Optimize server startup speed, client update caching, and HTTP 304 conditional downloads

src/client_updater.py

@@ -76,22 +76,48 @@ class ClientUpdater:
     def download_package(self, download_path_rel: str, expected_sha256: str, target_temp: str, timeout: int = 30) -> bool:
         """
         Downloads the client binary package from the server and validates its SHA-256 checksum.
+        Uses local binary hash checking and ETag conditional headers to avoid redundant downloads.
         """
+        # 1. If running binary already matches target SHA-256, skip downloading
+        target_exec = sys.executable
+        if expected_sha256 and os.path.exists(target_exec):
+            try:
+                local_sha = self.calculate_sha256(target_exec)
+                if local_sha and local_sha == expected_sha256.lower():
+                    print(f"[*] Local binary already matches target checksum ({local_sha[:12]}...). Skipping redundant download.")
+                    return True
+            except Exception:
+                pass
+
         base_url = self.get_server_base_url()
         download_url = f"{base_url.rstrip('/')}/{download_path_rel.lstrip('/')}"
 
         print(f"[*] Downloading client update package from {download_url}...")
-        req = urllib.request.Request(
-            download_url,
-            headers={"User-Agent": f"LOGAR-Client/{self.current_version} ({self.os_type})"}
-        )
-        with urllib.request.urlopen(req, timeout=timeout) as resp:
-            if resp.status != 200:
-                print(f"[!] Server returned HTTP {resp.status} during update download.")
-                return False
-            with open(target_temp, "wb") as f:
-                while chunk := resp.read(65536):
-                    f.write(chunk)
+        headers = {"User-Agent": f"LOGAR-Client/{self.current_version} ({self.os_type})"}
+        if expected_sha256:
+            headers["If-None-Match"] = f'"{expected_sha256}"'
+
+        req = urllib.request.Request(download_url, headers=headers)
+        try:
+            with urllib.request.urlopen(req, timeout=timeout) as resp:
+                if resp.status == 304:
+                    print("[+] Server returned 304 Not Modified. Local binary package is current.")
+                    return True
+                if resp.status != 200:
+                    print(f"[!] Server returned HTTP {resp.status} during update download.")
+                    return False
+                with open(target_temp, "wb") as f:
+                    while chunk := resp.read(65536):
+                        f.write(chunk)
+        except urllib.error.HTTPError as e:
+            if e.code == 304:
+                print("[+] Server returned 304 Not Modified. Local binary package is current.")
+                return True
+            print(f"[!] HTTP error during update download: {e}")
+            return False
+        except Exception as e:
+            print(f"[!] Error downloading update package: {e}")
+            return False
 
         # Verify SHA-256
         actual_sha256 = self.calculate_sha256(target_temp)