lolbradfitz/tinyderpclient

Change-Id: Idcc360abdcc723fcf5ccef9d539056c68b7aa2b2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/cmd/tinyderpclient/tinyderpclient.go b/cmd/tinyderpclient/tinyderpclient.go
new file mode 100644
index 000000000..746a216ff
--- /dev/null
+++ b/cmd/tinyderpclient/tinyderpclient.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"maps"
+	"net/http"
+	"slices"
+
+	"tailscale.com/derp/derphttp"
+	"tailscale.com/net/netmon"
+	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
+)
+
+func main() {
+	dm := &tailcfg.DERPMap{}
+	res, err := http.Get("https://controlplane.tailscale.com/derpmap/default")
+	if err != nil {
+		log.Fatalf("fetching DERPMap: %v", err)
+	}
+	defer res.Body.Close()
+	if err := json.NewDecoder(res.Body).Decode(dm); err != nil {
+		log.Fatalf("decoding DERPMap: %v", err)
+	}
+
+	region := slices.Sorted(maps.Keys(dm.Regions))[0]
+
+	netMon := netmon.NewStatic()
+	rc := derphttp.NewRegionClient(key.NewNode(), log.Printf, netMon, func() *tailcfg.DERPRegion {
+		return dm.Regions[region]
+	})
+	defer rc.Close()
+
+	if err := rc.Connect(context.Background()); err != nil {
+		log.Fatalf("rc.Connect: %v", err)
+	}
+}