--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/plugins/plugin_xep_0106.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+
+
+# SAT plugin for Explicit Message Encryption
+# Copyright (C) 2009-2021 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# 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 Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from libervia.backend.core.i18n import _
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core.log import getLogger
+from twisted.words.protocols.jabber import xmlstream
+from zope.interface import implementer
+from wokkel import disco
+
+log = getLogger(__name__)
+
+PLUGIN_INFO = {
+    C.PI_NAME: "JID Escaping",
+    C.PI_IMPORT_NAME: "XEP-0106",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0106"],
+    C.PI_DEPENDENCIES: [],
+    C.PI_MAIN: "XEP_0106",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""(Un)escape JID to use disallowed chars in local parts"""),
+}
+
+NS_JID_ESCAPING = r"jid\20escaping"
+ESCAPE_MAP = {
+    ' ': r'\20',
+    '"': r'\22',
+    '&': r'\26',
+    "'": r'\27',
+    '/': r'\2f',
+    ':': r'\3a',
+    '<': r'\3c',
+    '>': r'\3e',
+    '@': r'\40',
+    '\\': r'\5c',
+}
+
+
+class XEP_0106(object):
+
+    def __init__(self, host):
+        self.reverse_map = {v:k for k,v in ESCAPE_MAP.items()}
+
+    def get_handler(self, client):
+        return XEP_0106_handler()
+
+    def escape(self, text):
+        """Escape text
+
+        @param text(unicode): text to escape
+        @return (unicode): escaped text
+        @raise ValueError: text can't be escaped
+        """
+        if not text or text[0] == ' ' or text[-1] == ' ':
+            raise ValueError("text must not be empty, or start or end with a whitespace")
+        escaped = []
+        for c in text:
+            if c in ESCAPE_MAP:
+                escaped.append(ESCAPE_MAP[c])
+            else:
+                escaped.append(c)
+        return ''.join(escaped)
+
+    def unescape(self, escaped):
+        """Unescape text
+
+        @param escaped(unicode): text to unescape
+        @return (unicode): unescaped text
+        @raise ValueError: text can't be unescaped
+        """
+        if not escaped or escaped.startswith(r'\27') or escaped.endswith(r'\27'):
+            raise ValueError("escaped value must not be empty, or start or end with a "
+                             f"whitespace: rejected value is {escaped!r}")
+        unescaped = []
+        idx = 0
+        while idx < len(escaped):
+            char_seq = escaped[idx:idx+3]
+            if char_seq in self.reverse_map:
+                unescaped.append(self.reverse_map[char_seq])
+                idx += 3
+            else:
+                unescaped.append(escaped[idx])
+                idx += 1
+        return ''.join(unescaped)
+
+
+@implementer(disco.IDisco)
+class XEP_0106_handler(xmlstream.XMPPHandler):
+
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
+        return [disco.DiscoFeature(NS_JID_ESCAPING)]
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
+        return []