Merge pull request #5979 from bdach/brace-escaping-in-links

Fix bracket and parenthesis handling in existing link formats

Co-authored-by: Dan Balasescu <smoogipoo@smgi.me>

osu.Game.Tests/Chat/MessageFormatterTests.cs

@@ -119,6 +119,53 @@ namespace osu.Game.Tests.Chat
             Assert.AreEqual(11, result.Links[0].Length);
         }
 
+        [Test]
+        public void TestOldFormatLinkWithBalancedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a (tricky (one))[https://osu.ppy.sh]!" });
+
+            Assert.AreEqual("This is a tricky (one)!", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(12, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestOldFormatLinkWithEscapedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is (another loose bracket \\))[https://osu.ppy.sh]." });
+
+            Assert.AreEqual("This is another loose bracket ).", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(8, result.Links[0].Index);
+            Assert.AreEqual(23, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestOldFormatWithBackslashes()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This link (should end with a backslash \\)[https://osu.ppy.sh]." });
+            Assert.AreEqual("This link should end with a backslash \\.", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(29, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestOldFormatLinkWithEscapedAndBalancedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a (\\)super\\(\\( tricky (one))[https://osu.ppy.sh]!" });
+
+            Assert.AreEqual("This is a )super(( tricky (one)!", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(21, result.Links[0].Length);
+        }
+
         [Test]
         public void TestNewFormatLink()
         {
@@ -131,6 +178,42 @@ namespace osu.Game.Tests.Chat
             Assert.AreEqual(11, result.Links[0].Length);
         }
 
+        [Test]
+        public void TestNewFormatLinkWithEscapedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a [https://osu.ppy.sh nasty link with escaped brackets: \\] and \\[]" });
+
+            Assert.AreEqual("This is a nasty link with escaped brackets: ] and [", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(41, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestNewFormatLinkWithBackslashesInside()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a [https://osu.ppy.sh link \\ with \\ backslashes \\]" });
+
+            Assert.AreEqual("This is a link \\ with \\ backslashes \\", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(27, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestNewFormatLinkWithEscapedAndBalancedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a [https://osu.ppy.sh [link [with \\] too many brackets \\[ ]]]" });
+
+            Assert.AreEqual("This is a [link [with ] too many brackets [ ]]", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(36, result.Links[0].Length);
+        }
+
         [Test]
         public void TestMarkdownFormatLink()
         {
@@ -143,6 +226,53 @@ namespace osu.Game.Tests.Chat
             Assert.AreEqual(11, result.Links[0].Length);
         }
 
+        [Test]
+        public void TestMarkdownFormatLinkWithBalancedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a [tricky [one]](https://osu.ppy.sh)!" });
+
+            Assert.AreEqual("This is a tricky [one]!", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(12, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestMarkdownFormatLinkWithEscapedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is [another loose bracket \\]](https://osu.ppy.sh)." });
+
+            Assert.AreEqual("This is another loose bracket ].", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(8, result.Links[0].Index);
+            Assert.AreEqual(23, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestMarkdownFormatWithBackslashes()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This link [should end with a backslash \\](https://osu.ppy.sh)." });
+            Assert.AreEqual("This link should end with a backslash \\.", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(29, result.Links[0].Length);
+        }
+
+        [Test]
+        public void TestMarkdownFormatLinkWithEscapedAndBalancedBrackets()
+        {
+            Message result = MessageFormatter.FormatMessage(new Message { Content = "This is a [\\]super\\[\\[ tricky [one]](https://osu.ppy.sh)!" });
+
+            Assert.AreEqual("This is a ]super[[ tricky [one]!", result.DisplayContent);
+            Assert.AreEqual(1, result.Links.Count);
+            Assert.AreEqual("https://osu.ppy.sh", result.Links[0].Url);
+            Assert.AreEqual(10, result.Links[0].Index);
+            Assert.AreEqual(21, result.Links[0].Length);
+        }
+
         [Test]
         public void TestChannelLink()
         {

osu.Game.Tests/Visual/Online/TestSceneChatLink.cs

@@ -127,6 +127,9 @@ namespace osu.Game.Tests.Visual.Online
             addMessageWithChecks("is now playing [https://osu.ppy.sh/b/252238 IMAGE -MATERIAL- <Version 0>]", 1, true, expectedActions: LinkAction.OpenBeatmap);
             addMessageWithChecks("Let's (try)[https://osu.ppy.sh/home] [https://osu.ppy.sh/b/252238 multiple links] https://osu.ppy.sh/home", 3,
                 expectedActions: new[] { LinkAction.External, LinkAction.OpenBeatmap, LinkAction.External });
+            addMessageWithChecks("[https://osu.ppy.sh/home New link format with escaped [and \\[ paired] braces]", 1, expectedActions: LinkAction.External);
+            addMessageWithChecks("[Markdown link format with escaped [and \\[ paired] braces](https://osu.ppy.sh/home)", 1, expectedActions: LinkAction.External);
+            addMessageWithChecks("(Old link format with escaped (and \\( paired) parentheses)[https://osu.ppy.sh/home] and [[also a rogue wiki link]]", 2, expectedActions: new[] { LinkAction.External, LinkAction.External });
             // note that there's 0 links here (they get removed if a channel is not found)
             addMessageWithChecks("#lobby or #osu would be blue (and work) in the ChatDisplay test (when a proper ChatOverlay is present).");
             addMessageWithChecks("I am important!", 0, false, true);

osu.Game/Online/Chat/MessageFormatter.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text.RegularExpressions;
 
 namespace osu.Game.Online.Chat
@@ -10,16 +11,16 @@ namespace osu.Game.Online.Chat
     public static class MessageFormatter
     {
         // [[Performance Points]] -> wiki:Performance Points (https://osu.ppy.sh/wiki/Performance_Points)
-        private static readonly Regex wiki_regex = new Regex(@"\[\[([^\]]+)\]\]");
+        private static readonly Regex wiki_regex = new Regex(@"\[\[(?<text>[^\]]+)\]\]");
 
