBufferGrow) {
+			panic(errSmallBuffer)
+		}
+		slices.Grow(buf, len(key)+len(value))
+	}
+	k := hb.mustAppendSlice(key)
+	v := hb.mustAppendSlice(value)
+	if !h.flags.hasAny(disableNormalizing) {
+		// TODO
+	}
+	hb.headers = append(hb.headers, argsKV{
+		key:   k,
+		value: v,
+	})
+}
+
 func readRawHeaders(dst []byte, buf string) ([]byte, int, error) {
 	n := strings.IndexByte(buf, nChar)
 	if n < 0 {
@@ -142,217 +269,125 @@ func readRawHeaders(dst []byte, buf string) ([]byte, int, error) {
 		}
 	}
 }
+func (hb *headerBuf) noKV() argsKV { return argsKV{} }

-func (h *header) parseHeaders(buf []byte) (int, error) {
-	h.contentLength = -2
-	h.scanner = headerScanner{}
-	s := &h.scanner
-	s.b = buf
-	s.disableNormalizing = h.disableNormalizing
-	var err error
-	for s.next() {
-		key := b2s(s.key)
-		value := b2s(s.value)
-		if len(key) > 0 {
-			// Spaces between the header key and colon are not allowed.
-			// See RFC 7230, Section 3.2.4.
-
-			if strings.IndexByte(key, ' ') != -1 || strings.IndexByte(key, '\t') != -1 {
-				err = fmt.Errorf("invalid header key %q", s.key)
-				continue
+func (hb *headerBuf) nextKV(ss *scannerState) argsKV {
+	if !ss.initialized {
+		ss.nextColon = -1
+		ss.nextNewLine = -1
+		ss.initialized = true
 	}
-
-			if h.disableSpecialHeader {
-				h.h = appendArg(h.h, key, value, argsHasValue)
-				continue
+	buf := hb.buf[hb.off:]
+	bLen := len(buf)
+	if bLen >= 2 && buf[0] == rChar && buf[1] == nChar {
+		hb.off += 2
+		return hb.noKV() // \r\n\r\n Ends header.
 	}
-
-			switch s.key[0] | 0x20 {
-			case 'h':
-				if caseInsensitiveCompare(key, strHost) {
-					h.host = append(h.host[:0], value...)
-					continue
-				}
-			case 'u':
-				if caseInsensitiveCompare(key, strUserAgent) {
-					h.userAgent = append(h.userAgent[:0], value...)
-					continue
-				}
-			case 'c':
-				if caseInsensitiveCompare(key, strContentType) {
-					h.contentType = append(h.contentType[:0], value...)
-					continue
-				}
-				if caseInsensitiveCompare(key, strContentLength) {
-					if h.contentLength != -1 {
-						var nerr error
-						if h.contentLength, nerr = parseContentLength(b2s(s.value)); nerr != nil {
-							if err == nil {
-								err = nerr
-							}
-							h.contentLength = -2
-						} else {
-							h.contentLengthBytes = append(h.contentLengthBytes[:0], value...)
-						}
-					}
-					continue
-				}
-				if caseInsensitiveCompare(key, strConnection) {
-					if b2s(s.value) == strClose {
-						h.connectionClose = true
-					} else {
-						h.connectionClose = false
-						h.h = appendArg(h.h, key, value, argsHasValue)
-					}
-					continue
-				}
-			case 't':
-				if caseInsensitiveCompare(key, strTransferEncoding) {
-					if value != strIdentity {
-						h.contentLength = -1
-						h.h = setArg(h.h, strTransferEncoding, strChunked, argsHasValue)
-					}
-					continue
-				}
-				if caseInsensitiveCompare(key, strTrailer) {
-					if nerr := h.SetTrailer(value); nerr != nil {
-						if err == nil {
-							err = nerr
-						}
-					}
-					continue
-				}
-			}
-		}
-		h.h = appendArg(h.h, key, value, argsHasValue)
-	}
-	if s.err != nil && err == nil {
-		err = s.err
-	}
-	if err != nil {
-		h.connectionClose = true
-		return 0, err
-	}
-
-	if h.contentLength < 0 {
-		h.contentLengthBytes = h.contentLengthBytes[:0]
-	}
-	if h.noHTTP11 && !h.connectionClose {
-		// close connection for non-http/1.1 request unless 'Connection: keep-alive' is set.
-		v := peekArgStr(h.h, strConnection)
-		h.connectionClose = !hasHeaderValue(b2s(v), strKeepAlive)
-	}
-	return s.hLen, nil
-}
-
-func (s *headerScanner) next() bool {
-	if !s.initialized {
-		s.nextColon = -1
-		s.nextNewLine = -1
-		s.initialized = true
-	}
-	bLen := len(s.b)
-	if bLen >= 2 && s.b[0] == rChar && s.b[1] == nChar {
-		s.b = s.b[2:]
-		s.hLen += 2
-		return false
-	}
-	if bLen >= 1 && s.b[0] == nChar {
-		s.b = s.b[1:]
-		s.hLen++
-		return false
+	if bLen >= 1 && buf[0] == nChar {
+		hb.off++
+		return hb.noKV() // \n\n: Ends header.
 	}

 	var n int
-	if s.nextColon >= 0 {
-		n = s.nextColon
-		s.nextColon = -1
+	if ss.nextColon >= 0 {
+		n = ss.nextColon
+		ss.nextColon = -1
 	} else {
-		n = bytes.IndexByte(s.b, ':')
+		n = bytes.IndexByte(buf, ':')

