# Buggy code
def finalize_config(self, dps):
    """Perform consistency checks after initial config parsing."""

    def resolve_port_no(port_name):
        """Resolve port by name or number."""
        if port_name in port_by_name:
            return port_by_name[port_name].number
        elif port_name in self.ports:
            return port_name
        return None

    def resolve_vlan(vlan_name):
        """Resolve VLAN by name or VID."""
        if vlan_name in vlan_by_name:
            return vlan_by_name[vlan_name]
        elif vlan_name in self.vlans:
            return self.vlans[vlan_name]
        return None

    def resolve_stack_dps():
        """Resolve DP references in stacking config."""
        port_stack_dp = {}
        for port in self.stack_ports:
            stack_dp = port.stack["dp"]
            port_stack_dp[port] = dp_by_name[stack_dp]
        for port, dp in list(port_stack_dp.items()):
            port.stack["dp"] = dp
            stack_port_name = port.stack["port"]
            port.stack["port"] = dp.ports[stack_port_name]

    def resolve_mirror_destinations():
        """Resolve mirror port references and destinations."""
        mirror_from_port = {}
        for port in list(self.ports.values()):
            if port.mirror is not None:
                if port.mirror in port_by_name:
                    mirror_from_port[port] = port_by_name[port.mirror]
                else:
                    mirror_from_port[self.ports[port.mirror]] = port
        for port, mirror_destination_port in list(mirror_from_port.items()):
            port.mirror = mirror_destination_port.number
            mirror_destination_port.mirror_destination = True

    def resolve_names_in_acls():
        """Resolve config references in ACLs."""
        for acl in list(self.acls.values()):
            for rule_conf in acl.rules:
                for attrib, attrib_value in list(rule_conf.items()):
                    if attrib == "actions":
                        if "meter" in attrib_value:
                            meter_name = attrib_value["meter"]
                            assert meter_name in self.meters
                        if "mirror" in attrib_value:
                            port_name = attrib_value["mirror"]
                            port_no = resolve_port_no(port_name)
                            # in V2 config, we might have an ACL that does
                            # not apply to a DP.
                            if port_no is not None:
                                attrib_value["mirror"] = port_no
                                port = self.ports[port_no]
                                port.mirror_destination = True
                        if "output" in attrib_value:
                            output_values = attrib_value["output"]
                            if "port" in output_values:
                                port_name = output_values["port"]
                                port_no = resolve_port_no(port_name)
                                if port_no is not None:
                                    output_values["port"] = port_no
                            if "failover" in output_values:
                                failover = output_values["failover"]
                                resolved_ports = []
                                for port_name in failover["ports"]:
                                    port_no = resolve_port_no(port_name)
                                    if port_no is not None:
                                        resolved_ports.append(port_no)
                                failover["ports"] = resolved_ports

    def resolve_acls():
        """Resolve ACL references in config."""

        def build_acl(acl, vid=None):
            """Check that ACL can be built from config."""
            if acl.rules:
                assert valve_acl.build_acl_ofmsgs(
                    [acl],
                    self.wildcard_table,
                    valve_of.goto_table(self.wildcard_table),
                    2**16,
                    self.meters,
                    acl.exact_match,
                    vlan_vid=vid,
                )

        for vlan in list(self.vlans.values()):
            if vlan.acl_in:
                vlan.acl_in = self.acls[vlan.acl_in]
                build_acl(vlan.acl_in, vid=1)
        for port in list(self.ports.values()):
            if port.acl_in:
                if port.acl_in in self.acls:
                    port.acl_in = self.acls[port.acl_in]
                    build_acl(port.acl_in)
                else:
                    assert False, "Unconfigured acl for %s" % self.name

    def resolve_vlan_names_in_routers():
        """Resolve VLAN references in routers."""
        dp_routers = {}
        for router_name, router in list(self.routers.items()):
            vlans = []
            for vlan_name in router.vlans:
                vlan = resolve_vlan(vlan_name)
                if vlan is not None:
                    vlans.append(vlan)
            if len(vlans) > 1:
                dp_router = copy.copy(router)
                dp_router.vlans = vlans
                dp_routers[router_name] = dp_router
        self.routers = dp_routers

    assert self.ports, "no interfaces defined for %s" % self.name
    assert self.vlans, "no VLANs referenced by interfaces in %s" % self.name

    port_by_name = {}
    for port in list(self.ports.values()):
        port_by_name[port.name] = port
    dp_by_name = {}
    for dp in dps:
        dp_by_name[dp.name] = dp
    vlan_by_name = {}
    for vlan in list(self.vlans.values()):
        vlan_by_name[vlan.name] = vlan

    resolve_stack_dps()
    resolve_mirror_destinations()
    resolve_vlan_names_in_routers()
    resolve_names_in_acls()
    resolve_acls()

    for port in list(self.ports.values()):
        port.finalize()
    for vlan in list(self.vlans.values()):
        vlan.finalize()
    for acl in list(self.acls.values()):
        acl.finalize()
    for router in list(self.routers.values()):
        router.finalize()
    self.finalize()


# Traceback (KeyError)
Nov 16 02:50:28 faucet.exception ERROR    Unhandled exception, killing RYU
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/faucet/valve_util.py", line 34, in __koe
func(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/faucet/faucet.py", line 146, in _load_configs
new_config_file, self.logname)
File "/usr/lib/python3.6/site-packages/faucet/config_parser.py", line 50, in dp_parser
config_hashes, dps = _config_parser_v2(config_file, logname)
File "/usr/lib/python3.6/site-packages/faucet/config_parser.py", line 165, in _config_parser_v2
top_confs['vlans'])
File "/usr/lib/python3.6/site-packages/faucet/config_parser.py", line 133, in _dp_parser_v2
dp.finalize_config(dps)
File "/usr/lib/python3.6/site-packages/faucet/dp.py", line 509, in finalize_config
resolve_acls()
File "/usr/lib/python3.6/site-packages/faucet/dp.py", line 472, in resolve_acls
vlan.acl_in = self.acls[vlan.acl_in]
KeyError: 'office-vlan-protect'

