captiveportal example not working on some platforms

[tablatronix]

Hardware:

Board: doit v1, ESP32 Dev Module
Core Installation/update date: today
IDE name: platformio
Flash Frequency: ?40Mhz?
Upload Speed: ?115200?

Description:

using captiveportal example
No captive portal launches on windows, linux, android.
surprisingly it works on osx and ios.

[Testato]

Bug confirmed here on Arduino IDE also

[tablatronix]

I see lots of malformed dns packets in wireshark.

iturd-Pro:tools shawn$ dig google.com
;; Warning: Message parser reports malformed message packet.

; <<>> DiG 9.9.7-P3 <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42797
;; flags: qr rd ad; QUERY: 0, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; Query time: 8 msec
;; SERVER: 192.168.4.1#53(192.168.4.1)
;; WHEN: Sun Jan 28 18:09:06 CST 2018
;; MSG SIZE  rcvd: 12

wireshark
[Expert Info (Error/Malformed): Malformed Packet (Exception occurred)]

[tablatronix]

Source mac must not be a group address and lg and ig bits present, does that sound right?

[tablatronix]

Looks like dig always fails, since it sends additional rr OPT every time, I noticed OPT and PTRs fail.

Ill look into this again tomorrow on new machines and see what I see, might not be related at all.

[Testato]

Probably i found the problem:
The DNSserver redirect all to 192.168.1.1, instead of the captive portal IP (192.168.4.1)

Log made on Win10

[tablatronix]

Are you using the captiveportal example, it uses that address instead.

[tablatronix]

This fixes it, the dns repsones are not including the question along with the answer.
This is from esp8266, not sure why @me-no-dev left it out.

DNSServer.cpp diff

@@ -135,15 +119,35 @@
   if (_buffer == NULL) return;
   _dnsHeader->QR = DNS_QR_RESPONSE;
   _dnsHeader->ANCount = _dnsHeader->QDCount;
-  _dnsHeader->QDCount = 0;
+  _dnsHeader->QDCount = _dnsHeader->QDCount; 
+  //_dnsHeader->RA = 1;  
 
   _udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
   _udp.write(_buffer, _currentPacketSize);
+
+  _udp.write((uint8_t)192); //  answer name is a pointer
+  _udp.write((uint8_t)12);  // pointer to offset at 0x00c
+
+  _udp.write((uint8_t)0);   // 0x0001  answer is type A query (host address)
+  _udp.write((uint8_t)1);
+
+  _udp.write((uint8_t)0);   //0x0001 answer is class IN (internet address)
+  _udp.write((uint8_t)1);
+ 
   _udp.write((unsigned char*)&_ttl, 4);

DNSServer.cpp updated

void DNSServer::replyWithIP()
{
  if (_buffer == NULL) return;
  _dnsHeader->QR = DNS_QR_RESPONSE;
  _dnsHeader->ANCount = _dnsHeader->QDCount;
  _dnsHeader->QDCount = _dnsHeader->QDCount; 
  // _dnsHeader->QDCount = 0;

  _udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
  _udp.write(_buffer, _currentPacketSize);

  _udp.write((uint8_t)192); //  answer name is a pointer
  _udp.write((uint8_t)12);  // pointer to offset at 0x00c

  _udp.write((uint8_t)0);   // 0x0001  answer is type A query (host address)
  _udp.write((uint8_t)1);

  _udp.write((uint8_t)0);   //0x0001 answer is class IN (internet address)
  _udp.write((uint8_t)1);
  
  _udp.write((unsigned char*)&_ttl, 4);
  _udp.write((uint8_t)0);
  _udp.write((uint8_t)4);
  _udp.write(_resolvedIP, 4);
  _udp.endPacket();
}

[tablatronix]

for the original fix,
heres the blame
https://github.com/esp8266/Arduino/blame/20b7e480b5a3e9aeffc056020d816a2fad4cbe12/libraries/DNSServer/src/DNSServer.cpp

and forum post
http://www.esp8266.com/viewtopic.php?f=32&t=3618&start=36

[nicogon]

Have you found a solution for android 7? Still not showing up popup

[tablatronix]

I dont have android to test, this issue should be resolved. Do you have the latest commits? Are you using the captive portal example