 		// There can't be a \n inside the header name, check for this.
-		x := bytes.IndexByte(s.b, nChar)
+		x := bytes.IndexByte(buf, nChar)
 		if x < 0 {
 			// A header name should always at some point be followed by a \n
 			// even if it's the one that terminates the header block.
-			s.err = errNeedMore
-			return false
+			ss.err = errNeedMore
+			return hb.noKV()
 		}
 		if x < n {
 			// There was a \n before the :
-			s.err = errInvalidName
-			return false
+			ss.err = errInvalidName
+			return hb.noKV()
 		}
 	}
 	if n < 0 {
-		s.err = errNeedMore
-		return false
+		ss.err = errNeedMore
+		return hb.noKV()
 	}
-	s.key = s.b[:n]
-	normalizeHeaderKey(s.key, s.disableNormalizing)
+
+	if bytes.IndexByte(buf[:n], ' ') >= 0 || bytes.IndexByte(buf[:n], '\t') >= 0 {
+		// Spaces between the header key and colon are not allowed.
+		// See RFC 7230, Section 3.2.4.
+		ss.err = errInvalidName
+		return hb.noKV()
+	}
+
+	var resultKV argsKV
+	resultKV.key = hb.slice(buf[:n])
+	normalizeHeaderKey(buf[:n], ss.disableNormalizing)
 	n++
-	for len(s.b) > n && s.b[n] == ' ' {
+	for len(buf) > n && buf[n] == ' ' {
 		n++
 		// the newline index is a relative index, and lines below trimmed `s.b` by `n`,
 		// so the relative newline index also shifted forward. it's safe to decrease
 		// to a minus value, it means it's invalid, and will find the newline again.
-		s.nextNewLine--
+		ss.nextNewLine--
 	}
-	s.hLen += n
-	s.b = s.b[n:]
-	if s.nextNewLine >= 0 {
-		n = s.nextNewLine
-		s.nextNewLine = -1
+	ss.hLen += n
+	buf = buf[n:]
+	if ss.nextNewLine >= 0 {
+		n = ss.nextNewLine
+		ss.nextNewLine = -1
 	} else {
-		n = bytes.IndexByte(s.b, nChar)
+		n = bytes.IndexByte(buf, nChar)
 	}
 	if n < 0 {
-		s.err = errNeedMore
-		return false
+		ss.err = errNeedMore
+		return hb.noKV()
 	}
 	isMultiLineValue := false
 	for {
-		if n+1 >= len(s.b) {
+		if n+1 >= len(buf) {
 			break
 		}
-		if s.b[n+1] != ' ' && s.b[n+1] != '\t' {
+		if buf[n+1] != ' ' && buf[n+1] != '\t' {
 			break
 		}
-		d := bytes.IndexByte(s.b[n+1:], nChar)
+		d := bytes.IndexByte(buf[n+1:], nChar)
 		if d <= 0 {
 			break
-		} else if d == 1 && s.b[n+1] == rChar {
+		} else if d == 1 && buf[n+1] == rChar {
 			break
 		}
 		e := n + d + 1
-		if c := bytes.IndexByte(s.b[n+1:e], ':'); c >= 0 {
-			s.nextColon = c
-			s.nextNewLine = d - c - 1
+		if c := bytes.IndexByte(buf[n+1:e], ':'); c >= 0 {
+			ss.nextColon = c
+			ss.nextNewLine = d - c - 1
 			break
 		}
 		isMultiLineValue = true
 		n = e
 	}
-	if n >= len(s.b) {
-		s.err = errNeedMore
-		return false
+	if n >= len(buf) {
+		ss.err = errNeedMore
+		return hb.noKV()
 	}
-	oldB := s.b
-	s.value = s.b[:n]
-	s.hLen += n + 1
-	s.b = s.b[n+1:]
+	oldB := buf
+	value := buf[:n]
+	ss.hLen += n + 1
+	buf = buf[n+1:]

