generate_config: Move filters to external library

Clean and isolate main script logic from custom filters by moving
all them to a external library file.
Library has a function to load all the existing filters at once.

New enhanced IP handling custom filters:
 - ipnet_hostaddr
 - ipnet_hostmin
 - ipnet_hostmax
 - ipnet_broadcast
 - ipnet_netmask
 - ipnet_contains_ip
 - ipnet_contains_iprange
 - ipnet_range_size

ipnet filters work with proper IP network with prefixlen mask,
ensuring consistent IP calculations and error handling.

Previous IP handling filters should be deprecated.

Change-Id: I83c41d7ad3c6bd1d9df1deca6cc5b9d2481ecf52
Signed-off-by: Guillermo Herrero <guillermo.herrero@enea.com>

2 files changed, 212 insertions, 43 deletions

diff --git a/config/utils/gen_config_lib.py b/config/utils/gen_config_lib.py
new file mode 100644
index 00000000..e75387fb
--- /dev/null
+++ b/config/utils/gen_config_lib.py
@@ -0,0 +1,205 @@
+##############################################################################
+# Copyright (c) 2018 OPNFV and others.
+#
+# All rights reserved. This program and the accompanying materials
+# are made available under the terms of the Apache License, Version 2.0
+# which accompanies this distribution, and is available at
+# http://www.apache.org/licenses/LICENSE-2.0
+##############################################################################
+"""Library for generate_config functions and custom jinja2 filters"""
+
+import logging
+from ipaddress import IPv4Network, IPv4Address
+
+
+def load_custom_filters(environment):
+    """Load all defined filters into the jinja2 enviroment"""
+
+    # TODO deprecate ipaddr_index and netmask for the better ipnet ones
+    filter_list = {
+        'dpkg_arch': filter_dpkg_arch,
+        'ipnet_hostaddr': filter_ipnet_hostaddr,
+        'ipnet_hostmin': filter_ipnet_hostmin,
+        'ipnet_hostmax': filter_ipnet_hostmax,
+        'ipnet_broadcast': filter_ipnet_broadcast,
+        'ipnet_netmask': filter_ipnet_netmask,
+        'ipnet_contains_ip': filter_ipnet_contains_ip,
+        'ipnet_contains_iprange': filter_ipnet_contains_iprange,
+        'ipnet_range_size': filter_ipnet_range_size,
+        'ipaddr_index': filter_ipaddr_index,
+        'netmask': filter_netmask
+    }
+
+    for name, function in filter_list.items():
+        environment.filters[name] = function
+
+
+def filter_dpkg_arch(arch, to_dpkg=True):
+    """Convert DPKG-compatible from processor arch and vice-versa"""
+
+    # Processor architecture (as reported by $(uname -m))
+    # vs DPKG architecture mapping
+    dpkg_arch_table = {
+        'aarch64': 'arm64',
+        'x86_64': 'amd64',
+    }
+    arch_dpkg_table = dict(
+        zip(dpkg_arch_table.values(), dpkg_arch_table.keys()))
+
+    if to_dpkg:
+        return dpkg_arch_table[arch]
+    else:
+        return arch_dpkg_table[arch]
+
+
+def filter_ipnet_hostaddr(network_cidr, index):
+    """Return the host IP address on given index from an IP network"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+    try:
+        return IPv4Network(network_cidr_str)[index]
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+    except IndexError as ex:
+        logging.error(network_cidr_str + " has not enough range for "
+                      + str(index) + " host IPs.")
+        raise
+
+
+def filter_ipnet_broadcast(network_cidr):
+    """Return broadcast IP address from given IP network"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+    try:
+        return IPv4Network(network_cidr_str).broadcast_address
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_hostmin(network_cidr):
+    """Return the first host IP address from given IP network"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+    try:
+        return IPv4Network(network_cidr_str)[1]
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_hostmax(network_cidr):
+    """Return the last host IP address from given IP network"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+    try:
+        return IPv4Network(network_cidr_str)[-2]
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_netmask(network_cidr):
+    """Return the IP netmask from given IP network"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+    try:
+        return IPv4Network(network_cidr_str).netmask
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_contains_ip(network_cidr, ip_address):
+    """Check if an IP network cointains a given range"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+        ip_address_str = unicode(ip_address)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+        ip_address_str = str(ip_address)
+    try:
+        return IPv4Address(ip_address_str) in IPv4Network(network_cidr_str)
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_contains_iprange(network_cidr, range_start, range_end):
+    """Check if an IP network cointains a given range"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+        range_start_str = unicode(range_start)
+        range_end_str = unicode(range_end)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+        range_start_str = str(range_start)
+        range_end_str = str(range_end)
+    try:
+        ipnet = IPv4Network(network_cidr_str)
+        return (IPv4Address(range_start_str) in ipnet
+                and IPv4Address(range_end_str) in ipnet)
+    except ValueError as ex:
+        logging.error(network_cidr_str + " is not a valid network address")
+        raise
+
+
+def filter_ipnet_range_size(network_cidr, range_start, range_end):
+    """Get the size of an IP range between two IP addresses"""
+    try:
+        network_cidr_str = unicode(network_cidr)
+        range_start_str = unicode(range_start)
+        range_end_str = unicode(range_end)
+    except NameError as ex:
+        network_cidr_str = str(network_cidr)
+        range_start_str = str(range_start)
+        range_end_str = str(range_end)
+    try:
+        ipnet = IPv4Network(network_cidr_str)
+        ip1 = IPv4Address(range_start_str)
+        ip2 = IPv4Address(range_end_str)
+
+        if ip1 in ipnet and ip2 in ipnet:
+            index1 = list(ipnet.hosts()).index(ip1)
+            index2 = list(ipnet.hosts()).index(ip2)
+            ip_range_size = index2 - index1 + 1
+            return ip_range_size
+        else:
+            raise ValueError
+    except ValueError as ex:
+        logging.error(range_start_str + " and " + range_end_str +
+                      " are not valid IP addresses for range inside " +
+                      network_cidr_str)
+        raise
+
+
+# This filter is too simple and does not take network mask into account.
+# TODO Deprecate for filter_ipnet_hostaddr
+def filter_ipaddr_index(base_address, index):
+    """Return IP address in given network at given index"""
+    try:
+        base_address_str = unicode(base_address)
+    except NameError as ex:
+        base_address_str = str(base_address)
+    return IPv4Address(base_address_str) + int(index)
+
+
+# TODO deprecate for filter_ipnet_netmask
+def filter_netmask(prefix):
+    """Get netmask from prefix length integer"""
+    try:
+        prefix_str = unicode(prefix)
+    except NameError as ex:
+        prefix_str = str(prefix)
+    return IPv4Network("1.0.0.0/"+prefix_str).netmask
diff --git a/config/utils/generate_config.py b/config/utils/generate_config.py
index b2b52f0b..f1c395a5 100755
--- a/config/utils/generate_config.py
+++ b/config/utils/generate_config.py
@@ -7,60 +7,24 @@
 # which accompanies this distribution, and is available at
 # http://www.apache.org/licenses/LICENSE-2.0
 ##############################################################################
-"""This module does blah blah."""
+"""Generate configuration from PDF/IDF and jinja2 installer template"""
+
 import argparse
-import ipaddress
 import logging
 import os
+from subprocess import CalledProcessError, check_output
+import gen_config_lib
 import yaml
 from jinja2 import Environment, FileSystemLoader
-from subprocess import CalledProcessError, check_output
+
 
