p4dbg.py

#!/usr/bin/env python

# Copyright 2013-present Barefoot Networks, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

#
# Antonin Bas (antonin@barefootnetworks.com)
#
#

import nnpy
import struct
import sys
import json
import argparse
import cmd
from collections import defaultdict
from functools import wraps

try:
    import runtime_CLI
    with_runtime_CLI = True
except:
    with_runtime_CLI = False

parser = argparse.ArgumentParser(description='BM nanomsg debugger')
parser.add_argument('--socket', help='Nanomsg socket to which to subscribe',
                    action="store", default="ipc:///tmp/bmv2-0-debug.ipc")
parser.add_argument('--thrift-port', help='Thrift server port for table updates',
                    type=int, action="store", default=9090)
parser.add_argument('--thrift-ip', help='Thrift IP address for table updates',
                    type=str, action="store", default='localhost')
parser.add_argument('--json', help='JSON description of P4 program',
                    action="store", required=True)

args = parser.parse_args()

class FieldMap:
    def __init__(self):
        self.fields = {}
        self.fields_rev = {}

    def load_names(self, json_src):
        header_types_map = {}
        with open(json_src, 'r') as f:
            json_ = json.load(f)

            header_types = json_["header_types"]
            for h in header_types:
                header_type = h["name"]
                header_types_map[header_type] = h

            header_instances = json_["headers"]
            for h in header_instances:
                header = h["name"]
                header_type = header_types_map[h["header_type"]]
                for idx, (f_name, f_nbits) in enumerate(header_type["fields"]):
                    e = (".".join([header, f_name]), f_nbits)
                    self.fields[(header_type["id"], idx)] = e
                    self.fields_rev[e[0]] = (header_type["id"], idx)

    def get_name(self, header_id, offset):
        return self.fields[(header_id, offset)][0]

    def get_nbits(self, header_id, offset):
        return self.fields[(header_id, offset)][1]

    def get_id_from_name(self, name):
        return self.fields_rev[name]

    def get_all_fields(self):
        return self.fields_rev.keys()


field_map = FieldMap()

def get_name(header_id, offset):
    return field_map.get_name(header_id, offset)

def get_nbits(header_id, offset):
    return field_map.get_nbits(header_id, offset)

def get_field_id_from_name(name):
    header_id, offset = field_map.get_id_from_name(name)
    return (header_id << 32) | offset

def get_name_from_field_id(fid):
    header_id = fid >> 32
    offset = fid & 0xffffffff
    return get_name(header_id, offset)

def get_all_fields():
    return field_map.get_all_fields()

def enum(type_name, *sequential, **named):
    enums = dict(zip(sequential, range(len(sequential))), **named)
    reverse = dict((value, key) for key, value in enums.iteritems())

    @staticmethod
    def to_str(x):
        return reverse[x]
    enums['to_str'] = to_str

    @staticmethod
    def from_str(x):
        return enums[x]

    enums['from_str'] = from_str
    return type(type_name, (), enums)

class ObjectMap:
    ObjType = enum('ObjType',
                   'PARSER', 'PARSE STATE', 'CONTROL', 'TABLE')

    class _Map:
        def __init__(self):
            self.pname = None
            self.names = {}
            self.names_rev = {}

        def add_one(self, id_, name):
            self.names[id_] = name
            self.names_rev[name] = id_

    def __init__(self):
        self.store = defaultdict(ObjectMap._Map)
        self.ids = {
            1: "parser",
            2: "parse_state",
            3: "pipeline",
            4: "table",
            5: "condition",
            6: "action",
            7: "deparser",
        }
        self.ids_rev = {}
        for k, v in self.ids.items():
            self.ids_rev[v] = k

    def load_names(self, json_src):
        with open(json_src, 'r') as f:
            json_ = json.load(f)
            for type_ in {"parser", "deparser", "action", "pipeline"}:
                _map = self.store[type_]
                _map.pname = type_
                json_list = json_[type_ + "s"]
                for obj in json_list:
                    _map.add_one(obj["id"], obj["name"])

