1 files changed, 100 insertions, 0 deletions
diff --git a/python/vyos/validate.py b/python/vyos/validate.py
new file mode 100644
index 000000000..1b77f196a
--- /dev/null
+++ b/python/vyos/validate.py
@@ -0,0 +1,100 @@
+# Copyright 2018 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+import netifaces
+import ipaddress
+
+def is_ipv4(addr):
+    """
+    Check addr if it is an IPv4 address/network.
+
+    Return True/False
+    """
+    if ipaddress.ip_network(addr).version == 4:
+        return True
+    else:
+        return False
+
+def is_ipv6(addr):
+    """
+    Check addr if it is an IPv6 address/network.
+
+    Return True/False
+    """
+    if ipaddress.ip_network(addr).version == 6:
+        return True
+    else:
+        return False
+
+def is_addr_assigned(addr):
+    """
+    Verify if the given IPv4/IPv6 address is assigned to any interface on this
+    system.
+
+    Return True/False
+    """
+
+    # determine IP version (AF_INET or AF_INET6) depending on passed address
+    addr_type = netifaces.AF_INET
+    if is_ipv6(addr):
+        addr_type = netifaces.AF_INET6
+
+    for interface in netifaces.interfaces():
+        # check if the requested address type is configured at all
+        if addr_type in netifaces.ifaddresses(interface).keys():
+            # Check every IP address on this interface for a match
+            for ip in netifaces.ifaddresses(interface)[addr_type]:
+                # Check if it matches to the address requested
+                if ip['addr'] == addr:
+                    return True
+
+    return False
+
+def is_subnet_connected(subnet, primary=False):
+    """
+    Verify is the given IPv4/IPv6 subnet is connected to any interface on this
+    system.
+
+    primary check if the subnet is reachable via the primary IP address of this
+    interface, or in other words has a broadcast address configured. ISC DHCP
+    for instance will complain if it should listen on non broadcast interfaces.
+
+    Return True/False
+    """
+
+    # determine IP version (AF_INET or AF_INET6) depending on passed address
+    addr_type = netifaces.AF_INET
+    if is_ipv6(subnet):
+        addr_type = netifaces.AF_INET6
+
+    for interface in netifaces.interfaces():
+        # check if the requested address type is configured at all
+        if addr_type not in netifaces.ifaddresses(interface).keys():
+            continue
+
+        # An interface can have multiple addresses, but some software components
+        # only support the primary address :(
+        if primary:
+            ip = netifaces.ifaddresses(interface)[addr_type][0]['addr']
+            if ipaddress.ip_address(ip) in ipaddress.ip_network(subnet):
+                return True
+        else:
+            # Check every assigned IP address if it is connected to the subnet
+            # in question
+            for ip in netifaces.ifaddresses(interface)[addr_type]:
+                if ipaddress.ip_address(ip['addr']) in ipaddress.ip_network(subnet):
+                    return True
+
+    return False