worktips/src/common/dns_utils.cpp at master · worktipsdev/worktips · GitHub

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// 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"

// 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"

#include <random>

#include <boost/thread/mutex.hpp>

#include <boost/thread/thread.hpp>

#include <boost/algorithm/string/join.hpp>

#include <boost/optional.hpp>

using namespace epee;

#undef WORKTIPS_DEFAULT_LOG_CATEGORY

#define WORKTIPS_DEFAULT_LOG_CATEGORY "net.dns"

static const char *DEFAULT_DNS_PUBLIC_ADDR[] =

{

"194.150.168.168", // CCC (Germany)

"80.67.169.40", // FDN (France)

"89.233.43.71", // http://censurfridns.dk (Denmark)

"109.69.8.51", // punCAT (Spain)

"77.109.148.137", // Xiala.net (Switzerland)

"193.58.251.251", // SkyDNS (Russia)

};

static boost::mutex instance_lock;

namespace

{

* The following two functions were taken from unbound-anchor.c, from

* the unbound library packaged with this source. The license and source

* can be found in $PROJECT_ROOT/external/unbound

/* Cert builtin commented out until it's used, as the compiler complains

// return the built in root update certificate

static const char*

get_builtin_cert(void)

{

return

// The ICANN CA fetched at 24 Sep 2010. Valid to 2028

"-----BEGIN CERTIFICATE-----\n"

"MIIDdzCCAl+gAwIBAgIBATANBgkqhkiG9w0BAQsFADBdMQ4wDAYDVQQKEwVJQ0FO\n"

"TjEmMCQGA1UECxMdSUNBTk4gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkxFjAUBgNV\n"

"BAMTDUlDQU5OIFJvb3QgQ0ExCzAJBgNVBAYTAlVTMB4XDTA5MTIyMzA0MTkxMloX\n"

"DTI5MTIxODA0MTkxMlowXTEOMAwGA1UEChMFSUNBTk4xJjAkBgNVBAsTHUlDQU5O\n"

"IENlcnRpZmljYXRpb24gQXV0aG9yaXR5MRYwFAYDVQQDEw1JQ0FOTiBSb290IENB\n"

"MQswCQYDVQQGEwJVUzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAKDb\n"

"cLhPNNqc1NB+u+oVvOnJESofYS9qub0/PXagmgr37pNublVThIzyLPGCJ8gPms9S\n"

"G1TaKNIsMI7d+5IgMy3WyPEOECGIcfqEIktdR1YWfJufXcMReZwU4v/AdKzdOdfg\n"

"ONiwc6r70duEr1IiqPbVm5T05l1e6D+HkAvHGnf1LtOPGs4CHQdpIUcy2kauAEy2\n"

"paKcOcHASvbTHK7TbbvHGPB+7faAztABLoneErruEcumetcNfPMIjXKdv1V1E3C7\n"

"MSJKy+jAqqQJqjZoQGB0necZgUMiUv7JK1IPQRM2CXJllcyJrm9WFxY0c1KjBO29\n"

"iIKK69fcglKcBuFShUECAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNVHQ8B\n"

"Af8EBAMCAf4wHQYDVR0OBBYEFLpS6UmDJIZSL8eZzfyNa2kITcBQMA0GCSqGSIb3\n"

"DQEBCwUAA4IBAQAP8emCogqHny2UYFqywEuhLys7R9UKmYY4suzGO4nkbgfPFMfH\n"

"6M+Zj6owwxlwueZt1j/IaCayoKU3QsrYYoDRolpILh+FPwx7wseUEV8ZKpWsoDoD\n"

"2JFbLg2cfB8u/OlE4RYmcxxFSmXBg0yQ8/IoQt/bxOcEEhhiQ168H2yE5rxJMt9h\n"

"15nu5JBSewrCkYqYYmaxyOC3WrVGfHZxVI7MpIFcGdvSb2a1uyuua8l0BKgk3ujF\n"

"0/wsHNeP22qNyVO+XVBzrM8fk8BSUFuiT/6tZTYXRtEt5aKQZgXbKU5dUF3jT9qg\n"

"j/Br5BZw3X/zd325TvnswzMC1+ljLzHnQGGk\n"

"-----END CERTIFICATE-----\n"

;

