From a758b39ded59b0dc74b057ff4961f092ec46214a Mon Sep 17 00:00:00 2001
From: pluth <pluth@0t.re>
Date: Sun, 1 Oct 2023 12:38:00 +0200
Subject: [PATCH] spec-suggested character mapping for virtual localparts

---
 spec/unit/IrcServer.spec.js | 52 +++++++++++++++++++++++++++++++++++++
 src/irc/IrcServer.ts        | 19 +++++++++++---
 2 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/spec/unit/IrcServer.spec.js b/spec/unit/IrcServer.spec.js
index 5beb65217..ec454cddb 100644
--- a/spec/unit/IrcServer.spec.js
+++ b/spec/unit/IrcServer.spec.js
@@ -69,5 +69,57 @@ describe("IrcServer", function() {
             );
             expect(() => {server.getNick("@💩ケ:foobar")}).toThrow();
         });
+    })
+    describe("getUserLocalpart", function() {
+        it("does not touch valid characters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getUserLocalpart("foobar09.-+")).toEqual("irc.foobar_foobar09.-+");
+        });
+        it("encodes capital letters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getUserLocalpart("foOBaR_09.-+")).toEqual("irc.foobar_fo_o_ba_r__09.-+");
+        });
+        it("encodes invalid characters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getUserLocalpart("foobar=[m]")).toEqual("irc.foobar_foobar=3d=5bm=5d");
+        });
+        it("encodes both capital letters and invalid chars", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getUserLocalpart("f_oObAr=[m]")).toEqual("irc.foobar_f__o_ob_ar=3d=5bm=5d");
+        });
+    });
+    describe("getNickFromUserId", function() {
+        it("does not touch valid characters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getNickFromUserId("irc.foobar_foobar09.-+")).toEqual("foobar09.-+");
+        });
+        it("encodes capital letters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getNickFromUserId("irc.foobar_fo_o_ba_r__09.-+")).toEqual("foOBaR_09.-+");
+        });
+        it("decodes invalid characters", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getNickFromUserId("irc.foobar_foobar=3d=5bm=5d")).toEqual("foobar=[m]");
+        });
+        it("encodes both capital letters and invalid chars", function() {
+            const server = new IrcServer("irc.foobar",
+                extend(true, IrcServer.DEFAULT_CONFIG, {})
+            );
+            expect(server.getNickFromUserId("irc.foobar_f__o_ob_ar=3d=5bm=5d")).toEqual("f_oObAr=[m]");
+        });
     });
 });
diff --git a/src/irc/IrcServer.ts b/src/irc/IrcServer.ts
index c9cce65e8..34e0cb4ff 100644
--- a/src/irc/IrcServer.ts
+++ b/src/irc/IrcServer.ts
@@ -545,10 +545,16 @@ export class IrcServer {
     public getUserLocalpart(nick: string): string {
         // the template is just a literal string with special vars; so find/replace
         // the vars and strip the @
+
+        // https://spec.matrix.org/v1.8/appendices/#mapping-from-other-character-sets
+        const escaped = nick.replaceAll(/[A-Z_]/g, (c) => "_" + c.toLowerCase());
+        const escaped2 = escaped.replaceAll(/[^a-z0-9\.\_\-\/+]/g,
+            (c) => "=" + c.charCodeAt(0).toString(16).padStart(2, '0'));
+
         return renderTemplate(this.config.matrixClients.userTemplate, {
             server: this.domain,
-            nick,
-        }).substring(1).toLowerCase(); // the first character is guaranteed by config schema to be '@'
+            nick: escaped2,
+        }).substring(1); // the first character is guaranteed by config schema to be '@'
     }
 
     public claimsUserId(userId: string): boolean {
@@ -582,7 +588,14 @@ export class IrcServer {
         if (!match) {
             return null;
         }
-        return match[1];
+
+        // https://spec.matrix.org/v1.8/appendices/#mapping-from-other-character-sets
+        const unescaped = match[1].replaceAll(/=([0-9a-f][0-9a-f])/g,
+            (_m, g1) => String.fromCharCode(parseInt(g1, 16)));
+
+        const unescaped2 = unescaped.replaceAll(/_([a-z_])/g, (m, g1) => g1.toUppercase());
+
+        return unescaped2;
     }
 
     public getUserIdFromNick(nick: string): string {