jczic / microdnssrv Goto Github PK

A micro DNS server for MicroPython to simply respond to A queries on multi-domains with or without wildcards (used on Pycom modules & ESP32)

Home Page: https://microdnssrv.hc2.fr

License: MIT License

Python 100.00%

pycom micropython dns-server esp32 lopy wipy captive-portal dns wildcard hc2

microdnssrv's Introduction

MicroDNSSrv is a micro DNS server for MicroPython to simply respond to A queries (principally used on ESP32 and Pycom modules)

Very easy to integrate and very light with one file only :

"microDNSSrv.py"

Simple but effective :

Use it to embed a fast DNS server in yours modules
Simply responds to A queries (only)
Use a list of multiple domains
Include wildcards in the scheme of names
Use it to make a captive portal simply

Using microDNSSrv main class :

Name	Function
Constructor	`mds = MicroDNSSrv()`
Start DNS server	`mds.Start()`
Stop DNS server	`mds.Stop()`
Check if DNS server is running	`mds.IsStarted()`
Set the domain names list	`mds.SetDomainsList(domainsList)`

Basic example :

from microDNSSrv import MicroDNSSrv
domainsList = {
  "test.com"   : "1.1.1.1",
  "*test2.com" : "2.2.2.2",
  "*google*"   : "192.168.4.1",
  "*.toto.com" : "192.168.4.1",
  "www.site.*" : "192.168.4.1" }
mds = MicroDNSSrv(domainsList)
if mds.Start() :
  print("MicroDNSSrv started.")
else :
  print("Error to starts MicroDNSSrv...")

Using microDNSSrv speedly creation of the class :

from microDNSSrv import MicroDNSSrv
if MicroDNSSrv.Create( {
  "test.com"   : "1.1.1.1",
  "*test2.com" : "2.2.2.2",
  "*google*"   : "192.168.4.1",
  "*.toto.com" : "192.168.4.1",
  "www.site.*" : "192.168.4.1" } ) :
  print("MicroDNSSrv started.")
else :
  print("Error to starts MicroDNSSrv...")

Using for a captive portal :

MicroDNSSrv.Create({ '*' : '192.168.0.254' })

Can be used with MicroWebSrv easily.

By JC`zic for HC² ;')

Keep it simple, stupid 👍

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microdnssrv's Issues

Dns answers to partial FQDN match

I did an improvement in order to match a word in the fqdn asked.
Now in the domain list, you can put something like : {'"test" : "192.168.4.1"}
And making a DNS request on www.test.com, test.fr, test, will replay with "192.168.4.1".
This is useful for configuration web portal.

`
# ============================================================================
# ===( Server Thread )========================================================
# ============================================================================

def _serverProcess(self) :
    self._started = True
    debug = True
    while True :
        try :
            packet, cliAddr = self._server.recvfrom(256)
            domName = MicroDNSSrv._getAskedDomainName(packet)
            if domName:
                ipB = self._domList.get(domName.lower(), None)
                if debug and ipB:
                    print("DNS: full domain matched: " + domName.lower())

                if not ipB:
                    for word_a in domName.lower().split("."):
                        for word_b in self._domList.keys():
                            if word_a == word_b:
                                if debug:
                                    print("DNS: word matched: " + word_b)
                                ipB = self._domList.get(word_b, None)
                                break
                        if ipB:
                            break

                if not ipB:
                    ipB = self._domList.get('*', None)
                    if debug and ipB:
                        print("DNS: catchall matched.")

                if not ipB:
                    if debug:
                        print("DNS: no match found.")

                if ipB:
                    packet = MicroDNSSrv._getPacketAnswerA(packet, ipB)
                    if packet :
                        self._server.sendto(packet, cliAddr)

        except :
            if not self._started :
                break

Confused on how to get working

Here is my simple setup:


import network
from microDNSSrv import MicroDNSSrv

ap = network.WLAN(network.AP_IF)
ap.ifconfig(("192.168.4.1", "255.255.255.0", "192.168.0.1", "10.0.0.1"))
ap.active(True)
ap.config(essid = "Simple Test", password = "")

while ap.active() == False: pass

print('Created AP.')
print(ap.ifconfig())

if MicroDNSSrv.Create({"*": ap.ifconfig()[1]}):
    print("yay")
else:
    print("Error to starts MicroDNSSrv...")

print()
print("=======================================================================")
print()

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 80))
s.listen(5)

with open('index.html', 'r') as f:
    pageHTML = f.read()

while True:
    conn, addr = s.accept()
    print('Got a connection from %s' % str(addr))
    request = conn.recv(1024)
    print(request)
    conn.send(pageHTML)
    conn.close()

however, if I connect to the AP on my phone there is no prompt, and going to some arbitrary website does not redirect me. What am I doing wrong?

License ?

Hello JC, can you put a license header in your code please ?

DNS answer KO when OPTs in request

Hello JC, when a query has options (ex : DNSSEC options), the code reproduces it in the query section of answer. It is reproductible qith dig on linux. This leads to DNS client fuzzying.
I patched the code in order to send only the first query part and now it is working:

     def _getPacketAnswerA(packet, ipV4Bytes) :
        try :
            pos = 12
            while True :
                domPartLen = packet[pos]
                if (domPartLen == 0) :
                    break
                pos += 1 + domPartLen
            query_end = pos + 5

            return b''.join( [
                packet[:2],             # Query identifier
                b'\x85\x80',            # Flags and codes
                packet[4:6],            # Query question count
                b'\x00\x01',            # Answer record count
                b'\x00\x00',            # Authority record count
                b'\x00\x00',            # Additional record count
                packet[12:query_end],   # Query question
                b'\xc0\x0c',            # Answer name as pointer
                b'\x00\x01',            # Answer type A
                b'\x00\x01',            # Answer class IN
                b'\x00\x00\x00\x1E',    # Answer TTL 30 secondes
                b'\x00\x04',            # Answer data length
                ipV4Bytes ] )           # Answer data
        except :
            pass
        return None

Thread not started with Loboris firmware

Due to Loboris thread implementation, a thread name is required at start.
ex : start_new_thread("MicroDNSSrv", func, args)
A solution could be to detect Loboris firmware in the code (version='ESP32_LoBo_v3.1.14 on 2017-01-29')...

I have seen your JSON/RPC client, I think I will test it someday :-)

BR Gautier
(JC : je mets mes remarques sur git, cela peut servir à d'autres).