*/
package okhttp3.internal.ws

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

object WebSocketProtocol {
  /** Magic value which must be appended to the key in a response header. */
  internal const val ACCEPT_MAGIC = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"

  /*
  Each frame starts with two bytes of data.

   0 1 2 3 4 5 6 7    0 1 2 3 4 5 6 7
  +-+-+-+-+-------+  +-+-------------+

pkg net/http, type PushOptions struct, Header Header
pkg net/http, type PushOptions struct, Method string
pkg net/http, type Request struct, GetBody func() (io.ReadCloser, error)
pkg net/http, type Server struct, IdleTimeout time.Duration
pkg net/http, type Server struct, ReadHeaderTimeout time.Duration
pkg net/http, type Transport struct, ProxyConnectHeader Header
pkg net/http, var ErrAbortHandler error

  // Requests will be matched against the Host field in the following way:
  // 1. If host is precise, the request matches this rule if the http host header is equal to Host.
  // 2. If host is a wildcard, then the request matches this rule if the http host header
  // is to equal to the suffix (removing the first label) of the wildcard rule.
  // +optional
  optional string host = 1;

    NavigableSet<E> createSubSet(SortedSet<E> sortedSet, E firstExclusive, E lastExclusive) {
      NavigableSet<E> set = (NavigableSet<E>) sortedSet;
      if (from == Bound.NO_BOUND && to == Bound.INCLUSIVE) {
        return set.headSet(lastInclusive, true);
      } else if (from == Bound.EXCLUSIVE && to == Bound.NO_BOUND) {
        return set.tailSet(firstExclusive, false);
      } else if (from == Bound.EXCLUSIVE && to == Bound.EXCLUSIVE) {

				err = msgp.WrapError(err)
				return
			}
		}
	}
	return
}

// EncodeMsg implements msgp.Encodable
func (z *listPathOptions) EncodeMsg(en *msgp.Writer) (err error) {
	// map header, size 19
	// write "ID"
	err = en.Append(0xde, 0x0, 0x13, 0xa2, 0x49, 0x44)
	if err != nil {
		return
	}
	err = en.WriteString(z.ID)
	if err != nil {
		err = msgp.WrapError(err, "ID")
		return
	}

    eventListener.responseHeadersEnd(call, response)
  }

  @Throws(IOException::class)
  fun openResponseBody(response: Response): ResponseBody {
    try {
      val contentType = response.header("Content-Type")
      val contentLength = codec.reportedContentLength(response)
      val rawSource = codec.openResponseBodySource(response)
      val source = ResponseBodySource(rawSource, contentLength)

			if err != nil {
				err = msgp.WrapError(err)
				return
			}
		}
	}
	return
}

// EncodeMsg implements msgp.Encodable
func (z *metacache) EncodeMsg(en *msgp.Writer) (err error) {
	// map header, size 13
	// write "end"
	err = en.Append(0x8d, 0xa3, 0x65, 0x6e, 0x64)
	if err != nil {
		return
	}
	err = en.WriteTime(z.ended)
	if err != nil {
		err = msgp.WrapError(err, "ended")
		return
	}

import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;

/**
Do not use this class. Writing to the OutputStream of this type of socket
requires leaving a 4 byte prefix for the NBT header. IOW you must call
write( buf, 4, len ). Calling write( buf, 0, len ) will generate an error.
 */

public class NbtSocket extends Socket {

    private static final int SSN_SRVC_PORT = 139;

You can add code to be run with the `request`,  before any *path operation* receives it.

And also after the `response` is generated, before returning it.

For example, you could add a custom header `X-Process-Time` containing the time in seconds that it took to process the request and generate a response:

```Python hl_lines="10  12-13"
{!../../docs_src/middleware/tutorial001.py!}
```

/// tip

		if err != nil {
			if len(mfs) == 0 {
				writeErrorResponseJSON(r.Context(), w, toAdminAPIErr(r.Context(), err), r.URL)
				return
			}
		}

		contentType := expfmt.Negotiate(r.Header)
		w.Header().Set("Content-Type", string(contentType))

		enc := expfmt.NewEncoder(w, contentType)
		for _, mf := range mfs {
			if err := enc.Encode(mf); err != nil {
				// client may disconnect for any reasons