 PARSER = argparse.ArgumentParser()
 PARSER.add_argument("--yaml", "-y", type=str, required=True)
 PARSER.add_argument("--jinja2", "-j", type=str, required=True)
 ARGS = PARSER.parse_args()
 
-# Processor architecture vs DPKG architecture mapping
-DPKG_ARCH_TABLE = {
-    'aarch64': 'arm64',
-    'x86_64': 'amd64',
-}
-ARCH_DPKG_TABLE = dict(zip(DPKG_ARCH_TABLE.values(), DPKG_ARCH_TABLE.keys()))
-
-# Custom filter to allow simple IP address operations returning
-# a new address from an upper or lower (negative) index
-def ipaddr_index(base_address, index):
-    """Return IP address in given network at given index"""
-    try:
-        base_address_str = unicode(base_address)
-    #pylint: disable=unused-variable
-    except NameError as ex:
-        base_address_str = str(base_address)
-    return ipaddress.ip_address(base_address_str) + int(index)
-
-# Custom filter to transform a prefix netmask to IP address format netmask
-def netmask(prefix):
-    """Get netmask from prefix length integer"""
-    try:
-        prefix_str = unicode(prefix)
-    except NameError as ex:
-        prefix_str = str(prefix)
-    return ipaddress.IPv4Network("1.0.0.0/"+prefix_str).netmask
-
-# Custom filter to convert between processor architecture
-# (as reported by $(uname -m)) and DPKG-style architecture
-def dpkg_arch(arch, to_dpkg=True):
-    """Return DPKG-compatible from processor arch and vice-versa"""
-    if to_dpkg:
-        return DPKG_ARCH_TABLE[arch]
-    else:
-        return ARCH_DPKG_TABLE[arch]
-
 ENV = Environment(loader=FileSystemLoader(os.path.dirname(ARGS.jinja2)))
-ENV.filters['ipaddr_index'] = ipaddr_index
-ENV.filters['netmask'] = netmask
-ENV.filters['dpkg_arch'] = dpkg_arch
+gen_config_lib.load_custom_filters(ENV)
 
 # Run `eyaml decrypt` on the whole file, but only if PDF data is encrypted
 # Note: eyaml return code is 0 even if keys are not available
@@ -91,5 +55,5 @@ if os.path.exists(IDF_PATH):
 # Render template and print generated conf to console
 TEMPLATE = ENV.get_template(os.path.basename(ARGS.jinja2))
 
-#pylint: disable=superfluous-parens
+# pylint: disable=superfluous-parens
 print(TEMPLATE.render(conf=DICT))