def eval_table(self, ctx):
action_exprs = []
action_matches = []
forward_cond_copy = ctx.tmp_forward_cond
# only bother to evaluate if the table can actually hit
if not z3.is_false(self.locals["hit"]):
# note: the action lists are pass by reference here
# first evaluate all the constant entries
self.eval_const_entries(ctx, action_exprs, action_matches)
# then append dynamic table entries to the constant entries
# only do this if the table can actually be manipulated
if not self.immutable:
self.eval_table_entries(ctx, action_exprs, action_matches)
# finally start evaluating the default entry
var_store = ctx.checkpoint()
# this hits when the table is either missed, or no action matches
cond = z3.Or(self.locals["miss"], z3.Not(z3.Or(*action_matches)))
ctx.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.eval_default(ctx)
if ctx.get_exited():
ctx.restore(var_store)
ctx.set_exited(False)
ctx.tmp_forward_cond = forward_cond_copy
# generate a nested set of if expressions per available action
for cond, then_vars in action_exprs:
merge_attrs(ctx, cond, then_vars)
def eval_table(self, p4_state):
action_exprs = []
action_matches = []
context = p4_state.current_context()
forward_cond_copy = context.tmp_forward_cond
# only bother to evaluate if the table can actually hit
if not self.locals["hit"] == z3.BoolVal(False):
# note: the action lists are pass by reference here
# first evaluate all the constant entries
self.eval_const_entries(p4_state, action_exprs, action_matches)
# then append dynamic table entries to the constant entries
self.eval_table_entries(p4_state, action_exprs, action_matches)
# finally start evaluating the default entry
var_store, contexts = p4_state.checkpoint()
# this hits when the table is either missed, or no action matches
cond = z3.Or(self.locals["miss"], z3.Not(z3.Or(*action_matches)))
context.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.eval_default(p4_state)
if p4_state.has_exited:
p4_state.restore(var_store, contexts)
p4_state.has_exited = False
context.tmp_forward_cond = forward_cond_copy
# generate a nested set of if expressions per available action
for cond, then_vars in action_exprs:
merge_attrs(p4_state, cond, then_vars)
def handle_select(self, p4_state):
switches = []
select_conds = []
context = p4_state.current_context()
forward_cond_copy = context.tmp_forward_cond
match_list = p4_state.resolve_expr(self.match)
for parser_cond, parser_node in reversed(self.child):
case_expr = p4_state.resolve_expr(parser_cond)
cond = build_select_cond(p4_state, case_expr, match_list)
# state forks here
var_store, contexts = p4_state.checkpoint()
context.tmp_forward_cond = z3.And(forward_cond_copy, cond)
parser_node.eval(p4_state)
select_conds.append(cond)
if not p4_state.has_exited:
switches.append(
(context.tmp_forward_cond, p4_state.get_attrs()))
p4_state.has_exited = False
context.has_returned = False
p4_state.restore(var_store, contexts)
# this hits when the table is either missed, or no action matches
cond = z3.Not(z3.Or(*select_conds))
context.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.default.eval(p4_state)
p4_state.has_exited = False
context.has_returned = False
context.tmp_forward_cond = forward_cond_copy
for cond, then_vars in switches:
merge_attrs(p4_state, cond, then_vars)
def handle_select(self, ctx):
switches = []
select_conds = []
forward_cond_copy = ctx.tmp_forward_cond
match_list = ctx.resolve_expr(self.match)
for parser_cond, parser_node in self.child:
case_expr = ctx.resolve_expr(parser_cond)
cond = build_select_cond(ctx, case_expr, match_list)
# state forks here
var_store = ctx.checkpoint()
ctx.tmp_forward_cond = z3.And(forward_cond_copy, cond)
parser_node.eval(ctx)
select_conds.append(cond)
if not (ctx.get_exited() or z3.is_false(cond)):
switches.append((ctx.tmp_forward_cond, ctx.get_attrs()))
ctx.set_exited(False)
ctx.has_returned = False
ctx.restore(var_store)
# this hits when no select matches
cond = z3.Not(z3.Or(*select_conds))
ctx.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.default.eval(ctx)
ctx.set_exited(False)
ctx.has_returned = False
ctx.tmp_forward_cond = forward_cond_copy
for cond, then_vars in reversed(switches):
merge_attrs(ctx, cond, then_vars)
def eval(self, ctx):
cond = z3.simplify(
z3.And(z3.Not(z3.Or(*ctx.forward_conds)), ctx.tmp_forward_cond))
if not z3.is_false(cond):
ctx.return_states.append((cond, ctx.copy_attrs()))
ctx.has_returned = True
ctx.forward_conds.append(ctx.tmp_forward_cond)
def eval(self, ctx):
parser_state = self.parser_state
try:
parser_state.eval(ctx)
except ParserException:
RejectState().eval(ctx)
return
if self.is_terminal:
key = self.parser_state.name
tmp_forward_conds = []
sub_ctx = ctx
while not isinstance(sub_ctx, StaticContext):
tmp_forward_conds.append(sub_ctx.tmp_forward_cond)
sub_ctx = sub_ctx.parent_ctx
cond = z3.And(*tmp_forward_conds)
attrs = ctx.get_attrs()
# add the
if key in self.parser_tree.terminal_nodes:
orig_cond = self.parser_tree.terminal_nodes[key][0]
orig_dict = self.parser_tree.terminal_nodes[key][1]
merge_dicts(orig_dict, cond, attrs)
cond = z3.Or(orig_cond, cond)
attrs = orig_dict
self.parser_tree.terminal_nodes[key] = (cond, attrs)
return
if isinstance(self.child, list):