-	if n > 0 && s.value[n-1] == rChar {
+	if n > 0 && value[n-1] == rChar {
 		n--
 	}
-	for n > 0 && s.value[n-1] == ' ' {
+	for n > 0 && value[n-1] == ' ' {
 		n--
 	}
-	s.value = s.value[:n]
+	value = value[:n]
 	if isMultiLineValue {
-		s.value, s.b, s.hLen = normalizeHeaderValue(s.value, oldB, s.hLen)
+		value, buf, ss.hLen = normalizeHeaderValue(value, oldB, ss.hLen)
 	}
-	return true
+	resultKV.value = hb.slice(value)
+	return resultKV
 }

 func normalizeHeaderKey(b []byte, disableNormalizing bool) {
@@ -437,33 +472,6 @@ func parseContentLength(b string) (int, error) {
 	return v, nil
 }

-func hasHeaderValue(s, value string) bool {
-	var vs headerValueScanner
-	vs.b = s
-	for vs.next() {
-		if caseInsensitiveCompare(vs.value, value) {
-			return true
-		}
-	}
-	return false
-}
-
-func (s *headerValueScanner) next() bool {
-	b := s.b
-	if len(b) == 0 {
-		return false
-	}
-	n := strings.IndexByte(b, ',')
-	if n < 0 {
-		s.value = stripSpace(b)
-		s.b = b[len(b):]
-		return true
-	}
-	s.value = stripSpace(b[:n])
-	s.b = b[n+1:]
-	return true
-}
-
 func nextLine(b []byte) ([]byte, []byte, error) {
 	nNext := bytes.IndexByte(b, nChar)
 	if nNext < 0 {
@@ -552,6 +560,7 @@ func (h *header) readLoop(r *bufio.Reader, waitForMore bool) error {
 func (h *header) tryRead(r *bufio.Reader, n int) error {
 	h.resetSkipNormalize()
 	b, err := r.Peek(n)
+
 	if len(b) == 0 {
 		if err == io.EOF {
 			return err
@@ -577,35 +586,28 @@ func (h *header) tryRead(r *bufio.Reader, n int) error {
 		return fmt.Errorf("error when reading request headers: %w", err)
 	}
 	b = mustPeekBuffered(r)
-	headersLen, errParse := h.parse(b)
+	errParse := h.parse()
 	if errParse != nil {
 		return headerError("request", err, errParse, b, false)
 	}
-	mustDiscard(r, headersLen)
+	// mustDiscard(r, headersLen)
 	return nil
 }

+func (h *headerBuf) reset() {
+	*h = headerBuf{
+		buf:     h.buf[:0],
+		headers: h.headers[:0],
+		cookies: h.cookies[:0],
+	}
+}
+
 func (h *header) resetSkipNormalize() {
-	h.noHTTP11 = false
-	h.connectionClose = false
-
-	h.contentLength = 0
-	h.contentLengthBytes = h.contentLengthBytes[:0]
-
-	h.method = h.method[:0]
-	h.proto = h.proto[:0]
-	h.requestURI = h.requestURI[:0]
-	h.host = h.host[:0]
-	h.contentType = h.contentType[:0]
-	h.userAgent = h.userAgent[:0]
-	h.trailer = h.trailer[:0]
-	h.mulHeader = h.mulHeader[:0]
-
-	h.h = h.h[:0]
-	h.cookies = h.cookies[:0]
-	h.cookiesCollected = false
-
-	h.rawHeaders = h.rawHeaders[:0]
+	h.hbuf.reset()
+	*h = header{
+		hbuf:   h.hbuf,
+		logger: h.logger,
+	}
 }

 func headerError(typ string, err, errParse error, b []byte, secureErrorLogMessage bool) error {
@@ -638,6 +640,7 @@ func isOnlyCRLF(b []byte) bool {
 	}
 	return true
 }
+
 func headerErrorMsg(typ string, err error, b []byte, secureErrorLogMessage bool) error {
 	return fmt.Errorf("error when reading %s headers: %w. Buffer size=%d", typ, err, len(b))
 }
@@ -671,89 +674,19 @@ func mustDiscard(r *bufio.Reader, n int) {
 	}
 }

-// Peek returns header value for the given key.
-//
-// The returned value is valid until the request is released,
-// either though ReleaseRequest or your request handler returning.
-// Do not store references to returned value. Make copies instead.
-func (h *header) Peek(key string) []byte {
-	k := getHeaderKeyBytes(&h.bufKV, key, h.disableNormalizing)
-	return h.peek(b2s(k))
-}
-
 // Host returns Host header value.
 func (h *header) Host() []byte {
-	if h.disableSpecialHeader {
-		return peekArg(h.h, HeaderHost)
-	}
-	return h.host
-}
-
-func getHeaderKeyBytes(kv *argsKV, key string, disableNormalizing bool) []byte {
-	kv.key = append(kv.key[:0], key...)
-	normalizeHeaderKey(kv.key, disableNormalizing)
-	return kv.key
-}
-
-func peekArg(h []argsKV, k string) []byte {
-	for i, n := 0, len(h); i < n; i++ {
-		kv := &h[i]
-		if b2s(kv.key) == k {
-			return kv.value
-		}
-	}
-	return nil
-}
-
-func (h *header) peek(key string) []byte {
-	switch key {
-	case HeaderHost:
-		return h.Host()
-	case HeaderContentType:
-		return h.ContentType()
-	case HeaderUserAgent:
-		return h.UserAgent()
-	case HeaderConnection:
-		if h.ConnectionClose() {
-			return []byte(strClose)
-		}
-		return peekArg(h.h, key)
-	case HeaderContentLength:
-		return h.contentLengthBytes
-	case HeaderCookie:
-		if h.cookiesCollected {
-			return appendRequestCookieBytes(nil, h.cookies)
-		}
-		return peekArg(h.h, key)
-	case HeaderTrailer:
-		return appendArgsKey(nil, h.trailer, strCommaSpace)
-	default:
-		return peekArg(h.h, key)
-	}
+	return h.peekHeaderBytes(HeaderHost)
 }

