def delete_service_instance(serv_name):
'''
Precondition: check on serv_name existence has been performed
Deletes the last entry in the list of services. This could change
later to a random entry or something else.
'''
if len(_service_table[serv_name]) == 0:
return
packed_multiaddr = _service_table[serv_name][-1:][0]
nh.shutdown_instance(packed_multiaddr)
address = ma.get_address(packed_multiaddr)
_delete_serv_instance_entry(address)
_service_table[serv_name] = _service_table[serv_name][:-1]
# delete any connection tracks which this service has initiated
if ma.get_type(packed_multiaddr) == ma.IPV4:
flows = _check_flow_existence('*', v4=address)
if flows:
for flow_id in flows:
_del_flow(address, \
flow_id, \
_which_service_is_instance( \
ma.ip_to_packed_multiaddr( _flow_id_to_ip(flow_id) )\
))
elif ma.get_type(packed_multiaddr) == ma.IPV6:
pass
def _netns_resolvconf(netns):
'''
Each network namespace will now send dns requests to the bridge
'''
ret = os.system('mkdir -p /etc/netns/' + netns)
with open('/etc/netns/' + netns + '/resolv.conf', 'w+') as f:
f.write('nameserver ' + ma.get_address(bridge_ipv4_multiaddr))
def _connect_netns_to_bridge(netns, \
packed_multiaddr):
'''
Function to connect a given network namespace to the
orchestrator bridge.
'''
#TODO
# error handle
veth1, veth2 = _create_veth_pair()
# move one veth end to the proper namespace
_conn_ns_bridge(netns, veth1)
# assign the other veth end to the bridge
_slave_veth(veth2)
# bring everything up
_bring_up_if(bridge_netns, veth2)
_bring_up_if(netns, veth1)
_bring_up_if(netns, 'lo')
# assign ip address to netns
addr = ma.get_address(packed_multiaddr)
_assign_addr(netns, veth1, addr)
_def_route(netns, addr)
def serv_instance_exists(multi_addr, ip=None):
if ip:
if ip in _service_instances:
return True
else:
instance = ma.pack(multi_addr)
if ma.get_address(instance) in _service_instances:
return True
return False
def add_service_instance(serv_name, multi_addr):
'''
Precondition: checks on serv_name existence and
multi_addr validity have been performed
'''
packed_multiaddr = ma.pack(multi_addr)
_service_table[serv_name].append(packed_multiaddr)
_add_serv_instance_entry(ma.get_address(packed_multiaddr), multi_addr)
#TODO
# error handle
ret = nh.instantiate_service(multi_addr)
def network_init():
'''
Return None if unable to complete.
'''
#TODO
# error handle
# some failures aren't critical and probably shoudl accommodate for that if
# i have time
print("Creating netns for the orchestrator.")
ret = os.system('ip netns add ' + bridge_netns)
print("Creating the linux bridge.")
ret = os.system('ip netns exec ' + bridge_netns + ' \
ip link add ' + bridge_name + ' type bridge')
print("Adding IP address to bridge.")
# assign IPv4 address
_assign_addr(bridge_netns, \
bridge_name, \
ma.get_address(bridge_ipv4_multiaddr))
# assign IPv6 address
#ret = os.system('ip netns exec '+bridge_netns+' \
# ip address add '+ma.get_address(bridge_ipv6_multiaddr)+' \
# dev '+bridge_name)
print("Setting the devices for the bridge netns to be up.")
_bring_up_if(bridge_netns, 'lo')
_bring_up_if(bridge_netns, bridge_name)
print("Network namespace initialised.")
print("Orchestrator bridge resides on "\
+ma.get_address(bridge_ipv4_multiaddr)+subnet_mask)
print(
"For your namespaces to be able to communicate with each other, they \
need to be on the same subnet as the bridge.")
# initialise random number generator
random.seed(time.time())
'''
DNS Code heavily pulled from
https://github.com/pathes/fakedns/blob/master/fakedns.py
Cheers pathes
Modified as needed by ramwan <*****@*****.**>
'''
'''
Variable definitions
'''
_dns_active = False
_dns_ipv4 = None
#_dns_ipv6 = None
_dns4_thread = None
#_dns6_thread = None
dns_ipv4_addr = ma.get_address(bridge_ipv4_multiaddr)
#dns_ipv6_addr = ma.get_address(bridge_ipv6_multiaddr)
dns_header_length = 12
def listen():
'''
Initialises sockets in the orchestrator/bridge netns and starts separate
threads to listen on them.
'''
global _dns_active
global _dns_ipv4
#global dns_ipv6
global _dns4_thread
#global _dns6_thread
_dns_active = True
def get_flow_id(serv_name, v4=None, v6=None):
'''
Adds a flow entry to the flow bi-map. Checks for the existence of the a flow
between the sender and receiver first. If a flow already exists then that
flow id will be returned.
Returns None on error
NOTE:
doesn't support one automaton needing to talk to multiple automatons of the
same type.
'''
if v4:
exists = _check_flow_existence(serv_name, v4=v4)
# if the flow already exists we return the same flow ID
if exists == _FLOW_EXISTS:
return _conn_flow_id(_conn_key(v4, serv_name))
# if the flow exists but the receiving server is dead, we need to
# find a new receiver if there is one
elif exists == _FLOW_DEAD:
fid = _conn_flow_id(_conn_key(v4, serv_name))
# we don't need to call del() right now due to the implementation
# of the flow table. However it probably would be good to call it to
# make it clearer so I'm going to leave it here.
#
#_del_flow_id_to_ip(fid)
#_del_conn( _conn_key(v4, serv_name) )
instance = _get_random_instance(serv_name)
if instance == None:
return None
instance_addr = ma.get_address(instance)
# do iptables nat mappings
with nh.Namespace( nh.get_ns_name( \
nh.ma.ip_to_packed_multiaddr(v4) \
)):
ih.edit_nat_mapping(fid, new_source=v4,\
old_source=v4,\
new_dest=instance_addr,\
old_dest=_flow_id_to_ip[fid])
_add_flow_id_to_ip(instance_addr, fid)
_add_conn(v4, serv_name, fid)
return fid
# create new flow
elif exists == _FLOW_NOEXISTS:
instance = _get_random_instance(serv_name)
if instance == None:
return None
fid = _generate_flow_id()
instance_addr = ma.get_address(instance)
_add_ip_to_flow_id(v4, fid)
_add_flow_id_to_ip(instance_addr, fid)
# create connection tracking information
_add_conn(v4, serv_name, fid)
# do iptables nat mappings
with nh.Namespace( nh.get_ns_name( \
ma.ip_to_packed_multiaddr(v4) \
)):
ih.create_nat_mapping(fid, v4, instance_addr)
return fid
elif v6:
# TODO
return None
return None
