fix some certificate

main.py

@@ -12,6 +12,7 @@ import asyncio
 import json
 import logging
 import os
+import subprocess
 import sys
 
 from cert_installer import install_ca, is_ca_trusted
@@ -75,6 +76,70 @@ def parse_args():
     return parser.parse_args()
 
 
+def _windows_listener_details(host: str, port: int) -> tuple[str, str] | None:
+    """Best-effort lookup of the process listening on host:port on Windows."""
+    if os.name != "nt":
+        return None
+
+    try:
+        result = subprocess.run(
+            ["netstat", "-ano", "-p", "tcp"],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+    except Exception:
+        return None
+
+    port_suffix = f":{port}"
+    host_variants = {
+        f"{host}:{port}",
+        f"0.0.0.0:{port}",
+        f"[::]:{port}",
+        f"[::1]:{port}",
+        f"::{port}",
+    }
+
+    pid = None
+    for line in result.stdout.splitlines():
+        parts = line.split()
+        if len(parts) < 5 or parts[0] != "TCP":
+            continue
+        local_addr, state, candidate_pid = parts[1], parts[3].upper(), parts[4]
+        if state != "LISTENING":
+            continue
+        if local_addr in host_variants or local_addr.endswith(port_suffix):
+            pid = candidate_pid
+            break
+
+    if not pid:
+        return None
+
+    try:
+        proc = subprocess.run(
+            ["tasklist", "/FI", f"PID eq {pid}", "/FO", "CSV", "/NH"],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        line = proc.stdout.strip().splitlines()[0]
+        name = line.split(",")[0].strip('"') if line else "unknown"
+    except Exception:
+        name = "unknown"
+
+    return pid, name
+
+
+def _is_addr_in_use_error(exc: OSError) -> bool:
+    text = str(exc).lower()
+    return (
+        getattr(exc, "errno", None) in {48, 98, 10048}
+        or getattr(exc, "winerror", None) == 10048
+        or "address already in use" in text
+        or "only one usage of each socket address" in text
+    )
+
+
 def main():
     args = parse_args()
     config_path = args.config
@@ -196,6 +261,20 @@ def main():
 
     try:
         asyncio.run(ProxyServer(config).start())
+    except OSError as e:
+        if _is_addr_in_use_error(e):
+            host = config.get("listen_host", "127.0.0.1")
+            port = config.get("listen_port", 8080)
+            log.error("Cannot listen on %s:%d because that address is already in use.", host, port)
+            details = _windows_listener_details(host, port)
+            if details:
+                pid, name = details
+                log.error("Port %d is currently held by PID %s (%s).", port, pid, name)
+            log.error(
+                "Stop the other process or choose another port, for example: python main.py -p 9090"
+            )
+            sys.exit(1)
+        raise
     except KeyboardInterrupt:
         log.info("Stopped")