search

tonyp7 / esp32-wifi-manager

Captive Portal for ESP32 that can connect to a saved wireless network or start an access point where you can connect to existing wifis.
MIT License
673 stars 220 forks source link

DNS requests from Android11 cause disconnects #141

Open tofublock opened 3 years ago

tofublock commented 3 years ago

Prerequisites

Description

Building this project out of the box and trying to connect to the captive portal from Android11 I get "Header fields are too long for server to interpret", which is fixed by adjusting CONFIG_HTTPD_MAX_REQ_HDR_LEN=1024 in menuconfig (a lower value might work.) Connecting to the device after adjusting this I see the captive portal, but am kicked off the connection within about 5 seconds almost every time. After a few tries it sometimes stays on. I suspect that the problem is most likely with the DNS server. It seems that a lot of DNS requests from the connecting device bring the unwanted behaviour out more. All this happens with no log output - just a WIFI_EVENT_AP_STADISCONNECTED.

Similar behaviour is seen from a Win10 device with Firefox, where a browser full of AJAX tabs will prevent the captive portal from loading, but without a browser open it comes up fine. In this case at least the connection is not interrupted and navigating to 10.10.0.1 works.

Has anybody else seen this behaviour and found a way around it? My next guess would be to start poking around in the DNS server response, but I'm a bit out of my depth here...

Regardless of that issue, thanks a lot for this project, @tonyp7!

Steps to Reproduce

  1. Build and flash master branch as is and try to connect from Android11 => "Header fields are too long for server to interpret"
  2. Change CONFIG_HTTPD_MAX_REQ_HDR_LEN=1024 => Captive portal comes up for a few seconds, then WiFi disconnects

System Configuration

ESP-IDF 4.3 ESP32 chip revision 1

Vxs14 commented 2 years ago

Hy, i have got the same issue with ESP-IDF 4.2, did you find a solution ?

tofublock commented 2 years ago

Turning off the DNS server helps, at the cost of losing captive portal functionality.

Vxs14 commented 2 years ago

Thank you, indeed it helps for the connection but I should like to use some portal functionalities, i will try to rewrite the DNS code

tofublock commented 2 years ago

I found that only replying to a specific domain request helps a lot: Encapsulate lines 159 to 171 of dns_server.c in an if(strcmp(domain, "portal.info") == 0) block.

I'd be curious to know if you figure out more about it!