 // ConnectionClose returns true if 'Connection: close' header is set.
 func (h *header) ConnectionClose() bool {
-	return h.connectionClose
+	return h.flags.hasAny(connectionClose)
 }

 // UserAgent returns User-Agent header value.
 func (h *header) UserAgent() []byte {
-	if h.disableSpecialHeader {
-		return peekArg(h.h, HeaderUserAgent)
-	}
-	return h.userAgent
-}
-
-func appendArgsKey(dst []byte, args []argsKV, sep string) []byte {
-	for i, n := 0, len(args); i < n; i++ {
-		kv := &args[i]
-		dst = append(dst, kv.key...)
-		if i+1 < n {
-			dst = append(dst, sep...)
-		}
-	}
-	return dst
+	return h.peekHeaderBytes(HeaderUserAgent)
 }

 // b2s converts byte slice to a string without memory allocation.
@@ -5,17 +5,19 @@ import (
 	"log/slog"
 	"net/http"
 	"strconv"
-	"strings"
 	"unsafe"

 	"github.com/soypat/lneto/internal"
 )

 type headerBuf struct {
+	// buf[:len] holds entire HTTP header data, which may be normalized by [flags]. buf[off:len] holds data not yet processed during parsing.
 	buf []byte
-	off int // offset into buf for parsing.
+	// offset into buf for parsing.
+	off int
 	// args contains key-value store.
-	args []argsKV
+	headers []argsKV
+	cookies []argsKV
 }

 type tokint = uint16
@@ -25,38 +27,22 @@ type headerSlice struct {
 	len   tokint
 }

-type argSlice struct {
-	start tokint
-	len   tokint
-}
-
 type argsKV struct {
 	key   headerSlice
 	value headerSlice // value start >0 means value is present.
 }

+func (kv argsKV) isValid() bool {
+	return kv.key.start > 0
+}
+
+func (kv *argsKV) invalidate() {
+	*kv = argsKV{}
+}
+
 func (tb headerBuf) musttoken(slice headerSlice) []byte {
 	return tb.buf[slice.start : slice.start+slice.len]
 }
-func (tb headerBuf) mustargs(slice argSlice) []argsKV {
-	return tb.args[slice.start : slice.start+slice.len]
-}
-
-func (tb headerBuf) visitArgs(args argSlice, f func(k, v []byte)) {
-	a := tb.mustargs(args)
-	for _, arg := range a {
-		k := tb.musttoken(arg.key)
-		v := tb.musttoken(arg.value)
-		f(k, v)
-	}
-}
-
-func (tb headerBuf) visitArgsKey(args argSlice, f func(k []byte)) {
-	a := tb.mustargs(args)
-	for _, arg := range a {
-		f(tb.musttoken(arg.key))
-	}
-}

 func (tb headerBuf) slice(b []byte) headerSlice {
 	base := uintptr(unsafe.Pointer(&tb.buf[0]))
@@ -81,69 +67,37 @@ const (
 	connectionClose
 	noHTTP11
 	cookiesCollected
+	flagNoBufferGrow
+	flagOOMReached
 )

-func (f flags) hasAll(checkThese flags) bool {
-	return f&checkThese == checkThese
+func (f flags) hasAny(checkThese flags) bool {
+	return f&checkThese != 0
 }

 type header struct {
-	buf           headerBuf
+	hbuf          headerBuf
+	logger        *slog.Logger
 	contentLength int
-	h             argSlice
-	cookies       argSlice
-	trailer       argSlice

