Micropython AP - redirect all requests to index.html

[andypnz]

Hi. I have a micropython project that reads some sensor data and displays it on a html webpage. I connect to the project with it in AP mode. Currently I need to go to the specific URL (192.168.4.1) to view the webpage. I would like to change this so if I enter any URL, it redirects to 192.168.4.1 (index.html). I am happy to assume the device I connect with is setup to use DNS as provided by the AP:

ap.ifconfig(('192.168.4.1', '255.255.255.0', '192.168.4.1', '192.168.4.1'))
ap.config(essid="Battery Viewer", password="battery")

This code looks like it should do the job https://github.com/p-doyle/Micropython-DNSServer-Captive-Portal/tree/master

Any ideas (or other methods of doing this) much appreciated.....

I added these uasyncio tasks:

q=uasyncio.create_task(uasyncio.start_server(handle_client, "0.0.0.0", 80))   
r=uasyncio.create_task(run_dns_server())

And the main bit of code:

class DNSQuery:
	def __init__(self, data):
		self.data = data
		self.domain = ''
		tipo = (data[2] >> 3) & 15  # Opcode bits
		if tipo == 0:  # Standard query
			ini = 12
			lon = data[ini]
			while lon != 0:
				self.domain += data[ini + 1:ini + lon + 1].decode('utf-8') + '.'
				ini += lon + 1
				lon = data[ini]
		print("searched domain: " + self.domain)
	def response(self, ip):
		print("Response {} == {}".format(self.domain, ip))
		if self.domain:
			packet = self.data[:2] + b'\x81\x80'
			packet += self.data[4:6] + self.data[4:6] + b'\x00\x00\x00\x00'  # Questions and Answers Counts
			packet += self.data[12:]  # Original Domain Name Question
			packet += b'\xC0\x0C'  # Pointer to domain name
			packet += b'\x00\x01\x00\x01\x00\x00\x00\x3C\x00\x04'  # Response type, ttl and resource data length -> 4 bytes
			packet += bytes(map(int, ip.split('.')))  # 4bytes of IP
		print(packet)
		return packet

# function to handle incoming dns requests
async def run_dns_server():
    udps = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    # set non-blocking otherwise execution will stop at 'recvfrom' until a connection is received
    #  and this will prevent the other async threads from running
    udps.setblocking(False)
    # bind to port 53 on all interfaces
    udps.bind(('0.0.0.0', 53))      #53
    while True:
        try:
            gc.collect()
            data, addr = udps.recvfrom(4096)
            print("Incoming data...")
            print(data, addr)
            DNS = DNSQuery(data)    
            udps.sendto(DNS.response(SERVER_IP), addr)
            print("DNS response: ", (DNS.response(SERVER_IP), addr))
            print("Replying: {:s} -> {:s}".format(DNS.domain, SERVER_IP))
            await uasyncio.sleep_ms(100)
        except Exception as e:
            print("Timeout")
            await uasyncio.sleep_ms(3000)
    udps.close()

# function to handle incoming TCP connections
async def handle_client(reader, writer):
    try:
        gc.collect()
        data = await reader.read()
        message = data.decode()
        addr = writer.get_extra_info('peername')
        print('Received {} from {}'.format(message, addr))
        if len(message) > 0:
            response = 'HTTP/1.0 200 OK\r\n\r\n'
            print('HERE!')
            # load the template and return it to the client
            #with render_template('index.html') as f:
            with open('index.html') as f:
                response += f.read()
            yield from writer.awrite(response)
            yield from writer.aclose()
            print("client socket closed")
    except Exception as e:
        print('failed handling client: {}'.format(e))
    print('done with request from {}'.format(addr))

This is the output I get:

Incoming data...
b'1j\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x0ep140-fmfmobile\x06icloud\x03com\x00\x00A\x00\x01' ('192.168.4.16', 61793)
searched domain: p140-fmfmobile.icloud.com.
Response p140-fmfmobile.icloud.com. == 192.168.4.1
b'1j\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00\x0ep140-fmfmobile\x06icloud\x03com\x00\x00A\x00\x01\xc0\x0c\x00\x01\x00\x01\x00\x00\x00<\x00\x04\xc0\xa8\x04\x01'
Response p140-fmfmobile.icloud.com. == 192.168.4.1
b'1j\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00\x0ep140-fmfmobile\x06icloud\x03com\x00\x00A\x00\x01\xc0\x0c\x00\x01\x00\x01\x00\x00\x00<\x00\x04\xc0\xa8\x04\x01'
DNS response:  (b'1j\x81\x80\x00\x01\x00\x01\x00\x00\x00\x00\x0ep140-fmfmobile\x06icloud\x03com\x00\x00A\x00\x01\xc0\x0c\x00\x01\x00\x01\x00\x00\x00<\x00\x04\xc0\xa8\x04\x01', ('192.168.4.16', 61793))
Replying: p140-fmfmobile.icloud.com. -> 192.168.4.1
Timeout

I think 'async def handle_client' never runs......

[sophiedegran]

I have seen something whitch listen to dns port (AP port 53) and redirect to what port you want.
Look at pimoroni git - phew the file example is dns.py
Don't test but it seem good. Sure if you have both AP mode and STA that will hang! ;)
Tell me

[andypnz]

Thanks very much - I will look at that.....

[bidrohini]

You can see it in the output because the handle_client() function doesn't fully close the client connection after handling the request. To properly close the connection, you should call the close() method on the writer object after sending the response.

[andypnz]

Thanks.... I think udps.close() in async def run_dns_server(): covers that?

Actually, on testing again, it seems to be working - but seems to only redirect something like 'xyz.com' rather than any random entry....

[bixb922]

This approach probably does not fit what you need, but perhaps using MDNS setting network.hostname() might be useful. On the ESP32 (and probably other boards), MDNS works both in AP and STA mode, and avoids having to enter a specific IP in the browser.