// Copyright (c) 2014, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "common/dns_utils.h"
#include <cstring>
#include <sstream>
// check local first (in the event of static or in-source compilation of libunbound)
#include "unbound.h"
#include <stdlib.h>
#include "include_base_utils.h"
using namespace epee;
namespace tools
{
// fuck it, I'm tired of dealing with getnameinfo()/inet_ntop/etc
std::string ipv4_to_string(const char* src)
{
std::stringstream ss;
unsigned int bytes[4];
for (int i = 0; i < 4; i++)
{
unsigned char a = src[i];
bytes[i] = a;
}
ss << bytes[0] << "."
<< bytes[1] << "."
<< bytes[2] << "."
<< bytes[3];
return ss.str();
}
// this obviously will need to change, but is here to reflect the above
// stop-gap measure and to make the tests pass at least...
std::string ipv6_to_string(const char* src)
{
std::stringstream ss;
unsigned int bytes[8];
for (int i = 0; i < 8; i++)
{
unsigned char a = src[i];
bytes[i] = a;
}
ss << bytes[0] << ":"
<< bytes[1] << ":"
<< bytes[2] << ":"
<< bytes[3] << ":"
<< bytes[4] << ":"
<< bytes[5] << ":"
<< bytes[6] << ":"
<< bytes[7];
return ss.str();
}
// custom smart pointer.
// TODO: see if std::auto_ptr and the like support custom destructors
class ub_result_ptr
{
public:
ub_result_ptr()
{
ptr = nullptr;
}
~ub_result_ptr()
{
ub_resolve_free(ptr);
}
ub_result* ptr;
};
struct DNSResolverData
{
ub_ctx* m_ub_context;
};
DNSResolver::DNSResolver() : m_data(new DNSResolverData())
{
// init libunbound context
m_data->m_ub_context = ub_ctx_create();
char empty_string = '\0';
// look for "/etc/resolv.conf" and "/etc/hosts" or platform equivalent
ub_ctx_resolvconf(m_data->m_ub_context, &empty_string);
ub_ctx_hosts(m_data->m_ub_context, &empty_string);
}
DNSResolver::~DNSResolver()
{
if (m_data)
{
if (m_data->m_ub_context != NULL)
{
ub_ctx_delete(m_data->m_ub_context);
}
delete m_data;
}
}
std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
{
std::vector<std::string> addresses;
dnssec_available = false;
dnssec_valid = false;
char urlC[1000]; // waaaay too big, but just in case...
strncpy(urlC, url.c_str(), 999);
urlC[999] = '\0';
if (!check_address_syntax(urlC))
{
return addresses;
}
// destructor takes care of cleanup
ub_result_ptr result;
// call DNS resolver, blocking. if return value not zero, something went wrong
if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_A, DNS_CLASS_IN, &(result.ptr)))
{
if (result.ptr->havedata)
{
for (size_t i=0; result.ptr->data[i] != NULL; i++)
{
addresses.push_back(ipv4_to_string(result.ptr->data[i]));
}
}
}
return addresses;
}
std::vector<std::string> DNSResolver::get_ipv6(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
{
std::vector<std::string> addresses;
dnssec_available = false;
dnssec_valid = false;
char urlC[1000]; // waaaay too big, but just in case...
strncpy(urlC, url.c_str(), 999);
urlC[999] = '\0';
if (!check_address_syntax(urlC))
{
return addresses;
}
ub_result_ptr result;
// call DNS resolver, blocking. if return value not zero, something went wrong
if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_AAAA, DNS_CLASS_IN, &(result.ptr)))
{
if (result.ptr->havedata)
{
for (size_t i=0; result.ptr->data[i] != NULL; i++)
{
addresses.push_back(ipv6_to_string(result.ptr->data[i]));
}
}
}
return addresses;
}
std::vector<std::string> DNSResolver::get_txt_record(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
{
std::vector<std::string> records;
dnssec_available = false;
dnssec_valid = false;
char urlC[1000]; // waaaay too big, but just in case...
strncpy(urlC, url.c_str(), 999);
urlC[999] = '\0';
if (!check_address_syntax(urlC))
{
return records;
}
ub_result_ptr result;
// call DNS resolver, blocking. if return value not zero, something went wrong
if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_TXT, DNS_CLASS_IN, &(result.ptr)))
{
if (result.ptr->havedata)
{
for (size_t i=0; result.ptr->data[i] != NULL; i++)
{
// plz fix this, but this does NOT work and spills over into parts of memory it shouldn't: records.push_back(result.ptr->data[i]);
char *restxt;
restxt = (char*) calloc(result.ptr->len[i]+1, 1);
memcpy(restxt, result.ptr->data[i]+1, result.ptr->len[i]-1);
records.push_back(restxt);
}
}
}
return records;
}
DNSResolver& DNSResolver::instance()
{
static DNSResolver* staticInstance = NULL;
if (staticInstance == NULL)
{
staticInstance = new DNSResolver();
}
return *staticInstance;
}
bool DNSResolver::check_address_syntax(const std::string& addr)
{
// if string doesn't contain a dot, we won't consider it a url for now.
if (addr.find(".") == std::string::npos)
{
return false;
}
return true;
}
} // namespace tools