}

/** return the built in root DS trust anchor */

static const char* const*

get_builtin_ds(void)

{

static const char * const ds[] =

{

". IN DS 19036 8 2 49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5\n",

". IN DS 20326 8 2 E06D44B80B8F1D39A95C0B0D7C65D08458E880409BBC683457104237C7F8EC8D\n",

NULL

};

return ds;

}

/************************************************************

************************************************************

***********************************************************/

} // anonymous namespace

namespace tools

{

static const char *get_record_name(int record_type)

{

switch (record_type)

{

case DNS_TYPE_A: return "A";

case DNS_TYPE_TXT: return "TXT";

case DNS_TYPE_AAAA: return "AAAA";

default: return "unknown";

}

// fuck it, I'm tired of dealing with getnameinfo()/inet_ntop/etc

boost::optional<std::string> ipv4_to_string(const char* src, size_t len)

{

if (len < 4)

{

MERROR("Invalid IPv4 address: " << std::string(src, len));

return boost::none;

}

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...

boost::optional<std::string> ipv6_to_string(const char* src, size_t len)

{

if (len < 8)

{

MERROR("Invalid IPv4 address: " << std::string(src, len));

return boost::none;

}

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();

}

boost::optional<std::string> txt_to_string(const char* src, size_t len)

{

if (len == 0)

return boost::none;

return std::string(src+1, len-1);

}

// custom smart pointer.

// TODO: see if std::auto_ptr and the like support custom destructors

template<typename type, void (*freefunc)(type*)>

class scoped_ptr

{

public:

scoped_ptr():

ptr(nullptr)

{

}

scoped_ptr(type *p):

ptr(p)

{

}

~scoped_ptr()

{

freefunc(ptr);

}

operator type *() { return ptr; }

type **operator &() { return &ptr; }

type *operator->() { return ptr; }

operator const type*() const { return &ptr; }

private:

type* ptr;

};

typedef class scoped_ptr<ub_result,ub_resolve_free> ub_result_ptr;

struct DNSResolverData

{

ub_ctx* m_ub_context;

};

// work around for bug https://www.nlnetlabs.nl/bugs-script/show_bug.cgi?id=515 needed for it to compile on e.g. Debian 7

class string_copy {

public:

string_copy(const char *s): str(strdup(s)) {}

~string_copy() { free(str); }

operator char*() { return str; }

public:

char *str;

};

DNSResolver::DNSResolver() : m_data(new DNSResolverData())

{

int use_dns_public = 0;

std::vector<std::string> dns_public_addr;

if (auto res = getenv("DNS_PUBLIC"))

{

dns_public_addr = tools::dns_utils::parse_dns_public(res);

if (!dns_public_addr.empty())

{

MGINFO("Using public DNS server(s): " << boost::join(dns_public_addr, ", ") << " (TCP)");

use_dns_public = 1;

}

else

{

MERROR("Failed to parse DNS_PUBLIC");

}

// init libunbound context

m_data->m_ub_context = ub_ctx_create();

if (use_dns_public)

{

for (const auto &ip: dns_public_addr)

ub_ctx_set_fwd(m_data->m_ub_context, string_copy(ip.c_str()));

ub_ctx_set_option(m_data->m_ub_context, string_copy("do-udp:"), string_copy("no"));

ub_ctx_set_option(m_data->m_ub_context, string_copy("do-tcp:"), string_copy("yes"));

}

else {

// look for "/etc/resolv.conf" and "/etc/hosts" or platform equivalent

ub_ctx_resolvconf(m_data->m_ub_context, NULL);

ub_ctx_hosts(m_data->m_ub_context, NULL);

}

const char * const *ds = ::get_builtin_ds();

while (*ds)

{

MINFO("adding trust anchor: " << *ds);

ub_ctx_add_ta(m_data->m_ub_context, string_copy(*ds++));

}

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_record(const std::string& url, int record_type, boost::optional<std::string> (*reader)(const char *,size_t), bool& dnssec_available, bool& dnssec_valid)

{

std::vector<std::string> addresses;

dnssec_available = false;

dnssec_valid = false;

if (!check_address_syntax(url.c_str()))

{

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, string_copy(url.c_str()), record_type, DNS_CLASS_IN, &result))

