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/*******************************************************************************
* Copyright (c) 2017 Politecnico di Torino and others.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Apache License, Version 2.0
* which accompanies this distribution, and is available at
* http://www.apache.org/licenses/LICENSE-2.0
*******************************************************************************/
package mcnet.netobjs;
import java.util.ArrayList;
import java.util.List;
import com.microsoft.z3.BoolExpr;
import com.microsoft.z3.Context;
import com.microsoft.z3.DatatypeExpr;
import com.microsoft.z3.Expr;
import com.microsoft.z3.FuncDecl;
import com.microsoft.z3.IntExpr;
import com.microsoft.z3.Solver;
import com.microsoft.z3.Sort;
import mcnet.components.NetContext;
import mcnet.components.Network;
import mcnet.components.NetworkObject;
import mcnet.components.Tuple;
/** Represents a Firewall with the associated Access Control List
*
*/
public class AclFirewall extends NetworkObject{
List<BoolExpr> constraints;
Context ctx;
DatatypeExpr fw;
ArrayList<Tuple<DatatypeExpr,DatatypeExpr>> acls;
Network net;
NetContext nctx;
FuncDecl acl_func;
public AclFirewall(Context ctx, Object[]... args) {
super(ctx, args);
}
@Override
protected void init(Context ctx, Object[]... args) {
this.ctx = ctx;
isEndHost=false;
constraints = new ArrayList<BoolExpr>();
acls = new ArrayList<Tuple<DatatypeExpr,DatatypeExpr>>();
z3Node = ((NetworkObject)args[0][0]).getZ3Node();
fw = z3Node;
net = (Network)args[0][1];
nctx = (NetContext)args[0][2];
net.saneSend(this);
firewallSendRules();
}
/**
* Wrap add acls
* @param policy
*/
public void setPolicy(ArrayList<Tuple<DatatypeExpr, DatatypeExpr>> policy){
addAcls(policy);
}
public void addAcls(ArrayList<Tuple<DatatypeExpr,DatatypeExpr>> acls){
this.acls.addAll(acls);
}
@Override
public DatatypeExpr getZ3Node() {
return fw;
}
@Override
protected void addConstraints(Solver solver) {
BoolExpr[] constr = new BoolExpr[constraints.size()];
solver.add(constraints.toArray(constr));
aclConstraints(solver);
}
private void firewallSendRules (){
Expr p_0 = ctx.mkConst(fw+"_firewall_send_p_0", nctx.packet);
Expr n_0 = ctx.mkConst(fw+"_firewall_send_n_0", nctx.node);
Expr n_1 = ctx.mkConst(fw+"_firewall_send_n_1", nctx.node);
IntExpr t_0 = ctx.mkIntConst(fw+"_firewall_send_t_0");
IntExpr t_1 = ctx.mkIntConst(fw+"_firewall_send_t_1");
acl_func = ctx.mkFuncDecl(fw+"_acl_func", new Sort[]{nctx.address, nctx.address},ctx.mkBoolSort());
//Constraint1 send(fw, n_0, p, t_0) -> (exist n_1,t_1 : (recv(n_1, fw, p, t_1) &&
// t_1 < t_0 && !acl_func(p.src,p.dest))
constraints.add(
ctx.mkForall(new Expr[]{n_0, p_0, t_0},
ctx.mkImplies(
(BoolExpr)nctx.send.apply(new Expr[]{ fw, n_0, p_0, t_0}),
ctx.mkExists(new Expr[]{t_1},
ctx.mkAnd(ctx.mkLt(t_1,t_0),
ctx.mkExists(new Expr[]{n_1},
nctx.recv.apply(n_1, fw, p_0, t_1),1,null,null,null,null),
ctx.mkNot((BoolExpr)acl_func.apply(nctx.pf.get("src").apply(p_0), nctx.pf.get("dest").apply(p_0)))),1,null,null,null,null)),1,null,null,null,null));
}
private void aclConstraints(Solver solver){
if (acls.size() == 0)
return;
Expr a_0 = ctx.mkConst(fw+"_firewall_acl_a_0", nctx.address);
Expr a_1 = ctx.mkConst(fw+"_firewall_acl_a_1", nctx.address);
BoolExpr[] acl_map = new BoolExpr[acls.size()];
for(int y=0;y<acls.size();y++){
Tuple<DatatypeExpr,DatatypeExpr> tp = acls.get(y);
acl_map[y] = ctx.mkOr(ctx.mkAnd(ctx.mkEq(a_0,tp._1),ctx.mkEq(a_1,tp._2)), ctx.mkAnd(ctx.mkEq(a_0,tp._2),ctx.mkEq(a_1,tp._1)));
}
//Constraint2 acl_func(a_0,a_1) == or(foreach ip1,ip2 in acl_map ((a_0 == ip1 && a_1 == ip2)||(a_0 == ip2 && a_1 == ip1)))
solver.add(ctx.mkForall(new Expr[]{a_0, a_1},
ctx.mkEq(
acl_func.apply(a_0, a_1),
ctx.mkOr(acl_map)),1,null,null,null,null));
}
}
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