1 files changed, 89 insertions, 0 deletions
diff --git a/stacks/daemon/banlist.py b/stacks/daemon/banlist.py
new file mode 100644
index 0000000..061ed1f
--- /dev/null
+++ b/stacks/daemon/banlist.py
@@ -0,0 +1,89 @@
+"""Simple AX.25 source ban list for max25d — silent RX drop."""
+from __future__ import annotations
+
+import re
+import sys
+import threading
+from pathlib import Path
+from typing import Optional
+
+DEFAULT_BANS_FILE = Path("/etc/max25/bans.txt")
+
+_AX25_UI_SRC_RE = re.compile(r"\[AX25 UI ([^>]+)>")
+
+
+def extract_ax25_source(line: str) -> Optional[str]:
+    """Return source callsign from a formatted AX.25 UI RX line, or None."""
+    match = _AX25_UI_SRC_RE.search(line)
+    if not match:
+        return None
+    return match.group(1).strip().upper()
+
+
+def callsign_banned(ban_entry: str, source: str) -> bool:
+    """Match ban entry against an incoming source callsign."""
+    ban = ban_entry.strip().upper()
+    src = source.strip().upper()
+    if not ban or not src:
+        return False
+    if "-" in ban:
+        return ban == src
+    return ban == src.split("-", 1)[0]
+
+
+class BanList:
+    """Persistent set of banned AX.25 source addresses."""
+
+    def __init__(self, path: Path | str = DEFAULT_BANS_FILE) -> None:
+        self.path = Path(path)
+        self._lock = threading.Lock()
+        self._entries: set[str] = set()
+        self.load()
+
+    def load(self) -> None:
+        entries: set[str] = set()
+        try:
+            if self.path.is_file():
+                text = self.path.read_text(encoding="utf-8")
+                for raw in text.splitlines():
+                    line = raw.split("#", 1)[0].strip().upper()
+                    if line:
+                        entries.add(line)
+        except OSError as exc:
+            print(f"max25d: banlist load failed ({self.path}): {exc}", file=sys.stderr)
+        with self._lock:
+            self._entries = entries
+
+    def save(self) -> None:
+        lines = sorted(self._entries)
+        content = "\n".join(lines)
+        if content:
+            content += "\n"
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        self.path.write_text(content, encoding="utf-8")
+
+    def list(self) -> list[str]:
+        with self._lock:
+            return sorted(self._entries)
+
+    def add(self, callsign: str) -> None:
+        call = callsign.strip().upper()
+        with self._lock:
+            self._entries.add(call)
+            self.save()
+
+    def remove(self, callsign: str) -> bool:
+        call = callsign.strip().upper()
+        with self._lock:
+            if call not in self._entries:
+                return False
+            self._entries.remove(call)
+            self.save()
+            return True
+
+    def is_banned(self, source: str) -> bool:
+        src = source.strip().upper()
+        if not src:
+            return False
+        with self._lock:
+            return any(callsign_banned(entry, src) for entry in self._entries)