Development

routlin/mod_avahi.py

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+"""
+mod_avahi.py -- Avahi mDNS reflector configuration and management.
+
+Patches avahi-daemon.conf with the correct interface list and manages
+the avahi-daemon service lifecycle.
+"""
+
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import mod_shared as shared
+import mod_validation as validation
+
+AVAHI_CONF_FILE = Path("/etc/avahi/avahi-daemon.conf")
+
+
+# ===================================================================
+# State helpers
+# ===================================================================
+
+def avahi_enabled(data):
+    """Return True if at least one non-WireGuard VLAN has mdns_reflection enabled."""
+    return any(v.get("mdns_reflection") is True
+               for v in data.get("vlans", [])
+               if not validation.is_wg(v))
+
+def avahi_interfaces(data):
+    """Return list of interface names for VLANs with mdns_reflection enabled."""
+    return [
+        validation.derive_interface(v, data)
+        for v in data.get("vlans", [])
+        if v.get("mdns_reflection") is True and not validation.is_wg(v)
+    ]
+
+
+# ===================================================================
+# Config generation
+# ===================================================================
+
+def build_avahi_conf(data):
+    """Patch avahi-daemon.conf directives needed for cross-VLAN mDNS reflection.
+    Reads the existing file (default or previously patched) and modifies only
+    the specific directives we need, leaving everything else untouched.
+    Returns the patched config as a string. Caller is responsible for ensuring
+    the file exists before calling (apply_avahi guards this).
+    """
+    ifaces = avahi_interfaces(data)
+    content = AVAHI_CONF_FILE.read_text()
+
+    def set_directive(text, directive, value):
+        """Enable and set a directive, whether it is commented out or already set."""
+        pattern = re.compile(
+            rf"^#?\s*{re.escape(directive)}\s*=.*$", re.MULTILINE
+        )
+        replacement = f"{directive}={value}"
+        if pattern.search(text):
+            return pattern.sub(replacement, text)
+        return text + f"\n{replacement}\n"
+
+    content = set_directive(content, "use-ipv6",              "no")
+    content = set_directive(content, "disallow-other-stacks", "yes")
+    content = set_directive(content, "allow-interfaces",      ",".join(ifaces))
+    content = set_directive(content, "enable-reflector",      "yes")
+    content = set_directive(content, "disable-publishing",    "yes")
+
+    return content
+
+
+# ===================================================================
+# Apply
+# ===================================================================
+
+def apply_avahi(data):
+    """Write avahi-daemon.conf and ensure service is running."""
+    if not shutil.which("avahi-daemon"):
+        print("avahi-daemon is not installed.")
+        print("  -> Run: sudo python3 install.py")
+        return
+
+    ifaces = avahi_interfaces(data)
+
+    if len(ifaces) < 2:
+        print("mDNS reflection requires at least two VLANs in reflect_vlans. Skipping.")
+        return
+
+    if not AVAHI_CONF_FILE.exists():
+        print(f"WARNING: {AVAHI_CONF_FILE} not found. Run: sudo python3 install.py")
+        return
+
+    content  = build_avahi_conf(data)
+    existing = AVAHI_CONF_FILE.read_text()
+    changed  = existing != content
+    if changed:
+        AVAHI_CONF_FILE.write_text(content)
+        print(f"Written: {AVAHI_CONF_FILE}")
+        print(f"  Reflecting mDNS across: {', '.join(ifaces)}")
+    else:
+        print(f"Unchanged: {AVAHI_CONF_FILE}")
+
+    svc   = "avahi-daemon"
+    state = subprocess.run(
+        ["systemctl", "is-active", svc], capture_output=True, text=True
+    ).stdout.strip()
+
+    if state == "active":
+        if changed:
+            result = subprocess.run(["systemctl", "restart", svc],
+                                    capture_output=True, text=True)
+            if result.returncode == 0:
+                print("avahi-daemon restarted.")
+            else:
+                shared.service_warning("restart", "avahi-daemon", result.stderr)
+        else:
+            print("avahi-daemon: running, config unchanged.")
+    else:
+        subprocess.run(["systemctl", "enable", svc], capture_output=True, text=True)
+        result = subprocess.run(["systemctl", "start", svc],
+                                capture_output=True, text=True)
+        if result.returncode == 0:
+            print("avahi-daemon started.")
+        else:
+            shared.service_warning("start", "avahi-daemon", result.stderr)
+
+def disable_avahi():
+    """Stop and disable avahi-daemon."""
+    result = subprocess.run(
+        ["systemctl", "is-active", "avahi-daemon"], capture_output=True, text=True
+    )
+    if result.stdout.strip() == "active":
+        subprocess.run(["systemctl", "disable", "--now", "avahi-daemon"],
+                       capture_output=True, text=True)
+        print("avahi-daemon stopped and disabled.")
+    else:
+        print("avahi-daemon: not running, skipping.")