import assertk.assertions.isEqualTo
import assertk.assertions.isNull
import assertk.assertions.matches
import java.math.BigInteger
import java.security.KeyFactory
import java.security.spec.PKCS8EncodedKeySpec
import java.security.spec.X509EncodedKeySpec
import java.util.concurrent.TimeUnit
import okhttp3.testing.PlatformRule
import okhttp3.tls.HeldCertificate.Companion.decode
import okio.ByteString.Companion.decodeBase64

    // 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:
    // U+0000, U+0009, U+000A, U+000D, U+0020, "#", "%", "/", ":", "?", "@", "[", "\", and "]"
    // (excluding the characters covered above).
    if (" #%/:?@[\\]".indexOf(c) != -1) {
      return true
    }
  }

    CipherSuite.TLS_AES_256_GCM_SHA384,
    CipherSuite.TLS_CHACHA20_POLY1305_SHA256,
    CipherSuite.TLS_AES_128_CCM_SHA256,
    CipherSuite.TLS_AES_128_CCM_8_SHA256,
  )

/**
 * A TLS 1.3 only Connection Spec. This will be eventually be exposed
 * as part of MODERN_TLS or folded into the default OkHttp client once published and
 * available in JDK11 or Conscrypt.
 */
private val TLS_13 =
  ConnectionSpec.Builder(true)

    memory if web socket compression is negotiated but not used.


## Version 4.5.0-RC1

_2020-03-17_

**This release candidate turns on web socket compression.**

The [spec][rfc_7692] includes a sophisticated mechanism for client and server to negotiate
compression features. We strive to offer great performance in our default configuration and so we're

        val tlsEquipPlan = planWithCurrentOrInitialConnectionSpec(connectionSpecs, sslSocket)
        val connectionSpec = connectionSpecs[tlsEquipPlan.connectionSpecIndex]

        // Figure out the next connection spec in case we need a retry.
        retryTlsConnection = tlsEquipPlan.nextConnectionSpec(connectionSpecs, sslSocket)

        connectionSpec.apply(sslSocket, isFallback = tlsEquipPlan.isTlsFallback)

  constructor(name: ByteString, value: String) : this(name, value.encodeUtf8())

  override fun toString(): String = "${name.utf8()}: ${value.utf8()}"

  companion object {
    // Special header names defined in HTTP/2 spec.
    @JvmField val PSEUDO_PREFIX: ByteString = ":".encodeUtf8()

    const val RESPONSE_STATUS_UTF8 = ":status"
    const val TARGET_METHOD_UTF8 = ":method"
    const val TARGET_PATH_UTF8 = ":path"

You can build your own connection spec with a custom set of TLS versions and cipher suites. For example, this configuration is limited to three highly-regarded cipher suites. Its drawback is that it requires Android 5.0+ and a similarly current webserver.

```java
ConnectionSpec spec = new ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
    .tlsVersions(TlsVersion.TLS_1_2)

    @Throws(IOException::class)
    fun parse(responseHeaders: Headers): WebSocketExtensions {
      // Note that this code does case-insensitive comparisons, even though the spec doesn't specify
      // whether extension tokens and parameters are case-insensitive or not.

      var compressionEnabled = false
      var clientMaxWindowBits: Int? = null
      var clientNoContextTakeover = false

      assumeTrue(PlatformVersion.majorVersion != 8)
    }

    val sessionIds = mutableListOf<String>()

    enableTls()

    val tlsVersion = TlsVersion.forJavaName(tlsVersion)
    val spec =
      ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
        .tlsVersions(tlsVersion)
        .build()

    var reuseSession = false

    val sslContext = handshakeCertificates.sslContext()

import java.security.Signature
import java.security.cert.X509Certificate
import java.security.interfaces.ECPublicKey
import java.security.interfaces.RSAPrivateKey
import java.security.interfaces.RSAPublicKey
import java.security.spec.PKCS8EncodedKeySpec
import java.util.UUID
import java.util.concurrent.TimeUnit
import okhttp3.internal.canParseAsIpAddress
import okhttp3.tls.internal.der.AlgorithmIdentifier