initial commit

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+
+# Virtual environment
+env/
+venv/
+
+# Distribution / packaging
+*.egg-info/
+dist/
+build/
+
+# IDE settings
+.idea/
+.vscode/
+*.swp

LICENSE

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+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                    Version 2, December 2004
+
+ Copyright (C) 2004 Sam Hocevar <[email protected]>
+
+ Everyone is permitted to copy and distribute verbatim or modified
+ copies of this license document, and changing it is allowed as long
+ as the name is changed.
+
+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. You just DO WHAT THE FUCK YOU WANT TO.
+

README.md

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+# Deem and Nets
+
+**Deem and Nets** is a primitive DNS implementation. The name was chosen at random, you could see it in multiple ways:
+- Say deem and nets fast and it sounds like DNS
+- See it as "Demand nets" since DNS places several demands on networks
+
+You can choose it means whatever.
+
+## Features
+
+- Parses the DNS message header (including flags and counts).
+- Server provides structured output to help visualize DNS query components.
+- Serves as a foundation for future expansions, such as resolving DNS queries and supporting various DNS record types.
+
+## Directory Structure
+
+```
+deem-and-nets
+├── README.md              # Project documentation
+├── requirements.txt       # Python dependencies
+└── src/                   # Source code
+    ├── message/
+    │   ├── builder.py     # Future DNS message builder
+    │   ├── parser.py      # Current DNS message parser
+    ├── records/
+    │   └── types.py       # DNS record types (e.g., A, CNAME, etc.)
+    ├── resolver/
+    │   ├── cache.py       # Future caching mechanism
+    │   └── resolver.py    # Future DNS resolver logic
+    └── server.py          # UDP DNS server
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.12+ (as indicated by the virtual environment)
+- `pip` for installing dependencies
+
+### Installation
+
+1. Clone the repository:
+
+```bash
+git clone https://github.com/pindjouf/deem-and-nets.git
+cd deem-and-nets
+```
+
+2. Set up a virtual environment:
+
+```bash
+python3 -m venv env
+source env/bin/activate
+pip install -r requirements.txt
+```
+
+### Usage
+
+1. Start the UDP server:
+
+```bash
+python src/server.py
+```
+
+2. Send a DNS query to the server:
+
+```bash
+dig @127.0.0.1 -p 53053 example.com
+```
+
+or
+
+```bash
+nslookup -port=53053 -querytype=A example.com 127.0.0.1
+```
+
+I recommend `nslookup` since it provides valid flags, unlike `dig`.
+
+3. Analyze the parsed DNS header output.
+
+### Current Limitations
+
+- Only parses the DNS message header.
+- No support for response generation or DNS record resolution yet.
+
+## Roadmap
+
+- Add DNS response generation.
+- Implement caching for better performance.
+- Expand support for DNS record types (A, AAAA, CNAME, etc.).
+- Implement advanced features like recursion and authoritative responses.
+
+## Contributing
+
+Contributions are welcome! Feel free to open issues or submit pull requests.
+
+## License
+
+This project is licensed under the WTFPL License - see the [LICENSE](LICENSE) file for details.

requirements.txt

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+pydantic

src/message/builder.py

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+query1 = "30940120000100000000000106676f6f676c6503636f6d000001000100002904d000000000000c000a0008ac27df40c4bdd64d"
+query2 = "39140120000100000000000106676f6f676c6503636f6d000001000100002904d000000000000c000a00081852df91ed3d89be"

