refactor: move manually created tchar table to bytesconv_table_gen (v…

…alyala#1689)

bytesconv_table_gen.go

@@ -98,12 +98,34 @@ func main() {
 		return a
 	}()
 
+	tcharTable := func() [128]byte {
+		// Should match net/textproto's validHeaderFieldByte(c byte) bool
+		// Defined by RFC 9110 5.6.2
+		//      tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
+		//      "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA
+		var a [128]byte
+		for _, v := range "!#$%&'*+-.^_`|~" {
+			a[v] = 1
+		}
+		for i := 'a'; i <= 'z'; i++ {
+			a[i] = 1
+		}
+		for i := 'A'; i <= 'Z'; i++ {
+			a[i] = 1
+		}
+		for i := '0'; i <= '9'; i++ {
+			a[i] = 1
+		}
+		return a
+	}()
+
 	w := bytes.NewBufferString(pre)
 	fmt.Fprintf(w, "const hex2intTable = %q\n", hex2intTable)
 	fmt.Fprintf(w, "const toLowerTable = %q\n", toLowerTable)
 	fmt.Fprintf(w, "const toUpperTable = %q\n", toUpperTable)
 	fmt.Fprintf(w, "const quotedArgShouldEscapeTable = %q\n", quotedArgShouldEscapeTable)
 	fmt.Fprintf(w, "const quotedPathShouldEscapeTable = %q\n", quotedPathShouldEscapeTable)
+	fmt.Fprintf(w, "const tcharTable = %q\n", tcharTable)
 
 	if err := os.WriteFile("bytesconv_table.go", w.Bytes(), 0o660); err != nil {
 		log.Fatal(err)

header.go

@@ -548,26 +548,7 @@ func (h *ResponseHeader) AddTrailerBytes(trailer []byte) error {
 // validHeaderFieldByte returns true if c is a valid tchar as defined
 // by section 5.6.2 of [RFC9110].
 func validHeaderFieldByte(c byte) bool {
-	return c < 128 && tcharTable[c]
-}
-
-//	 tchar  = "!" / "#" / "$" / "%" / "&" / "'" / "*"
-//			   / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
-//			   / DIGIT / ALPHA
-//
-// See: https://www.rfc-editor.org/rfc/rfc9110#tokens
-var tcharTable = [128]bool{
-	'!': true, '#': true, '$': true, '%': true, '&': true, '\'': true, '*': true, '+': true,
-	'-': true, '.': true, '^': true, '_': true, '`': true, '|': true, '~': true,
-	'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true, '8': true, '9': 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,
-	'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,
+	return c < 128 && tcharTable[c] == 1
 }
 
 // VisitHeaderParams calls f for each parameter in the given header bytes.