[bgpcfgd] Add bgpcfgd support for static routes (#7233)

Why I did it
Add bgpcfgd support for static routes.

How I did it
Add bgpcfgd support to subscribe changes in STATIC_ROUTE table in CONFIG_DB and program via vtysh. The key of STATIC_ROUTE table is formatted as STATIC_ROUTE|vrf|ip_prefix, while the vrf is optional. If would be treated the same as "default" if no vrf is given.

Add unit tests.

Author: shi-su

src/sonic-bgpcfgd/bgpcfgd/main.py

@@ -15,6 +15,7 @@
 from .managers_db import BGPDataBaseMgr
 from .managers_intf import InterfaceMgr
 from .managers_setsrc import ZebraSetSrc
+from .managers_static_rt import StaticRouteMgr
 from .runner import Runner, signal_handler
 from .template import TemplateFabric
 from .utils import read_constants
@@ -53,6 +54,8 @@ def do_work():
         BGPAllowListMgr(common_objs, "CONFIG_DB", "BGP_ALLOWED_PREFIXES"),
         # BBR Manager
         BBRMgr(common_objs, "CONFIG_DB", "BGP_BBR"),
+        # Static Route Managers
+        StaticRouteMgr(common_objs, "CONFIG_DB", "STATIC_ROUTE"),
     ]
     runner = Runner(common_objs['cfg_mgr'])
     for mgr in managers:

