From 5621f7cedd32dbdd0e8b0ead9cba915c61b91475 Mon Sep 17 00:00:00 2001
From: Stefano Marinelli <stefano@dragas.it>
Date: Thu, 9 May 2024 15:23:06 +0200
Subject: [PATCH] Added DNS support

---
 README.md    | 48 ++++++++++++++++++++++++++++--------------------
 checkmyip.py | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 4a131bc..a2ac283 100644
--- a/README.md
+++ b/README.md
@@ -1,29 +1,37 @@
 # CheckMyIP - [myip.bsd.cafe](https://myip.bsd.cafe)
 
-A Telnet, SSH and Simple HTTP Based Public IP Address Lookup Service
+A Telnet, SSH, DNS and Simple HTTP Based Public IP Address Lookup Service
 
 
 -----------------------------------------
 
 ### USAGE
 
--   **TELNET**:
-    -   Default: `telnet myip.bsd.cafe`
-    -   IPv4: `telnet myip4.bsd.cafe`
-    -   IPv6: `telnet myip6.bsd.cafe`
--   **SSH**:
-    -   Default: `ssh myip.bsd.cafe`
-    -   IPv4: `ssh myip4.bsd.cafe`
-    -   IPv6: `ssh myip6.bsd.cafe`
-    -   Your SSH client may require you to enter a username. You can use anything you want (`ssh -l imrootbitch myip.bsd.cafe`)
--   **CURL**:
-    -   Default: `curl -L myip.bsd.cafe`
-    -   IPv4: `curl -L myip4.bsd.cafe`
-    -   IPv6: `curl -L myip6.bsd.cafe`
--   **WGET**:
-    -   Default: `wget -qO- myip.bsd.cafe`
-    -   IPv4: `wget -qO- myip4.bsd.cafe`
-    -   IPv6: `wget -qO- myip6.bsd.cafe`
+#### DNS
+- **DNS TXT Record**:
+  - Retrieve your IP via a DNS TXT record: `dig +short myip.bsd.cafe TXT @myip.bsd.cafe`
+
+#### Telnet
+- **Default**: `telnet myip.bsd.cafe`
+- **IPv4**: `telnet myip4.bsd.cafe`
+- **IPv6**: `telnet myip6.bsd.cafe`
+
+#### SSH
+- **Default**: `ssh myip.bsd.cafe`
+- **IPv4**: `ssh myip4.bsd.cafe`
+- **IPv6**: `ssh myip6.bsd.cafe`
+- Your SSH client may require you to enter a username. You can use anything you want (`ssh -l username myip.bsd.cafe`)
+
+#### CURL
+- **Default**: `curl -L myip.bsd.cafe`
+- **IPv4**: `curl -L myip4.bsd.cafe`
+- **IPv6**: `curl -L myip6.bsd.cafe`
+
+#### WGET
+- **Default**: `wget -qO- myip.bsd.cafe`
+- **IPv4**: `wget -qO- myip4.bsd.cafe`
+- **IPv6**: `wget -qO- myip6.bsd.cafe`
+
 
 -----------------------------------------
 ###   VERSION   ###
@@ -74,7 +82,7 @@ If you would rather set up your own private instance of CheckMyIP, then you can
 Install Dependencies (for example, on a FreeBSD jail)
 
 ```
-pkg install python39 py39-gssapi py39-paramiko
+pkg install python39 py39-gssapi py39-paramiko py39-dnspython
 ```
 
 Clone Repo and install
@@ -152,4 +160,4 @@ Visit the BSD Cafe Brew page (https://brew.bsd.cafe/BSDCafe/checkmyip) and eithe
 Original code by [John W Kerns](https://github.com/packetsar/checkmyip)
 
 [logo]: /checkmyip_icon-100.gif
-[whatismyip]: https://www.whatismyip.com/
\ No newline at end of file
+[whatismyip]: https://www.whatismyip.com/
diff --git a/checkmyip.py b/checkmyip.py
index bbbd0f9..7df33d3 100644
--- a/checkmyip.py
+++ b/checkmyip.py
@@ -21,6 +21,8 @@ import json
 import jinja2
 import paramiko
 import threading
+from dnslib import DNSRecord, DNSHeader, RR, TXT, QTYPE
+
 
 
 ##### Jinja formatting for logging queries #####
@@ -43,6 +45,40 @@ j2send = """{
 "sponsor": "Served by BSD Cafe, https://bsd.cafe/"
 }""" % version
 
+##### DNS Server Functionality #####
+class DNSResponder:
+    def __init__(self, address='::', port=5553):
+        self.address = address
+        self.port = port
+        self.sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+        self.sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 0)  # Enables dual-stack mode
+        self.sock.bind((self.address, self.port))
+
+    def run(self):
+        print("DNS Server listening on port 53 for both IPv4 and IPv6")
+        while True:
+            data, addr = self.sock.recvfrom(1024)
+            threading.Thread(target=self.handle_query, args=(data, addr)).start()
+
+    def handle_query(self, data, addr):
+        try:
+            request = DNSRecord.parse(data)
+            qname = request.q.qname
+            qtype = request.q.qtype
+            ip, port, *_ = addr  # Get IP and port; ignore other details
+
+            # Normalize IPv6 address (remove IPv4 mapping if exists)
+            if ip.startswith("::ffff:"):
+                ip = ip[7:]
+
+            # Only respond to TXT queries for myip.bsd.cafe
+            if qname.matchGlob('myip.bsd.cafe') and qtype == QTYPE.TXT:
+                response = DNSRecord(DNSHeader(id=request.header.id, qr=1, aa=1, ra=1), q=request.q)
+                response.add_answer(RR(qname, QTYPE.TXT, ttl=60, rdata=TXT(ip)))
+                self.sock.sendto(response.pack(), addr)
+        except Exception as e:
+            print(f"Error handling DNS query: {e}")
+
 
 ##### Handles all prnting to console and logging to the logfile #####
 class log_management:
@@ -263,6 +299,11 @@ def start():
 			args=(talker, talkers[talker]))
 		thread.daemon = True
 		thread.start()
+	# Start DNS server in a new thread
+	dns_server = DNSResponder()
+	dns_thread = threading.Thread(target=dns_server.run)
+	dns_thread.daemon = True
+	dns_thread.start()
 	while True:  # While loop to allow a CTRL-C interrupt when interactive
 		try:
 			time.sleep(1)