            # self.store["pipeline"].pname = "control"
            self.store["pipeline"].pname = "pipeline"

            for pipeline in json_["pipelines"]:
                _map = self.store["table"]
                _map.pname = "table"
                tables = pipeline["tables"]
                for obj in tables:
                    _map.add_one(obj["id"], obj["name"])

                _map = self.store["condition"]
                _map.pname = "condition"
                conds = pipeline["conditionals"]
                for obj in conds:
                    _map.add_one(obj["id"], obj["name"])

            for parser in json_["parsers"]:
                _map = self.store["parse_state"]
                _map.pname = "parse_state"
                parse_states = parser["parse_states"]
                for obj in parse_states:
                    _map.add_one(obj["id"], obj["name"])

    def resolve_ctr(self, ctr):
        type_id = ctr >> 24
        obj_id = ctr & 0xffffff
        type_id = type_id & 0x7f

        assert(type_id in self.ids)
        type_ = self.ids[type_id]
        _map = self.store[type_]

        return _map.pname, _map.names[obj_id]

    def lookup_ctr(self, type_name, obj_name):
        type_id = self.ids_rev[type_name]
        _map = self.store[type_name]
        obj_id = _map.names_rev[obj_name]

        ctr = type_id << 24
        ctr |= obj_id
        return ctr

obj_map = ObjectMap()

def resolve_ctr(ctr):
    return obj_map.resolve_ctr(ctr)

def lookup_ctr(type_name, obj_name):
    return obj_map.lookup_ctr(type_name, obj_name)

MsgType = enum('MsgType',
               'PACKET_IN', 'PACKET_OUT',
               'FIELD_VALUE',
               'CONTINUE',
               'NEXT',
               'GET_VALUE',
               'GET_BACKTRACE', 'BACKTRACE',
               'BREAK_PACKET_IN', 'REMOVE_PACKET_IN',
               'STOP_PACKET_IN', 'RESUME_PACKET_IN',
               'FILTER_NOTIFICATIONS',
               'SET_WATCHPOINT', 'UNSET_WATCHPOINT',
               'STATUS',
               'RESET',
               'KEEP_ALIVE',
               'ATTACH', 'DETACH',)


class Msg(object):
    def __init__(self, **kwargs):
        self.type = None

    def extract(self, msg):
        return 0

    def generate(self):
        return []

    def __str__(self):
        return ""

def make_extract_function(P, fmt):
    def extract(self, msg):
        # investigate why super() not working?
        # offset = super(P, self).extract(msg)
        offset = P.extract(self, msg)
        for name, uf, src in fmt:
            if type(uf) is int:
                width = getattr(self, src)
                f = ">%ds" % (uf * width)
            else:
                assert(src is None)
                assert(type(uf) is str)
                f = uf
                width = struct.calcsize(f)
            v, = struct.unpack_from(f, msg, offset)
            offset += width
            setattr(self, name, v)
            if type(uf) is int:
                if width == 0:
                    v_str = None
                    v_int = None
                else:
                    v_str = ':'.join(x.encode('hex') for x in v)
                    v_int = int(v.encode('hex'), 16)
                setattr(self, name + "_str", v_str)
                setattr(self, name + "_int", v_int)
        return offset

    return extract

def make_str_function(P, fmt):
    def str_func(self):
        s = P.__str__(self)
        for name, uf, _ in fmt:
            s += name + ": "
            if type(uf) is int:
                s += getattr(self, name + "_str")
                s += " (" + str(getattr(self, name + "_int")) + ") "
            else:
                s += str(getattr(self, name))
            s += "\t"
        return s

    return str_func

def make_generate_function(P, fmt):
    def generate(self):
        s = P.generate(self)
        for name, uf, src in fmt:
            v = getattr(self, name)
            if type(uf) is int:
                width = getattr(self, src)
                f = ">%ds" % (uf * width)
            else:
                assert(src is None)
                assert(type(uf) is str)
                f = uf
            # encoding problem if using string
            # nnpy expects unicode, which does not roll
            s += list(struct.pack(f, v))
        return s