-	host               headerSlice
-	contentLengthBytes headerSlice
-	contentType        headerSlice
-	userAgent          headerSlice
 	method     headerSlice
-	proto              headerSlice
 	requestURI headerSlice
-	rawHeaders         headerSlice
-	mulHeader          headerSlice
+	proto      headerSlice

 	flags flags
-	logger *slog.Logger
 }

 func (h *header) Set(key, value string) {
-	h.bufKV.key = append(h.bufKV.key[:0], key...)
-	normalizeHeaderKey(h.bufKV.key, h.disableNormalizing)
-	h.SetCanonical(b2s(h.bufKV.key), value)
+	h.SetCanonical(key, value) //TODO: implement non-canonical.
 }

 func (h *header) Add(key, value string) {
-	if h.setSpecialHeader(key, value) {
-		return
-	}
-	k := getHeaderKeyBytes(&h.bufKV, key, h.disableNormalizing)
-	h.h = appendArg(h.h, b2s(k), value, argsHasValue)
-}
-
-// ContentEncoding returns Content-Encoding header value.
-func (h *header) ContentEncoding() []byte {
-	return peekArg(h.h, strContentEncoding)
-}
-
-// SetContentEncoding sets Content-Encoding header value.
-func (h *header) SetContentEncoding(contentEncoding string) {
-	h.Set(strContentEncoding, contentEncoding)
-}
-
-// SetContentType sets Content-Type header value.
-func (h *header) SetContentType(contentType string) {
-	h.contentType = append(h.contentType[:0], contentType...)
+	h.appendHeader(key, value)
 }

 // ContentType returns Content-Type header value.
 func (h *header) ContentType() []byte {
-	contentType := h.contentType
-	if !h.noDefaultContentType && len(h.contentType) == 0 {
-		contentType = append(contentType, defaultContentType...)
-	}
-	return contentType
+	return h.peekHeaderBytes(HeaderContentType)
 }

 // SetCanonical sets the given 'key: value' header assuming that
@@ -152,109 +106,36 @@ func (h *header) ContentType() []byte {
 // If the header is set as a Trailer (forbidden trailers will not be set, see SetTrailer for more details),
 // it will be sent after the chunked request body.
 func (h *header) SetCanonical(key, value string) {
-	if h.setSpecialHeader(key, value) {
-		return
+	kv := h.peekPtrHeader(key)
+	if kv != nil {
+		kv.invalidate()
 	}
-	h.setNonSpecial(key, value)
-}
-
-// setSpecialHeader handles special headers and return true when a header is processed.
-func (h *header) setSpecialHeader(key, value string) bool {
-	if len(key) == 0 || h.disableSpecialHeader {
-		return false
-	}
-	h.trace("setSpecialHeader", slog.String("key", key), slog.String("value", value))
-	switch key[0] | 0x20 {
-	case 'c':
-		switch {
-		case caseInsensitiveCompare(strContentType, key):
-			h.SetContentType(value)
-			return true
-		case caseInsensitiveCompare(strContentLength, key):
-			if contentLength, err := parseContentLength(value); err == nil {
-				h.contentLength = contentLength
-				h.contentLengthBytes = append(h.contentLengthBytes[:0], value...)
-			}
-			return true
-		case caseInsensitiveCompare(strConnection, key):
-			if strClose == value {
-				h.SetConnectionClose()
-			} else {
-				h.ResetConnectionClose()
-				h.setNonSpecial(key, value)
-			}
-			return true
-		case caseInsensitiveCompare(strCookie, key):
-			h.collectCookies()
-			h.cookies = parseRequestCookies(h.cookies, value)
-			return true
-		}
-	case 't': // OK
-		if caseInsensitiveCompare(strTransferEncoding, key) {
-			// Transfer-Encoding is managed automatically.
-			return true
-		} else if caseInsensitiveCompare(strTrailer, key) {
-			_ = h.SetTrailer(value)
-			return true
-		}
-	case 'h':
-		if caseInsensitiveCompare(strHost, key) {
-			h.SetHost(value)
-			return true
-		}
-	case 'u':
-		if caseInsensitiveCompare(strUserAgent, key) {
-			h.SetUserAgent(value)
-			return true
-		}
-	}
-
-	return false
+	h.appendHeader(key, value)
 }

 // SetHost sets Host header value.
 func (h *header) SetHost(host string) {
-	h.host = append(h.host[:0], host...)
+	h.Set(HeaderHost, host)
 }

 // SetUserAgent sets User-Agent header value.
 func (h *header) SetUserAgent(userAgent string) {
-	h.userAgent = append(h.userAgent[:0], userAgent...)
+	h.Set(HeaderUserAgent, userAgent)
 }

 // SetConnectionClose sets 'Connection: close' header.
 func (h *header) SetConnectionClose() {
-	h.connectionClose = true
+	h.flags |= connectionClose
 }

 // ResetConnectionClose clears 'Connection: close' header if it exists.
 func (h *header) ResetConnectionClose() {
-	if h.connectionClose {
-		h.connectionClose = false
-		h.h = delAllArgs(h.h, strConnection)
+	if h.flags.hasAny(connectionClose) {
+		h.flags &^= connectionClose
+		// h.h = delAllArgs(h.h, strConnection) // TODO
 	}
 }

