feat: dhcpv4: send current hostname, fix spec compliance of renewals

This adds support for automatically registering node hostnames in DNS by
sending the current hostname to DHCP via option 12. If the current hostname is
updated, issue a new DISCOVER to propagate the update to DHCP (updating the
hostname on lease renewals is not universally supported by DHCP servers). This
addition maintains the previous functionality where the node can also request
its hostname from the DHCP server. The received hostname will be processed and
prioritized as usual by the `network.HostnameSpecController`.

This change set also contains fixes to make DHCP renewals compliant with RFC
2131, specifically avoiding sending the server identifier and requested IP
address when issuing renewals using a previous offer. This also uncovered
issues and missing features in the upstream `insomniacslk/dhcp` library, the
fixes and improvements for which are now finally merged.

Sending hostname updates have been tested against `dnsmasq` and the built-in
DHCP + DNS services in Windows Server. Hostname retrieval from DHCP and edge
cases with overridden hostnames from different configuration layers have been
extensively tested against `dnsmasq`.

Signed-off-by: Dennis Marttinen <twelho@welho.tech>
Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>

api/resource/definitions/network/network.proto

@@ -96,14 +96,14 @@ message HardwareAddrSpec {
   bytes hardware_addr = 2;
 }
 
-// HostnameSpecSpec describes node nostname.
+// HostnameSpecSpec describes node hostname.
 message HostnameSpecSpec {
   string hostname = 1;
   string domainname = 2;
   talos.resource.definitions.enums.NetworkConfigLayer config_layer = 3;
 }
 
-// HostnameStatusSpec describes node nostname.
+// HostnameStatusSpec describes node hostname.
 message HostnameStatusSpec {
   string hostname = 1;
   string domainname = 2;

go.mod

@@ -65,7 +65,7 @@ require (
 	github.com/hashicorp/go-multierror v1.1.1
 	github.com/hashicorp/go-version v1.6.0
 	github.com/hetznercloud/hcloud-go v1.41.0
-	github.com/insomniacslk/dhcp v0.0.0-20230307103557-e252950ab961
+	github.com/insomniacslk/dhcp v0.0.0-20230327135226-74ae03f2425e
 	github.com/jsimonetti/rtnetlink v1.3.1
 	github.com/jxskiss/base62 v1.1.0
 	github.com/martinlindhe/base36 v1.1.1

go.sum

@@ -813,8 +813,8 @@ github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANyt
 github.com/inconshreveable/mousetrap v1.0.1/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
-github.com/insomniacslk/dhcp v0.0.0-20230307103557-e252950ab961 h1:x/YtdDlmypenG1te/FfH6LVM+3krhXk5CFV8VYNNX5M=
-github.com/insomniacslk/dhcp v0.0.0-20230307103557-e252950ab961/go.mod h1:IKrnDWs3/Mqq5n0lI+RxA2sB7MvN/vbMBP3ehXg65UI=
+github.com/insomniacslk/dhcp v0.0.0-20230327135226-74ae03f2425e h1:8ChxkWKTVYg7LKBvYNLNRnlobgbPrzzossZUoST2T7o=
+github.com/insomniacslk/dhcp v0.0.0-20230327135226-74ae03f2425e/go.mod h1:IKrnDWs3/Mqq5n0lI+RxA2sB7MvN/vbMBP3ehXg65UI=
 github.com/j-keck/arping v0.0.0-20160618110441-2cf9dc699c56/go.mod h1:ymszkNOg6tORTn+6F6j+Jc8TOr5osrynvN6ivFWZ2GA=
 github.com/jmespath/go-jmespath v0.0.0-20160202185014-0b12d6b521d8/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=
 github.com/jmespath/go-jmespath v0.0.0-20160803190731-bd40a432e4c7/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=