    return generate

def make_init_function(P, t, fmt):
    def init_func(self, **kwargs):
        P.__init__(self, **kwargs)
        self.type = t
        if not fmt:
            return
        for k, v in kwargs.items():
            if k not in zip(*fmt)[0]:
                continue
            setattr(self, k, v)

    return init_func

def decorate_msg(P, t, fmt):
    def wrapper(K):
        K.__init__ = make_init_function(P, t, fmt)
        K.extract = make_extract_function(P, fmt)
        K.generate = make_generate_function(P, fmt)
        K.__str__ = make_str_function(P, fmt)
        return K
    return wrapper

@decorate_msg(
    Msg, None,
    [("type", "i", None), ("switch_id", "i", None), ("req_id", "Q", None)],
)
class BasicMsg(Msg):
    pass

@decorate_msg(
    BasicMsg, None,
    [("packet_id", "Q", None), ("copy_id", "Q", None)],
)
class EventMsg(BasicMsg):
    pass

@decorate_msg(
    EventMsg, MsgType.PACKET_IN,
    [("port", "i", None)],
)
class Msg_PacketIn(EventMsg):
    pass

@decorate_msg(
    EventMsg, MsgType.PACKET_OUT,
    [("port", "i", None)],
)
class Msg_PacketOut(EventMsg):
    pass

@decorate_msg(
    EventMsg, MsgType.FIELD_VALUE,
    [("fid", "Q", None), ("nbytes", "i", None), ("bytes", 1, "nbytes")],
)
class Msg_FieldValue(EventMsg):
    pass

def _test():
    m = Msg_FieldValue()
    req = struct.pack("iiQQQQi", MsgType.FIELD_VALUE, 0, 99, 1, 2, 55, 3)
    req += struct.pack(">3s", "\x01\x02\x03")
    m.extract(req)
    s = m.generate()
    assert(s == list(req))

_test()

@decorate_msg(BasicMsg, MsgType.CONTINUE, [])
class Msg_Continue(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.NEXT, [])
class Msg_Next(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.GET_VALUE,
    [("packet_id", "Q", None), ("copy_id", "Q", None), ("fid", "Q", None)],
)
class Msg_GetValue(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.GET_BACKTRACE,
    [("packet_id", "Q", None), ("copy_id", "Q", None)],
)
class Msg_GetBacktrace(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.BACKTRACE,
    [("packet_id", "Q", None), ("copy_id", "Q", None),
     ("nb", "i", None), ("ctrs", 4, "nb")],
)
class Msg_Backtrace(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.BREAK_PACKET_IN, [])
class Msg_BreakPacketIn(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.REMOVE_PACKET_IN, [])
class Msg_RemovePacketIn(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.STOP_PACKET_IN, [])
class Msg_StopPacketIn(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.RESUME_PACKET_IN, [])
class Msg_ResumePacketIn(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.FILTER_NOTIFICATIONS,
    [("nb", "i", None), ("ids", 16, "nb")],
)
class Msg_FilterNotifications(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.SET_WATCHPOINT,
    [("fid", "Q", None)],
)
class Msg_SetWatchpoint(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.UNSET_WATCHPOINT,
    [("fid", "Q", None)],
)
class Msg_UnsetWatchpoint(BasicMsg):
    pass

@decorate_msg(
    BasicMsg, MsgType.STATUS,
    [("status", "i", None), ("aux", "Q", None)],
)
class Msg_Status(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.RESET, [])
class Msg_Reset(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.KEEP_ALIVE, [])
class Msg_KeepAlive(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.ATTACH, [])
class Msg_Attach(BasicMsg):
    pass

