DNS for Pharo (Smalltalk)

This is an implementation of DNS encoding/decoding, transport. It includes the beginning of a stub resolver and should be a modern replacement for NetNameResolver.

Example usage

A DNSQuery can be sent over UDP, TCP or TLS (TLS over TCP). An example query sent over UDP is:

PaleoDNSTLSTransport new
	destAddress: #[8 8 4 4] port: 853;
	timeout: 2 seconds;
	query: (PaleoDNSQuery new
			   transactionId: (SharedRandom globalGenerator nextInt: 65535);
				addQuestion: (PaleoRRA new rr_name: 'pharo.org.');
				addAdditional: (PaleoRROpt new udpPayloadSize: 4096))

Your contribution here

If you are interested to modernize Pharo, want to learn about a protocol we use all the time. Then please consider making a contribution.

Below you can see a list of tasks and who implemented them. Most of them are bite sized tasks and easy to implement.

Unix integration

• Parse /etc/hosts and build local database (todo)
• Parse /etc/resolv.conf (todo)
• Parse hosts: in /etc/nsswitch.conf

MacOS integration

• Get system configuration?

Windows integration

• Tell me!

Stub resolver

• Add a basic stub resolver
• Add validation (transactionId match, qname matches)
• Add caching and respect TTL
• Add 0x20 randomization to the qname
• Respect platform settings

Transport

• Validate UDP src addr/port match the dest one
• Validate TLS certificate
• Add DNS over HTTP (DoH) support
• Learn reasonable timeouts for look-up based on past look-ups.

Resource Records:

Not all of them are equally important. The list attempts to order them in importannce.

• A record (zecke)

• OPT record (zecke)

• AAAA record

• NS record

• CNAME record

• SOA record

• SRV record

• MX record

• TXT record

• NULL record

• PTR record

• HINFO record

• MINFO record

• RP record

• AFSDB record

• RT record

• SIG record

• KEY record

• LOC record

• NAPTR record

• KX record

• CERT record

• DNAME record

• APL record

• DS record

• SSHFP record

• IPSECKEY record

• RRSIG record

• NSEC record

• DNSKEY record

• DHCID record

• NSEC3 record

• NSEC3PARAM record

• TLSA record

• CDS record

• CDNSKEY record

• SPF record

• NID record

• L32 record

• L64 record

• LP record

• EUI48 record

• EUI64 record

• TKEY record

• TSIG record

• IXFR record

• AFXR record

• ANY record

• URI record

• CAA record

EDNS Options

EDNS(0) is a way to extend DNS. The OPT record will contain a list of options. The most prominent is the Client Subnet Option (ECS).

• Client Subnet (RFC 7871)
• Padding (RFC 8467)

DNSSEC

DNSSEC allows an authoriative server to sign a response and a validating resolver will validate this. It's a complicated protocol and we could add support here (e.g. to build a resolver).

DANE

DNS-Based Authentication of Named Entities (DANE) is a separate root of trust anchored in DNS. This could be integrated with Zinc. The primary RFC is 6698.