src/message/parser.py

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+from pydantic import BaseModel
+from typing import List
+
+class DomainLabel(BaseModel):
+    length: int
+    value: str
+
+class Flags(BaseModel):
+    qr: int
+    opcode: int
+    authoritative_answer: int
+    truncation: int
+    recursion_desired: int
+    recursion_available: int
+    zero: int
+    response_code: int
+
+class Header(BaseModel):
+    id: bytes
+    flags: Flags
+    question_count: int
+    answer_count: int
+    authority_count: int
+    additional_records_count: int
+
+class Question(BaseModel):
+    labels: List[DomainLabel]
+    zero_byte_terminator: int
+    q_type: int
+    q_class: int
+
+class Query(BaseModel):
+    header: Header
+    question: Question
+
+class OpcodeToken:
+    def get_token(self, flags: str) -> dict:
+        bin_opcode = "0b" + flags
+        opcode_value = int(bin_opcode, 2)
+
+        opcode_token = ""
+        match opcode_value:
+            case 0:
+                opcode_token = "Standard query"
+            case 1:
+                opcode_token = "Inverse query"
+            case 2:
+                opcode_token = "Server status request"
+            case 3:
+                opcode_token = "Reserved"
+
+        return { 'value': opcode_value, 'meaning': opcode_token }
+
+class rCodeToken:
+    def get_token(self, flags: str) -> dict:
+        bin_rcode = "0b" + flags
+        rcode_value = int(bin_rcode, 2)
+
+        rcode_token = ""
+        match rcode_value:
+            case 0:
+                rcode_token = "Success"
+            case 1:
+                rcode_token = "Format specification error"
+            case 2:
+                rcode_token = "Server Failure"
+            case 3:
+                rcode_token = "Query does not exist in domain"
+            case 4:
+                rcode_token = "Type is not supported by the server"
+            case 5:
+                rcode_token = "Nonexecution of queries by server due to policy reasons"
+
+        return { 'value': rcode_value, 'meaning': rcode_token }
+
+def hex_to_bin(hex_string: str) -> str:
+    return bin(int(hex_string, 16))[2:].zfill(16)
+
+def parse_flags(flags: str) -> dict:
+    opcode = OpcodeToken()
+    rcode = rCodeToken()
+                       # pseudo-index flags: 0 1234 5 6 7 8 910 1234
+                            # Example flags: 0 0000 0 0 1 0 010 0000
+    data = {
+        'qr': {'value': 1, 'meaning': "response"} if int(flags[0]) == 1 else {'value': 0, 'meaning': "request"},
+        'opcode': opcode.get_token(flags[1:5]),
+        'authoritative_answer': {'value': 1, 'meaning': "authoritative"} if int(flags[5]) == 1 else {'value': 0, 'meaning': "non-authoritative"},
+        'truncation': {'value': 1, 'meaning': "Truncated"} if int(flags[6]) == 1 else {'value': 0, 'meaning': "Not truncated"},
+        'recursion_desired': {'value': 1, 'meaning': "Recursion requested"} if int(flags[7]) == 1 else {'value': 0, 'meaning': "Recursion not requested"},
+        'recursion_available': {'value': 1, 'meaning': "Recursion available"} if int(flags[8]) == 1 else {'value': 0, 'meaning': "Recursion not available"},
+        'zero': {'value': 0, 'meaning': "Reserved"} if int(flags[9:12], 2) == 0 else {'value': int(flags[9:12], 2), 'meaning': "Error (should be zero)"},
+        'rcode': rcode.get_token(flags[12:16])
+    }
+
+    return data
+
+def pretty_print(header: Header, tokenized_flags, binary_flags, query):
+    print("\nDNS Query Analysis")
+    print("=" * 60)
+    print(f"Base Query: {query}")
+    print("\nDNS Header")
+    print("=" * 60)
+    print(f"Transaction ID: 0x{header.id.hex()} (bytes: {header.id})")
+    print("=" * 60)
+    print("Counts:")
+    print(f"  Questions: {header.question_count}")
+    print(f"  Answers: {header.answer_count}")
+    print(f"  Authority RRs: {header.authority_count}")
+    print(f"  Additional RRs: {header.additional_records_count}")
+    print("=" * 60)
+    print("")
+    print("Tokenized Flags:")
+    print("=" * 60)
+    print(f"Binary Flags: {binary_flags}")
+
+    for key, value in tokenized_flags.items():
+        print(f"{key.replace('_', ' ').title():20}: {value['value']} - {value['meaning']}")
+
+    print("=" * 60)
+
+def parser(query: str):
+    flags_substring = query[4:8]
+    binary_flags = hex_to_bin(flags_substring)
+    tokenized_flags = parse_flags(binary_flags)
+
+    flags = Flags(
+        qr=tokenized_flags['qr']['value'],
+        opcode=tokenized_flags['opcode']['value'],
+        authoritative_answer=tokenized_flags['authoritative_answer']['value'],
+        truncation=tokenized_flags['truncation']['value'],
+        recursion_desired=tokenized_flags['recursion_desired']['value'],
+        recursion_available=tokenized_flags['recursion_available']['value'],
+        zero=tokenized_flags['zero']['value'],
+        response_code=tokenized_flags['rcode']['value']
+    )
+    header = Header(
+        id=bytes.fromhex(query[0:4]),
+        flags=flags,
+        question_count=int(query[8:12], 16),
+        answer_count=int(query[12:16], 16),
+        authority_count=int(query[16:20], 16),
+        additional_records_count=int(query[20:24], 16)
+    )
+
+    pretty_print(header, tokenized_flags, binary_flags, query)

src/server.py

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+import socket
+from message import parser
+
+server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+server_socket.bind(("127.0.0.1", 53053))
+
+while True:
+    (client_socket, address) = server_socket.recvfrom(1024)
+    parser.parser(client_socket.hex())
+    print()