# there is a switch case try to untangle it.
self.handle_select(ctx)
elif isinstance(self.child, ParserNode):
# direct descendant, continue the evaluation
self.child.eval(ctx)
def eval_cases(self, p4_state, cases):
case_exprs = []
case_matches = []
context = p4_state.current_context()
forward_cond_copy = context.tmp_forward_cond
for case in reversed(cases.values()):
var_store, contexts = p4_state.checkpoint()
context.tmp_forward_cond = z3.And(forward_cond_copy, case["match"])
case["case_block"].eval(p4_state)
if not (context.has_returned or p4_state.has_exited):
then_vars = p4_state.get_attrs()
case_exprs.append((case["match"], then_vars))
context.has_returned = False
p4_state.has_exited = False
p4_state.restore(var_store, contexts)
case_matches.append(case["match"])
var_store, contexts = p4_state.checkpoint()
cond = z3.Not(z3.Or(*case_matches))
context.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.default_case.eval(p4_state)
if context.has_returned or p4_state.has_exited:
p4_state.restore(var_store, contexts)
context.has_returned = False
p4_state.has_exited = False
context.tmp_forward_cond = forward_cond_copy
for cond, then_vars in case_exprs:
merge_attrs(p4_state, cond, then_vars)
def eval(self, p4_state):
context = p4_state.current_context()
if self.expr is None:
expr = None
else:
# resolve the expr before restoring the state
expr = p4_state.resolve_expr(self.expr)
if isinstance(context.return_type, z3.BitVecSortRef):
expr = z3_cast(expr, context.return_type)
# we return a complex typed expression list, instantiate
if isinstance(expr, list):
instance = gen_instance(p4_state, "undefined",
context.return_type)
instance.set_list(expr)
expr = instance
cond = z3.simplify(
z3.And(z3.Not(z3.Or(*context.forward_conds)),
context.tmp_forward_cond))
if not cond == z3.BoolVal(False):
context.return_states.append((cond, p4_state.copy_attrs()))
if expr is not None:
context.return_exprs.append((cond, expr))
context.has_returned = True
context.forward_conds.append(context.tmp_forward_cond)
def eval_switch_table_matches(self, ctx, table):
cases = OrderedDict()
if table.immutable:
# if the table is immutable we can only match on const entries
for c_keys, (action_name, _) in table.const_entries:
const_matches = []
# check if the action of the entry is even present
if action_name not in self.case_blocks:
continue
# compute the match key
# FIXME: Deal with side effects here
# Maybe just checkpoint and restore? Ugh. So expensive...
match_cond = table.get_const_matches(ctx, c_keys)
action = table.actions[action_name][0]
if action_name in cases:
prev_match, _ = cases[action_name]
match_cond = z3.Or(match_cond, prev_match)
const_matches.append(match_cond)
cases[action_name] = (
match_cond, self.case_blocks[action_name])
# we also need to process the default action separately
# this basically hits only if no other case matches
_, action_name, _ = table.default_action
match_cond = z3.Not(z3.Or(*const_matches))
if action_name in cases:
prev_match, _ = cases[action_name]
match_cond = z3.Or(match_cond, prev_match)
const_matches.append(match_cond)
cases[action_name] = (match_cond, self.case_blocks[action_name])
else:
# otherwise we are dealing with a normal table
# just insert the match entries combined with the hit expression
add_default = None
for case_name, case_block in self.case_blocks.items():
match_var = table.tbl_action
action = table.actions[case_name][0]
match_cond = z3.And(table.locals["hit"], (action == match_var))
cases[case_name] = (match_cond, case_block)
# we need to check if the default is in the cases
# this implies that the "default" case can never be executed
if case_name == table.default_action[1]:
add_default = (case_name, (z3.BoolVal(True), case_block))
if add_default and len(table.actions) == len(cases):
cases[add_default[0]] = add_default[1]
return cases
def eval_cases(self, ctx, cases):
case_exprs = []
case_matches = []
forward_cond_copy = ctx.tmp_forward_cond
fall_through_matches = []
for case_match, case_block in cases.values():
# there is no block for the switch
# this expressions falls through to the next switch case
if not case_block:
fall_through_matches.append(case_match)
continue
# matches the condition OR all the other fall-through switches
case_match = z3.Or(case_match, *fall_through_matches)
fall_through_matches.clear()
var_store = ctx.checkpoint()
ctx.tmp_forward_cond = z3.And(
