[getdns-users] Using EDNS and ECS in Getdns query

[Willem Toorop]

Hi Supraja,

Here is an example of a query sending a ECS option (containing
185.49.140.0/22), a NSID option and a Client Cookie to an authoritative
server. Because it is an authoritative server, the Recursion Desired bit
is set to 0.

getdns_query -s @216.239.32.10 '{
    header: { rd: 0 }
  , add_opt_parameters:
    { options: [ { option_code: 3
                 , option_data: "" }
               , { option_code: 8
                 , option_data: 0x00011600B9318C }
               ]
    }
  }' o-o.myaddr.l.google.com. TXT +edns_cookies

This authoritative (which is one of Google's b.t.w.) does not respond to
the NSID and COOKIE option, but it does return the ECS option in a TXT RR:

{
  "answer_type": GETDNS_NAMETYPE_DNS,
  "canonical_name": <bindata for o-o.myaddr.l.google.com.>,
  "replies_full":
  [
     <bindata of 0x0c4384000001000200000001036f2d6f...>
  ],
  "replies_tree":
  [
    {
      "additional":
      [
        {
          "do": 0,
          "extended_rcode": 0,
          "rdata":
          {
            "options":
            [
              {
                "option_code": 8,
                "option_data": <bindata of 0x00011616b9318c>
              }
            ],
            "rdata_raw": <bindata of 0x0008000700011616b9318c>
          },
          "type": GETDNS_RRTYPE_OPT,
          "udp_payload_size": 512,
          "version": 0,
          "z": 0
        }
      ],
      "answer":
      [
        {
          "class": GETDNS_RRCLASS_IN,
          "name": <bindata for o-o.myaddr.l.google.com.>,
          "rdata":
          {
            "rdata_raw": <bindata of 0x0d3138352e34392e3134312e3237>,
            "txt_strings":
            [
               <bindata of "185.49.141.27">
            ]
          },
          "ttl": 60,
          "type": GETDNS_RRTYPE_TXT
        },
        {
          "class": GETDNS_RRCLASS_IN,
          "name": <bindata for o-o.myaddr.l.google.com.>,
          "rdata":
          {
            "rdata_raw": <bindata of 0x2365646e73302d636c69656e742d7375...>,
            "txt_strings":
            [
               <bindata of "edns0-client-subnet 185.49.140.0"...>
            ]
          },
          "ttl": 60,
          "type": GETDNS_RRTYPE_TXT
        }
      ],
      "answer_type": GETDNS_NAMETYPE_DNS,
      "authority": [],
      "canonical_name": <bindata for o-o.myaddr.l.google.com.>,
      "header":
      {
        "aa": 1,
        "ad": 0,
        "ancount": 2,
        "arcount": 1,
        "cd": 0,
        "id": 3139,
        "nscount": 0,
        "opcode": GETDNS_OPCODE_QUERY,
        "qdcount": 1,
        "qr": 1,
        "ra": 0,
        "rcode": GETDNS_RCODE_NOERROR,
        "rd": 0,
        "tc": 0,
        "z": 0
      },
      "question":
      {
        "qclass": GETDNS_RRCLASS_IN,
        "qname": <bindata for o-o.myaddr.l.google.com.>,
        "qtype": GETDNS_RRTYPE_TXT
      }
    }
  ],
  "status": GETDNS_RESPSTATUS_GOOD
}

Does this help you further?

Cheers,

-- Willem

Op 24-02-2021 om 19:49 schreef supraja sridhar via Users:
> Hi,
> 
> I want to send ECS and a string in the EDNS field to a DNS resolver
> using a Getdns query.
> 
> Following are the steps I am following to implement the same - 
> 
> A dict for opt parameters.
> A list for options.
> A dict for the ECS option and another one EDNS. 
> Set the ECS options at index 0 in the options list and EDNS in the
> options list at index 1.
> 
> But I see neither the ECS nor the EDNS option being set. It would be
> helpful if someone can share an example snippet to achieve the same.
> 
> Thanks,
> Supraja
> 
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