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yswery / PHP-DNS-SERVER

An Authoritative DNS Server written purely in PHP
MIT License
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nmap udp scan crashes the server #80

Closed nkakouros closed 5 years ago

nkakouros commented 5 years ago

Steps to reproduce:

  1. sudo php examples/example.php
  2. sudo nmap -sU -p53 127.0.0.1

This crashes the dns server with the following trace:

PHP Notice:  Undefined offset: 0 in /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php on line 126
PHP Fatal error:  Uncaught Error: Call to a member function getName() on null in /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php:126
Stack trace:
#0 /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php(102): yswery\DNS\Server->handleQueryFromStream('\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00')
#1 /home/nikos/Projects/PHP-DNS-SERVER/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php(123): yswery\DNS\Server->onMessage('\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00', '127.0.0.1:35464', Object(React\Datagram\Socket))
#2 /home/nikos/Projects/PHP-DNS-SERVER/vendor/react/datagram/src/Socket.php(75): Evenement\EventEmitter->emit('message', Array)
#3 /home/nikos/Projects/PHP-DNS-SERVER/vendor/react/event-loop/src/StreamSelectLoop.php(238): React\Datagram\Socket->onReceive(Resource id #62)
#4 /home/nikos/Projects/PHP-DNS-SERVER/vendor/react/event-loop/src/StreamSelectLoop.php(205): React\EventLoop\StreamSelectLoop->waitForStreamActivity(NULL)
#5 /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php(88): React\EventLoo in /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php on line 126

Running tcpdump -i lo port 53 -vvv in parallel with nmap, shows the following captured packets being sent from nmap:

tcpdump: listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
18:13:33.344773 IP (tos 0x0, ttl 49, id 30626, offset 0, flags [none], proto UDP (17), length 40)
    nikos-laptop.localdomain.45844 > nikos-laptop.localdomain.domain: [udp sum ok] 0 stat [0q] (12)

Here is a screenshot of the packet in wireshark: screenshot_20181120_181557

samuelwilliams commented 5 years ago

This might be because the server just assumes that the DNS packet has a question, your packet has none. This should be an easy fix.

samuelwilliams commented 5 years ago

@tterranigma give the latest commit a go

nkakouros commented 5 years ago

It fails again with:

[nikos@localhost PHP-DNS-SERVER]$ sudo php example/example.php 
[2018-11-21T23:05:14+00:00] info: Server started.
[2018-11-21T23:05:14+00:00] info: Listening on 0.0.0.0:53
PHP Notice:  Undefined offset: 0 in /home/nikos/Projects/PHP-DNS-SERVER/src/Resolver/SystemResolver.php on line 44
PHP Fatal error:  Uncaught Error: Call to a member function getName() on null in /home/nikos/Projects/PHP-DNS-SERVER/src/Resolver/SystemResolver.php:46
Stack trace:
#0 /home/nikos/Projects/PHP-DNS-SERVER/src/Resolver/StackableResolver.php(35): yswery\DNS\Resolver\SystemResolver->getAnswer(Array)
#1 /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php(129): yswery\DNS\Resolver\StackableResolver->getAnswer(Array)
#2 /home/nikos/Projects/PHP-DNS-SERVER/src/Server.php(102): yswery\DNS\Server->handleQueryFromStream('\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00')
#3 /home/nikos/Projects/PHP-DNS-SERVER/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php(123): yswery\DNS\Server->onMessage('\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00', '127.0.0.1:48652', Object(React\Datagram\Socket))
#4 /home/nikos/Projects/PHP-DNS-SERVER/vendor/react/datagram/src/Socket.php(75): Evenement\EventEmitter->emit('message', Array)
#5 /home/nikos/Projects/PHP-DNS-SERVER/vendor/react/event-loop/src/StreamSelectLoop.php(238): React\Datagram\ in /home/nikos/Projects/PHP-DNS-SERVER/src/Resolver/SystemResolver.php on line 46
samuelwilliams commented 5 years ago

@tterranigma give the latest commit a go - I'm having issues with my system so I can't run my linux boxes at the moment to test

nkakouros commented 5 years ago

Yep! It worked!

[nikos@localhost PHP-DNS-SERVER]$ sudo nmap 127.0.0.1 -sU -p 53
Starting Nmap 7.70 ( https://nmap.org ) at 2018-11-23 22:28 CET
Nmap scan report for nikos-laptop.localdomain (127.0.0.1)
Host is up (0.0038s latency).

PORT   STATE SERVICE
53/udp open  domain

Nmap done: 1 IP address (1 host up) scanned in 0.14 seconds

Thank you for the time you devoted on this issue!

samuelwilliams commented 5 years ago

Issue resolved in v1.1.3