dns_utils: factor TXT record loading code from checkpoint code

src/common/dns_utils.cpp

@@ -37,6 +37,7 @@
 
 #include <stdlib.h>
 #include "include_base_utils.h"
+#include <random>
 #include <boost/filesystem/fstream.hpp>
 using namespace epee;
 namespace bf = boost::filesystem;
@@ -451,6 +452,108 @@ std::string get_account_address_as_str_from_url(const std::string& url, bool& dn
   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)
+{
+  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;
+    }
+    records[cur_index].clear();
+  } 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

src/common/dns_utils.h

@@ -165,6 +165,8 @@ std::vector<std::string> addresses_from_url(const std::string& url, bool& dnssec
 
 std::string get_account_address_as_str_from_url(const std::string& url, bool& dnssec_valid);
 
+bool load_txt_records_from_dns(std::vector<std::string> &records, const std::vector<std::string> &dns_urls);
+
 }  // namespace tools::dns_utils
 
 }  // namespace tools

src/cryptonote_basic/checkpoints.cpp

@@ -42,30 +42,6 @@ using namespace epee;
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "checkpoints"
 
-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;
-  }
-} // anonymous namespace
-
 namespace cryptonote
 {
   //---------------------------------------------------------------------------
@@ -230,6 +206,8 @@ namespace cryptonote
 
   bool checkpoints::load_checkpoints_from_dns(bool testnet)
   {
+    std::vector<std::string> records;
+
     // All four MoneroPulse domains have DNSSEC on and valid
     static const std::vector<std::string> dns_urls = { "checkpoints.moneropulse.se"
 						     , "checkpoints.moneropulse.org"
@@ -243,87 +221,10 @@ namespace cryptonote
 							     , "testpoints.moneropulse.co"
     };
 
-    std::vector<std::vector<std::string> > records;
+    if (!tools::dns_utils::load_txt_records_from_dns(records, testnet ? testnet_dns_urls : dns_urls))
-    records.resize(dns_urls.size());
+      return true; // why true ?
 
-    std::random_device rd;
+    for (const auto& record : records)
-    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;
-      if (testnet)
-      {
-        url = testnet_dns_urls[cur_index];
-      }
-      else
-      {
-        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;
-      }
-      records[cur_index].clear();
-    } 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 true;
-    }
-
-    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 true;
-    }
-
-    for (auto& record : records[good_records_index])
     {
       auto pos = record.find(":");
       if (pos != std::string::npos)