Allow name@domain.tld for OpenAlias lookups

Based on tewinget's update.
Make OpenAlias address format independent of existing DNS functions.

Add tests.

Test:

make debug-test
cd build/debug/tests/unit_tests
# test that regular DNS functions work, including IPv4 lookups.
# also test function that converts OpenAlias address format
make && ./unit_tests --gtest_filter=DNSResolver*
# test that OpenAlias addresses like donate@getmonero.org work from
# wallet tools
make && ./unit_tests --gtest_filter=AddressFromURL.Success

src/common/dns_utils.cpp

@@ -304,6 +304,19 @@ std::vector<std::string> DNSResolver::get_txt_record(const std::string& url, boo
   return records;
 }
 
+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()
 {
   static DNSResolver* staticInstance = NULL;

src/common/dns_utils.h

@@ -100,6 +100,18 @@ public:
   // TODO: modify this to accomodate DNSSEC
    std::vector<std::string> get_txt_record(const std::string& url, bool& dnssec_available, bool& dnssec_valid);
 
+  /**
+   * @brief Gets a DNS address from OpenAlias format
+   *
+   * If the address looks good, but contains one @ symbol, replace that with a .
+   * e.g. donate@getmonero.org becomes donate.getmonero.org
+   *
+   * @param oa_addr  OpenAlias address
+   *
+   * @return dns_addr  DNS address
+   */
+  std::string get_dns_format_from_oa_address(const std::string& oa_addr);
+
   /**
    * @brief Gets the singleton instance of DNSResolver
    *

src/wallet/wallet2.cpp

@@ -1016,7 +1016,8 @@ std::vector<std::string> wallet2::addresses_from_url(const std::string& url, boo
   std::vector<std::string> addresses;
   // get txt records
   bool dnssec_available, dnssec_isvalid;
-  auto records = tools::DNSResolver::instance().get_txt_record(url, dnssec_available, dnssec_isvalid);
+  std::string oa_addr = tools::DNSResolver::instance().get_dns_format_from_oa_address(url);
+  auto records = tools::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)

tests/unit_tests/address_from_url.cpp

@@ -93,6 +93,14 @@ TEST(AddressFromURL, Success)
   {
     EXPECT_STREQ(addr.c_str(), addresses[0].c_str());
   }
+
+  // OpenAlias address with an @ instead of first .
+  addresses = tools::wallet2::addresses_from_url("donate@getmonero.org", dnssec_result);
+  EXPECT_EQ(1, addresses.size());
+  if (addresses.size() == 1)
+  {
+    EXPECT_STREQ(addr.c_str(), addresses[0].c_str());
+  }
 }
 
 TEST(AddressFromURL, Failure)

tests/unit_tests/dns_resolver.cpp

@@ -148,4 +148,12 @@ TEST(DNSResolver, GetTXTRecord)
   {
     std::cout << "TXT record for donate.getmonero.org: " << rec << std::endl;
   }
+
+  // replace first @ with .
+  std::string addr = tools::DNSResolver::instance().get_dns_format_from_oa_address("donate@getmonero.org");
+  EXPECT_STREQ("donate.getmonero.org", addr.c_str());
+
+  // no change
+  addr = tools::DNSResolver::instance().get_dns_format_from_oa_address("donate.getmonero.org");
+  EXPECT_STREQ("donate.getmonero.org", addr.c_str());
 }