IDN Data
========

In order to implement Nameprep (RFC 3491), OkHttp uses Unicode tables specified in Stringprep
(RFC 3454). Fragments of this RFC are dumped into the files in this directory and parsed by
`StringprepTablesReader` into a model that can be used at runtime.

This format is chosen to make it easy to validate that these tables are consistent with the RFC.

```
cd okhttp/src/test/resources/okhttp3/internal/idn/

 * 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
 */
class SimpleIdnaMappingTable internal constructor(
  internal val mappings: List<Mapping>,
) {
  /**

 * limitations under the License.
 */
@file:Suppress("ktlint:standard:filename")

package okhttp3.internal

import okhttp3.internal.idn.IDNA_MAPPING_TABLE
import okhttp3.internal.idn.Punycode
import okio.Buffer

/**
 * Quick and dirty pattern to differentiate IP addresses from hostnames. This is an approximation
 * of Android's private InetAddress#isNumeric API.
 *

 * limitations under the License.
 */
package okhttp3.internal.idn

import okio.Buffer
import okio.ByteString.Companion.encodeUtf8

/**
 * An [RFC 3492] punycode decoder for converting ASCII to Unicode domain name labels. This is
 * intended for use in Internationalized Domain Names (IDNs).
 *
 * This class contains a Kotlin implementation of the pseudocode specified by RFC 3492. It includes

      emoji_generator: !!python/name:materialx.emoji.to_svg
  - pymdownx.inlinehilite
  - pymdownx.magiclink
  - pymdownx.smartsymbols
  - pymdownx.superfences
  - pymdownx.tilde
  - pymdownx.tabbed:
      alternate_style: true
  - tables

plugins:
  - search
  - redirects:
      redirect_maps:
        # Redirect all feature pages to features/*
        'caching.md': 'features/caching.md'

import okio.Options
import okio.Path
import okio.buffer
import okio.use

class StringprepTablesReader(
  private val fileSystem: FileSystem,
) {
  /**
   * Returns a [Stringprep] that uses the tables of Nameprep ([RFC 3491]).
   *
   * [RFC 3491]: https://datatracker.ietf.org/doc/html/rfc3491
   */
  fun readNameprep(base: Path): Stringprep {
    val unassigned = readCodePointSet(base / "rfc3454.A.1.txt")

    assertEquals(1, binarySearch(0, 6) { index -> 3.compareTo(table[index]) })
    assertEquals(2, binarySearch(0, 6) { index -> 5.compareTo(table[index]) })
    assertEquals(3, binarySearch(0, 6) { index -> 7.compareTo(table[index]) })
    assertEquals(4, binarySearch(0, 6) { index -> 9.compareTo(table[index]) })
    assertEquals(5, binarySearch(0, 6) { index -> 11.compareTo(table[index]) })

  const val FLAG_COMPRESSED = 0x20 // Used for data.

  /** Lookup table for valid frame types. */
  private val FRAME_NAMES =
    arrayOf(
      "DATA", "HEADERS", "PRIORITY", "RST_STREAM", "SETTINGS", "PUSH_PROMISE", "PING", "GOAWAY",
      "WINDOW_UPDATE", "CONTINUATION",
    )

  /**
   * Lookup table for valid flags for DATA, HEADERS, CONTINUATION. Invalid combinations are
   * represented in binary.

          if (publicSuffixByteIndex == publicSuffixLength) break

          if (labels[currentLabelIndex].size == currentLabelByteIndex) {
            // We've exhausted our current label. Either there are more labels to compare, in which
            // case we expect a dot as the next character. Otherwise, we've checked all our labels.
            if (currentLabelIndex == labels.size - 1) {
              break
            } else {

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.idn

import okio.BufferedSink

/**
 * An IDNA mapping table optimized for small code and data size.
 *
 * Code Points in Sections
 * =======================
 *
 * The full range of code points is 0..0x10fffe. We can represent any of these code points with 21
 * bits.
 *