Dns message validate

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

Validate DNS message hex structure: counts, names, compression, and OPT records.

Use when you need to: validate dns message wire structure · check dns packet section counts · is this dns hex structurally valid.

Decide before calling

Read the versioned contract and the supported scope below. Reuse dns-message-validate@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-validate@1.0.0 for validate dns message wire structure. 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

• validate dns message wire structure
• check dns packet section counts
• is this dns hex structurally valid
• find a truncated dns message
• check dns compression pointer safety
• accept or reject a dns message shape
• בדיקת מבנה של הודעת די אן אס

Not supported

• return the parsed questions and records
• repair a malformed dns message
• check dnssec or authenticate the sender
• explain individual header flag names

Behavior

• A lowercase even-length hex string within the byte cap is checked as one RFC 1035 message. Syntax that is not hex throws invalid_input. A message past a declared cap throws limit_exceeded before the structural walk when the cap is visible up front.
• A structurally illegal message returns valid false, a snake_case reason, the decoded byte length, zero section counts, and the byte offset of the failure. Reasons include truncated_header, truncated_name, truncated_record, truncated_rdata, truncated_opt, trailing_bytes, reserved_label, bad_pointer, forward_pointer, compression_loop, opt_name, opt_section and multiple_opt.
• A non-zero header Z is valid. The TC bit alone does not make a complete message invalid. Unknown type, class, opcode and RCODE values are valid. OPT framing follows RFC 6891 Section 6.
• On success, reason and offset are null and the section counts are the header counts. opt_count is 0 or 1.
• 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

• valid (boolean, required)
• reason (string or null, required): min length 1
• message_bytes (integer, required): min 0; max 512
• question_count (integer, required): min 0; max 32
• answer_count (integer, required): min 0; max 32
• authority_count (integer, required): min 0; max 32
• additional_count (integer, required): min 0; max 32
• opt_count (integer, required): min 0; max 1
• offset (integer or null, required): min 0; max 512

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": {
    "valid": true,
    "reason": null,
    "message_bytes": 27,
    "question_count": 0,
    "answer_count": 1,
    "authority_count": 0,
    "additional_count": 0,
    "opt_count": 0,
    "offset": null
  }
}

How to call it

MCP

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

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

HTTP (no key)

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

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

CLI

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

Get the client at /clients/cli/.

Related tools

• Email address list validate: Check RFC 5322 address-list syntax, including dots, quotes, comments, and groups.
• Email mailbox validate: Check one RFC 5322 mailbox for syntax only and return a stable reason code.
• Dns message encode: Encode a structured DNS message to canonical uncompressed RFC 1035 wire hex.
• Dns message parse: Parse a DNS message hex string into the RFC 1035 header, questions, and resource records.
• Dns header flags explain: Explain an RFC 1035 DNS header flags word, with reserved Z as an integer 0 through 7.
• Dns rdata decode: Decode DNS RDATA hex for A, AAAA, NS, CNAME, PTR, MX, TXT, SOA, SRV, or unknown.