bare-operating-system/packages/bare-os-booter/lib/posix/bare-os-socket-bridge.js

/**
 * POSIX socket-FD bridge helpers (logical dup, shutdown, sendmsg prep).
 * Takes the guest ctx; no executeKernel closure.
 */
import {
  bareOsEnsureSocketSlotAliasKeys,
  bareOsParseSendmsgScmRights,
  bareOsScmRightsMaxFds,
  wantPosixSocketScmRights
} from './bare-os-socket-scm-rights.js'
import {
  bareOsFlattenSendmsgIovs,
  bareOsSendmsgAncillaryRejectReason
} from './bare-os-posix-syscall-helpers.js'

/**
 * @param {Record<string, unknown>} c ctx
 * @param {number} srcFd
 * @returns {number | null}
 */
export function bareOsDupLogicalFdForScm(c, srcFd) {
  const k = String(Number(srcFd) >>> 0)
  const bridge = c.bareOsSocketBridgeByFd
  const slot = bridge && typeof bridge === 'object' ? bridge[k] : null
  if (slot && typeof slot === 'object') {
    if (
      slot.state === 'listening' ||
      slot.state === 'created' ||
      slot.state === 'bound'
    ) {
      return null
    }
    bareOsEnsureSocketSlotAliasKeys(slot, k)
    const st = c.bareOsPosixFdSimState
    const newFd = st.nextFd++
    if (st.nextFd > 65530) return null
    const nk = String(newFd)
    if (
      !c.bareOsSocketBridgeByFd ||
      typeof c.bareOsSocketBridgeByFd !== 'object'
    )
      return null
    c.bareOsSocketBridgeByFd[nk] = slot
    slot.aliasKeys.add(nk)
    const targ = c.bareOsLogicalFds[k] || 'bare-os-socket-bridge:dup'
    c.bareOsRegisterLogicalFd(newFd, String(targ))
    const fl = c.bareOsLogicalFdFlags[k]
    if (typeof fl === 'number') c.bareOsLogicalFdFlags[nk] = fl
    return newFd
  }
  const target = c.bareOsLogicalFds[k]
  if (!target) return null
  const st = c.bareOsPosixFdSimState
  const newFd = st.nextFd++
  if (st.nextFd > 65530) return null
  const nk = String(newFd)
  c.bareOsRegisterLogicalFd(newFd, String(target))
  const fl = c.bareOsLogicalFdFlags[k]
  if (typeof fl === 'number') c.bareOsLogicalFdFlags[nk] = fl
  return newFd
}

/**
 * @param {Record<string, unknown>} c ctx
 * @param {number} fd
 */
export async function bareOsShutdownSocketBridgeFd(c, fd, howMaybe) {
  const k = String(Number(fd) >>> 0)
  const bridge = c.bareOsSocketBridgeByFd
  if (!bridge || typeof bridge !== 'object') {
    return {
      ok: false,
      op: 'shutdown',
      code: 'EINVAL',
      errnoHint: 'EINVAL',
      note: 'shutdown: not a bridge fd'
    }
  }
  const slot = bridge[k]
  if (!slot || typeof slot !== 'object') {
    return {
      ok: false,
      op: 'shutdown',
      code: 'EINVAL',
      errnoHint: 'EINVAL',
      note: 'shutdown: not a bridge fd'
    }
  }
  bareOsEnsureSocketSlotAliasKeys(slot, k)
  const howN = Number(howMaybe)
  const how = Number.isFinite(howN)
    ? Math.min(2, Math.max(0, Math.floor(howN)))
    : 2
  const tcpHalf =
    slot.transport === 'tcp' &&
    slot.state === 'connected' &&
    slot.sock &&
    (how === 0 || how === 1)
  if (tcpHalf) {
    if (how === 0) slot.tcpShutRd = true
    if (how === 1) {
      slot.tcpShutWr = true
      try {
        slot.sock.end?.()
      } catch (_) {}
    }
    return {
      ok: true,
      op: 'shutdown',
      bridge: true,
      posixAlignment: 'partial',
      how,
      note:
        how === 0
          ? 'TCP bridge: SHUT_RD — recv drains then EOF; poll marks readable when queue drained after peer FIN.'
          : 'TCP bridge: SHUT_WR — further send returns EPIPE-shaped failure.'
    }
  }
  delete bridge[k]
  c.bareOsUnregisterLogicalFd(fd)
  slot.aliasKeys.delete(k)
  if (slot.aliasKeys.size > 0) {
    return {
      ok: true,
      op: 'shutdown',
      bridge: true,
      posixAlignment: 'partial',
      scmRightsRefDup: true
    }
  }
  if (slot.state === 'listening' && slot.server) {
    try {
      slot.server.close?.()
    } catch (_) {}
    slot.server = null
    if (Array.isArray(slot.acceptQueue)) {
      for (const w of slot.acceptQueue) {
        try {
          w.sock?.destroy?.()
        } catch (_) {}
      }
      slot.acceptQueue = []
    }
    slot.state = 'closed'
    return {
      ok: true,
      op: 'shutdown',
      bridge: true,
      posixAlignment: 'partial'
    }
  }
  if (
    (slot.state === 'connected' || slot.state === 'udp_bound') &&
    slot.sock
  ) {
    try {
      slot.sock.destroy?.()
    } catch (_) {}
    try {
      await slot.sock.close?.()
    } catch (_) {}
    slot.state = 'closed'
    return {
      ok: true,
      op: 'shutdown',
      bridge: true,
      posixAlignment: 'partial'
    }
  }
  return {
    ok: false,
    op: 'shutdown',
    code: 'ENOTSUP',
    errnoHint: 'ENOTSUP',
    posixAlignment: 'ENOTSUP',
    note: 'shutdown: bridge fd not connected, bound, or listening.'
  }
}

