Dns message parse

dns-message-parse · version 1.0.0 · Communications · free, no key needed

Parse a DNS message hex string into the RFC 1035 header, questions, and resource records.

Use when you need to: parse dns message wire hex · decode rfc 1035 dns packet · read dns header questions and records.

Decide before calling

Read the versioned contract and the supported scope below. Reuse dns-message-parse@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use dns-message-parse@1.0.0 for parse dns message wire hex. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• parse dns message wire hex
• decode rfc 1035 dns packet
• read dns header questions and records
• expand compressed names in a dns message
• dns query packet hex to fields
• structured fields from a dns message
• פענוח הודעת די אן אס מקוד הקס

Not supported

• resolve a dns name on the network
• validate dnssec signatures or check AD and CD
• decode A MX TXT or SOA rdata into fields
• convert a name to punycode

Behavior

• Input message_hex is lowercase even-length hexadecimal of one RFC 1035 message, with no TCP length prefix.
• The header returns every RFC 1035 Section 4.1.1 field. QR, AA, TC, RD and RA are booleans. Opcode is an integer 0..15 and RCODE is an integer 0..15. Z is an integer 0..7 covering diagram columns 9 through 11; AD and CD are not separate fields, so flags 0x0070 yield z 7.
• Questions and records keep unknown type and class codes. RDATA other than an OPT record is preserved as lowercase rdata_hex and is not interpreted.
• An OPT record (type 41) is accepted only in the additional section, only with the root name, and at most once. Its CLASS, TTL and RDATA are also returned as udp_payload_size, extended RCODE, version, dnssec_ok (the DO bit), a 15-bit z, and option tuples. Unknown option codes are kept.
• Compression pointers must target an earlier offset. A pointer cycle is compression_loop. The TC bit is preserved and does not by itself make a complete message invalid. Header counts must match the records present; leftover bytes are trailing_bytes.
• Names are absolute. Parsing emits a canonical presentation: dot-separated labels, root as ".", printable ASCII other than "." and "\" as itself, and every other octet as a three-digit decimal escape. Letter case is preserved.
• Caps are enforced before or during the walk: message bytes, total records, name octets, label octets, pointer hops, RDATA bytes and OPT options. A count above the record cap fails before the body is read.
• Disclaimer: format transform only; provides no confidentiality, integrity, or authenticity.

Input

• message_hex (string, required): min length 0; max length 1024; pattern ^([0-9a-f]{2})*$

Output

• header (object, required)
• questions (array of object, required): max items 32
• answers (array of object, required): max items 32
• authority (array of object, required): max items 32
• additional (array of object, required): max items 32

Limits

• max message bytes: 512
• max hex chars: 1024
• max records: 32
• max name octets: 255
• max label octets: 63
• max pointer hops: 16
• max rdata bytes: 489
• max opt options: 16

Example

Request input:

{
  "message_hex": "03e50800000000010000000000000100010000000000040a010034"
}

Response:

{
  "result": {
    "header": {
      "id": 997,
      "qr": false,
      "opcode": 1,
      "aa": false,
      "tc": false,
      "rd": false,
      "ra": false,
      "z": 0,
      "rcode": 0,
      "qdcount": 0,
      "ancount": 1,
      "nscount": 0,
      "arcount": 0
    },
    "questions": [],
    "answers": [
      {
        "name": ".",
        "type": 1,
        "class": 1,
        "ttl": 0,
        "rdata_hex": "0a010034",
        "opt": null
      }
    ],
    "authority": [],
    "additional": []
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "dns-message-parse",
  "version": "1.0.0",
  "input": {
    "message_hex": "03e50800000000010000000000000100010000000000040a010034"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/dns-message-parse/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"message_hex":"03e50800000000010000000000000100010000000000040a010034"}'

The machine-readable contract is at /v1/tools/dns-message-parse/versions/1.0.0.

CLI

node cli.mjs run dns-message-parse 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Dns message encode: Encode a structured DNS message to canonical uncompressed RFC 1035 wire hex.
• Dns header flags explain: Explain an RFC 1035 DNS header flags word, with reserved Z as an integer 0 through 7.
• Email address list parse: Parse an RFC 5322 address-list into ordered mailboxes, groups, and a canonical form.
• Dns rdata decode: Decode DNS RDATA hex for A, AAAA, NS, CNAME, PTR, MX, TXT, SOA, SRV, or unknown.
• Email address list format: Format mailboxes and groups as one deterministic RFC 5322 address-list.
• Dns message validate: Validate DNS message hex structure: counts, names, compression, and OPT records.