builder.header("", "Value")
    }
    assertFailsWith<IllegalArgumentException> {
      builder.addHeader("", "Value")
    }
  }

  @Test
  fun headerAllowsTabOnlyInValues() {
    val builder = Request.Builder()
    builder.header("key", "sample\tvalue")
    assertFailsWith<IllegalArgumentException> {
      builder.header("sample\tkey", "value")
    }
  }

    val proxyConnectRequest =
      Request.Builder()
        .url(route.address.url)
        .method("CONNECT", null)
        .header("Host", route.address.url.toHostHeader(includeDefaultPort = true))
        .header("Proxy-Connection", "Keep-Alive") // For HTTP/1.0 proxies like Squid.
        .header("User-Agent", USER_AGENT)
        .build()

    val fakeAuthChallengeResponse =
      Response.Builder()

      fun create(
        headers: Headers?,
        body: RequestBody,
      ): Part {
        require(headers?.get("Content-Type") == null) { "Unexpected header: Content-Type" }
        require(headers?.get("Content-Length") == null) { "Unexpected header: Content-Length" }
        return Part(headers, body)
      }

      @JvmStatic
      fun createFormData(
        name: String,
        value: String,

import okhttp3.internal.ws.WebSocketProtocol.toggleMask
import okio.Buffer
import okio.BufferedSource
import okio.ByteString

/**
 * An [RFC 6455][rfc_6455]-compatible WebSocket frame reader.
 *
 * This class is not thread safe.
 *
 * [rfc_6455]: http://tools.ietf.org/html/rfc6455
 */
class WebSocketReader(
  private val isClient: Boolean,
  val source: BufferedSource,

  /**
   * Returns true if this cookie's domain should be interpreted as a single host name, or false if
   * it should be interpreted as a pattern. This flag will be false if its `Set-Cookie` header
   * included a `domain` attribute.
   *
   * For example, suppose the cookie's domain is `example.com`. If this flag is true it matches

    This includes overly-long domain names (longer than 253 characters), overly-long labels (more
    than 63 characters between dots), and empty labels.
 *  New: Don't include the `Content-Length` header in multipart bodies. Servers must delimit
    OkHttp's request bodies using the boundary only. (This change makes OkHttp more consistent with
    browsers and other HTTP clients.)

          nextRequest = route.address.proxyAuthenticator.authenticate(route, response)
            ?: throw IOException("Failed to authenticate with proxy")

          if ("close".equals(response.header("Connection"), ignoreCase = true)) {
            return nextRequest
          }
        }

        else -> throw IOException("Unexpected response code for CONNECT: ${response.code}")
      }
    }
  }

        "custom-foo",
        "custom-header",
        "custom-bar",
        "custom-header",
        "custom-baz",
        "custom-header",
      )
    bytesIn.writeByte(0x40) // Literal indexed
    bytesIn.writeByte(0x0a) // Literal name (len = 10)
    bytesIn.writeUtf8("custom-foo")
    bytesIn.writeByte(0x0d) // Literal value (len = 13)
    bytesIn.writeUtf8("custom-header")
    bytesIn.writeByte(0x40) // Literal indexed

    assertThat(request.header("Host")).isNull()
    assertThat(request.header("Accept-Encoding")).isNull()

    // No extra headers in the application's response.
    val response = client.newCall(request).execute()
    assertThat(request.header("Content-Encoding")).isNull()
    assertThat(response.body.string()).isEqualTo("abcabcabc")
  }

  @Test

          (length0 and 0b0111_1111).toLong()
        }
      }

    // Note that this may be be an encoded "end of data" header.
    return DerHeader(tagClass, tag, constructed, length)
  }

  /**
   * Consume a header and execute [block], which should consume the entire value described by the
   * header. It is an error to not consume a full value in [block].
   */
  internal inline fun <T> read(
    name: String?,