/*
* 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.
*/
#include "dns.hh"
#include "ednsoptions.hh"
#include "iputils.hh"
/* extract a specific EDNS0 option from a pointer on the beginning rdLen of the OPT RR */
int getEDNSOption(char* optRR, const size_t len, uint16_t wantedOption, char ** optionValue, size_t * optionValueSize)
{
assert(optRR != NULL);
assert(optionValue != NULL);
assert(optionValueSize != NULL);
size_t pos = 0;
if (len < DNS_RDLENGTH_SIZE)
return EINVAL;
const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
size_t rdPos = 0;
pos += DNS_RDLENGTH_SIZE;
if ((pos + rdLen) > len) {
return EINVAL;
}
while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) &&
rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) {
const uint16_t optionCode = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
pos += EDNS_OPTION_CODE_SIZE;
rdPos += EDNS_OPTION_CODE_SIZE;
const uint16_t optionLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
pos += EDNS_OPTION_LENGTH_SIZE;
rdPos += EDNS_OPTION_LENGTH_SIZE;
if (optionLen > (rdLen - rdPos) || optionLen > (len - pos))
return EINVAL;
if (optionCode == wantedOption) {
*optionValue = optRR + pos - (EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE);
*optionValueSize = optionLen + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE;
return 0;
}
else {
/* skip this option */
pos += optionLen;
rdPos += optionLen;
}
}
return ENOENT;
}
/* extract all EDNS0 options from a pointer on the beginning rdLen of the OPT RR */
int getEDNSOptions(const char* optRR, const size_t len, EDNSOptionViewMap& options)
{
assert(optRR != NULL);
size_t pos = 0;
if (len < DNS_RDLENGTH_SIZE)
return EINVAL;
const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
size_t rdPos = 0;
pos += DNS_RDLENGTH_SIZE;
if ((pos + rdLen) > len) {
return EINVAL;
}
while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) &&
rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) {
const uint16_t optionCode = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
pos += EDNS_OPTION_CODE_SIZE;
rdPos += EDNS_OPTION_CODE_SIZE;
const uint16_t optionLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
pos += EDNS_OPTION_LENGTH_SIZE;
rdPos += EDNS_OPTION_LENGTH_SIZE;
if (optionLen > (rdLen - rdPos) || optionLen > (len - pos))
return EINVAL;
EDNSOptionViewValue value;
value.content = optRR + pos;
value.size = optionLen;
options[optionCode].values.push_back(std::move(value));
/* skip this option */
pos += optionLen;
rdPos += optionLen;
}
return 0;
}
void generateEDNSOption(uint16_t optionCode, const std::string& payload, std::string& res)
{
const uint16_t ednsOptionCode = htons(optionCode);
const uint16_t payloadLen = htons(payload.length());
res.append((const char *) &ednsOptionCode, sizeof ednsOptionCode);
res.append((const char *) &payloadLen, sizeof payloadLen);
res.append(payload);
}