From 8b9386898394bc749ea4e926f8b2e3f3e8e8e5c3 Mon Sep 17 00:00:00 2001
From: Johannes Kimmel <fff@bareminimum.eu>
Date: Fri, 17 Nov 2023 17:01:29 +0100
Subject: [PATCH] restrict available subnet sizes

---
 index.html         | 12 +++---------
 ipalloc/ipalloc.go | 14 +++++++++++---
 main.go            | 17 +++++++++++++++--
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/index.html b/index.html
index e691568..3ad4ca4 100644
--- a/index.html
+++ b/index.html
@@ -112,15 +112,9 @@
 		</details>
 
 		<div id="control" hx-swap="none">
-			<button hx-get="/api/alloc/32">/32</button>
-			<button hx-get="/api/alloc/31">/31</button>
-			<button hx-get="/api/alloc/30">/30</button>
-			<button hx-get="/api/alloc/29">/29</button>
-			<button hx-get="/api/alloc/28">/28</button>
-			<button hx-get="/api/alloc/27">/27</button>
-			<button hx-get="/api/alloc/26">/26</button>
-			<button hx-get="/api/alloc/25">/25</button>
-			<button hx-get="/api/alloc/24">/24</button>
+			{{- range .Api.AllowedLengths }}
+			<button hx-get="/api/alloc/{{ . }}">/{{ . }}</button>
+			{{- end }}
 		</div>
 
 		{{ block "update" .Update }}<div id="updatemsg" class="card {{ .Type }}" hx-swap-oob="morph">{{ with .Content }}{{ . }}{{ end }}</div>{{ end }}
diff --git a/ipalloc/ipalloc.go b/ipalloc/ipalloc.go
index e7ab035..f03814a 100644
--- a/ipalloc/ipalloc.go
+++ b/ipalloc/ipalloc.go
@@ -266,13 +266,21 @@ func (t *tree) Dot() string {
 
 type DB struct {
 	sync.Mutex
-	provisions *tree
+	provisions     *tree
+	allowedLengths []int
 }
 
-func NewDB(prefix string) *DB {
-	return &DB{provisions: &tree{prefix: netip.MustParsePrefix(prefix)}}
+func NewDB(prefix string, allowedLengths ...int) *DB {
+	p := netip.MustParsePrefix(prefix)
+	if canonical := p.Masked(); p.Addr() != canonical.Addr() {
+		log.Fatalf("Prefix %q is not in canonical form, use: %q", p, canonical)
+	}
+	return &DB{provisions: &tree{prefix: p}, allowedLengths: allowedLengths}
 }
 
+func (db *DB) AllowedLengths() []int {
+	return slices.Clip(db.allowedLengths)
+}
 func (db *DB) Used() []netip.Prefix {
 	db.Lock()
 	defer db.Unlock()
diff --git a/main.go b/main.go
index e30c408..0e4e55c 100644
--- a/main.go
+++ b/main.go
@@ -32,7 +32,10 @@ func (s *server) setup() {
 	s.mux.HandleFunc("/api/print/", s.apiPrint)
 	//s.mux.HandleFunc("/api/provision/", s.apiProvision)
 
-	s.ipdb = ipalloc.NewDB("10.83.46.0/23")
+	s.ipdb = ipalloc.NewDB("10.83.46.0/23", 32, 29, 28, 27, 26)
+	//s.ipdb = ipalloc.NewDB("fd43:5602:29bd:fffe::/64", 128, 127, 126)
+	//s.ipdb = ipalloc.NewDB("fd43:5602:29bd:ffff:ffff:ffff:0:0/96", 128, 127, 126)
+	//s.ipdb = ipalloc.NewDB("fd43:5602:29bd:ffff:ffff:ffff:ffff:0/112", 128)
 	s.tmpl = template.Must(template.ParseFS(webcontent, "index.html"))
 }
 
@@ -59,7 +62,17 @@ type UpdateMessage struct {
 }
 
 func (s *server) template(w http.ResponseWriter, r *http.Request) {
-	err := s.tmpl.Execute(w, PageContent{Api: s.ipdb, Treemap: s.ipdb.Treemap()})
+	err := s.tmpl.Execute(w,
+		PageContent{
+			Api: s.ipdb,
+			Update: UpdateMessage{
+				Type:    "hint",
+				Content: template.HTML("&nbsp;"),
+			},
+			Treemap: s.ipdb.Treemap(),
+		},
+	)
+	
 	if err != nil {
 		log.Println(err)
 	}