"<name" is parsed as a valid domain

[WaLLy3K]

In raising this issue, I confirm the following:

• I have read and understood the contributors guide.
• The issue I am reporting can be replicated
• The issue I am reporting isn't a duplicate

How familiar are you with the codebase?:

0

---

[BUG] Expected Behaviour:
When browsing the WebUI or retrieving stats directly from FTL, all the results returned should be domain names

[BUG] Actual Behaviour:
Once in a while, <name is returned as a domain name

[BUG] Steps to reproduce:
No idea. I have seen this occur on multiple days, and I definitely don't have IPv6 enabled on any of my devices or routing hardware.

Log file output
From /var/log/pihole.log:

May  1 05:37:38 dnsmasq[26983]: query[A] Helios from 10.0.0.6
May  1 05:37:38 dnsmasq[26983]: /etc/hosts Helios is 10.0.0.6
May  1 05:37:38 dnsmasq[26983]: query[AAAA] Helios from 10.0.0.6
May  1 05:37:38 dnsmasq[26983]: cached Helios is NODATA-IPv6
May  1 05:37:38 dnsmasq[26983]: query[A] <name unprintable> from 10.0.0.6
May  1 05:37:38 dnsmasq[26983]: forwarded <name unprintable> to 123.456.789.112
May  1 05:37:38 dnsmasq[26983]: validation result is SECURE

Device specifics

Hardware Type: Raspberry Pi 3B
OS: DietPi v149

[DL6ER]

I see that there is a domain sanitization routine in dnsmasq's code:

/* There can be names in the cache containing control chars, don't 
   mess up logging or open security holes. */
static char *sanitise(char *name)
{
  unsigned char *r;
  if (name)
    for (r = (unsigned char *)name; *r; r++)
      if (!isprint((int)*r))
	return "<name unprintable>";

  return name;
}

which can return <name unprintable> instead of the real domain name if the name contains control characters (for whatever reason). Even though FTL handles this domain name correctly as, when looking at the debug output

[2017-05-01 12:56:15.208] New domain: <name unprintable> (679/1000)
[2017-05-01 12:56:15.218] New client: 10.0.0.6 (7/10)

is shown, actually the web interface seems to mess up things here as it does not expect any blank spaces in the domain name (this is also why you see only <name in the tables).

This behavior could be fixed in two ways:

1. Ignore the lines that contain <name unprintable> as domain altogether
2. Dig through the web interface code and try to identify what has to be changed.