{

dnssec_available = (result->secure || result->bogus);

dnssec_valid = result->secure && !result->bogus;

if (result->havedata)

{

for (size_t i=0; result->data[i] != NULL; i++)

{

boost::optional<std::string> res = (*reader)(result->data[i], result->len[i]);

if (res)

{

MINFO("Found \"" << *res << "\" in " << get_record_name(record_type) << " record for " << url);

addresses.push_back(*res);

}

return addresses;

}

std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dnssec_available, bool& dnssec_valid)

{

return get_record(url, DNS_TYPE_A, ipv4_to_string, dnssec_available, dnssec_valid);

}

std::vector<std::string> DNSResolver::get_ipv6(const std::string& url, bool& dnssec_available, bool& dnssec_valid)

{

return get_record(url, DNS_TYPE_AAAA, ipv6_to_string, dnssec_available, dnssec_valid);

}

std::vector<std::string> DNSResolver::get_txt_record(const std::string& url, bool& dnssec_available, bool& dnssec_valid)

{

return get_record(url, DNS_TYPE_TXT, txt_to_string, dnssec_available, dnssec_valid);

}

std::string DNSResolver::get_dns_format_from_oa_address(const std::string& oa_addr)

{

std::string addr(oa_addr);

auto first_at = addr.find("@");

if (first_at == std::string::npos)

return addr;

// convert name@domain.tld to name.domain.tld

addr.replace(first_at, 1, ".");

return addr;

}

DNSResolver& DNSResolver::instance()

{

boost::lock_guard<boost::mutex> lock(instance_lock);

static DNSResolver staticInstance;

return staticInstance;

}

DNSResolver DNSResolver::create()

{

return DNSResolver();

}

bool DNSResolver::check_address_syntax(const char *addr) const

{

// if string doesn't contain a dot, we won't consider it a url for now.

if (strchr(addr,'.') == NULL)

{

return false;

}

return true;

}

namespace dns_utils

{

//-----------------------------------------------------------------------

// TODO: parse the string in a less stupid way, probably with regex

std::string address_from_txt_record(const std::string& s)

{

// make sure the txt record has "oa1:xmr" and find it

auto pos = s.find("oa1:xmr");

if (pos == std::string::npos)

return {};

// search from there to find "recipient_address="

pos = s.find("recipient_address=", pos);

if (pos == std::string::npos)

return {};

pos += 18; // move past "recipient_address="

// find the next semicolon

auto pos2 = s.find(";", pos);

if (pos2 != std::string::npos)

{

// length of address == 95, we can at least validate that much here

if (pos2 - pos == 95)

{

return s.substr(pos, 95);

}

else if (pos2 - pos == 106) // length of address == 106 --> integrated address

{

return s.substr(pos, 106);

}

return {};

}

/**

* @brief gets a worktips address from the TXT record of a DNS entry

* gets the worktips address from the TXT record of the DNS entry associated

* with <url>. If this lookup fails, or the TXT record does not contain an

* XMR address in the correct format, returns an empty string. <dnssec_valid>

* will be set true or false according to whether or not the DNS query passes

* DNSSEC validation.

* @param url the url to look up

* @param dnssec_valid return-by-reference for DNSSEC status of query

* @return a worktips address (as a string) or an empty string

std::vector<std::string> addresses_from_url(const std::string& url, bool& dnssec_valid)

{

std::vector<std::string> addresses;

// get txt records

bool dnssec_available, dnssec_isvalid;

std::string oa_addr = DNSResolver::instance().get_dns_format_from_oa_address(url);

auto records = DNSResolver::instance().get_txt_record(oa_addr, dnssec_available, dnssec_isvalid);

// TODO: update this to allow for conveying that dnssec was not available

if (dnssec_available && dnssec_isvalid)

{

dnssec_valid = true;

}

else dnssec_valid = false;

// for each txt record, try to find a worktips address in it.

for (auto& rec : records)

{

std::string addr = address_from_txt_record(rec);

if (addr.size())

{

addresses.push_back(addr);

}

return addresses;

}

std::string get_account_address_as_str_from_url(const std::string& url, bool& dnssec_valid, std::function<std::string(const std::string&, const std::vector<std::string>&, bool)> dns_confirm)

{

// attempt to get address from dns query

auto addresses = addresses_from_url(url, dnssec_valid);

if (addresses.empty())