-func (h *header) SetContentRange(startPos, endPos, contentLength int) {
-	b := h.bufKV.value[:0]
-	b = append(b, strBytes...)
-	b = append(b, ' ')
-	b = appendUint(b, startPos)
-	b = append(b, '-')
-	b = appendUint(b, endPos)
-	b = append(b, '/')
-	b = appendUint(b, contentLength)
-	h.bufKV.value = b
-
-	h.setNonSpecial(strContentRange, b2s(h.bufKV.value))
-}
-
-// setNonSpecial directly put into map i.e. not a basic header.
-func (h *header) setNonSpecial(key string, value string) {
-	h.trace("httpx:setNonSpecial", slog.String("key", key), slog.String("value", value))
-	h.h = setArg(h.h, key, value, argsHasValue)
-}
-
 func appendUint(b []byte, v int) []byte {
 	if v < 0 {
 		panic("negative uint")
@@ -271,144 +152,8 @@ func (h *header) ContentLength() int {
 	return h.contentLength
 }

-// SetContentLength sets Content-Length header value.
-//
-// Content-Length may be negative:
-// -1 means Transfer-Encoding: chunked.
-// -2 means Transfer-Encoding: identity.
-func (h *header) SetContentLength(contentLength int) {
-	h.contentLength = contentLength
-	if contentLength >= 0 {
-		h.contentLengthBytes = appendUint(h.contentLengthBytes[:0], contentLength)
-		h.h = delAllArgs(h.h, strTransferEncoding)
-	} else {
-		h.contentLengthBytes = h.contentLengthBytes[:0]
-		h.h = setArg(h.h, strTransferEncoding, strChunked, argsHasValue)
-	}
-}
-
 var ErrBadTrailer = errors.New("contain forbidden trailer")

-// SetTrailer sets Trailer header value for chunked request
-// to indicate which headers will be sent after the body.
-//
-// Use Set to set the trailer header later.
-//
-// Trailers are only supported with chunked transfer.
-// Trailers allow the sender to include additional headers at the end of chunked messages.
-//
-// The following trailers are forbidden:
-// 1. necessary for message framing (e.g., Transfer-Encoding and Content-Length),
-// 2. routing (e.g., Host),
-// 3. request modifiers (e.g., controls and conditionals in Section 5 of [RFC7231]),
-// 4. authentication (e.g., see [RFC7235] and [RFC6265]),
-// 5. response control data (e.g., see Section 7.1 of [RFC7231]),
-// 6. determining how to process the payload (e.g., Content-Encoding, Content-Type, Content-Range, and Trailer)
-//
-// Return ErrBadTrailer if contain any forbidden trailers.
-func (h *header) SetTrailer(trailer string) error {
-	h.trailer = h.trailer[:0]
-	return h.AddTrailer(trailer)
-}
-
-// AddTrailerBytes add Trailer header value for chunked response
-// to indicate which headers will be sent after the body.
-//
-// Use Set to set the trailer header later.
-//
-// Trailers are only supported with chunked transfer.
-// Trailers allow the sender to include additional headers at the end of chunked messages.
-//
-// The following trailers are forbidden:
-// 1. necessary for message framing (e.g., Transfer-Encoding and Content-Length),
-// 2. routing (e.g., Host),
-// 3. request modifiers (e.g., controls and conditionals in Section 5 of [RFC7231]),
-// 4. authentication (e.g., see [RFC7235] and [RFC6265]),
-// 5. response control data (e.g., see Section 7.1 of [RFC7231]),
-// 6. determining how to process the payload (e.g., Content-Encoding, Content-Type, Content-Range, and Trailer)
-//
-// Return ErrBadTrailer if contain any forbidden trailers.
-func (h *header) AddTrailer(trailer string) error {
-	h.trace("httpx:AddTrailer", slog.String("trailer", trailer))
-	var err error
-	for i := -1; i+1 < len(trailer); {
-		trailer = trailer[i+1:]
-		i = strings.IndexByte(trailer, ',')
-		if i < 0 {
-			i = len(trailer)
-		}
-		key := stripSpace(trailer[:i])
-		// Forbidden by RFC 7230, section 4.1.2
-		if isBadTrailer(key) {
-			err = ErrBadTrailer
-			continue
-		}
-		h.bufKV.key = append(h.bufKV.key[:0], key...)
-		normalizeHeaderKey(h.bufKV.key, h.disableNormalizing)
-		h.trailer = appendArg(h.trailer, b2s(h.bufKV.key), "", argsNoValue)
-	}
-
-	return err
-}
-
-func isBadTrailer(key string) bool {
-	if len(key) == 0 {
-		return true
-	}
-
-	switch key[0] | 0x20 {
-	case 'a':
-		return caseInsensitiveCompare(key, strAuthorization)
-	case 'c':
-		if len(key) > len(HeaderContentType) && caseInsensitiveCompare(key[:8], strContentType[:8]) {
-			// skip compare prefix 'Content-'
-			return caseInsensitiveCompare(key[8:], strContentEncoding[8:]) ||
-				caseInsensitiveCompare(key[8:], strContentLength[8:]) ||
-				caseInsensitiveCompare(key[8:], strContentType[8:]) ||
-				caseInsensitiveCompare(key[8:], strContentRange[8:])
-		}
-		return caseInsensitiveCompare(key, strConnection)
-	case 'e':
-		return caseInsensitiveCompare(key, strExpect)
-	case 'h':
-		return caseInsensitiveCompare(key, strHost)
-	case 'k':
-		return caseInsensitiveCompare(key, strKeepAlive)
-	case 'm':
-		return caseInsensitiveCompare(key, strMaxForwards)
-	case 'p':
-		if len(key) > len(HeaderProxyConnection) && caseInsensitiveCompare(key[:6], strProxyConnection[:6]) {
-			// skip compare prefix 'Proxy-'
-			return caseInsensitiveCompare(key[6:], strProxyConnection[6:]) ||
-				caseInsensitiveCompare(key[6:], strProxyAuthenticate[6:]) ||
-				caseInsensitiveCompare(key[6:], strProxyAuthorization[6:])
-		}
-	case 'r':
-		return caseInsensitiveCompare(key, strRange)
-	case 't':
-		return caseInsensitiveCompare(key, strTE) ||
-			caseInsensitiveCompare(key, strTrailer) ||
-			caseInsensitiveCompare(key, strTransferEncoding)
-	case 'w':
-		return caseInsensitiveCompare(key, strWWWAuthenticate)
-	}
-	return false
-}
-
-// RawHeaders returns raw header key/value bytes.
-//
-// Depending on server configuration, header keys may be normalized to
-// capital-case in place.
-//
-// This copy is set aside during parsing, so empty slice is returned for all
-// cases where parsing did not happen. Similarly, request line is not stored
-// during parsing and can not be returned.
-//
-// The slice is not safe to use after the handler returns.
-func (h *header) RawHeaders() []byte {
-	return h.rawHeaders
-}
-
 // DisableNormalizing disables header names' normalization.
 //
 // By default all the header names are normalized by uppercasing
@@ -422,90 +167,72 @@ func (h *header) RawHeaders() []byte {
 //
 // Disable header names' normalization only if know what are you doing.
 func (h *header) DisableNormalizing() {
-	h.disableNormalizing = true
-}
-
-// DisableSpecialHeader disables special header processing.
-// fasthttp will not set any special headers for you, such as Host, Content-Type, User-Agent, etc.
-// You must set everything yourself.
-// If RequestHeader.Read() is called, special headers will be ignored.
-// This can be used to control case and order of special headers.
-// This is generally not recommended.
-func (h *header) DisableSpecialHeader() {
-	h.disableSpecialHeader = true
+	h.flags |= disableNormalizing
 }

