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routlin/mod_shared.py

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+"""
+mod_shared.py -- Constants and helpers shared across all routlin modules.
+"""
+
+import ipaddress
+import os
+from pathlib import Path
+import mod_validation as validation
+
+PRODUCT_NAME     = "routlin"
+SCRIPT_DIR       = Path(__file__).parent
+DNSMASQ_CONF_DIR = Path(f"/etc/dnsmasq-{PRODUCT_NAME}")
+LEASES_DIR       = Path("/var/lib/misc")
+SYSTEMD_DIR      = Path("/etc/systemd/system")
+
+
+# ===================================================================
+# Process / error helpers
+# ===================================================================
+
+def is_root():
+    return os.geteuid() == 0
+
+
+def service_warning(action, svc, stderr):
+    msg = stderr.strip()
+    print(f"WARNING: Failed to {action} {svc}: {msg}")
+    if "not found" in msg.lower() or "not-found" in msg.lower():
+        print(f"  -> Package may not be installed. Run: sudo python3 install.py")
+
+
+def chown_to_script_dir_owner(path):
+    try:
+        stat = SCRIPT_DIR.stat()
+        os.chown(path, stat.st_uid, stat.st_gid)
+    except OSError:
+        pass
+
+
+# ===================================================================
+# Network / VLAN utilities
+# ===================================================================
+
+def prefix_to_dotted(n):
+    mask = (0xFFFFFFFF << (32 - int(n))) & 0xFFFFFFFF
+    return '.'.join(str((mask >> (8 * i)) & 0xFF) for i in (3, 2, 1, 0))
+
+
+def network_for(vlan):
+    return ipaddress.IPv4Network(f"{vlan['subnet']}/{vlan['subnet_mask']}", strict=False)
+
+
+def lowest_quartet_ip(vlan):
+    """Return the server_identity IP with the lowest last-octet value, or None if there are no valid identities."""
+    identities = vlan.get("server_identities", [])
+    ips = []
+    for s in identities:
+        try:
+            ips.append(ipaddress.IPv4Address(s["ip"]))
+        except (KeyError, ValueError):
+            pass
+    if not ips:
+        return None
+    return str(min(ips, key=lambda ip: ip.packed[-1]))
+
+
+def resolve_vlan_options(vlan):
+    """
+    Resolve gateway, dns_server, and ntp_server for a VLAN.
+
+    For both WG and non-WG VLANs: gateway defaults to the lowest-last-octet
+    server_identity IP unless overridden in explicit_overrides. The gateway
+    override must be one of the server_identity IPs.
+
+    WG VLANs: ntp_server is None (WireGuard has no DHCP so NTP cannot be
+    advertised to peers). Overrides live in vpn_information.explicit_overrides.
+
+    Non-WG VLANs: overrides live in dhcp_information.explicit_overrides.
+    Returns a dict with keys: gateway, dns_server, ntp_server.
+    """
+    if validation.is_wg(vlan):
+        vpi       = vlan["vpn_information"]
+        overrides = vpi.get("explicit_overrides", {})
+        default   = lowest_quartet_ip(vlan) or str(next(network_for(vlan).hosts()))
+        gateway   = overrides.get("gateway", "") or default
+        dns       = overrides.get("dns_servers", "") or gateway
+        return {
+            "gateway":    gateway,
+            "dns_servers": dns,
+            "ntp_servers": None,
+        }
+    overrides = vlan.get("dhcp_information", {}).get("explicit_overrides", {})
+    default   = lowest_quartet_ip(vlan)
+    def _resolve(key):
+        v = overrides.get(key, "")
+        if isinstance(v, list):
+            return ','.join(v) if v else default
+        return v or default
+    return {
+        "gateway":    overrides.get("gateway", "") or default,
+        "dns_servers": _resolve("dns_servers"),
+        "ntp_servers": _resolve("ntp_servers"),
+    }
+
+
+def is_physical(vlan):
+    return vlan.get("vlan_id") == 1
+
+
+# ===================================================================
+# VLAN naming / path helpers
+# ===================================================================
+
+def networkd_stem(vlan):
+    return f"10-{PRODUCT_NAME}-{vlan['name']}"
+
+
+def vlan_service_name(vlan, iface):
+    if validation.is_wg(vlan):
+        return f"dnsmasq-{PRODUCT_NAME}-{vlan['name']}-{iface}"
+    return f"dnsmasq-{PRODUCT_NAME}-{vlan['name']}"
+
+
+def vlan_service_file(vlan, iface):
+    return SYSTEMD_DIR / f"{vlan_service_name(vlan, iface)}.service"
+
+
+def vlan_conf_file(vlan):
+    return DNSMASQ_CONF_DIR / f"{vlan['name']}.conf"
+
+
+def vlan_leases_file(vlan):
+    return LEASES_DIR / f"dnsmasq-{PRODUCT_NAME}-{vlan['name']}.leases"
+
+
+def vlan_pid_file(vlan):
+    return Path("/run") / f"dnsmasq-{PRODUCT_NAME}-{vlan['name']}.pid"