@decorate_msg(BasicMsg, MsgType.DETACH, [])
class Msg_Detach(BasicMsg):
    pass

MsgTypeToCLS = {
    MsgType.PACKET_IN : Msg_PacketIn,
    MsgType.PACKET_OUT : Msg_PacketOut,
    MsgType.FIELD_VALUE : Msg_FieldValue,
    MsgType.CONTINUE : Msg_Continue,
    MsgType.NEXT : Msg_Next,
    MsgType.GET_VALUE : Msg_GetValue,
    MsgType.GET_BACKTRACE : Msg_GetBacktrace,
    MsgType.BACKTRACE : Msg_Backtrace,
    MsgType.BREAK_PACKET_IN : Msg_BreakPacketIn,
    MsgType.REMOVE_PACKET_IN : Msg_RemovePacketIn,
    MsgType.STOP_PACKET_IN : Msg_StopPacketIn,
    MsgType.RESUME_PACKET_IN : Msg_ResumePacketIn,
    MsgType.FILTER_NOTIFICATIONS : Msg_FilterNotifications,
    MsgType.SET_WATCHPOINT : Msg_SetWatchpoint,
    MsgType.UNSET_WATCHPOINT : Msg_UnsetWatchpoint,
    MsgType.STATUS : Msg_Status,
    MsgType.RESET : Msg_Reset,
    MsgType.KEEP_ALIVE : Msg_KeepAlive,
    MsgType.ATTACH : Msg_Attach,
    MsgType.DETACH : Msg_Detach,
}

CLSToMsgType = {}
for k, v in MsgTypeToCLS.items():
    CLSToMsgType[v] = k

FIELD_ID_CTR = 0xffffffffffffffff
FIELD_ID_COND = 0xfffffffffffffffe
FIELD_ID_ACTION = 0xfffffffffffffffd

class UIn_Error(Exception):
    def __init__(self, info=""):
        self.info = info

    def __str__(self):
        return self.info

class UIn_Warning(Exception):
    def __init__(self, info=""):
        self.info = info

    def __str__(self):
        return self.info

def handle_bad_input(f):
    @wraps(f)
    def handle(*args, **kwargs):
        try:
            return f(*args, **kwargs)
        except UIn_Error as e:
            print "Error:", e
        except UIn_Warning as e:
            print "Error:", e
    return handle

class DebuggerAPI(cmd.Cmd):
    prompt = 'P4DBG: '
    intro = "Prototype for Debugger UI"

    def __init__(self, addr):
        cmd.Cmd.__init__(self)
        self.addr = addr
        self.sok = nnpy.Socket(nnpy.AF_SP, nnpy.REQ)
        try:
            self.sok.connect(self.addr)
        except:
            print "Impossible to connect to provided socket (bad format?)"
            sys.exit(1)
        self.req_id = 0
        self.switch_id = 0
        self.break_packet_in = False
        self.stop_packet_in = False
        # right now we never remove elements from this
        self.skips = set()
        self.skips_all = set()
        self.current_packet_id = None
        self.current_copy_id = None

        self.get_me_a_prompt = False
        self.attached = False

    def attach(self):
        print "Connecting to the switch..."
        self.send_attach()
        self.attached = True
        print "Connection established"

    def send_attach(self):
        req = Msg_Attach(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        self.wps = set()
        self.bps = set()

    def do_EOF(self, line):
        print "Detaching from switch"
        self.say_bye()
        return True

    def say_bye(self):
        # This whole function is kind of hacky
        self.sok.setsockopt(nnpy.SOL_SOCKET, nnpy.RCVTIMEO, 500)
        self.sok.setsockopt(nnpy.SOL_SOCKET, nnpy.SNDTIMEO, 500)

        req = Msg_Detach(switch_id = 0, req_id = self.get_req_id())
        status = self.sok.send(req.generate())
        try:
            msg = self.wait_for_msg()
        except:
            return
        self.check_msg_CLS(msg, Msg_Status)
        self.wps = set()

    def send_reset(self):
        req = Msg_Reset(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        self.wps = set()
        self.bps = set()

    def packet_id_str(self, packet_id, copy_id):
        return ".".join([str(packet_id), str(copy_id)])

    def at_least_n_args(self, args, n):
        if len(args) < n:
            raise UIn_Error("Insufficient number of args")

