Related issue: #2688
- DnsClass and DnsType
- Make DnsClass and DnsType implement Comparable
- Optimize the message generation of IllegalArgumentException,
by pre-populating the list of the expected parameters
- Move the static methods up
- Relax the validation rule of DnsClass so that a user can define a
CLASS which is not listed in the RFC 1035
- valueOf(int) does not throw IllegalArgumentException anymore as long
as the specified value is an unsigned short.
- Rename create() and forName() to valueOf() so that they look like a
real enum
- Rename type() and clazz() to intValue() so that they conform to our
naming convention
- Add missing null checks in DnsEntry
Motivation:
DNS class and type were represented as integers rather than an enum or a
similar dedicated value type. This can be a potential source of a
parameter order bug which might be difficult to track down.
Modifications:
Add DnsClass and DnsType to replace integer parameters
Result:
Type safety and less error-proneness
Motivation:
When decoding the NAME field in a DNS Resource Record, DnsResponseDecoder
can raise a NullPointerException if the NAME field contains a loop.
Modification:
Instead of raising an NPE, raise CorruptedFrameException so that the
exception itself has meaning.
Result:
Less confusing when a malformed DNS RR is received
Motivation:
NullPointerException is raised when a DNS response conrains a resource
record whose NAME is empty, which is the case for the authority section.
Modification:
Allow an empty name for DnsEntry. Only disallow an empty name for
DnsQuestion.
Result:
Fixes#2686
Motivation:
DNS packets that contain pointers in a loop will cause
DnsResponseDecoder.readName() to infinite loop.
Modifications:
Fixed DnsResponseDecoder.readName() to detect when packets have loops
and return null instead.
Result:
It is no longer possible to cause Netty to infinite loop by sending it malformed
DNS packets with a loop.
Motivation:
As part of GSOC 2013 we had @mbakkar working on a DNS codec but did not integrate it yet as it needs some cleanup. This commit is based on @mbakkar's work and provide the codec for DNS.
Modifications:
Add DNS codec
Result:
Reusable DNS codec will be included in netty.
This PR also includes a AsynchronousDnsResolver which allows to resolve DNS entries in a non blocking way by make use
of the dns codec and netty transport itself.
