serverless-dns: DNS packet encode / decode unhandled exceptions

After adding a caching layer, reliance on dns-packet encoding / decoding has gone up. In our tests, these unhandled exceptions have cropped up in the meanwhile:

  "exceptions": [
    {
      "name": "TypeError",
      "message": "Failed to execute function: parameter 1 is not of type 'Response'.",
    }
  ],
  "logs": [
    {
      "message": [
        "Error At : DNSParserWrap -> Encode"
      ],
      "level": "error",
    },
    {
      "message": [
        "TypeError: e.copy is not a function\n    at Object.encode (worker.js:10:13483)\n    at Object.encode (worker.js:10:33416)\n    at ce (worker.js:10:35934)\n    at ne (worker.js:10:35051)\n    at de.Encode (worker.js:10:36285)\n    at Ue.dnsBlockResponse (worker.js:10:44687)\n    at vt.Rt (worker.js:10:82128)\n    at vt.executePlugin (worker.js:10:80457)\n    at async worker.js:10:82801"
      ],
      "level": "error",
    }
  ],

 "outcome": "exception",
  "scriptName": null,
  "exceptions": [
    {
      "name": "TypeError",
      "message": "Failed to execute function: parameter 1 is not of type 'Response'.",
    }
  ],
  "logs": [
    {
      "message": [
        "Error At : DNSParserWrap -> Encode"
      ],
      "level": "error",
    },
    {
      "message": [
        "TypeError: e.copy is not a function\n    at Object.encode (worker.js:10:13483)\n    at Object.encode (worker.js:10:33416)\n    at ce (worker.js:10:35934)\n    at ne (worker.js:10:35051)\n    at de.Encode (worker.js:10:36285)\n    at Ue.dnsBlockResponse (worker.js:10:44687)\n    at vt.Rt (worker.js:10:82128)\n    at vt.executePlugin (worker.js:10:80457)\n    at async worker.js:10:82801"
      ],
      "level": "error",
    }
  ],

About this issue

Original URL
State: closed
Created 3 years ago
Comments: 16 (16 by maintainers)

Commits related to this issue

refactor(dns-resolver): Check upstream res. length (prev. commit + this) for serverless-dns/serverless-dns#25 — committed to serverless-dns/dns-blocker by amithm7 3 years ago
fix(dns-resolver): Check upstream server 5xx error serverless-dns/serverless-dns#25 — committed to serverless-dns/dns-blocker by amithm7 3 years ago
fix: GET & POST methods only; cors headers for browsers #25 — committed to serverless-dns/serverless-dns by amithm7 3 years ago

Most upvoted comments

some more from development instance. This happens routinely.

 2021-12-04T21:59:08.842 app[28243a82] maa [info] Error At : DNSParserWrap -> Decode
2021-12-04T21:59:08.843 app[28243a82] maa [info] RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range. It must be >= 0 and <= 312. Received 430
2021-12-04T21:59:08.843 app[28243a82] maa [info] at new NodeError (node:internal/errors:371:5)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at boundsError (node:internal/buffer:86:9)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at Buffer.readUInt16BE (node:internal/buffer:332:5)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at Object.question.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1875:31)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at decodeList (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1995:19)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at Module.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1935:12)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at DNSParserWrap.Decode (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsParserWrap.js:17:24)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at DNSBlock.RethinkModule (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsBlock.js:35:51)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at RethinkPlugin.executePlugin (file:///node-dir/plugin.js:127:50)
2021-12-04T21:59:08.843 app[28243a82] maa [info] at runMicrotasks (<anonymous>)

2021-12-04T21:59:08.844 app[28243a82] maa [info] Error At : DNSBlock -> RethinkModule
2021-12-04T21:59:08.844 app[28243a82] maa [info] RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range. It must be >= 0 and <= 312. Received 430
2021-12-04T21:59:08.844 app[28243a82] maa [info] at new NodeError (node:internal/errors:371:5)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at boundsError (node:internal/buffer:86:9)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at Buffer.readUInt16BE (node:internal/buffer:332:5)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at Object.question.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1875:31)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at decodeList (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1995:19)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at Module.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1935:12)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at DNSParserWrap.Decode (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsParserWrap.js:17:24)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at DNSBlock.RethinkModule (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsBlock.js:35:51)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at RethinkPlugin.executePlugin (file:///node-dir/plugin.js:127:50)
2021-12-04T21:59:08.844 app[28243a82] maa [info] at runMicrotasks (<anonymous>)
2021-12-04T21:59:08.844 app[28243a82] maa [info] {"isException":true,"exceptionStack":"RangeError [ERR_OUT_OF_RANGE]: The value of \"offset\" is out of range. It must be >= 0 and <= 312. Received 430\n at new NodeError (node:internal/errors:371:5)\n at boundsError (node:internal/buffer:86:9)\n at Buffer.readUInt16BE (node:internal/buffer:332:5)\n at Object.question.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1875:31)\n at decodeList (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1995:19)\n at Module.decode (file:///node-dir/node_modules/@serverless-dns/dns-parser/index.js:1935:12)\n at DNSParserWrap.Decode (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsParserWrap.js:17:24)\n at DNSBlock.RethinkModule (file:///node-dir/node_modules/@serverless-dns/dns-operation/dnsBlock.js:35:51)\n at RethinkPlugin.executePlugin (file:///node-dir/plugin.js:127:50)\n at runMicrotasks (<anonymous>)","exceptionFrom":"DNSBlock RethinkModule","data":false}

A GET Request is created by DoT handler, maybe I should revert it back to POST. If this happening because of URL length being too large. But I find that unlikely too.

Yes, locally upstream POST. Safer since POST can handle arbitrary sized requests.

ignoramous on Dec 5, 2021

I guess, we are long done with this one with all the recent changes and refactors.

ignoramous on Jan 6, 2022

Okay, making changes…

amithm7 on Dec 25, 2021

Could set 405 res code from command-control.

Currently there are no checks for request method I believe. What is not a GET is assumed to be POST.

CORS headers also set “Allow request methods” to all (*), it should be modified to be just POST & GET (and OPTIONS?)

amithm7 on Dec 24, 2021

One of the decoding errors was caused by this array buffer of upstream response:

6e 6f 20 64 6f 77 6e 73 74 72 65 61 6d 20 73 65 72 76 65 72 20 61 76 61 69 6c 61 62 6c 65

This is not a dns-packet. It is text that says: “no downstream server available”.

Searching the web shows this: https://github.com/PowerDNS/pdns/blob/f9f6a6257e43133d98a7295994d0a7c50b80e261/pdns/dnsdistdist/doh.cc#L400 Maybe what upstream (quad9 (10)) could be using.

Checking response code from upstream before decoding will probably reduce many of these errors.

Edit: It is 502 Response Code when this happens.

Error At : DNSParserWrap -> Decode
@DNSResolver->updateCache: Failed decoding response body buffer => resp code: 502 resp body buf: ArrayBuffer {
  [Uint8Contents]: <6e 6f 20 64 6f 77 6e 73 74 72 65 61 6d 20 73 65 72 76 65 72 20 61 76 61 69 6c 61 62 6c 65>,
  byteLength: 30
}
Error At : DNSResolver -> RethinkModule
RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range. It must be >= 0 and <= 28. Received 123

amithm7 on Jan 6, 2022