    def exactly_n_args(self, args, n):
        if len(args) != n:
            raise UIn_Error(
                "Wrong number of args, expected %d but got %d" % (n, len(args))
            )

    def continue_or_next(self, req, is_next):
        while True:
            self.sok.send(req.generate())
            while True:
                try:
                    msg = self.wait_for_msg()
                    break
                except KeyboardInterrupt:
                    self.get_me_a_prompt = True
            if msg.type == MsgType.KEEP_ALIVE:
                if self.get_me_a_prompt == True:
                    self.get_me_a_prompt = False
                    return
            else:
                self.check_msg_CLS(msg, EventMsg)
                if msg.packet_id in self.skips_all:
                    continue
                if (msg.packet_id, msg.copy_id) in self.skips:
                    continue
                # a little hacky
                if (not is_next) and (msg.type == MsgType.FIELD_VALUE) and\
                   (msg.fid == FIELD_ID_CTR) and (msg.bytes_int not in self.bps):
                    continue
                break
        self.current_packet_id = msg.packet_id
        self.current_copy_id = msg.copy_id
        print "New event for packet", self.packet_id_str(msg.packet_id, msg.copy_id)
        return msg

    def special_update(self, id_, v):
        if id_ == FIELD_ID_CTR:
            type_name, obj_name = resolve_ctr(v)
            if 0x80 & (v >> 24):
                print "Exiting", type_name, "'%s'" % obj_name
            else:
                print "Entering", type_name, "'%s'" % obj_name
        elif id_ == FIELD_ID_COND:
            print "Condition evaluated to", bool(v)

    @handle_bad_input
    def do_continue(self, line):
        "Starts / resumes packet processing: continue(c)"
        req = Msg_Continue(switch_id = 0, req_id = self.get_req_id())
        msg = self.continue_or_next(req, False)
        if msg is None:
            return
        if msg.type == MsgType.FIELD_VALUE:
            if msg.fid in {FIELD_ID_CTR, FIELD_ID_COND, FIELD_ID_ACTION}:
                self.special_update(msg.fid, msg.bytes_int)
                return
            assert(msg.fid in self.wps)
            print "Watchpoint hit for field", get_name_from_field_id(msg.fid)
            print "New value is", msg.bytes_str, "(%d)" % msg.bytes_int
        elif msg.type == MsgType.PACKET_IN:
            print "Packet in!"
        # elif msg.type == MsgType.PACKET_OUT:
        #     pass
        else:
            assert(0)

    @handle_bad_input
    def do_next(self, line):
        "Go to next field update: next(n)"
        req = Msg_Next(switch_id = 0, req_id = self.get_req_id())
        msg = self.continue_or_next(req, True)
        if msg is None:
            return
        if msg.type == MsgType.FIELD_VALUE:
            if msg.fid in {FIELD_ID_CTR, FIELD_ID_COND, FIELD_ID_ACTION}:
                self.special_update(msg.fid, msg.bytes_int)
                return
            print "Update for field", get_name_from_field_id(msg.fid)
            print "New value is", msg.bytes_str, "(%d)" % msg.bytes_int
        elif msg.type == MsgType.PACKET_IN:
            print "Packet in!"
        # elif msg.type == MsgType.PACKET_OUT:
        #     pass
        else:
            assert(0)

    @handle_bad_input
    def do_reset(self, line):
        "Resets all state, including at the switch"
        self.send_reset()

    def field_id_from_name(self, field_name):
        if field_name == "$cond":
            return FIELD_ID_COND
        elif field_name == "$action":
            return FIELD_ID_ACTION
        else:
            try:
                field_id = get_field_id_from_name(field_name)
                return field_id
            except:
                raise UIn_Error("Unknow field name '%s'" % field_name)

    @handle_bad_input
    def do_set_wp(self, line):
        "Sets a watchpoint on a field: set_wp(w) <field_name>"
        args = line.split()
        self.exactly_n_args(args, 1)

        field_id = self.field_id_from_name(args[0])

        req = Msg_SetWatchpoint(
            switch_id = 0, req_id = self.get_req_id(), fid = field_id
        )
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.wps.add(field_id)

    def complete_set_wp(self, text, line, start_index, end_index):
        fields = sorted(get_all_fields())
        if not text:
            return fields
        return [f for f in fields if f.startswith(text)]