{

LOG_ERROR("wrong address: " << url);

return {};

}

return dns_confirm(url, addresses, dnssec_valid);

}

namespace

{

bool dns_records_match(const std::vector<std::string>& a, const std::vector<std::string>& b)

{

if (a.size() != b.size()) return false;

for (const auto& record_in_a : a)

{

bool ok = false;

for (const auto& record_in_b : b)

{

if (record_in_a == record_in_b)

{

ok = true;

break;

}

if (!ok) return false;

}

return true;

}

bool load_txt_records_from_dns(std::vector<std::string> &good_records, const std::vector<std::string> &dns_urls)

{

// Prevent infinite recursion when distributing

if (dns_urls.empty()) return false;

std::vector<std::vector<std::string> > records;

records.resize(dns_urls.size());

std::random_device rd;

std::mt19937 gen(rd());

std::uniform_int_distribution<int> dis(0, dns_urls.size() - 1);

size_t first_index = dis(gen);

// send all requests in parallel

std::vector<boost::thread> threads(dns_urls.size());

std::deque<bool> avail(dns_urls.size(), false), valid(dns_urls.size(), false);

for (size_t n = 0; n < dns_urls.size(); ++n)

{

threads[n] = boost::thread([n, dns_urls, &records, &avail, &valid](){

records[n] = tools::DNSResolver::instance().get_txt_record(dns_urls[n], avail[n], valid[n]);

});

}

for (size_t n = 0; n < dns_urls.size(); ++n)

threads[n].join();

size_t cur_index = first_index;

{

const std::string &url = dns_urls[cur_index];

if (!avail[cur_index])

{

records[cur_index].clear();

LOG_PRINT_L2("DNSSEC not available for checkpoint update at URL: " << url << ", skipping.");

}

if (!valid[cur_index])

{

records[cur_index].clear();

LOG_PRINT_L2("DNSSEC validation failed for checkpoint update at URL: " << url << ", skipping.");

}

cur_index++;

if (cur_index == dns_urls.size())

{

cur_index = 0;

}

} while (cur_index != first_index);

size_t num_valid_records = 0;

for( const auto& record_set : records)

{

if (record_set.size() != 0)

{

num_valid_records++;

}

if (num_valid_records < 2)

{

LOG_PRINT_L0("WARNING: no two valid MoneroPulse DNS checkpoint records were received");

return false;

}

int good_records_index = -1;

for (size_t i = 0; i < records.size() - 1; ++i)

{

if (records[i].size() == 0) continue;

for (size_t j = i + 1; j < records.size(); ++j)

{

if (dns_records_match(records[i], records[j]))

{

good_records_index = i;

break;

}

if (good_records_index >= 0) break;

}

if (good_records_index < 0)

{

LOG_PRINT_L0("WARNING: no two MoneroPulse DNS checkpoint records matched");

return false;

}

good_records = records[good_records_index];

return true;

}

std::vector<std::string> parse_dns_public(const char *s)

{

unsigned ip0, ip1, ip2, ip3;

char c;

std::vector<std::string> dns_public_addr;

if (!strcmp(s, "tcp"))

{

for (size_t i = 0; i < sizeof(DEFAULT_DNS_PUBLIC_ADDR) / sizeof(DEFAULT_DNS_PUBLIC_ADDR[0]); ++i)

dns_public_addr.push_back(DEFAULT_DNS_PUBLIC_ADDR[i]);

LOG_PRINT_L0("Using default public DNS server(s): " << boost::join(dns_public_addr, ", ") << " (TCP)");

}

else if (sscanf(s, "tcp://%u.%u.%u.%u%c", &ip0, &ip1, &ip2, &ip3, &c) == 4)

{

if (ip0 > 255 || ip1 > 255 || ip2 > 255 || ip3 > 255)

{

MERROR("Invalid IP: " << s << ", using default");

}

else

{

dns_public_addr.push_back(std::string(s + strlen("tcp://")));

}

else

{

MERROR("Invalid DNS_PUBLIC contents, ignored");

}

return dns_public_addr;

}

} // namespace tools::dns_utils

} // namespace tools

worktips/src/common/dns_utils.cpp at master · worktipsdev/worktips · GitHub

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