src/sonic-bgpcfgd/bgpcfgd/managers_static_rt.py

@@ -0,0 +1,173 @@
+import traceback
+from .log import log_crit, log_err, log_debug
+from .manager import Manager
+from .template import TemplateFabric
+import socket
+
+class StaticRouteMgr(Manager):
+    """ This class updates static routes when STATIC_ROUTE table is updated """
+    def __init__(self, common_objs, db, table):
+        """
+        Initialize the object
+        :param common_objs: common object dictionary
+        :param db: name of the db
+        :param table: name of the table in the db
+        """
+        super(StaticRouteMgr, self).__init__(
+            common_objs,
+            [],
+            db,
+            table,
+        )
+
+        self.static_routes = {}
+
+    OP_DELETE = 'DELETE'
+    OP_ADD = 'ADD'
+
+    def set_handler(self, key, data):
+        vrf, ip_prefix = self.split_key(key)
+        is_ipv6 = TemplateFabric.is_ipv6(ip_prefix)
+
+        arg_list    = lambda v: v.split(',') if len(v.strip()) != 0 else None
+        bkh_list    = arg_list(data['blackhole']) if 'blackhole' in data else None
+        nh_list     = arg_list(data['nexthop']) if 'nexthop' in data else None
+        intf_list   = arg_list(data['ifname']) if 'ifname' in data else None
+        dist_list   = arg_list(data['distance']) if 'distance' in data else None
+        nh_vrf_list = arg_list(data['nexthop-vrf']) if 'nexthop-vrf' in data else None
+
+        try:
+            ip_nh_set = IpNextHopSet(is_ipv6, bkh_list, nh_list, intf_list, dist_list, nh_vrf_list)
+            cur_nh_set = self.static_routes.get(vrf, {}).get(ip_prefix, IpNextHopSet(is_ipv6))
+            cmd_list = self.static_route_commands(ip_nh_set, cur_nh_set, ip_prefix, vrf)
+        except Exception as exc:
+            log_crit("Got an exception %s: Traceback: %s" % (str(exc), traceback.format_exc()))
+            return False
+
+        if cmd_list:
+            self.cfg_mgr.push_list(cmd_list)
+            log_debug("Static route {} is scheduled for updates".format(key))
+        else:
+            log_debug("Nothing to update for static route {}".format(key))
+
+        self.static_routes.setdefault(vrf, {})[ip_prefix] = ip_nh_set
+
+        return True
+
+
+    def del_handler(self, key):
+        vrf, ip_prefix = self.split_key(key)
+        is_ipv6 = TemplateFabric.is_ipv6(ip_prefix)
+
+        ip_nh_set = IpNextHopSet(is_ipv6)
+        cur_nh_set = self.static_routes.get(vrf, {}).get(ip_prefix, IpNextHopSet(is_ipv6))
+        cmd_list = self.static_route_commands(ip_nh_set, cur_nh_set, ip_prefix, vrf)
+
+        if cmd_list:
+            self.cfg_mgr.push_list(cmd_list)
+            log_debug("Static route {} is scheduled for updates".format(key))
+        else:
+            log_debug("Nothing to update for static route {}".format(key))
+
+        self.static_routes.setdefault(vrf, {}).pop(ip_prefix, None)
+
+    @staticmethod
+    def split_key(key):
+        """
+        Split key into vrf name and prefix.
+        :param key: key to split
+        :return: vrf name extracted from the key, ip prefix extracted from the key
+        """
+        if '|' not in key:
+            return 'default', key
+        else:
+            return tuple(key.split('|', 1))
+
+    def static_route_commands(self, ip_nh_set, cur_nh_set, ip_prefix, vrf):
+        diff_set = ip_nh_set.symmetric_difference(cur_nh_set)
+
+        op_cmd_list = {}
+        for ip_nh in diff_set:
+            if ip_nh in cur_nh_set:
+                op = self.OP_DELETE
+            else:
+                op = self.OP_ADD
+
+            op_cmds = op_cmd_list.setdefault(op, [])
+            op_cmds.append(self.generate_command(op, ip_nh, ip_prefix, vrf))
+
+        cmd_list = op_cmd_list.get(self.OP_DELETE, [])
+        cmd_list += op_cmd_list.get(self.OP_ADD, [])
+
+        return cmd_list
+
+    def generate_command(self, op, ip_nh, ip_prefix, vrf):
+        return '{}{} route {}{}{}'.format(
+            'no ' if op == self.OP_DELETE else '',
+            'ipv6' if ip_nh.af == socket.AF_INET6 else 'ip',
+            ip_prefix,
+            ip_nh,
+            ' vrf {}'.format(vrf) if vrf != 'default' else ''
+        )
+
+class IpNextHop:
+    def __init__(self, af_id, blackhole, dst_ip, if_name, dist, vrf):
+        zero_ip = lambda af: '0.0.0.0' if af == socket.AF_INET else '::'
+        self.af = af_id
+        self.blackhole = 'false' if blackhole is None or blackhole == '' else blackhole
+        self.distance = 0 if dist is None else int(dist)
+        if self.blackhole == 'true':
+            dst_ip = if_name = vrf = None
+        self.ip = zero_ip(af_id) if dst_ip is None or dst_ip == '' else dst_ip
+        self.interface = '' if if_name is None else if_name
+        self.nh_vrf = '' if vrf is None else vrf
+        if self.blackhole != 'true' and self.is_zero_ip() and len(self.interface.strip()) == 0:
+            log_err('Mandatory attribute not found for nexthop')
+            raise ValueError
+    def __eq__(self, other):
+        return (self.af == other.af and self.blackhole == other.blackhole and
+                self.ip == other.ip and self.interface == other.interface and
+                self.distance == other.distance and self.nh_vrf == other.nh_vrf)
+    def __ne__(self, other):
+        return (self.af != other.af or self.blackhole != other.blackhole or
+                self.ip != other.ip or self.interface != other.interface or
+                self.distance != other.distance or self.nh_vrf != other.nh_vrf)
+    def __hash__(self):
+        return hash((self.af, self.blackhole, self.ip, self.interface, self.distance, self.nh_vrf))
+    def is_zero_ip(self):
+        return sum([x for x in socket.inet_pton(self.af, self.ip)]) == 0
+    def __format__(self, format):
+        ret_val = ''
+        if self.blackhole == 'true':
+            ret_val += ' blackhole'
+        if not (self.ip is None or self.is_zero_ip()):
+            ret_val += ' %s' % self.ip
+        if not (self.interface is None or self.interface == ''):
+            ret_val += ' %s' % self.interface
+        if not (self.distance is None or self.distance == 0):
+            ret_val += ' %d' % self.distance
+        if not (self.nh_vrf is None or self.nh_vrf == ''):
+            ret_val += ' nexthop-vrf %s' % self.nh_vrf
+        return ret_val
+
+class IpNextHopSet(set):
+    def __init__(self, is_ipv6, bkh_list = None, ip_list = None, intf_list = None, dist_list = None, vrf_list = None):
+        super(IpNextHopSet, self).__init__()
+        af = socket.AF_INET6 if is_ipv6 else socket.AF_INET
+        if bkh_list is None and ip_list is None and intf_list is None:
+            # empty set, for delete case
+            return
+        nums = {len(x) for x in [bkh_list, ip_list, intf_list, dist_list, vrf_list] if x is not None}
+        if len(nums) != 1:
+            log_err("Lists of next-hop attribute have different sizes: %s" % nums)
+            for x in [bkh_list, ip_list, intf_list, dist_list, vrf_list]:
+                log_debug("List: %s" % x)
+            raise ValueError
+        nh_cnt = nums.pop()
+        item = lambda lst, i: lst[i] if lst is not None else None
+        for idx in range(nh_cnt):
+            try:
+                self.add(IpNextHop(af, item(bkh_list, idx), item(ip_list, idx), item(intf_list, idx),
+                                   item(dist_list, idx), item(vrf_list, idx), ))
+            except ValueError:
+                continue