 // Method returns HTTP request method.
 func (h *header) Method() []byte {
-	if len(h.method) == 0 {
-		h.method = append(h.method, http.MethodGet...)
-	}
-	return h.method
+	return h.hbuf.musttoken(h.method)
 }

 func (h *header) SetMethod(method string) {
-	h.method = append(h.method[:0], method...)
+	h.method = h.reuseOrAppend(h.method, method)
 }

 // SetRequestURI sets RequestURI for the first HTTP request line.
 func (h *header) SetRequestURI(requestURI string) {
-	h.requestURI = append(h.requestURI[:0], requestURI...)
+	h.requestURI = h.reuseOrAppend(h.requestURI, requestURI)
 }

 // RequestURI returns RequestURI from the first HTTP request line.
 func (h *header) RequestURI() []byte {
-	requestURI := h.requestURI
-	if len(requestURI) == 0 {
-		requestURI = append(requestURI, '/')
+	if h.requestURI.start == 0 {
+		return nil
+	} else if h.requestURI.len == 0 {
+		h.requestURI = h.appendSlice("/")
 	}
-	return requestURI
+	return h.hbuf.musttoken(h.requestURI)
 }

 // Protocol returns HTTP protocol.
 func (h *header) Protocol() []byte {
-	if len(h.proto) == 0 {
-		h.proto = append(h.proto, strHTTP11...)
+	if h.proto.len == 0 {
+		h.proto = h.appendSlice(strHTTP11)
 	}
-	return h.proto
+	return h.hbuf.musttoken(h.proto)
 }

 func (h *header) SetProtocol(protocol string) {
-	h.proto = append(h.proto[:0], protocol...)
+	h.proto = h.reuseOrAppend(h.proto, protocol)
 }

 // AppendReqRespCommon appends request/response common header representation to dst and returns the extended buffer.
 func (h *header) AppendReqRespCommon(dst []byte) []byte {
-	for i, n := 0, len(h.h); i < n; i++ {
-		kv := &h.h[i]
-		// Exclude trailer from header
-		exclude := false
-		for _, t := range h.trailer {
-			if b2s(kv.key) == b2s(t.key) {
-				exclude = true
-				break
-			}
-		}
-		if !exclude {
-			dst = appendHeaderLine(dst, b2s(kv.key), b2s(kv.value))
+	for i, n := 0, len(h.hbuf.headers); i < n; i++ {
+		kv := &h.hbuf.headers[i]
+		if kv.isValid() {
+			key := h.hbuf.musttoken(kv.key)
+			value := h.hbuf.musttoken(kv.value)
+			dst = appendHeaderLine(dst, b2s(key), b2s(value))
 		}
 	}