         // (test)[https://osu.ppy.sh/b/1234] -> test (https://osu.ppy.sh/b/1234)
-        private static readonly Regex old_link_regex = new Regex(@"\(([^\)]*)\)\[([a-z]+://[^ ]+)\]");
+        private static readonly Regex old_link_regex = new Regex(@"\((?<text>(((?<=\\)[\(\)])|[^\(\)])*(((?<open>\()(((?<=\\)[\(\)])|[^\(\)])*)+((?<close-open>\))(((?<=\\)[\(\)])|[^\(\)])*)+)*(?(open)(?!)))\)\[(?<url>[a-z]+://[^ ]+)\]");
 
         // [https://osu.ppy.sh/b/1234 Beatmap [Hard] (poop)] -> Beatmap [hard] (poop) (https://osu.ppy.sh/b/1234)
-        private static readonly Regex new_link_regex = new Regex(@"\[([a-z]+://[^ ]+) ([^\[\]]*(((?<open>\[)[^\[\]]*)+((?<close-open>\])[^\[\]]*)+)*(?(open)(?!)))\]");
+        private static readonly Regex new_link_regex = new Regex(@"\[(?<url>[a-z]+://[^ ]+) (?<text>(((?<=\\)[\[\]])|[^\[\]])*(((?<open>\[)(((?<=\\)[\[\]])|[^\[\]])*)+((?<close-open>\])(((?<=\\)[\[\]])|[^\[\]])*)+)*(?(open)(?!)))\]");
 
         // [test](https://osu.ppy.sh/b/1234) -> test (https://osu.ppy.sh/b/1234) aka correct markdown format
-        private static readonly Regex markdown_link_regex = new Regex(@"\[([^\]]*)\]\(([a-z]+://[^ ]+)\)");
+        private static readonly Regex markdown_link_regex = new Regex(@"\[(?<text>(((?<=\\)[\[\]])|[^\[\]])*(((?<open>\[)(((?<=\\)[\[\]])|[^\[\]])*)+((?<close-open>\])(((?<=\\)[\[\]])|[^\[\]])*)+)*(?(open)(?!)))\]\((?<url>[a-z]+://[^ ]+)\)");
 
         // advanced, RFC-compatible regular expression that matches any possible URL, *but* allows certain invalid characters that are widely used
         // This is in the format (<required>, [optional]):
@@ -48,7 +49,7 @@ namespace osu.Game.Online.Chat
         // Unicode emojis
         private static readonly Regex emoji_regex = new Regex(@"(\uD83D[\uDC00-\uDE4F])");
 
-        private static void handleMatches(Regex regex, string display, string link, MessageFormatterResult result, int startIndex = 0, LinkAction? linkActionOverride = null)
+        private static void handleMatches(Regex regex, string display, string link, MessageFormatterResult result, int startIndex = 0, LinkAction? linkActionOverride = null, char[] escapeChars = null)
         {
             int captureOffset = 0;
 
@@ -58,16 +59,20 @@ namespace osu.Game.Online.Chat
 
                 var displayText = string.Format(display,
                     m.Groups[0],
-                    m.Groups.Count > 1 ? m.Groups[1].Value : "",
-                    m.Groups.Count > 2 ? m.Groups[2].Value : "").Trim();
+                    m.Groups["text"].Value,
+                    m.Groups["url"].Value).Trim();
 
                 var linkText = string.Format(link,
                     m.Groups[0],
-                    m.Groups.Count > 1 ? m.Groups[1].Value : "",
-                    m.Groups.Count > 2 ? m.Groups[2].Value : "").Trim();
+                    m.Groups["text"].Value,
+                    m.Groups["url"].Value).Trim();
 
                 if (displayText.Length == 0 || linkText.Length == 0) continue;
 
+                // Remove backslash escapes in front of the characters provided in escapeChars
+                if (escapeChars != null)
+                    displayText = escapeChars.Aggregate(displayText, (current, c) => current.Replace($"\\{c}", c.ToString()));
+
                 // Check for encapsulated links
                 if (result.Links.Find(l => (l.Index <= index && l.Index + l.Length >= index + m.Length) || (index <= l.Index && index + m.Length >= l.Index + l.Length)) == null)
                 {
@@ -183,13 +188,13 @@ namespace osu.Game.Online.Chat
             var result = new MessageFormatterResult(toFormat);
 
             // handle the [link display] format
-            handleMatches(new_link_regex, "{2}", "{1}", result, startIndex);
+            handleMatches(new_link_regex, "{1}", "{2}", result, startIndex, escapeChars: new[] { '[', ']' });
 
             // handle the standard markdown []() format
-            handleMatches(markdown_link_regex, "{1}", "{2}", result, startIndex);
+            handleMatches(markdown_link_regex, "{1}", "{2}", result, startIndex, escapeChars: new[] { '[', ']' });
 
             // handle the ()[] link format
-            handleMatches(old_link_regex, "{1}", "{2}", result, startIndex);
+            handleMatches(old_link_regex, "{1}", "{2}", result, startIndex, escapeChars: new[] { '(', ')' });
 
             // handle wiki links
             handleMatches(wiki_regex, "{1}", "https://osu.ppy.sh/wiki/{1}", result, startIndex);