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/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <set>
#include <vector>
#include "Constants.hpp"
#include "SelfAwareness.hpp"
#include "RuntimeEnvironment.hpp"
#include "Node.hpp"
#include "Topology.hpp"
#include "Packet.hpp"
#include "Peer.hpp"
#include "Switch.hpp"
// Entry timeout -- make it fairly long since this is just to prevent stale buildup
#define ZT_SELFAWARENESS_ENTRY_TIMEOUT 600000
namespace ZeroTier {
class _ResetWithinScope
{
public:
_ResetWithinScope(void *tPtr,uint64_t now,int inetAddressFamily,InetAddress::IpScope scope) :
_now(now),
_tPtr(tPtr),
_family(inetAddressFamily),
_scope(scope) {}
inline void operator()(Topology &t,const SharedPtr<Peer> &p) { p->resetWithinScope(_tPtr,_scope,_family,_now); }
private:
uint64_t _now;
void *_tPtr;
int _family;
InetAddress::IpScope _scope;
};
SelfAwareness::SelfAwareness(const RuntimeEnvironment *renv) :
RR(renv),
_phy(128)
{
}
void SelfAwareness::iam(void *tPtr,const Address &reporter,const InetAddress &receivedOnLocalAddress,const InetAddress &reporterPhysicalAddress,const InetAddress &myPhysicalAddress,bool trusted,uint64_t now)
{
const InetAddress::IpScope scope = myPhysicalAddress.ipScope();
if ((scope != reporterPhysicalAddress.ipScope())||(scope == InetAddress::IP_SCOPE_NONE)||(scope == InetAddress::IP_SCOPE_LOOPBACK)||(scope == InetAddress::IP_SCOPE_MULTICAST))
return;
Mutex::Lock _l(_phy_m);
PhySurfaceEntry &entry = _phy[PhySurfaceKey(reporter,receivedOnLocalAddress,reporterPhysicalAddress,scope)];
if ( (trusted) && ((now - entry.ts) < ZT_SELFAWARENESS_ENTRY_TIMEOUT) && (!entry.mySurface.ipsEqual(myPhysicalAddress)) ) {
// Changes to external surface reported by trusted peers causes path reset in this scope
TRACE("physical address %s for scope %u as seen from %s(%s) differs from %s, resetting paths in scope",myPhysicalAddress.toString().c_str(),(unsigned int)scope,reporter.toString().c_str(),reporterPhysicalAddress.toString().c_str(),entry.mySurface.toString().c_str());
entry.mySurface = myPhysicalAddress;
entry.ts = now;
entry.trusted = trusted;
// Erase all entries in this scope that were not reported from this remote address to prevent 'thrashing'
// due to multiple reports of endpoint change.
// Don't use 'entry' after this since hash table gets modified.
{
Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
PhySurfaceKey *k = (PhySurfaceKey *)0;
PhySurfaceEntry *e = (PhySurfaceEntry *)0;
while (i.next(k,e)) {
if ((k->reporterPhysicalAddress != reporterPhysicalAddress)&&(k->scope == scope))
_phy.erase(*k);
}
}
// Reset all paths within this scope and address family
_ResetWithinScope rset(tPtr,now,myPhysicalAddress.ss_family,(InetAddress::IpScope)scope);
RR->topology->eachPeer<_ResetWithinScope &>(rset);
} else {
// Otherwise just update DB to use to determine external surface info
entry.mySurface = myPhysicalAddress;
entry.ts = now;
entry.trusted = trusted;
}
}
void SelfAwareness::clean(uint64_t now)
{
Mutex::Lock _l(_phy_m);
Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
PhySurfaceKey *k = (PhySurfaceKey *)0;
PhySurfaceEntry *e = (PhySurfaceEntry *)0;
while (i.next(k,e)) {
if ((now - e->ts) >= ZT_SELFAWARENESS_ENTRY_TIMEOUT)
_phy.erase(*k);
}
}
std::vector<InetAddress> SelfAwareness::getSymmetricNatPredictions()
{
/* This is based on ideas and strategies found here:
* https://tools.ietf.org/html/draft-takeda-symmetric-nat-traversal-00
*
* For each IP address reported by a trusted (upstream) peer, we find
* the external port most recently reported by ANY peer for that IP.
*
* We only do any of this for global IPv4 addresses since private IPs
* and IPv6 are not going to have symmetric NAT.
*
* SECURITY NOTE:
*
* We never use IPs reported by non-trusted peers, since this could lead
* to a minor vulnerability whereby a peer could poison our cache with
* bad external surface reports via OK(HELLO) and then possibly coax us
* into suggesting their IP to other peers via PUSH_DIRECT_PATHS. This
* in turn could allow them to MITM flows.
*
* Since flows are encrypted and authenticated they could not actually
* read or modify traffic, but they could gather meta-data for forensics
* purpsoes or use this as a DOS attack vector. */
std::map< uint32_t,std::pair<uint64_t,unsigned int> > maxPortByIp;
InetAddress theOneTrueSurface;
bool symmetric = false;
{
Mutex::Lock _l(_phy_m);
{ // First get IPs from only trusted peers, and perform basic NAT type characterization
Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
PhySurfaceKey *k = (PhySurfaceKey *)0;
PhySurfaceEntry *e = (PhySurfaceEntry *)0;
while (i.next(k,e)) {
if ((e->trusted)&&(e->mySurface.ss_family == AF_INET)&&(e->mySurface.ipScope() == InetAddress::IP_SCOPE_GLOBAL)) {
if (!theOneTrueSurface)
theOneTrueSurface = e->mySurface;
else if (theOneTrueSurface != e->mySurface)
symmetric = true;
maxPortByIp[reinterpret_cast<const struct sockaddr_in *>(&(e->mySurface))->sin_addr.s_addr] = std::pair<uint64_t,unsigned int>(e->ts,e->mySurface.port());
}
}
}
{ // Then find max port per IP from a trusted peer
Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
PhySurfaceKey *k = (PhySurfaceKey *)0;
PhySurfaceEntry *e = (PhySurfaceEntry *)0;
while (i.next(k,e)) {
if ((e->mySurface.ss_family == AF_INET)&&(e->mySurface.ipScope() == InetAddress::IP_SCOPE_GLOBAL)) {
std::map< uint32_t,std::pair<uint64_t,unsigned int> >::iterator mp(maxPortByIp.find(reinterpret_cast<const struct sockaddr_in *>(&(e->mySurface))->sin_addr.s_addr));
if ((mp != maxPortByIp.end())&&(mp->second.first < e->ts)) {
mp->second.first = e->ts;
mp->second.second = e->mySurface.port();
}
}
}
}
}
if (symmetric) {
std::vector<InetAddress> r;
for(unsigned int k=1;k<=3;++k) {
for(std::map< uint32_t,std::pair<uint64_t,unsigned int> >::iterator i(maxPortByIp.begin());i!=maxPortByIp.end();++i) {
unsigned int p = i->second.second + k;
if (p > 65535) p -= 64511;
InetAddress pred(&(i->first),4,p);
if (std::find(r.begin(),r.end(),pred) == r.end())
r.push_back(pred);
}
}
return r;
}
return std::vector<InetAddress>();
}
} // namespace ZeroTier
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