-	if len(h.trailer) > 0 {
-		aux := appendArgsKey(nil, h.trailer, strCommaSpace)
-		dst = appendHeaderLine(dst, strTrailer, b2s(aux))
-	}
+	// if len(h.trailer) > 0 {
+	// 	aux := appendArgsKey(nil, h.trailer, strCommaSpace)
+	// 	dst = appendHeaderLine(dst, strTrailer, b2s(aux))
+	// }

 	// there is no need in h.collectCookies() here, since if cookies aren't collected yet,
 	// they all are located in h.h.
-	n := len(h.cookies)
-	if n > 0 && !h.disableSpecialHeader {
+	n := len(h.hbuf.cookies)
+	if n > 0 && !h.flags.hasAny(disableSpecialHeader) {
 		dst = append(dst, strCookie...)
 		dst = append(dst, strColonSpace...)
-		dst = appendRequestCookieBytes(dst, h.cookies)
+		h.hbuf.appendRequestCookieBytes(dst)
 		dst = append(dst, strCRLF...)
 	}

-	if h.ConnectionClose() && !h.disableSpecialHeader {
+	if h.ConnectionClose() && !h.flags.hasAny(disableSpecialHeader) {
 		dst = appendHeaderLine(dst, strConnection, strClose)
 	}

@@ -524,31 +251,37 @@ func (h *header) ignoreBody() bool {
 }

 func (h *header) collectCookies() {
-	if h.cookiesCollected {
+	if h.flags.hasAny(cookiesCollected) {
 		return
 	}
+	n := len(h.hbuf.headers)
+	for i := 0; i < n; i++ {
+		kv := h.hbuf.headers[i]
+		if kv.isValid() && caseInsensitiveCompare(b2s(h.hbuf.musttoken(kv.key)), HeaderCookie) {
+			cookie := h.hbuf.musttoken(kv.value)
+			for len(cookie) > 0 {
+				key, value, n := parseCookie(cookie)
+				h.hbuf.cookies = append(h.hbuf.cookies, argsKV{
+					key:   h.hbuf.slice(key),
+					value: h.hbuf.slice(value),
+				})
+				cookie = cookie[n:]
+			}
+		}
+	}
+	h.flags |= cookiesCollected
+}
+
+func (h *header) parseReqCookie(value []byte) {

-	for i, n := 0, len(h.h); i < n; i++ {
-		kv := &h.h[i]
-		if caseInsensitiveCompare(b2s(kv.key), strCookie) {
-			h.cookies = parseRequestCookies(h.cookies, b2s(kv.value))
-			tmp := *kv
-			copy(h.h[i:], h.h[i+1:])
-			n--
-			i--
-			h.h[n] = tmp
-			h.h = h.h[:n]
-		}
-	}
-	h.cookiesCollected = true
 }

 func (h *header) MethodIs(method string) bool {
-	return b2s(h.method) == method
+	return b2s(h.Method()) == method
 }

 // IsGet returns true if request method is GET.
-func (h *header) IsGet() bool { return len(h.method) == 0 || h.MethodIs(http.MethodGet) }
+func (h *header) IsGet() bool { return h.method.len == 0 || h.MethodIs(http.MethodGet) }

 // IsHead returns true if request method is HEAD.
 func (h *header) IsHead() bool { return h.MethodIs(http.MethodHead) }
@@ -575,7 +308,7 @@ func (h *header) IsTrace() bool { return h.MethodIs(http.MethodTrace) }
 func (h *header) IsPatch() bool { return h.MethodIs(http.MethodPatch) }

 // IsHTTP11 returns true if the request is HTTP/1.1.
-func (h *header) IsHTTP11() bool { return !h.noHTTP11 }
+func (h *header) IsHTTP11() bool { return !h.flags.hasAny(noHTTP11) }

 // Embed this type into a struct, which mustn't be copied,
 // so `go vet` gives a warning if this struct is copied.
@@ -596,27 +329,3 @@ func (h *header) debug(msg string, attrs ...slog.Attr) {
 func (h *header) info(msg string, attrs ...slog.Attr) {
 	internal.LogAttrs(h.logger, slog.LevelInfo, msg, attrs...)
 }
-
-func normalizeHeaderKey(b []byte, disableNormalizing bool) {
-	if disableNormalizing {
-		return
-	}
-
-	n := len(b)
-	if n == 0 {
-		return
-	}
-
-	b[0] = toUpperTable[b[0]]
-	for i := 1; i < n; i++ {
-		p := &b[i]
-		if *p == '-' {
-			i++
-			if i < n {
-				b[i] = toUpperTable[b[i]]
-			}
-			continue
-		}
-		*p = toLowerTable[*p]
-	}
-}