From b0f4be70477ca0399ee6c869ae960d70f7098a85 Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 23 Oct 2023 22:41:17 +0000
Subject: [PATCH] dns: refactor GetRecords() to allow commands other than sync

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 pkg/dns/error.go   | 12 +++++++++
 pkg/dns/manager.go | 63 +++++++++++++++++++++++++++++++++++++++++++---
 pkg/dns/sync.go    | 17 +++++--------
 3 files changed, 78 insertions(+), 14 deletions(-)
 create mode 100644 pkg/dns/error.go

diff --git a/pkg/dns/error.go b/pkg/dns/error.go
new file mode 100644
index 0000000..abe9126
--- /dev/null
+++ b/pkg/dns/error.go
@@ -0,0 +1,12 @@
+package dns
+
+import "errors"
+
+var (
+	// ErrNoDNSProvider indicates a [libdns.Provider] wasn't assigned
+	// to the [Manager]
+	ErrNoDNSProvider = errors.New("dns provider not specified")
+
+	// ErrNoDomain indicates a domain wasn't specified
+	ErrNoDomain = errors.New("domain not specified")
+)
diff --git a/pkg/dns/manager.go b/pkg/dns/manager.go
index 8e29252..24dd62f 100644
--- a/pkg/dns/manager.go
+++ b/pkg/dns/manager.go
@@ -2,15 +2,16 @@ package dns
 
 import (
 	"context"
-	"errors"
 	"io/fs"
 	"net/netip"
 	"strings"
 
 	"darvaza.org/core"
 	"darvaza.org/slog"
-	"git.jpi.io/amery/jpictl/pkg/cluster"
+	"github.com/libdns/libdns"
 	"golang.org/x/net/publicsuffix"
+
+	"git.jpi.io/amery/jpictl/pkg/cluster"
 )
 
 // Manager is a DNS Manager instance
@@ -71,7 +72,7 @@ func (mgr *Manager) setDefaults() error {
 	}
 
 	if mgr.domain == "" || mgr.suffix == "" {
-		return errors.New("domain not specified")
+		return ErrNoDomain
 	}
 
 	for _, opt := range opts {
@@ -120,6 +121,62 @@ func NewManager(opts ...ManagerOption) (*Manager, error) {
 	return mgr, nil
 }
 
+// GetRecords pulls all the address records on DNS for our domain,
+// optionally only those matching the given names.
+func (mgr *Manager) GetRecords(ctx context.Context, names ...string) ([]libdns.Record, error) {
+	if mgr.p == nil {
+		return nil, ErrNoDNSProvider
+	}
+
+	recs, err := mgr.p.GetRecords(ctx, mgr.domain)
+	switch {
+	case err != nil:
+		// failed
+		return nil, err
+	case len(recs) == 0:
+		// empty
+		return []libdns.Record{}, nil
+	case mgr.suffix == "" && len(names) == 0:
+		// unfiltered
+		return recs, nil
+	default:
+		// filtered
+		recs = mgr.filterRecords(recs, names...)
+		return recs, nil
+	}
+}
+
+func (mgr *Manager) filterRecords(recs []libdns.Record, names ...string) []libdns.Record {
+	out := make([]libdns.Record, 0, len(recs))
+	for _, rr := range recs {
+		name, ok := mgr.matchSuffix(rr)
+		switch {
+		case !ok:
+			// skip, wrong subdomain
+			continue
+		case len(names) == 0:
+			// unfiltered, take it
+		case !core.SliceContains(names, name):
+			// skip, not one of the requested names
+			continue
+		}
+
+		out = append(out, rr)
+	}
+
+	return out
+}
+
+func (mgr *Manager) matchSuffix(rr libdns.Record) (string, bool) {
+	if mgr.suffix == "" {
+		// no suffix
+		return rr.Name, true
+	}
+
+	// remove suffix
+	return strings.CutSuffix(rr.Name, mgr.suffix)
+}
+
 // AddHost registers a host
 func (mgr *Manager) AddHost(_ context.Context, zone string, id int,
 	active bool, addrs ...netip.Addr) error {
diff --git a/pkg/dns/sync.go b/pkg/dns/sync.go
index 05b73cb..712022c 100644
--- a/pkg/dns/sync.go
+++ b/pkg/dns/sync.go
@@ -2,7 +2,6 @@ package dns
 
 import (
 	"context"
-	"errors"
 	"net/netip"
 	"sort"
 	"strings"
@@ -48,18 +47,14 @@ func SortSyncAddrSlice(s []SyncAddr) []SyncAddr {
 	return s
 }
 
-// GetRecords pulls all the address records on DNS for our domain
-func (mgr *Manager) GetRecords(ctx context.Context) ([]SyncAddrRecord, error) {
-	if mgr.p == nil {
-		return nil, errors.New("dns provider not specified")
-	}
-
-	recs, err := mgr.p.GetRecords(ctx, mgr.domain)
+// GetSyncRecords pulls all the address records on DNS for our domain
+func (mgr *Manager) GetSyncRecords(ctx context.Context) ([]SyncAddrRecord, error) {
+	recs, err := mgr.GetRecords(ctx)
 	if err != nil {
 		return nil, err
 	}
 
-	return mgr.filteredRecords(recs)
+	return mgr.filteredSyncRecords(recs)
 }
 
 // AsSyncAddr converts a A or AAAA [libdns.Record] into a [SyncAddr]
@@ -94,7 +89,7 @@ func (mgr *Manager) AsSyncAddr(rr libdns.Record) (SyncAddr, bool, error) {
 	return out, true, nil
 }
 
-func (mgr *Manager) filteredRecords(recs []libdns.Record) ([]SyncAddrRecord, error) {
+func (mgr *Manager) filteredSyncRecords(recs []libdns.Record) ([]SyncAddrRecord, error) {
 	// filter and convert
 	cache := make(map[string][]SyncAddr)
 	for _, rr := range recs {
@@ -137,7 +132,7 @@ func (mgr *Manager) filteredRecords(recs []libdns.Record) ([]SyncAddrRecord, err
 
 // Sync updates all the address records on DNS for our domain
 func (mgr *Manager) Sync(ctx context.Context) error {
-	current, err := mgr.GetRecords(ctx)
+	current, err := mgr.GetSyncRecords(ctx)
 	if err != nil {
 		return core.Wrap(err, "GetRecords")
 	}