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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef PACKETCACHE_HH
#define PACKETCACHE_HH
#include "ednsoptions.hh"
#include "misc.hh"
#include "iputils.hh"
class PacketCache : public boost::noncopyable
{
public:
static uint32_t canHashPacket(const std::string& packet, uint16_t* ecsBegin, uint16_t* ecsEnd)
{
uint32_t ret = 0;
ret = burtle(reinterpret_cast<const unsigned char*>(packet.c_str()) + 2, sizeof(dnsheader) - 2, ret); // rest of dnsheader, skip id
size_t packetSize = packet.size();
size_t pos = sizeof(dnsheader);
const char* end = packet.c_str() + packetSize;
const char* p = packet.c_str() + pos;
for(; p < end && *p; ++p, ++pos) { // XXX if you embed a 0 in your qname we'll stop lowercasing there
const unsigned char l = dns_tolower(*p); // label lengths can safely be lower cased
ret=burtle(&l, 1, ret);
} // XXX the embedded 0 in the qname will break the subnet stripping
const struct dnsheader* dh = reinterpret_cast<const struct dnsheader*>(packet.c_str());
const char* skipBegin = p;
const char* skipEnd = p;
if (ecsBegin != nullptr && ecsEnd != nullptr) {
*ecsBegin = 0;
*ecsEnd = 0;
}
/* we need at least 1 (final empty label) + 2 (QTYPE) + 2 (QCLASS)
+ OPT root label (1), type (2), class (2) and ttl (4)
+ the OPT RR rdlen (2)
= 16
*/
if(ntohs(dh->arcount)==1 && (pos+16) < packetSize) {
char* optionBegin = nullptr;
size_t optionLen = 0;
/* skip the final empty label (1), the qtype (2), qclass (2) */
/* root label (1), type (2), class (2) and ttl (4) */
int res = getEDNSOption(const_cast<char*>(reinterpret_cast<const char*>(p)) + 14, end - (p + 14), EDNSOptionCode::ECS, &optionBegin, &optionLen);
if (res == 0) {
skipBegin = optionBegin;
skipEnd = optionBegin + optionLen;
if (ecsBegin != nullptr && ecsEnd != nullptr) {
*ecsBegin = optionBegin - packet.c_str();
*ecsEnd = *ecsBegin + optionLen;
}
}
}
if (skipBegin > p) {
ret = burtle(reinterpret_cast<const unsigned char*>(p), skipBegin-p, ret);
}
if (skipEnd < end) {
ret = burtle(reinterpret_cast<const unsigned char*>(skipEnd), end-skipEnd, ret);
}
return ret;
}
static uint32_t canHashPacket(const std::string& packet)
{
uint32_t ret = 0;
ret = burtle(reinterpret_cast<const unsigned char*>(packet.c_str()) + 2, sizeof(dnsheader) - 2, ret); // rest of dnsheader, skip id
size_t packetSize = packet.size();
size_t pos = sizeof(dnsheader);
const char* end = packet.c_str() + packetSize;
const char* p = packet.c_str() + pos;
for(; p < end && *p; ++p) { // XXX if you embed a 0 in your qname we'll stop lowercasing there
const unsigned char l = dns_tolower(*p); // label lengths can safely be lower cased
ret=burtle(&l, 1, ret);
} // XXX the embedded 0 in the qname will break the subnet stripping
if (p < end) {
ret = burtle(reinterpret_cast<const unsigned char*>(p), end-p, ret);
}
return ret;
}
static bool queryHeaderMatches(const std::string& cachedQuery, const std::string& query)
{
if (cachedQuery.size() != query.size()) {
return false;
}
return (cachedQuery.compare(/* skip the ID */ 2, sizeof(dnsheader) - 2, query, 2, sizeof(dnsheader) - 2) == 0);
}
static bool queryMatches(const std::string& cachedQuery, const std::string& query, const DNSName& qname)
{
if (!queryHeaderMatches(cachedQuery, query)) {
return false;
}
size_t pos = sizeof(dnsheader) + qname.wirelength();
return (cachedQuery.compare(pos, cachedQuery.size() - pos, query, pos, query.size() - pos) == 0);
}
static bool queryMatches(const std::string& cachedQuery, const std::string& query, const DNSName& qname, uint16_t ecsBegin, uint16_t ecsEnd)
{
if (!queryHeaderMatches(cachedQuery, query)) {
return false;
}
size_t pos = sizeof(dnsheader) + qname.wirelength();
if (ecsBegin != 0 && ecsBegin >= pos && ecsEnd > ecsBegin) {
if (cachedQuery.compare(pos, ecsBegin - pos, query, pos, ecsBegin - pos) != 0) {
return false;
}
if (cachedQuery.compare(ecsEnd, cachedQuery.size() - ecsEnd, query, ecsEnd, query.size() - ecsEnd) != 0) {
return false;
}
}
else {
if (cachedQuery.compare(pos, cachedQuery.size() - pos, query, pos, query.size() - pos) != 0) {
return false;
}
}
return true;
}
};
#endif /* PACKETCACHE_HH */
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