Identify tailnet callers once per connection; list processes via sysctl

internal/peer/peer.go

@@ -0,0 +1,37 @@
+package peer
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"sync"
+
+	"tailscale.com/client/local"
+	"tailscale.com/client/tailscale/apitype"
+)
+
+type key struct{}
+
+type peer struct {
+	mu  sync.Mutex
+	who *apitype.WhoIsResponse
+}
+
+func ConnContext(ctx context.Context, _ net.Conn) context.Context {
+	return context.WithValue(ctx, key{}, &peer{})
+}
+
+func WhoIs(r *http.Request, lc *local.Client) (*apitype.WhoIsResponse, error) {
+	p := r.Context().Value(key{}).(*peer)
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.who != nil {
+		return p.who, nil
+	}
+	who, err := lc.WhoIs(r.Context(), r.RemoteAddr)
+	if err != nil {
+		return nil, err
+	}
+	p.who = who
+	return who, nil
+}