common: do not use DNS to determine if address is local

Co-authored-by: j-berman <justinberman@protonmail.com>

src/common/util.cpp

@@ -610,13 +610,6 @@ namespace tools
 
   bool is_local_address(const std::string &address)
   {
-    // always assume Tor/I2P addresses to be untrusted by default
-    if (is_privacy_preserving_network(address))
-    {
-      MDEBUG("Address '" << address << "' is Tor/I2P, non local");
-      return false;
-    }
-
     // extract host
     epee::net_utils::http::url_content u_c;
     if (!epee::net_utils::parse_url(address, u_c))
@@ -630,20 +623,22 @@ namespace tools
       return false;
     }
 
-    // resolve to IP
-    boost::asio::io_service io_service;
-    boost::asio::ip::tcp::resolver resolver(io_service);
-    boost::asio::ip::tcp::resolver::query query(u_c.host, "");
-    boost::asio::ip::tcp::resolver::iterator i = resolver.resolve(query);
-    while (i != boost::asio::ip::tcp::resolver::iterator())
+    if (u_c.host == "localhost" || boost::ends_with(u_c.host, ".localhost")) { // RFC 6761 (6.3)
+      MDEBUG("Address '" << address << "' is local");
+      return true;
+    }
+
+    boost::system::error_code ec;
+    const auto parsed_ip = boost::asio::ip::address::from_string(u_c.host, ec);
+    if (ec) {
+      MDEBUG("Failed to parse '" << address << "' as IP address: " << ec.message() << ". Considering it not local");
+      return false;
+    }
+
+    if (parsed_ip.is_loopback())
     {
-      const boost::asio::ip::tcp::endpoint &ep = *i;
-      if (ep.address().is_loopback())
-      {
-        MDEBUG("Address '" << address << "' is local");
-        return true;
-      }
-      ++i;
+      MDEBUG("Address '" << address << "' is local");
+      return true;
     }
 
     MDEBUG("Address '" << address << "' is not local");

tests/unit_tests/CMakeLists.txt

@@ -91,6 +91,7 @@ set(unit_tests_sources
   unbound.cpp
   uri.cpp
   variant.cpp
+  util.cpp
   varint.cpp
   ver_rct_non_semantics_simple_cached.cpp
   ringct.cpp

tests/unit_tests/util.cpp

@@ -0,0 +1,50 @@
+// Copyright (c) 2023-2023, 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 "gtest/gtest.h"
+
+#include "common/util.h"
+
+TEST(LocalAddress, localhost) { ASSERT_TRUE(tools::is_local_address("localhost")); }
+TEST(LocalAddress, localhost_port) { ASSERT_TRUE(tools::is_local_address("localhost:18081")); }
+TEST(LocalAddress, localhost_suffix) { ASSERT_TRUE(tools::is_local_address("test.localhost")); }
+TEST(LocalAddress, loopback) { ASSERT_TRUE(tools::is_local_address("127.0.0.1")); }
+TEST(LocalAddress, loopback_port) { ASSERT_TRUE(tools::is_local_address("127.0.0.1:18081")); }
+TEST(LocalAddress, loopback_protocol) { ASSERT_TRUE(tools::is_local_address("http://127.0.0.1")); }
+TEST(LocalAddress, loopback_hi) { ASSERT_TRUE(tools::is_local_address("127.255.255.255")); }
+TEST(LocalAddress, loopback_lo) { ASSERT_TRUE(tools::is_local_address("127.0.0.0")); }
+TEST(LocalAddress, loopback_ipv6) { ASSERT_TRUE(tools::is_local_address("[0:0:0:0:0:0:0:1]")); }
+
+TEST(LocalAddress, onion) { ASSERT_FALSE(tools::is_local_address("vww6ybal4bd7szmgncyruucpgfkqahzddi37ktceo3ah7ngmcopnpyyd.onion")); }
+TEST(LocalAddress, i2p) { ASSERT_FALSE(tools::is_local_address("xmrto2bturnore26xmrto2bturnore26xmrto2bturnore26xmr2.b32.i2p")); }
+TEST(LocalAddress, valid_ip) { ASSERT_FALSE(tools::is_local_address("1.2.3.4")); }
+TEST(LocalAddress, valid_ipv6) { ASSERT_FALSE(tools::is_local_address("[0:0:0:0:0:0:0:2]")); }
+TEST(LocalAddress, valid_domain) { ASSERT_FALSE(tools::is_local_address("getmonero.org")); }
+TEST(LocalAddress, local_prefix) { ASSERT_FALSE(tools::is_local_address("localhost.com")); }
+TEST(LocalAddress, invalid) { ASSERT_FALSE(tools::is_local_address("test")); }
+TEST(LocalAddress, empty) { ASSERT_FALSE(tools::is_local_address("")); }