forward_cond_copy, case_match)
case_block.eval(ctx)
if not (ctx.has_returned or ctx.get_exited()):
then_vars = ctx.get_attrs()
case_exprs.append((case_match, then_vars))
ctx.has_returned = False
ctx.set_exited(False)
ctx.restore(var_store)
case_matches.append(case_match)
var_store = ctx.checkpoint()
# process the default expression
cond = z3.Not(z3.Or(*case_matches))
if not z3.is_false(cond):
ctx.tmp_forward_cond = z3.And(forward_cond_copy, cond)
self.default_case.eval(ctx)
if ctx.has_returned or ctx.get_exited():
ctx.restore(var_store)
ctx.has_returned = False
ctx.set_exited(False)
ctx.tmp_forward_cond = forward_cond_copy
# merge all the expressions in reverse order
for cond, then_vars in reversed(case_exprs):
merge_attrs(ctx, cond, then_vars)
def eval(self, p4_state):
# FIXME: This checkpointing should not be necessary
# Figure out what is going on
var_store, contexts = p4_state.checkpoint()
forward_conds = []
tmp_forward_conds = []
for context in reversed(p4_state.contexts):
context.copy_out(p4_state)
forward_conds.extend(context.forward_conds)
tmp_forward_conds.append(context.tmp_forward_cond)
context = p4_state.current_context()
cond = z3.simplify(
z3.And(z3.Not(z3.Or(*forward_conds)), z3.And(*tmp_forward_conds)))
if not cond == z3.BoolVal(False):
p4_state.exit_states.append((cond, p4_state.get_z3_repr()))
p4_state.has_exited = True
p4_state.restore(var_store, contexts)
context.forward_conds.append(context.tmp_forward_cond)
def eval(self, ctx):
# FIXME: This checkpointing should not be necessary
# Figure out what is going on
var_store = ctx.checkpoint()
forward_conds = []
tmp_forward_conds = []
sub_ctx = ctx
while not isinstance(sub_ctx, StaticContext):
sub_ctx.copy_out(ctx)
forward_conds.extend(sub_ctx.forward_conds)
tmp_forward_conds.append(sub_ctx.tmp_forward_cond)
sub_ctx = sub_ctx.parent_ctx
cond = z3.simplify(
z3.And(z3.Not(z3.Or(*forward_conds)), z3.And(*tmp_forward_conds)))
if not z3.is_false(cond):
ctx.add_exit_state(cond, ctx.get_p4_state().get_members(ctx))
ctx.set_exited(True)
ctx.restore(var_store)
ctx.forward_conds.append(ctx.tmp_forward_cond)
def eval(self, p4_state):
# FIXME: This checkpointing should not be necessary
# Figure out what is going on
forward_conds = []
tmp_forward_conds = []
for context in reversed(p4_state.contexts):
forward_conds.extend(context.forward_conds)
tmp_forward_conds.append(context.tmp_forward_cond)
context = p4_state.current_context()
cond = z3.And(z3.Not(z3.Or(*forward_conds)),
z3.And(*tmp_forward_conds))
var_store, contexts = p4_state.checkpoint()
for member_name, _ in p4_state.members:
member_val = p4_state.resolve_reference(member_name)
if isinstance(member_val, StructInstance):
member_val.deactivate()
p4_state.exit_states.append((cond, p4_state.get_z3_repr()))
p4_state.restore(var_store, contexts)
p4_state.has_exited = True
context.forward_conds.append(context.tmp_forward_cond)
def eval(self, ctx):
# FIXME: This checkpointing should not be necessary
# Figure out what is going on
forward_conds = []
tmp_forward_conds = []
sub_ctx = ctx
while not isinstance(sub_ctx, StaticContext):
forward_conds.extend(sub_ctx.forward_conds)
tmp_forward_conds.append(sub_ctx.tmp_forward_cond)
sub_ctx = sub_ctx.parent_ctx
cond = z3.And(z3.Not(z3.Or(*forward_conds)),
z3.And(*tmp_forward_conds))
var_store = ctx.checkpoint()
for member_name, _ in ctx.get_p4_state().members:
member_val = ctx.resolve_reference(member_name)
if isinstance(member_val, StructInstance):
member_val.deactivate()
ctx.add_exit_state(cond, ctx.get_p4_state().get_members(ctx))
ctx.restore(var_store)
ctx.set_exited(True)
ctx.forward_conds.append(ctx.tmp_forward_cond)
def eval(self, ctx):
if self.expr is None:
expr = None
else:
# resolve the expr before restoring the state
expr = ctx.resolve_expr(self.expr)
if isinstance(ctx.return_type, z3.BitVecSortRef):
expr = z3_cast(expr, ctx.return_type)
# we return a complex typed expression list, instantiate
if isinstance(expr, list):
# name is meaningless here so keep it empty
instance = ctx.gen_instance("", ctx.return_type)
instance.set_list(expr)
expr = instance
cond = z3.simplify(z3.And(z3.Not(z3.Or(*ctx.forward_conds)),
ctx.tmp_forward_cond))
if not z3.is_false(cond):
ctx.return_states.append((cond, ctx.copy_attrs()))
if expr is not None:
ctx.return_exprs.append((cond, expr))
ctx.has_returned = True
ctx.forward_conds.append(ctx.tmp_forward_cond)
