feat: implement comprehensive error diagnostics and structured error codes for VPN connectivity, API fetching, and proxy initialization.

proxy_server.py

@@ -51,7 +51,11 @@ def resolve_dns_over_tun0(host: str, dns_server: str = "8.8.8.8", timeout: float
         sock.settimeout(timeout)
         try:
             sock.setsockopt(socket.SOL_SOCKET, socket.SO_BINDTODEVICE, b"tun0")
-        except OSError:
+        except OSError as e:
+            if "operation not permitted" in str(e).lower() or e.errno == 1:
+                print("[DNS 绑定失败] [错误代码 3006] DNS 解析绑定 tun0 权限不足，请确保程序以 root 权限运行！", flush=True)
+            elif "no such device" in str(e).lower() or e.errno == 19:
+                print("[DNS 绑定失败] [错误代码 3004] DNS 解析绑定 tun0 失败，网卡设备不存在，请检查 VPN 连接！", flush=True)
             return None
         sock.sendto(packet, (dns_server, 53))
         resp, _ = sock.recvfrom(2048)
@@ -131,6 +135,10 @@ def create_connection(address: tuple[str, int], timeout: float = 20) -> socket.s
             return sock
         except OSError as e:
             err = e
+            if "operation not permitted" in str(e).lower() or e.errno == 1:
+                err = OSError(f"[错误代码 3006] [ERR_PROXY_BIND_TUN_PERM_DENIED] 绑定虚拟网卡 tun0 失败，权限不足！必须以 root 权限运行，或者进程缺少 CAP_NET_RAW 权限。")
+            elif "no such device" in str(e).lower() or e.errno == 19:
+                err = OSError(f"[错误代码 3004] [ERR_ROUTE_DEV_NOT_FOUND] 绑定虚拟网卡 tun0 失败，找不到设备！这通常是因为 OpenVPN 核心未能成功连接或已被异常终止。")
             if sock is not None:
                 sock.close()
     if err is not None:
@@ -255,7 +263,10 @@ def start_proxy_server(host: str, port: int) -> None:
         server.listen(256)
         print(f"HTTP/SOCKS5 proxy listening on {host}:{port}", flush=True)
     except Exception as e:
-        print(f"[ERROR] Failed to start HTTP/SOCKS5 proxy on {host}:{port}: {e}", flush=True)
+        import vpn_utils
+        diag = vpn_utils.diagnose_local_obstructions(port)
+        diag_msg = diag[1] if diag else str(e)
+        print(f"[ERROR] Failed to start HTTP/SOCKS5 proxy on {host}:{port}: {diag_msg}", flush=True)
         return
 
     while True: