domainLabelsUtf8Bytes,
            labelIndex,
          )
        if (rule != null) {
          exception = rule
          break
        }
      }
    }

    if (exception != null) {
      // Signal we've identified an exception rule.
      exception = "!$exception"
      return exception.split('.')
    } else if (exactMatch == null && wildcardMatch == null) {
      return PREVAILING_RULE
    }

          while (!canceled && reader.processNextEvent()) {
          }
        }
      } catch (e: Exception) {
        val exception =
          when {
            canceled -> IOException("canceled", e)
            else -> e
          }
        listener.onFailure(this, exception, response)
        return
      }
      if (canceled) {
        listener.onFailure(this, IOException("canceled"), response)

        dep -->> dep: Raise other exception
    end
    dep ->> operation: Run dependency, e.g. DB session
    opt raise
        operation -->> dep: Raise HTTPException
        dep -->> handler: Auto forward exception
        handler -->> client: HTTP error response
        operation -->> dep: Raise other exception
        dep -->> handler: Auto forward exception
    end

import okhttp3.AsyncDns
import okhttp3.ExperimentalOkHttpApi

/**
 * DNS implementation based on android.net.DnsResolver, which submits a request for
 * A or AAAA records, and returns the addresses or exception.
 *
 * Two instances must be used to get all results for an address.
 *
 * @param network network to use, if not selects the default network.
 */
@RequiresApi(Build.VERSION_CODES.Q)
@ExperimentalOkHttpApi

            @Throws(Exception::class)
            public
            override fun doExecute(bufferedWriter: BufferedWriter) {
                val packages = Implementation(excludes.get()).collectPackages(classpath.files.map(File::toPath))
                packages.dump(false, object : ErroringAction<String>() {
                    @Throws(Exception::class)
                    override fun doExecute(s: String) {

We can also use this same approach to access the request body in an exception handler.

All we need to do is handle the request inside a `try`/`except` block:

```Python hl_lines="13  15"
{!../../../docs_src/custom_request_and_route/tutorial002.py!}
```

If an exception occurs, the`Request` instance will still be in scope, so we can read and make use of the request body when handling the error:

        logger.fine("$this connection from ${raw.inetAddress} failed: $e")
      } catch (e: Exception) {
        logger.log(Level.SEVERE, "$this connection from ${raw.inetAddress} crashed", e)
      }
    }
  }

  internal inner class SocketHandler(private val raw: Socket) {
    private var sequenceNumber = 0

    @Throws(Exception::class)
    fun handle() {
      if (!processTunnelRequests()) return

            - iter_bytes
            - iter_json
            - send_text
            - send_bytes
            - send_json
            - close

When a client disconnects, a `WebSocketDisconnect` exception is raised, you can catch it.

You can import it directly form `fastapi`:

```python
from fastapi import WebSocketDisconnect
```

::: fastapi.WebSocketDisconnect

## WebSockets - additional classes

    val subjectCaCerts = subjectToCaCerts[issuer] ?: return null

    return subjectCaCerts.firstOrNull {
      try {
        cert.verify(it.publicKey)
        return@firstOrNull true
      } catch (_: Exception) {
        return@firstOrNull false
      }
    }
  }

  override fun equals(other: Any?): Boolean {
    return other === this ||
      (other is BasicTrustRootIndex && other.subjectToCaCerts == subjectToCaCerts)

    val route: Route,
    val call: Call,
  ) : ConnectionEvent()

  data class ConnectFailed(
    override val timestampNs: Long,
    val route: Route,
    val call: Call,
    val exception: IOException,
  ) : ConnectionEvent() {
    override fun closes(event: ConnectionEvent): Boolean = event is ConnectStart && call == event.call && route == event.route
  }

  data class ConnectEnd(