    @handle_bad_input
    def do_unset_wp(self, line):
        "Unsets a watchpoint on a field: unset_wp <field_name>"
        args = line.split()
        self.exactly_n_args(args, 1)

        field_id = self.field_id_from_name(args[0])

        if field_id not in self.wps:
            raise UIn_Warning("No watchpoint previously set for this field")

        req = Msg_UnsetWatchpoint(
            switch_id = 0, req_id = self.get_req_id(), fid = field_id
        )
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.wps.remove(field_id)

    def complete_unset_wp(self, text, line, start_index, end_index):
        fields = sorted([get_name_from_field_id(f) for f in self.wps])
        if not text:
            return fields
        return [f for f in fields if f.startswith(text)]

    @handle_bad_input
    def do_show_wps(self, line):
        "Shows all the watchpoints set: show_wps"
        for f_name in map(get_name_from_field_id, self.wps):
            print f_name

    @handle_bad_input
    def do_break(self, line):
        "Sets a break point for a parser, parse_state, pipeline, table, condition, action or deparser: break(b) <obj type (e.g. parser)> <obj name (e.g. start)>"
        args = line.split()
        self.exactly_n_args(args, 2)

        try:
            ctr = lookup_ctr(args[0], args[1])
        except:
            raise UIn_Error("Invalid object for breakpoint")

        if not self.bps:
            req = Msg_SetWatchpoint(
                switch_id = 0, req_id = self.get_req_id(), fid = FIELD_ID_CTR
            )
            self.sok.send(req.generate())
            msg = self.wait_for_msg()
            self.check_msg_CLS(msg, Msg_Status)
            assert(msg.status == 0)
        self.bps.add(ctr)

    def complete_break(self, text, line, start_index, end_index):
        args = line.split()
        args_cnt = len(args)
        obj_types = obj_map.ids.values()
        fields = sorted(get_all_fields())
        if (args_cnt == 1 and not text) or\
           (args_cnt == 2 and text):
            return [t for t in obj_types if t.startswith(text)]
        if (args_cnt == 2 and not text) or\
           (args_cnt == 3 and text):
            obj_type = args[1]
            obj_names = obj_map.store[obj_type].names.values()
            return [n for n in obj_names if n.startswith(text)]
        return []

    @handle_bad_input
    def do_delete(self, line):
        "Unsets a break point, previously set with the 'break' command: delete(d) <obj_type> <obj_name>"
        args = line.split()
        self.exactly_n_args(args, 2)

        try:
            ctr = lookup_ctr(args[0], args[1])
        except:
            raise UIn_Error("Invalid object for breakpoint")

        if ctr not in self.bps:
            raise UIn_Warning("No breakpoint previously set for this object")

        self.bps.remove(ctr)

    def complete_delete(self, text, line, start_index, end_index):
        args = line.split()
        args_cnt = len(args)
        if not self.bps:
            return []
        objs = map(resolve_ctr, self.bps)
        if (args_cnt == 1 and not text) or\
           (args_cnt == 2 and text):
            return [t for t in zip(*objs)[0] if t.startswith(text)]
        if (args_cnt == 2 and not text) or\
           (args_cnt == 3 and text):
            return [n for t, n in objs if t == args[1] and n.startswith(text)]
        return []

    @handle_bad_input
    def do_show_bps(self, line):
        "Shows all the breakpoints set: show_bps"
        for t, n in map(resolve_ctr, self.bps):
            print t, "'%s'" % n

    def get_req_id(self):
        req_id = self.req_id
        self.req_id += 1
        return req_id

    def current_packet_id_str(self):
        return ".".join([str(self.current_packet_id),
                         str(self.current_copy_id)])

    def packet_id_from_str(self, id_):
        try:
            packet_id, copy_id = id_.split(".")
            packet_id, copy_id = int(packet_id), int(copy_id)
            return packet_id, copy_id
        except:
            raise UIn_Error("Bad packet id format '%s', should be of the form <1>.<2>" % id_)

