From f0b4138f1f6ecb86c971dd7edf72a92d54e22721 Mon Sep 17 00:00:00 2001
From: Thomas Winget <tewinget@gmail.com>
Date: Mon, 29 Sep 2014 16:30:47 -0400
Subject: various changes to runtime checkpoint updating

json checkpoints will be checked every 10 minutes, dns every 60.

json checkpoints always enforced, dns still with flag.

conflicting checkpoints is hard fail, but soft if dns enforce flag not
set and dns checkpoints are wonky.
---
 src/cryptonote_core/checkpoints_create.cpp | 43 ++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 5 deletions(-)

(limited to 'src/cryptonote_core/checkpoints_create.cpp')

diff --git a/src/cryptonote_core/checkpoints_create.cpp b/src/cryptonote_core/checkpoints_create.cpp
index b81353539..808bc46a7 100644
--- a/src/cryptonote_core/checkpoints_create.cpp
+++ b/src/cryptonote_core/checkpoints_create.cpp
@@ -32,6 +32,7 @@
 #include "common/dns_utils.h"
 #include "include_base_utils.h"
 #include <sstream>
+#include <random>
 #include "storages/portable_storage_template_helper.h" // epee json include
 
 namespace cryptonote
@@ -110,15 +111,47 @@ bool load_checkpoints_from_json(cryptonote::checkpoints& checkpoints, std::strin
   return true;
 }
 
-bool load_checkpoints_from_dns(cryptonote::checkpoints& checkpoints, const std::string& url)
+bool load_checkpoints_from_dns(cryptonote::checkpoints& checkpoints)
 {
+  static const std::vector<std::string> dns_urls = { "checkpoints.moneropulse.se"
+						   , "checkpoints.moneropulse.org"
+						   , "checkpoints.moneropulse.net"
+						   , "checkpoints.moneropulse.co"
+  };
   bool avail, valid;
-  auto records = tools::DNSResolver::instance().get_txt_record(url, avail, valid);
+  std::vector<std::string> records;
+
+  std::random_device rd;
+  std::mt19937 gen(rd());
+  std::uniform_int_distribution<int> dis(0, dns_urls.size() - 1);
+  int first_index = dis(gen);
+
+  int cur_index = first_index;
+  do
+  {
+    records = tools::DNSResolver::instance().get_txt_record(dns_urls[cur_index], avail, valid);
+    if (records.size() == 0 || (avail && !valid))
+    {
+      cur_index++;
+      if (cur_index == dns_urls.size())
+      {
+	cur_index = 0;
+      }
+      continue;
+    }
+    break;
+  } while (cur_index != first_index);
+
+  if (records.size() == 0)
+  {
+    LOG_PRINT_L1("Fetching checkpoints from DNS TXT records failed, no TXT records available.");
+    return true;
+  }
 
   if (avail && !valid)
   {
-    LOG_ERROR("DNSSEC present and failed validation for query to" << url);
-    return false;
+    LOG_PRINT_L0("DNSSEC present and failed validation for query last url, and all other urls either failed validation or returned no records");
+    return true;
   }
 
   for (auto& record : records)
@@ -154,7 +187,7 @@ bool load_checkpoints_from_dns(cryptonote::checkpoints& checkpoints, const std::
 bool load_new_checkpoints(cryptonote::checkpoints& checkpoints, std::string json_hashfile_fullpath)
 {
   // TODO: replace hard-coded url with const string or #define
-  return (load_checkpoints_from_json(checkpoints, json_hashfile_fullpath) && load_checkpoints_from_dns(checkpoints, "checkpoints.moneropulse.org"));
+  return (load_checkpoints_from_json(checkpoints, json_hashfile_fullpath) && load_checkpoints_from_dns(checkpoints));
 }
 
 }  // namespace cryptonote
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