val c = this[i]
    // The WHATWG Host parsing rules accepts some character codes which are invalid by
    // definition for OkHttp's host header checks (and the WHATWG Host syntax definition). Here
    // we rule out characters that would cause problems in host headers.
    if (c <= '\u001f' || c >= '\u007f') {
      return true
    }
    // Check for the characters mentioned in the WHATWG Host parsing spec:

  }

  /**
   * Strip unexpected characters when converting to URI (which is more strict).
   * https://github.com/square/okhttp/issues/5667
   */
  @Test
  fun hostToUriStripsCharacters() {
    val httpUrl = "http://example\".com/".toHttpUrl()
    assertThat(httpUrl.toUri().toString()).isEqualTo("http://example.com/")
  }

  /** Confirm that URI retains other characters. https://github.com/square/okhttp/issues/5236 */
  @Test

 *
 * This implementation is optimized for readability over efficiency.
 *
 * This implements non-transitional processing by preserving deviation characters.
 *
 * This implementation's STD3 rules are configured to `UseSTD3ASCIIRules=false`. This is
 * permissive and permits the `_` character.
 *
 * [mapping table]: https://www.unicode.org/reports/tr46/#IDNA_Mapping_Table
 * [mapping step]: https://www.unicode.org/reports/tr46/#ProcessingStepMap

  @Test fun mixedCasePunycode() {
    testDecodeOnly(
      unicode = "ليهمابتكلموشعربي؟",
      punycode = "Xn--EgBpDaJ6Bu4bXfGeHfVwXn",
    )
  }

  /**
   * It's invalid to have a label longer than 63 characters. If that's requested, the encoder may
   * overflow and return null.
   */
  @Test fun overflowEncodingOversizedLabel() {
    val a1000 = "a".repeat(1000)
    val a1000MaxCodePoint = a1000 + "\udbff\udfff"

    // Host names are special:
    //
    //  * Several characters are forbidden and must throw exceptions if used.
    //  * They don't use percent escaping at all.
    //  * They use punycode for internationalization.
    //  * URI is much more strict than HttpUrl or URL on what's accepted.
    //
    // HttpUrl is quite lenient with what characters it accepts. In particular, characters like '{'

}

/**
 * Returns the next index in this at or after [startIndex] that is a character from
 * [characters]. Returns the input length if none of the requested characters can be found.
 */
private fun String.indexOfElement(
  characters: String,
  startIndex: Int = 0,
): Int {
  for (i in startIndex until length) {
    if (this[i] in characters) {
      return i
    }
  }
  return length

      verifyHostname(hostname, it)
    }
  }

  /**
   * This is like [toLowerCase] except that it does nothing if this contains any non-ASCII
   * characters. We want to avoid lower casing special chars like U+212A (Kelvin symbol) because
   * they can return ASCII characters that match real hostnames.
   */
  private fun String.asciiToLowercase(): String {
    return when {

        .build()
    assertThat(headers.parseChallenges("WWW-Authenticate")).containsExactly(
      Challenge("Digest", mapOf()),
    )
  }

  @Disabled("TODO(jwilson): reject parameters that use invalid characters")
  @Test
  fun doubleQuoteInToken() {
    val headers =
      Headers.Builder()
        .add("WWW-Authenticate", "Digest,,,, Basic ,,,realm=my\"realm")
        .build()

 *
 * Percent encoding replaces a character (like `\ud83c\udf69`) with its UTF-8 hex bytes (like
 * `%F0%9F%8D%A9`). This approach works for whitespace characters, control characters, non-ASCII
 * characters, and characters that already have another meaning in a particular context.
 *
 * Percent encoding is used in every URL component except for the hostname. But the set of

    if (size == i + 1L) return null // Dangling escape.
    result.write(this, i)
    // Consume '\'.
    readByte()
    result.write(this, 1L) // The escaped character.
  }
}

/**
 * Consumes and returns a non-empty token, terminating at special characters in
 * [TOKEN_DELIMITERS]. Returns null if the buffer is empty or prefixed with a delimiter.
 */
private fun Buffer.readToken(): String? {