    @handle_bad_input
    def do_print(self, line):
        "Prints the value of a field for a packet: print(p) <packet_id> <field_name>"
        args = line.split()
        self.at_least_n_args(args, 1)

        if len(args) == 1:
            if self.current_packet_id is None:
                raise UIn_Error("Cannot use this command because no packets have been observed yet")
            print "Packet id not specified, assuming current packet (%s)" \
                % self.current_packet_id_str()
            packet_id = self.current_packet_id
            copy_id = self.current_copy_id
            field_name = args[0]
        else:
            packet_id, copy_id = self.packet_id_from_str(args[0])
            field_name = args[1]

        field_id = self.field_id_from_name(field_name)

        req = Msg_GetValue(
            switch_id = 0, req_id = self.get_req_id(),
            packet_id = packet_id, copy_id = copy_id, fid = field_id
        )
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        if msg.type == MsgType.STATUS:
            if msg.status == 1:
                print "Unknown packet id. Maybe it left the switch already"
            elif msg.status == 2:
                print "We have not received a value for this field,"\
                    " maybe it is not valid (yet), or the value is 0"
                pass
            else:
                assert(0)
            return
        self.check_msg_CLS(msg, Msg_FieldValue)
        print msg.bytes_str, "(%d)" % msg.bytes_int

    def complete_print(self, text, line, start_index, end_index):
        args = line.split()
        args_cnt = len(args)
        fields = sorted(get_all_fields())
        return [f for f in fields if f.startswith(text)]

    @handle_bad_input
    def do_backtrace(self, line):
        "Show a backtrace of contexts entered by packet: backtrace(bt) <packet_id>"
        args = line.split()

        if len(args) == 0:
            if self.current_packet_id is None:
                raise UIn_Error("Cannot use this command because no packets have been observed yet")
            print "Packet id not specified, assuming current packet (%s)" \
                % self.current_packet_id_str()
            packet_id = self.current_packet_id
            copy_id = self.current_copy_id
        else:
            packet_id, copy_id = self.packet_id_from_str(args[0])

        req = Msg_GetBacktrace(
            switch_id = 0, req_id = self.get_req_id(),
            packet_id = packet_id, copy_id = copy_id
        )
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        if msg.type == MsgType.STATUS:
            if msg.status == 1:
                print "Unknown packet id. Maybe it left the switch already"
            else:
                assert(0)
            return
        self.check_msg_CLS(msg, Msg_Backtrace)
        ctrs = struct.unpack("%di" % msg.nb, msg.ctrs)
        bt = []
        for ctr in ctrs:
            type_name, obj_name = resolve_ctr(ctr)
            bt += ["%s '%s'" % (type_name, obj_name)]
        print " -> ".join(bt)

    @handle_bad_input
    def do_break_packet_in(self, line):
        "Breaks everytime a new packet enters the switch"
        req = Msg_BreakPacketIn(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.break_packet_in = True

    @handle_bad_input
    def do_remove_packet_in(self, line):
        "Remove breakpoint set by break_packet_in"
        if not self.break_packet_in:
            print "Packet in breakpoint was not previously set"
            return
        req = Msg_RemovePacketIn(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.break_packet_in = False

    @handle_bad_input
    def do_stop_packet_in(self, line):
        "Stop accepting packets into the switch"
        req = Msg_StopPacketIn(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.stop_packet_in = True

    @handle_bad_input
    def do_resume_packet_in(self, line):
        "Start accepting packets into the switch again (undoes stop_packet_in)"
        if not self.stop_packet_in:
            print "stop_packet_in was not being enforced"
            return
        req = Msg_ResumePacketIn(switch_id = 0, req_id = self.get_req_id())
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)
        self.stop_packet_in = False

