1 files changed, 238 insertions, 1 deletions

diff --git a/src/common/dns_utils.cpp b/src/common/dns_utils.cpp
index e6e53a5c0..ab38cbbae 100644
--- a/src/common/dns_utils.cpp
+++ b/src/common/dns_utils.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2014-2016, The Monero Project
+// Copyright (c) 2014-2017, The Monero Project
 //
 // All rights reserved.
 //
@@ -26,7 +26,10 @@
 // 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/command_line.h"
+#include "common/i18n.h"
 #include "common/dns_utils.h"
+#include "cryptonote_basic/cryptonote_basic_impl.h"
 #include <cstring>
 #include <sstream>
 // check local first (in the event of static or in-source compilation of libunbound)
@@ -34,10 +37,14 @@
 
 #include <stdlib.h>
 #include "include_base_utils.h"
+#include <random>
 #include <boost/filesystem/fstream.hpp>
 using namespace epee;
 namespace bf = boost::filesystem;
 
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "net.dns"
+
 static boost::mutex instance_lock;
 
 namespace
@@ -323,4 +330,234 @@ bool DNSResolver::check_address_syntax(const char *addr) const
   return true;
 }
 
+namespace dns_utils
+{
+
+const char *tr(const char *str) { return i18n_translate(str, "tools::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 <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 monero 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 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, bool cli_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 {};
+  }
+  // for now, move on only if one address found
+  if (addresses.size() > 1)
+  {
+    LOG_ERROR("not yet supported: Multiple Monero addresses found for given URL: " << url);
+    return {};
+  }
+  if (!cli_confirm)
+    return addresses[0];
+  // prompt user for confirmation.
+  // inform user of DNSSEC validation status as well.
+  std::string dnssec_str;
+  if (dnssec_valid)
+  {
+    dnssec_str = tr("DNSSEC validation passed");
+  }
+  else
+  {
+    dnssec_str = tr("WARNING: DNSSEC validation was unsuccessful, this address may not be correct!");
+  }
+  std::stringstream prompt;
+  prompt << tr("For URL: ") << url
+         << ", " << dnssec_str << std::endl
+         << tr(" Monero Address = ") << addresses[0]
+         << std::endl
+         << tr("Is this OK? (Y/n) ")
+  ;  
+  // prompt the user for confirmation given the dns query and dnssec status
+  std::string confirm_dns_ok = command_line::input_line(prompt.str());
+  if (std::cin.eof())
+  {
+    return {};
+  }
+  if (!command_line::is_yes(confirm_dns_ok))
+  {
+    std::cout << tr("you have cancelled the transfer request") << std::endl;
+    return {};
+  }
+  return addresses[0];
+}
+
+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);
+
+  bool avail, valid;
+  size_t cur_index = first_index;
+  do
+  {
+    std::string url = dns_urls[cur_index];
+
+    records[cur_index] = tools::DNSResolver::instance().get_txt_record(url, avail, valid);
+    if (!avail)
+    {
+      records[cur_index].clear();
+      LOG_PRINT_L2("DNSSEC not available for checkpoint update at URL: " << url << ", skipping.");
+    }
+    if (!valid)
+    {
+      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;
+}
+
+}  // namespace tools::dns_utils
+
 }  // namespace tools