/**
 * @param {Record<string, unknown>} c ctx (`c.env` is the guest shell env)
 * @param {Record<string, unknown>} args
 */
export function prepareBridgeSendmsg(c, args) {
  const a =
    args && typeof args === 'object'
      ? /** @type {Record<string, unknown>} */ (args)
      : {}
  const env =
    c && c.env && typeof c.env === 'object'
      ? /** @type {Record<string, string | undefined>} */ (c.env)
      : {}
  const scmOn = wantPosixSocketScmRights(env)
  const parsed = bareOsParseSendmsgScmRights(
    a,
    scmOn,
    bareOsScmRightsMaxFds(env)
  )
  if (!parsed.ok) {
    return {
      ok: false,
      err: {
        ok: false,
        op: 'sendmsg',
        code: 'ENOTSUP',
        errnoHint: 'ENOTSUP',
        posixAlignment: 'ENOTSUP',
        ancillaryReject: parsed.reject,
        note: 'sendmsg: ancillary control rejected (see ancillaryReject).'
      }
    }
  }
  if (!scmOn) {
    const leg = bareOsSendmsgAncillaryRejectReason(a)
    if (leg) {
      return {
        ok: false,
        err: {
          ok: false,
          op: 'sendmsg',
          code: 'ENOTSUP',
          errnoHint: 'ENOTSUP',
          posixAlignment: 'ENOTSUP',
          ancillaryReject: leg,
          note: 'sendmsg: ancillary control messages (cmsgs/control/controllen/msgHdr.*) are unsupported on the socket FD bridge without BARE_OS_POSIX_SOCKET_SCM_RIGHTS; use payload-only send or bare IPC.'
        }
      }
    }
  }
  /** @type {{ from: number; to: number }[]} */
  const scmRightsLocalDup = []
  for (const src of parsed.fds) {
    const to = bareOsDupLogicalFdForScm(c, src)
    if (to == null) {
      return {
        ok: false,
        err: {
          ok: false,
          op: 'sendmsg',
          code: 'EBADF',
          errnoHint: 'EBADF',
          posixAlignment: 'ENOTSUP',
          note: 'sendmsg: SCM_RIGHTS logical dup failed (unknown fd, idle/listen/bound socket, or FD budget).'
        }
      }
    }
    scmRightsLocalDup.push({ from: Number(src) >>> 0, to })
  }
  const f = bareOsFlattenSendmsgIovs(a)
  if (!f.ok) return { ok: false, err: f.err }
  return {
    ok: true,
    payload: f.buf,
    scmRightsLocalDup
  }
}