feat: embedded derp

internal/derp/derp.go

@@ -0,0 +1,63 @@
+package derp
+
+import (
+	"encoding/json"
+	"github.com/hashicorp/go-getter"
+	"github.com/hashicorp/go-multierror"
+	"github.com/jsiebens/ionscale/internal/config"
+	"os"
+	"tailscale.com/tailcfg"
+)
+
+func LoadDERPSources(c *config.Config) (*tailcfg.DERPMap, error) {
+	derpMap := &tailcfg.DERPMap{
+		Regions: map[int]*tailcfg.DERPRegion{},
+	}
+
+	var merr *multierror.Error
+	for _, src := range c.DERP.Sources {
+		dm, err := loadDERPSource(src)
+		if err != nil {
+			merr = multierror.Append(merr, err)
+			continue
+		}
+
+		for id, r := range dm.Regions {
+			derpMap.Regions[id] = r
+		}
+	}
+
+	if !c.DERP.Server.Disabled {
+		dm := c.DefaultDERPMap()
+		for id, r := range dm.Regions {
+			derpMap.Regions[id] = r
+		}
+	}
+
+	return derpMap, merr.ErrorOrNil()
+}
+
+func loadDERPSource(src string) (*tailcfg.DERPMap, error) {
+	temp, err := os.CreateTemp(os.TempDir(), "derp-*.json")
+	if err != nil {
+		return nil, err
+	}
+	defer os.Remove(temp.Name())
+
+	if err := getter.Get(temp.Name(), src, getter.WithMode(getter.ClientModeFile)); err != nil {
+		return nil, err
+	}
+
+	content, err := os.ReadFile(temp.Name())
+	if err != nil {
+		return nil, err
+	}
+
+	var dm tailcfg.DERPMap
+
+	if err := json.Unmarshal(content, &dm); err != nil {
+		return nil, err
+	}
+
+	return &dm, nil
+}