From e0d8592dc1ef80bdd77bc423546e47e2ae3a025c Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 11 Sep 2023 23:26:47 +0000
Subject: [PATCH] dns: introduce AddrRecord{} to abstract A/AAAA entries

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 go.mod            |  1 +
 go.sum            |  2 ++
 pkg/dns/dns.go    |  2 ++
 pkg/dns/record.go | 89 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+)
 create mode 100644 pkg/dns/dns.go
 create mode 100644 pkg/dns/record.go

diff --git a/go.mod b/go.mod
index da2402f..939924e 100644
--- a/go.mod
+++ b/go.mod
@@ -11,6 +11,7 @@ require (
 	darvaza.org/slog/handlers/discard v0.4.5
 	github.com/gofrs/uuid/v5 v5.0.0
 	github.com/hack-pad/hackpadfs v0.2.1
+	github.com/libdns/libdns v0.2.1
 	github.com/mgechev/revive v1.3.3
 	github.com/spf13/cobra v1.7.0
 	golang.org/x/crypto v0.12.0
diff --git a/go.sum b/go.sum
index 3029c5c..b0a0a72 100644
--- a/go.sum
+++ b/go.sum
@@ -36,6 +36,8 @@ github.com/hack-pad/hackpadfs v0.2.1 h1:FelFhIhv26gyjujoA/yeFO+6YGlqzmc9la/6iKMI
 github.com/hack-pad/hackpadfs v0.2.1/go.mod h1:khQBuCEwGXWakkmq8ZiFUvUZz84ZkJ2KNwKvChs4OrU=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/libdns/libdns v0.2.1 h1:Wu59T7wSHRgtA0cfxC+n1c/e+O3upJGWytknkmFEDis=
+github.com/libdns/libdns v0.2.1/go.mod h1:yQCXzk1lEZmmCPa857bnk4TsOiqYasqpyOEeSObbb40=
 github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
diff --git a/pkg/dns/dns.go b/pkg/dns/dns.go
new file mode 100644
index 0000000..ca95946
--- /dev/null
+++ b/pkg/dns/dns.go
@@ -0,0 +1,2 @@
+// Package dns manages DNS entries for the cluster
+package dns
diff --git a/pkg/dns/record.go b/pkg/dns/record.go
new file mode 100644
index 0000000..2f8810d
--- /dev/null
+++ b/pkg/dns/record.go
@@ -0,0 +1,89 @@
+package dns
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/netip"
+	"sort"
+	"time"
+
+	"darvaza.org/core"
+	"github.com/libdns/libdns"
+)
+
+// SortAddrSlice sorts a slice of [netip.Addr]
+func SortAddrSlice(s []netip.Addr) []netip.Addr {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Less(s[j])
+	})
+	return s
+}
+
+// SortAddrRecords sorts a slice of [AddrRecord]
+// by Name and Address
+func SortAddrRecords(s []AddrRecord) []AddrRecord {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Name < s[j].Name
+	})
+
+	for _, p := range s {
+		SortAddrSlice(p.Addr)
+	}
+
+	return s
+}
+
+// AddrRecord represents an A or AAAA record
+type AddrRecord struct {
+	Name string
+	Addr []netip.Addr
+}
+
+// Sort sorts the addresses of the record
+func (rr *AddrRecord) Sort() {
+	SortAddrSlice(rr.Addr)
+}
+
+// Export converts the record into libdns.Record
+func (rr *AddrRecord) Export() []libdns.Record {
+	out := make([]libdns.Record, len(rr.Addr))
+	for i, addr := range rr.Addr {
+		out[i] = libdns.Record{
+			Name:  rr.Name,
+			TTL:   time.Second * 1,
+			Type:  core.IIf(addr.Is6(), "AAAA", "A"),
+			Value: addr.String(),
+		}
+	}
+
+	return out
+}
+
+// WriteTo writes the record in BIND notation
+func (rr *AddrRecord) WriteTo(w io.Writer) (int64, error) {
+	var total int
+	for _, addr := range rr.Addr {
+		n, err := fmt.Fprint(w,
+			rr.Name, "\t",
+			1, "\t",
+			core.IIf(addr.Is6(), "AAAA", "A"), "\t",
+			addr.String(), "\n")
+
+		switch {
+		case err != nil:
+			return 0, err
+		case n > 0:
+			total += n
+		}
+	}
+
+	return int64(total), nil
+}
+
+// String converts the record into BIND entries
+func (rr *AddrRecord) String() string {
+	var buf bytes.Buffer
+	_, _ = rr.WriteTo(&buf)
+	return buf.String()
+}