# Fixed code
def finalize_config(self, dps):
    """Perform consistency checks after initial config parsing."""

    def resolve_port_no(port_name):
        """Resolve port by name or number."""
        if port_name in port_by_name:
            return port_by_name[port_name].number
        elif port_name in self.ports:
            return port_name
        return None

    def resolve_vlan(vlan_name):
        """Resolve VLAN by name or VID."""
        if vlan_name in vlan_by_name:
            return vlan_by_name[vlan_name]
        elif vlan_name in self.vlans:
            return self.vlans[vlan_name]
        return None

    def resolve_stack_dps():
        """Resolve DP references in stacking config."""
        port_stack_dp = {}
        for port in self.stack_ports:
            stack_dp = port.stack["dp"]
            port_stack_dp[port] = dp_by_name[stack_dp]
        for port, dp in list(port_stack_dp.items()):
            port.stack["dp"] = dp
            stack_port_name = port.stack["port"]
            port.stack["port"] = dp.ports[stack_port_name]

    def resolve_mirror_destinations():
        """Resolve mirror port references and destinations."""
        mirror_from_port = {}
        for port in list(self.ports.values()):
            if port.mirror is not None:
                if port.mirror in port_by_name:
                    mirror_from_port[port] = port_by_name[port.mirror]
                else:
                    mirror_from_port[self.ports[port.mirror]] = port
        for port, mirror_destination_port in list(mirror_from_port.items()):
            port.mirror = mirror_destination_port.number
            mirror_destination_port.mirror_destination = True

    def resolve_names_in_acls():
        """Resolve config references in ACLs."""
        for acl in list(self.acls.values()):
            for rule_conf in acl.rules:
                for attrib, attrib_value in list(rule_conf.items()):
                    if attrib == "actions":
                        if "meter" in attrib_value:
                            meter_name = attrib_value["meter"]
                            assert meter_name in self.meters
                        if "mirror" in attrib_value:
                            port_name = attrib_value["mirror"]
                            port_no = resolve_port_no(port_name)
                            # in V2 config, we might have an ACL that does
                            # not apply to a DP.
                            if port_no is not None:
                                attrib_value["mirror"] = port_no
                                port = self.ports[port_no]
                                port.mirror_destination = True
                        if "output" in attrib_value:
                            output_values = attrib_value["output"]
                            if "port" in output_values:
                                port_name = output_values["port"]
                                port_no = resolve_port_no(port_name)
                                if port_no is not None:
                                    output_values["port"] = port_no
                            if "failover" in output_values:
                                failover = output_values["failover"]
                                resolved_ports = []
                                for port_name in failover["ports"]:
                                    port_no = resolve_port_no(port_name)
                                    if port_no is not None:
                                        resolved_ports.append(port_no)
                                failover["ports"] = resolved_ports

    def resolve_acls():
        """Resolve ACL references in config."""

        def build_acl(acl, vid=None):
            """Check that ACL can be built from config."""
            if acl.rules:
                assert valve_acl.build_acl_ofmsgs(
                    [acl],
                    self.wildcard_table,
                    valve_of.goto_table(self.wildcard_table),
                    2**16,
                    self.meters,
                    acl.exact_match,
                    vlan_vid=vid,
                )

        for vlan in list(self.vlans.values()):
            if vlan.acl_in:
                if vlan.acl_in in self.acls:
                    vlan.acl_in = self.acls[vlan.acl_in]
                    build_acl(vlan.acl_in, vid=1)
                else:
                    assert False, "Unconfigured vlan for %s" % self.name
        for port in list(self.ports.values()):
            if port.acl_in:
                if port.acl_in in self.acls:
                    port.acl_in = self.acls[port.acl_in]
                    build_acl(port.acl_in)
                else:
                    assert False, "Unconfigured acl for %s" % self.name

    def resolve_vlan_names_in_routers():
        """Resolve VLAN references in routers."""
        dp_routers = {}
        for router_name, router in list(self.routers.items()):
            vlans = []
            for vlan_name in router.vlans:
                vlan = resolve_vlan(vlan_name)
                if vlan is not None:
                    vlans.append(vlan)
            if len(vlans) > 1:
                dp_router = copy.copy(router)
                dp_router.vlans = vlans
                dp_routers[router_name] = dp_router
        self.routers = dp_routers

    assert self.ports, "no interfaces defined for %s" % self.name
    assert self.vlans, "no VLANs referenced by interfaces in %s" % self.name

    port_by_name = {}
    for port in list(self.ports.values()):
        port_by_name[port.name] = port
    dp_by_name = {}
    for dp in dps:
        dp_by_name[dp.name] = dp
    vlan_by_name = {}
    for vlan in list(self.vlans.values()):
        vlan_by_name[vlan.name] = vlan

    resolve_stack_dps()
    resolve_mirror_destinations()
    resolve_vlan_names_in_routers()
    resolve_names_in_acls()
    resolve_acls()

    for port in list(self.ports.values()):
        port.finalize()
    for vlan in list(self.vlans.values()):
        vlan.finalize()
    for acl in list(self.acls.values()):
        acl.finalize()
    for router in list(self.routers.values()):
        router.finalize()
    self.finalize()