    @handle_bad_input
    def do_filter_notifications(self, line):
        "Filter notifications to some packet_ids: filter_notifications <packet ids>*"
        args = line.split()
        pids = []
        for pid in args:
            if "." in pid:
                packet_id, copy_id = self.packet_id_from_str(args[0])
            else:
                try:
                    packet_id = int(pid)
                    copy_id = 0xffffffffffffffff
                except:
                    raise UIn_Error("Bad format for packet id")
            pids.append( (packet_id, copy_id) )

        s = ""
        for packet_id, copy_id in pids:
            s += struct.pack("QQ", packet_id, copy_id)

        req = Msg_FilterNotifications(
            switch_id = 0, req_id = self.get_req_id(),
            nb = len(pids), ids = s
        )
        self.sok.send(req.generate())
        msg = self.wait_for_msg()
        self.check_msg_CLS(msg, Msg_Status)
        assert(msg.status == 0)

    @handle_bad_input
    def do_skip(self, line):
        "Skip all future notifications for this packet"
        if self.current_packet_id is None:
            return
        assert(self.current_copy_id is not None)
        self.skips.add( (self.current_packet_id, self.current_copy_id) )

    @handle_bad_input
    def do_skip_all(self, line):
        "Skip all future notifications for this packet and its descendants"
        if self.current_packet_id is None:
            return
        assert(self.current_copy_id is not None)
        self.skips_all.add(self.current_packet_id)

    # TODO(antonin): improve this a little bit
    # e.g. avoid loading the JSON everytime
    def do_CLI(self, line):
        "Connects to the bmv2 using the CLI, e.g. CLI table_dump <table_name>"
        if not with_runtime_CLI:
            return UIn_Error("Runtime CLI not available")
        services = runtime_CLI.RuntimeAPI.get_thrift_services(
            runtime_CLI.PreType.None)
        standard_client, mc_client = runtime_CLI.thrift_connect(
            args.thrift_ip, args.thrift_port, services)
        runtime_CLI.RuntimeAPI(
            runtime_CLI.PreType.None, standard_client, mc_client).onecmd(line)

    def complete_CLI(self, text, line, start_index, end_index):
        args_ = line.split()
        args_cnt = len(args_)
        runtime_CLI.load_json(args.json)
        if (args_cnt == 1 and not text) or\
           (args_cnt == 2 and text):
            return runtime_CLI.RuntimeAPI(None, None, None).completenames(
                " ".join(args_[1:]))
        else:
            complete = "complete_" + args_[1]
            method = getattr(runtime_CLI.RuntimeAPI(None, None, None), complete)
            return method(text, " ".join(args_[1:]), start_index, end_index)

    def wait_for_msg(self):
        data = self.sok.recv()
        msg = BasicMsg()
        msg.extract(data)
        msg_type = msg.type
        msg = MsgTypeToCLS[msg_type]()
        msg.extract(data)
        # print "Message received"
        # print msg
        return msg

    def check_msg_CLS(self, msg, CLS):
        assert(isinstance(msg, CLS))

# Adding command shortcuts
shortcuts = {
    "continue" : "c",
    "next" : "n",
    "print" : "p",
    "set_wp" : "w",
    "backtrace" : "bt",
    "break" : "b",
    "delete" : "d",
}
for long_name, short_name in shortcuts.items():
    f_do = getattr(DebuggerAPI, "do_" + long_name)
    setattr(DebuggerAPI, "do_" + short_name, f_do)
    if hasattr(DebuggerAPI, "complete_" + long_name):
        f_complete = getattr(DebuggerAPI, "complete_" + long_name)
        setattr(DebuggerAPI, "complete_" + short_name, f_complete)

def main():
    json_src = args.json

    if json_src:
        field_map.load_names(json_src)
        obj_map.load_names(json_src)

    c = DebuggerAPI(args.socket)
    try:
        c.attach()
        c.cmdloop()
    except KeyboardInterrupt:
        if c.attached:
            c.say_bye()
    except Exception as e:
        print "Unknow error, detaching and exiting"
        print e
        if c.attached:
            c.say_bye()

if __name__ == "__main__":
    main()