T5099: IPoE-server add option next-pool for named ip pools

In cases with multiple named IP pools, it is required the option 'next'
to be sure that if IP addresses ended in one pool, then they would
begin to be allocated from the next named pool.

For accel-ppp it requires specific order as pool must be defined
before we can use it with the 'next-option'

set service ipoe-server client-ip-pool name first-pool subnet '192.0.2.0/25'
set service ipoe-server client-ip-pool name first-pool next-pool 'second-pool'
set service ipoe-server client-ip-pool name second-pool subnet '203.0.113.0/25'

[ip-pool]
203.0.113.0/25,name=second-pool
192.0.2.0/25,name=first-pool,next=second-pool

1 files changed, 97 insertions, 0 deletions

diff --git a/src/conf_mode/service_ipoe-server.py b/src/conf_mode/service_ipoe-server.py
index 4fabe170f..95c72df47 100755
--- a/src/conf_mode/service_ipoe-server.py
+++ b/src/conf_mode/service_ipoe-server.py
@@ -15,6 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import jmespath
 
 from sys import exit
 
@@ -29,9 +30,92 @@ from vyos import ConfigError
 from vyos import airbag
 airbag.enable()
 
+
 ipoe_conf = '/run/accel-pppd/ipoe.conf'
 ipoe_chap_secrets = '/run/accel-pppd/ipoe.chap-secrets'
 
+
+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:
+            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 ValueError(
+                    f"Pool '{next_pool_name}' not defined in configuration data"
+                )
+
+        if not resolved_pools:
+            raise ValueError("Circular reference in configuration data")
+
+        for pool in resolved_pools:
+            unresolved_pools.pop(pool)
+
+    return pools
+
+
 def get_config(config=None):
     if config:
         conf = config
@@ -43,6 +127,19 @@ def get_config(config=None):
 
     # retrieve common dictionary keys
     ipoe = get_accel_dict(conf, base, ipoe_chap_secrets)
+
+    if jmespath.search('client_ip_pool.name', ipoe):
+        dict_named_pools = jmespath.search('client_ip_pool.name', ipoe)
+        # Multiple named pools require ordered values T5099
+        ipoe['ordered_named_pools'] = get_pools_in_order(dict_named_pools)
+        # T5099 'next-pool' option
+        if jmespath.search('client_ip_pool.name.*.next_pool', ipoe):
+            for pool, pool_config in ipoe['client_ip_pool']['name'].items():
+                if 'next_pool' in pool_config:
+                    ipoe['first_named_pool'] = pool
+                    ipoe['first_named_pool_subnet'] = pool_config
+                    break
+
     return ipoe