add graphviz dot download endpoint

ipalloc/ipalloc.go

@@ -327,6 +327,9 @@ func (db *DB) All() []*tree {
 	})
 	return ret
 }
+func (db *DB) Dot() string {
+	return db.provisions.Dot()
+}
 func (db *DB) Alloc(bits int) (*tree, error) {
 	db.Lock()
 	defer db.Unlock()
@@ -407,7 +410,7 @@ func prefixShape(p netip.Prefix) Rect {
 	return Rect{
 		Y: 0,
 		X: 0,
-		H: 1 << (bits / 2),
+		H: 1 << (bits / 2), // TODO: handle overflow for normal ipv6 subnet sizes :)
 		W: 1 << ((bits + 1) / 2),
 	}
 }

main.go

@@ -4,6 +4,7 @@ import (
 	"embed"
 	"fmt"
 	"html/template"
+	"io"
 	"log"
 	"net/http"
 	"net/netip"
@@ -30,6 +31,7 @@ func (s *server) setup() {
 
 	s.mux.HandleFunc("/api/used/", s.apiUsed)
 	s.mux.HandleFunc("/api/print/", s.apiPrint)
+	s.mux.HandleFunc("/api/treemap.dot", s.apiDot)
 	//s.mux.HandleFunc("/api/provision/", s.apiProvision)
 
 	s.ipdb = ipalloc.NewDB("10.83.46.0/23", 32, 29, 28, 27, 26)
@@ -72,7 +74,13 @@ func (s *server) template(w http.ResponseWriter, r *http.Request) {
 			Treemap: s.ipdb.Treemap(),
 		},
 	)
-	
+
+	if err != nil {
+		log.Println(err)
+	}
+}
+func (s *server) apiDot(w http.ResponseWriter, r *http.Request) {
+	_, err := io.WriteString(w, s.ipdb.Dot())
 	if err != nil {
 		log.Println(err)
 	}