socket-to-conn.ts

import { CodeError } from '@libp2p/interface'
import { ipPortToMultiaddr as toMultiaddr } from '@libp2p/utils/ip-port-to-multiaddr'
import { duplex } from 'stream-to-it'
import { CLOSE_TIMEOUT, SOCKET_TIMEOUT } from './constants.js'
import { multiaddrToNetConfig } from './utils.js'
import type { ComponentLogger, MultiaddrConnection, CounterGroup } from '@libp2p/interface'
import type { AbortOptions, Multiaddr } from '@multiformats/multiaddr'
import type { Socket } from 'net'

interface ToConnectionOptions {
  listeningAddr?: Multiaddr
  remoteAddr?: Multiaddr
  localAddr?: Multiaddr
  socketInactivityTimeout?: number
  socketCloseTimeout?: number
  metrics?: CounterGroup
  metricPrefix?: string
  logger: ComponentLogger
}

/**
 * Convert a socket into a MultiaddrConnection
 * https://github.com/libp2p/interface-transport#multiaddrconnection
 */
export const toMultiaddrConnection = (socket: Socket, options: ToConnectionOptions): MultiaddrConnection => {
  let closePromise: Promise<void> | null = null
  const log = options.logger.forComponent('libp2p:tcp:socket')
  const metrics = options.metrics
  const metricPrefix = options.metricPrefix ?? ''
  const inactivityTimeout = options.socketInactivityTimeout ?? SOCKET_TIMEOUT
  const closeTimeout = options.socketCloseTimeout ?? CLOSE_TIMEOUT

  // Check if we are connected on a unix path
  if (options.listeningAddr?.getPath() != null) {
    options.remoteAddr = options.listeningAddr
  }

  if (options.remoteAddr?.getPath() != null) {
    options.localAddr = options.remoteAddr
  }

  let remoteAddr: Multiaddr

  if (options.remoteAddr != null) {
    remoteAddr = options.remoteAddr
  } else {
    if (socket.remoteAddress == null || socket.remotePort == null) {
      // this can be undefined if the socket is destroyed (for example, if the client disconnected)
      // https://nodejs.org/dist/latest-v16.x/docs/api/net.html#socketremoteaddress
      throw new CodeError('Could not determine remote address or port', 'ERR_NO_REMOTE_ADDRESS')
    }

    remoteAddr = toMultiaddr(socket.remoteAddress, socket.remotePort)
  }

  const lOpts = multiaddrToNetConfig(remoteAddr)
  const lOptsStr = lOpts.path ?? `${lOpts.host ?? ''}:${lOpts.port ?? ''}`
  const { sink, source } = duplex(socket)

  // by default there is no timeout
  // https://nodejs.org/dist/latest-v16.x/docs/api/net.html#socketsettimeouttimeout-callback
  socket.setTimeout(inactivityTimeout, () => {
    log('%s socket read timeout', lOptsStr)
    metrics?.increment({ [`${metricPrefix}timeout`]: true })

    // only destroy with an error if the remote has not sent the FIN message
    let err: Error | undefined
    if (socket.readable) {
      err = new CodeError('Socket read timeout', 'ERR_SOCKET_READ_TIMEOUT')
    }

    // if the socket times out due to inactivity we must manually close the connection
    // https://nodejs.org/dist/latest-v16.x/docs/api/net.html#event-timeout
    socket.destroy(err)
  })

  socket.once('close', () => {
    log('%s socket close', lOptsStr)
    metrics?.increment({ [`${metricPrefix}close`]: true })

    // In instances where `close` was not explicitly called,
    // such as an iterable stream ending, ensure we have set the close
    // timeline
    if (maConn.timeline.close == null) {
      maConn.timeline.close = Date.now()
    }
  })

  socket.once('end', () => {
    // the remote sent a FIN packet which means no more data will be sent
    // https://nodejs.org/dist/latest-v16.x/docs/api/net.html#event-end
    log('%s socket end', lOptsStr)
    metrics?.increment({ [`${metricPrefix}end`]: true })
  })

  const maConn: MultiaddrConnection = {
    async sink (source) {
      try {
        await sink((async function * () {
          for await (const buf of source) {
            if (buf instanceof Uint8Array) {
              yield buf
            } else {
              yield buf.subarray()
            }
          }
        })())
      } catch (err: any) {
        // If aborted we can safely ignore
        if (err.type !== 'aborted') {
          // If the source errored the socket will already have been destroyed by
          // duplex(). If the socket errored it will already be
          // destroyed. There's nothing to do here except log the error & return.
          log.error('%s error in sink', lOptsStr, err)
        }
      }

      // we have finished writing, send the FIN message
      socket.end()
    },

    source,

    // If the remote address was passed, use it - it may have the peer ID encapsulated
    remoteAddr,

    timeline: { open: Date.now() },

    async close (options: AbortOptions = {}) {
      if (socket.destroyed) {
        log('The %s socket is destroyed', lOptsStr)
        return
      }

      if (closePromise != null) {
        log('The %s socket is closed or closing', lOptsStr)
        return closePromise
      }

      if (options.signal == null) {
        const signal = AbortSignal.timeout(closeTimeout)

        options = {
          ...options,
          signal
        }
      }

      const abortSignalListener = (): void => {
        socket.destroy(new CodeError('Destroying socket after timeout', 'ERR_CLOSE_TIMEOUT'))
      }

      options.signal?.addEventListener('abort', abortSignalListener)

      try {
        log('%s closing socket', lOptsStr)
        closePromise = new Promise<void>((resolve, reject) => {
          socket.once('close', () => {
            // socket completely closed
            log('%s socket closed', lOptsStr)

            resolve()
          })
          socket.once('error', (err: Error) => {
            log('%s socket error', lOptsStr, err)

            // error closing socket
            if (maConn.timeline.close == null) {
              maConn.timeline.close = Date.now()
            }
            if (!socket.destroyed) {
              reject(err)
            }
            // if socket is destroyed, 'closed' event will be emitted later to resolve the promise
          })

          // shorten inactivity timeout
          socket.setTimeout(closeTimeout)

          // close writable end of the socket
          socket.end()

          if (socket.writableLength > 0) {
            // there are outgoing bytes waiting to be sent
            socket.once('drain', () => {
              log('%s socket drained', lOptsStr)

              // all bytes have been sent we can destroy the socket (maybe) before the timeout
              socket.destroy()
            })
          } else {
            // nothing to send, destroy immediately, no need for the timeout
            socket.destroy()
          }
        })

        await closePromise
      } catch (err: any) {
        this.abort(err)
      } finally {
        options.signal?.removeEventListener('abort', abortSignalListener)
      }
    },

    abort: (err: Error) => {
      log('%s socket abort due to error', lOptsStr, err)

      // the abortSignalListener may already destroyed the socket with an error
      if (!socket.destroyed) {
        socket.destroy(err)
      }

      if (maConn.timeline.close == null) {
        maConn.timeline.close = Date.now()
      }
    },

    log
  }

  return maConn
}