Function resolveHostname

packages/vite/src/node/utils.ts:964–990

(
  optionsHost: string | boolean | undefined,
)

}

export async function resolveHostname(
  optionsHost: string | boolean | undefined,
): Promise<Hostname> {
  let host: string | undefined
  if (optionsHost === undefined || optionsHost === false) {
    // Use a secure default
    host = 'localhost'
  } else if (optionsHost === true) {
    // If passed --host in the CLI without arguments
    host = undefined // undefined typically means 0.0.0.0 or :: (listen on all IPs)
  } else {
    host = optionsHost
  }

  // Set host name to localhost when possible
  let name = host === undefined || wildcardHosts.has(host) ? 'localhost' : host

  if (host === 'localhost') {
    // See #8647 for more details.
    const localhostAddr = await getLocalhostAddressIfDiffersFromDNS()
    if (localhostAddr) {
      name = localhostAddr
    }
  }

  return { host, name }
}

export function extractHostnamesFromCerts(
  certs: HttpsServerOptions['cert'] | undefined,