accel-ppp: T5688: Standardized pool configuration in accel-ppp

Standardized pool configuration for all accel-ppp services.
1. Only named pools are used now.
2. Allows all services to use range in x.x.x.x/mask
   and x.x.x.x-x.x.x.y format
3. next-pool can be used in all services
2. Allows to use in ipoe gw-ip-address without pool configuration
   which allows to use Fraimed-IP-Address attribute by radius.
3. Default pool name should be explicidly configured
   with default-pool.
4. In ipoe netmask and range subnet can be different.

1 files changed, 193 insertions, 0 deletions

diff --git a/python/vyos/accel_ppp_util.py b/python/vyos/accel_ppp_util.py
new file mode 100644
index 000000000..757d447a2
--- /dev/null
+++ b/python/vyos/accel_ppp_util.py
@@ -0,0 +1,193 @@
+# Copyright 2023 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/>.
+
+# The sole purpose of this module is to hold common functions used in
+# all kinds of implementations to verify the CLI configuration.
+# It is started by migrating the interfaces to the new get_config_dict()
+# approach which will lead to a lot of code that can be reused.
+
+# NOTE: imports should be as local as possible to the function which
+# makes use of it!
+
+from vyos import ConfigError
+from vyos.utils.dict import dict_search
+
+
+def get_pools_in_order(data: dict) -> list:
+    """Return a list of dictionaries representing pool data in the order
+    in which they should be allocated. Pool must be defined before we can
+    use it with 'next-pool' option.
+
+    Args:
+        data: A dictionary of pool data, where the keys are pool names and the
+        values are dictionaries containing the 'subnet' key and the optional
+        'next_pool' key.
+
+    Returns:
+        list: A list of dictionaries
+
+    Raises:
+        ValueError: If a 'next_pool' key references a pool name that
+                    has not been defined.
+        ValueError: If a circular reference is found in the 'next_pool' keys.
+
+    Example:
+        config_data = {
+        ... 'first-pool': {
+        ... 'next_pool': 'second-pool',
+        ... 'subnet': '192.0.2.0/25'
+        ... },
+        ... 'second-pool': {
+        ... 'next_pool': 'third-pool',
+        ... 'subnet': '203.0.113.0/25'
+        ... },
+        ... 'third-pool': {
+        ... 'subnet': '198.51.100.0/24'
+        ... },
+        ... 'foo': {
+        ... 'subnet': '100.64.0.0/24',
+        ... 'next_pool': 'second-pool'
+        ... }
+        ... }
+
+        % get_pools_in_order(config_data)
+        [{'third-pool': {'subnet': '198.51.100.0/24'}},
+        {'second-pool': {'next_pool': 'third-pool', 'subnet': '203.0.113.0/25'}},
+        {'first-pool': {'next_pool': 'second-pool', 'subnet': '192.0.2.0/25'}},
+        {'foo': {'next_pool': 'second-pool', 'subnet': '100.64.0.0/24'}}]
+    """
+    pools = []
+    unresolved_pools = {}
+
+    for pool, pool_config in data.items():
+        if "next_pool" not in pool_config or not pool_config["next_pool"]:
+            pools.insert(0, {pool: pool_config})
+        else:
+            unresolved_pools[pool] = pool_config
+
+    while unresolved_pools:
+        resolved_pools = []
+
+        for pool, pool_config in unresolved_pools.items():
+            next_pool_name = pool_config["next_pool"]
+
+            if any(p for p in pools if next_pool_name in p):
+                index = next(
+                    (i for i, p in enumerate(pools) if next_pool_name in p), None
+                )
+                pools.insert(index + 1, {pool: pool_config})
+                resolved_pools.append(pool)
+            elif next_pool_name in unresolved_pools:
+                # next pool not yet resolved
+                pass
+            else:
+                raise ConfigError(
+                    f"Pool '{next_pool_name}' not defined in configuration data"
+                )
+
+        if not resolved_pools:
+            raise ConfigError("Circular reference in configuration data")
+
+        for pool in resolved_pools:
+            unresolved_pools.pop(pool)
+
+    return pools
+
+
+def verify_accel_ppp_base_service(config, local_users=True):
+    """
+    Common helper function which must be used by all Accel-PPP services based
+    on get_config_dict()
+    """
+    # vertify auth settings
+    if local_users and dict_search("authentication.mode", config) == "local":
+        if (
+            dict_search("authentication.local_users", config) is None
+            or dict_search("authentication.local_users", config) == {}
+        ):
+            raise ConfigError(
+                "Authentication mode local requires local users to be configured!"
+            )
+
+        for user in dict_search("authentication.local_users.username", config):
+            user_config = config["authentication"]["local_users"]["username"][user]
+
+            if "password" not in user_config:
+                raise ConfigError(f'Password required for local user "{user}"')
+
+            if "rate_limit" in user_config:
+                # if up/download is set, check that both have a value
+                if not {"upload", "download"} <= set(user_config["rate_limit"]):
+                    raise ConfigError(
+                        f'User "{user}" has rate-limit configured for only one '
+                        "direction but both upload and download must be given!"
+                    )
+
+    elif dict_search("authentication.mode", config) == "radius":
+        if not dict_search("authentication.radius.server", config):
+            raise ConfigError("RADIUS authentication requires at least one server")
+
+        for server in dict_search("authentication.radius.server", config):
+            radius_config = config["authentication"]["radius"]["server"][server]
+            if "key" not in radius_config:
+                raise ConfigError(f'Missing RADIUS secret key for server "{server}"')
+
+    if "name_server_ipv4" in config:
+        if len(config["name_server_ipv4"]) > 2:
+            raise ConfigError(
+                "Not more then two IPv4 DNS name-servers " "can be configured"
+            )
+
+    if "name_server_ipv6" in config:
+        if len(config["name_server_ipv6"]) > 3:
+            raise ConfigError(
+                "Not more then three IPv6 DNS name-servers " "can be configured"
+            )
+
+    if "client_ipv6_pool" in config:
+        ipv6_pool = config["client_ipv6_pool"]
+        if "delegate" in ipv6_pool:
+            if "prefix" not in ipv6_pool:
+                raise ConfigError(
+                    'IPv6 "delegate" also requires "prefix" to be defined!'
+                )
+
+            for delegate in ipv6_pool["delegate"]:
+                if "delegation_prefix" not in ipv6_pool["delegate"][delegate]:
+                    raise ConfigError("delegation-prefix length required!")
+
+
+def verify_accel_ppp_ip_pool(vpn_config):
+    """
+    Common helper function which must be used by Accel-PPP
+    services (pptp, l2tp, sstp, pppoe) to verify client-ip-pool
+    """
+    if dict_search("client_ip_pool", vpn_config):
+        for pool_name, pool_config in vpn_config["client_ip_pool"].items():
+            next_pool = dict_search(f"next_pool", pool_config)
+            if next_pool:
+                if next_pool not in vpn_config["client_ip_pool"]:
+                    raise ConfigError(f'Next pool "{next_pool}" does not exist')
+                if not dict_search(f"range", pool_config):
+                    raise ConfigError(
+                        f'Pool "{pool_name}" does not contain range but next-pool exists'
+                    )
+
+    if not dict_search("gateway_address", vpn_config):
+        raise ConfigError("Server requires gateway-address to be configured!")
+    default_pool = dict_search("default_pool", vpn_config)
+    if default_pool:
+        if default_pool not in dict_search("client_ip_pool", vpn_config):
+            raise ConfigError(f'Default pool "{default_pool}" does not exists')