6 examples of 'javascript dns lookup' in JavaScript

7
static lookup(host) {
8
    return Promise.resolve(NetAddress.UNSPECIFIED);
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}

12
function dnsLookup (hostname: string): Promise {
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  return new Promise((resolve, reject) => {
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    dns.lookup(hostname, 4, (err, address) => {
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      if (err) return reject(err)
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      resolve(address)
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    })
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  })
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}

95
dns.resolve(host, function onLookup(err, addresses, family) {
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    if (err) {
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        return;
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    }
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    var bool = true;
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    addresses.forEach(function (item){
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        if (item == ip) {
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            bool = false;
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            return;
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        }
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    });
106
    bool && logHost(host, ip, "被检测到可能配置了系统host：", "warn");
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});

125
function dnsResolve(host) {
126
    try {
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        return dns.resolve(host, 0).getNextAddrAsString();
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    } catch (e) {
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        return null;
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    }
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}

17
async lookup(hostname) {
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	try {
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		let ip = this.cache.get(hostname);
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		if (ip) {
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			return ip;
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		}
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		const t = new Date();
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		ip = hostname;
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		for (let depth = 0; !_isIP(ip) && depth < 5; depth++) {
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			ip = await this._lookup(ip).catch(error => {
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				logger.debug(error);
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				return ip;
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			});
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		}
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		if (!_isIP(ip)) {
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			throw new Error(`BAD IP FORMAT (${ip})`);
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		}
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		logger.debug(`[DNS] ${hostname} -> ${ip} (${new Date() - t} ms)`);
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		this.cache.set(hostname, ip);
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		return ip;
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	} catch (error) {
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		logger.debug(`[DNS] cannot resolve hostname ${hostname} (${error})`);
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	}
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}

46
async [DNSLOOKUP](url, args) {
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  let parsed;
48
  if (typeof url === 'string') {
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    parsed = utils.safeParseURL(url);
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    // invalid url or relative url
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    if (!parsed) return { url, args };
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  } else {
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    parsed = url;
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  }
55
  // hostname must exists
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  const hostname = parsed.hostname;
57
58
  // don't lookup when hostname is IP
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  if (hostname && IP_REGEX.test(hostname)) {
60
    return { url, args };
61
  }
62
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  args = args || {};
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  args.headers = args.headers || {};
65
  // set host header is not exists
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  if (!args.headers.host && !args.headers.Host) {
67
    // host must combine with hostname:port, node won't use `parsed.host`
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    args.headers.host = parsed.port ? `${hostname}:${parsed.port}` : hostname;
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  }
70
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  const record = this.dnsCache.get(hostname);
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  const now = Date.now();
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  if (record) {
74
    if (now - record.timestamp >= this.dnsCacheLookupInterval) {
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      // make sure next request don't refresh dns query
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      record.timestamp = now;
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      this[UPDATE_DNS](hostname, args).catch(err => this.app.emit('error', err));
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    }
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    return { url: formatDnsLookupUrl(hostname, url, record.ip), args };
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  }
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  const address = await this[UPDATE_DNS](hostname, args);
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  return { url: formatDnsLookupUrl(hostname, url, address), args };
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}