// Copyright (c) 2014-2017, 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" // check local first (in the event of static or in-source compilation of libunbound) #include "unbound.h" #include #include "include_base_utils.h" #include #include using namespace epee; namespace bf = boost::filesystem; #undef MONERO_DEFAULT_LOG_CATEGORY #define MONERO_DEFAULT_LOG_CATEGORY "net.dns" #define DEFAULT_DNS_PUBLIC_ADDR "8.8.4.4" 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* get_builtin_ds(void) { return ". IN DS 19036 8 2 49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5\n"; } /************************************************************ ************************************************************ ***********************************************************/ } // anonymous namespace namespace tools { // fuck it, I'm tired of dealing with getnameinfo()/inet_ntop/etc std::string ipv4_to_string(const char* src, size_t len) { assert(len >= 4); 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, size_t len) { assert(len >= 8); 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(); } std::string txt_to_string(const char* src, size_t len) { return std::string(src+1, len-1); } // custom smart pointer. // TODO: see if std::auto_ptr and the like support custom destructors template 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_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::string dns_public_addr = DEFAULT_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: " << 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) { ub_ctx_set_fwd(m_data->m_ub_context, dns_public_addr.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); } ub_ctx_add_ta(m_data->m_ub_context, string_copy(::get_builtin_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 DNSResolver::get_record(const std::string& url, int record_type, std::string (*reader)(const char *,size_t), bool& dnssec_available, bool& dnssec_valid) { std::vector 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->secure && result->bogus)); dnssec_valid = result->secure && !result->bogus; if (result->havedata) { for (size_t i=0; result->data[i] != NULL; i++) { addresses.push_back((*reader)(result->data[i], result->len[i])); } } } return addresses; } std::vector 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 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 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 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 monero address from the TXT record of a DNS entry * * gets the monero address from the TXT record of the DNS entry associated * with . If this lookup fails, or the TXT record does not contain an * XMR address in the correct format, returns an empty string. * 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 monero address (as a string) or an empty string */ std::vector addresses_from_url(const std::string& url, bool& dnssec_valid) { std::vector 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 monero 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&, 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& a, const std::vector& 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 &good_records, const std::vector &dns_urls) { // Prevent infinite recursion when distributing if (dns_urls.empty()) return false; std::vector > records; records.resize(dns_urls.size()); std::random_device rd; std::mt19937 gen(rd()); std::uniform_int_distribution dis(0, dns_urls.size() - 1); size_t first_index = dis(gen); // send all requests in parallel std::vector threads(dns_urls.size()); std::deque 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; do { 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::string parse_dns_public(const char *s) { unsigned ip0, ip1, ip2, ip3; char c; std::string dns_public_addr; if (!strcmp(s, "tcp")) { dns_public_addr = DEFAULT_DNS_PUBLIC_ADDR; LOG_PRINT_L0("Using default public DNS server: " << 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 = std::string(s + strlen("tcp://")); } } else { MERROR("Invalid DNS_PUBLIC contents, ignored"); } return dns_public_addr; } } // namespace tools::dns_utils } // namespace tools