p2p: fix exclusive node DNS resolution for certain hosts

Fixes monero-project#8633. The function `append_net_address` did not parse hostname + port addresses (e.g. `bar:29080`) correctly if the hostname did not contain a `'.'` character.

@vtnerd comments 1

clear up 2nd conditional statement

src/net/parse.cpp

@@ -38,7 +38,7 @@ namespace net
 {
     void get_network_address_host_and_port(const std::string& address, std::string& host, std::string& port)
     {
-        // require ipv6 address format "[addr:addr:addr:...:addr]:port"
+        // If IPv6 address format with port "[addr:addr:addr:...:addr]:port"
         if (address.find(']') != std::string::npos)
         {
             host = address.substr(1, address.rfind(']') - 1);
@@ -47,6 +47,12 @@ namespace net
                 port = address.substr(address.rfind(':') + 1);
             }
         }
+        // Else if IPv6 address format without port e.g. "addr:addr:addr:...:addr"
+        else if (std::count(address.begin(), address.end(), ':') >= 2)
+        {
+            host = address;
+        }
+        // Else IPv4, Tor, I2P address or hostname
         else
         {
             host = address.substr(0, address.rfind(':'));

src/net/parse.h

@@ -38,6 +38,16 @@
 
 namespace net
 {
+    /*!
+     * \brief Takes a valid address string (IP, Tor, I2P, or DNS name) and splits it into host and port
+     *
+     * The host of an IPv6 addresses in the format "[x:x:..:x]:port" will have the braces stripped.
+     * For example, when the address is "[ffff::2023]", host will be set to "ffff::2023".
+     *
+     * \param address The address string one wants to split
+     * \param[out] host The host part of the address string. Is always set.
+     * \param[out] port The port part of the address string. Is only set when address string contains a port.
+    */
     void get_network_address_host_and_port(const std::string& address, std::string& host, std::string& port);
 
     /*!

src/p2p/net_node.inl

@@ -645,20 +645,10 @@ namespace nodetool
   {
     using namespace boost::asio;
 
-    std::string host = addr;
+    // Split addr string into host string and port string
+    std::string host;
     std::string port = std::to_string(default_port);
-    size_t colon_pos = addr.find_last_of(':');
-    size_t dot_pos = addr.find_last_of('.');
-    size_t square_brace_pos = addr.find('[');
-
-    // IPv6 will have colons regardless.  IPv6 and IPv4 address:port will have a colon but also either a . or a [
-    // as IPv6 addresses specified as address:port are to be specified as "[addr:addr:...:addr]:port"
-    // One may also specify an IPv6 address as simply "[addr:addr:...:addr]" without the port; in that case
-    // the square braces will be stripped here.
-    if ((std::string::npos != colon_pos && std::string::npos != dot_pos) || std::string::npos != square_brace_pos)
-    {
-      net::get_network_address_host_and_port(addr, host, port);
-    }
+    net::get_network_address_host_and_port(addr, host, port);
     MINFO("Resolving node address: host=" << host << ", port=" << port);
 
     io_service io_srv;

tests/unit_tests/net.cpp

@@ -936,6 +936,41 @@ TEST(get_network_address, ipv4subnet)
     EXPECT_STREQ("12.34.0.0/16", address->str().c_str());
 }
 
+namespace
+{
+    void na_host_and_port_test(std::string addr, std::string exp_host, std::string exp_port)
+    {
+        std::string host{"xxxxx"};
+        std::string port{"xxxxx"};
+        net::get_network_address_host_and_port(addr, host, port);
+        EXPECT_EQ(exp_host, host);
+        EXPECT_EQ(exp_port, port);
+    }
+} // anonymous namespace
+
+TEST(get_network_address_host_and_port, ipv4)
+{
+    na_host_and_port_test("9.9.9.9", "9.9.9.9", "xxxxx");
+    na_host_and_port_test("9.9.9.9:18081", "9.9.9.9", "18081");
+}
+
+TEST(get_network_address_host_and_port, ipv6)
+{
+    na_host_and_port_test("::ffff", "::ffff", "xxxxx");
+    na_host_and_port_test("[::ffff]", "::ffff", "xxxxx");
+    na_host_and_port_test("[::ffff]:00231", "::ffff", "00231");
+    na_host_and_port_test("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff", "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff", "xxxxx");
+    na_host_and_port_test("[7777:7777:7777:7777:7777:7777:7777:7777]", "7777:7777:7777:7777:7777:7777:7777:7777", "xxxxx");
+    na_host_and_port_test("[7777:7777:7777:7777:7777:7777:7777:7777]:48080", "7777:7777:7777:7777:7777:7777:7777:7777", "48080");
+}
+
+TEST(get_network_address_host_and_port, hostname)
+{
+    na_host_and_port_test("localhost", "localhost", "xxxxx");
+    na_host_and_port_test("bar:29080", "bar", "29080"); // Issue https://github.com/monero-project/monero/issues/8633
+    na_host_and_port_test("xmrchain.net:18081", "xmrchain.net", "18081");
+}
+
 namespace
 {
     using stream_type = boost::asio::ip::tcp;