Add the cloak_nick module to cloak based on a nickname.

docs/conf/modules.conf.example

@@ -617,6 +617,40 @@
 #       prefix="MyNet-"
 #       suffix=".IP">
 
+#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
+# Nickname cloak module: Adds the "nick" (user nickname) cloak method.
+#<module name="cloak_nick">
+#
+#-#-#-#-#-#-#-#-#-#- ACCOUNT CLOAK CONFIGURATION -#-#-#-#-#-#-#-#-#-#-#
+# To use the cloak_nick module you must define a <cloak> tag. This    #
+# tag can have the following fields.                                  #
+#                                                                     #
+#  class    - If non-empty then a comma-delimited list of connect     #
+#             class names that a user has to be in to get the cloak   #
+#             from this tag.                                          #
+#                                                                     #
+#  prefix   - A freeform value to prefix cloaks with. This must not   #
+#             contain spaces.                                         #
+#                                                                     #
+#  suffix    - A freeform value to suffix cloaks with. This must not  #
+#              contain spaces.                                        #
+#                                                                     #
+#  sanitize - If enabled then any characters in the nickname that are #
+#             not valid in a hostname will be removed rather than     #
+#             than skipping the cloak method.                         #
+#                                                                     #
+# IMPORTANT: Changing these details will break all of your existing   #
+# bans. If you do not want this to happen you can define multiple     #
+# cloak tags. The first will be used for hostnames and the rest will  #
+# be used for checking if a user is banned in a channel.              #
+#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
+#
+#<cloak method="nick"
+#       class=""
+#       prefix="MyNet"
+#       suffix="ip"
+#       sanitize="yes">
+
 #-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
 # HMAC-SHA256 cloak module: Adds the "hmac-sha256" (hostname or IP) and
 # "hmac-sha256-ip" (IP only) cloak methods. This is the recommended

src/modules/m_cloak_nick.cpp

@@ -0,0 +1,143 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2023 Sadie Powell <sadie@witchery.services>
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "inspircd.h"
+#include "modules/cloak.h"
+
+class NickMethod final
+	: public Cloak::Method
+{
+protected:
+	// The characters which are valid in a hostname.
+	const CharState& hostmap;
+
+	// The prefix for cloaks (e.g. MyNet).
+	const std::string prefix;
+
+	// Whether to strip non-host characters from the cloak.
+	const bool sanitize;
+
+	// The suffix for IP cloaks (e.g. IP).
+	const std::string suffix;
+
+public:
+	NickMethod(const Cloak::Engine* engine, const std::shared_ptr<ConfigTag>& tag, const CharState& hm) ATTR_NOT_NULL(2)
+		: Cloak::Method(engine, tag)
+		, hostmap(hm)
+		, prefix(tag->getString("prefix"))
+		, sanitize(tag->getBool("sanitize", true))
+		, suffix(tag->getString("suffix"))
+	{
+	}
+
+	std::string Generate(LocalUser* user) override ATTR_NOT_NULL(2)
+	{
+		if (!MatchesUser(user))
+			return {}; // We shouldn't cloak this user.
+
+		std::string safenick;
+		safenick.reserve(user->nick.length());
+		for (const auto chr : user->nick)
+		{
+			if (!hostmap.test(static_cast<unsigned char>(chr)))
+			{
+				if (!sanitize)
+					return {}; // Contains invalid characters.
+
+				continue;
+			}
+
+			safenick.push_back(chr);
+		}
+
+		if (safenick.empty())
+			return {}; // No cloak.
+
+		return prefix + safenick + suffix;
+	}
+
+	std::string Generate(const std::string& hostip) override
+	{
+		// We can't generate nick cloaks without a user.
+		return {};
+	}
+
+	void GetLinkData(Module::LinkData& data, std::string& compatdata) override
+	{
+		data["prefix"]   = prefix;
+		data["sanitize"] = sanitize ? "yes" : "no";
+		data["suffix"]   = suffix;
+	}
+};
+
+class NickEngine final
+	: public Cloak::Engine
+{
+public:
+	// The characters which are valid in a hostname.
+	CharState hostmap;
+
+	NickEngine(Module* Creator)
+		: Cloak::Engine(Creator, "nick")
+	{
+	}
+
+	Cloak::MethodPtr Create(const std::shared_ptr<ConfigTag>& tag, bool primary) override
+	{
+		return std::make_shared<NickMethod>(this, tag, hostmap);
+	}
+};
+
+class ModuleCloakNick final
+	: public Module
+{
+private:
+	Cloak::API cloakapi;
+	NickEngine nickcloak;
+
+public:
+	ModuleCloakNick()
+		: Module(VF_VENDOR, "Adds the nick cloaking method for use with the cloak module.")
+		, cloakapi(this)
+		, nickcloak(this)
+	{
+	}
+
+	void ReadConfig(ConfigStatus& status) override
+	{
+		CharState newhostmap;
+		const auto& tag = ServerInstance->Config->ConfValue("hostname");
+		for (const auto chr : tag->getString("charmap", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.-_/0123456789", 1))
+		{
+			// A hostname can not contain NUL, LF, CR, or SPACE.
+			if (chr == 0x00 || chr == 0x0A || chr == 0x0D || chr == 0x20)
+				throw ModuleException(this, INSP_FORMAT("<hostname:charmap> can not contain character 0x{:02X} ({})", chr, chr));
+			newhostmap.set(static_cast<unsigned char>(chr));
+		}
+		std::swap(newhostmap, nickcloak.hostmap);
+	}
+
+	void OnUserPostNick(User* user, const std::string& oldnick) override
+	{
+		LocalUser* luser = IS_LOCAL(user);
+		if (luser && cloakapi)
+			cloakapi->ResetCloaks(luser, true);
+	}
+};
+
+MODULE_INIT(ModuleCloakNick)