support numeric suffixes to magnet link parameter names

ChangeLog

@@ -1,3 +1,4 @@
+	* support magnet link parameters with number siffixes
 	* consistently use "lt" namespace in examples and documentation
 	* fix Mingw build to use native cryptoAPI
 

src/magnet_uri.cpp

@@ -185,6 +185,16 @@ namespace libtorrent {
 			string_view value;
 			std::tie(value, sv) = split_string(sv, '&');
 
+			// parameter names are allowed to have a .<number>-suffix.
+			// the number has no meaning, just strip it
+			// if the characters after the period are not digits, don't strip
+			// anything
+			string_view number;
+			string_view stripped_name;
+			std::tie(stripped_name, number) = split_string(name, '.');
+			if (std::all_of(number.begin(), number.end(), [](char const c) { return is_digit(c); } ))
+				name = stripped_name;
+
 			if (name == "dn"_sv) // display name
 			{
 				error_code e;

test/test_magnet.cpp

@@ -538,3 +538,23 @@ TORRENT_TEST(parse_magnet_select_only_invalid_quotes)
 	test_select_only("magnet:?xt=urn:btih:cdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcd"
 		"&dn=foo&so=\"1,2\"", {});
 }
+
+TORRENT_TEST(magnet_tr_x_uri)
+{
+	add_torrent_params p = parse_magnet_uri("magnet:"
+		"?tr.0=udp://1"
+		"&tr.1=http://2"
+		"&tr=http://3"
+		"&xt=urn:btih:c352cdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcd");
+	TEST_CHECK((p.trackers == std::vector<std::string>{
+		"udp://1", "http://2", "http://3"}));
+
+	TEST_CHECK((p.tracker_tiers == std::vector<int>{0, 1, 2 }));
+
+	p = parse_magnet_uri("magnet:"
+		"?tr.a=udp://1"
+		"&tr.1=http://2"
+		"&xt=urn:btih:c352cdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcd");
+	TEST_CHECK((p.trackers == std::vector<std::string>{"http://2" }));
+	TEST_CHECK((p.tracker_tiers == std::vector<int>{0}));
+}