From 28e7cf8e5b4621655a08f2158ee8f6049a6d402c Mon Sep 17 00:00:00 2001
From: Kumi <git@kumi.email>
Date: Thu, 14 Sep 2023 14:44:51 +0200
Subject: [PATCH] Start LDAP implementation

---
 core/management/commands/serveldap.py | 16 +++++
 ldap/__init__.py                      |  0
 ldap/server.py                        | 87 +++++++++++++++++++++++++++
 requirements.txt                      |  1 +
 4 files changed, 104 insertions(+)
 create mode 100644 core/management/commands/serveldap.py
 create mode 100644 ldap/__init__.py
 create mode 100644 ldap/server.py

diff --git a/core/management/commands/serveldap.py b/core/management/commands/serveldap.py
new file mode 100644
index 0000000..0c9e314
--- /dev/null
+++ b/core/management/commands/serveldap.py
@@ -0,0 +1,16 @@
+from django.core.management.base import BaseCommand
+from django.conf import settings
+
+from ldap.server import LDAPServer
+
+from twisted.internet.protocol import Factory
+from twisted.internet import reactor
+
+class Command(BaseCommand):
+    help = 'Provides a simple LDAP server'
+
+    def handle(self, *args, **kwargs):
+        factory = Factory()
+        factory.protocol = LDAPServer
+        reactor.listenTCP(10389, factory)
+        reactor.run()
diff --git a/ldap/__init__.py b/ldap/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/ldap/server.py b/ldap/server.py
new file mode 100644
index 0000000..260df85
--- /dev/null
+++ b/ldap/server.py
@@ -0,0 +1,87 @@
+from zope.interface import implementer
+from twisted.internet import reactor, defer
+from twisted.internet.protocol import Factory
+from ldaptor.protocols.ldap import ldapserver, ldapsyntax, distinguishedname, ldaperrors
+from ldaptor import interfaces, entry
+from django.contrib.auth import get_user_model, authenticate
+from django.core.exceptions import ObjectDoesNotExist
+
+User = get_user_model()
+
+@implementer(interfaces.IConnectedLDAPEntry)
+class DjangoUserEntry:
+    def __init__(self, user):
+        self.dn = distinguishedname.DistinguishedName('cn={},dc=kumidc'.format(user.username))
+        self.attributes = {'cn': [user.username,], 'email': [user.email,]}
+
+    def search(self, filterObject, attributes=None):
+        # This ignores the filter and always returns the authenticated user
+        # This LDAP server is only meant to be used for authentication, not as a directory service
+        return defer.succeed([self])
+
+    def lookup(self):
+        return defer.succeed(self)
+
+    def bind(self, password):
+        username = self.dn.split(',')[0].split('=')[1]
+        user = authenticate(username=username, password=password)
+
+        if user is not None:
+            self.__init__(user)
+            return defer.succeed(self)
+        else:
+            return defer.fail()
+
+class LDAPServer(ldapserver.LDAPServer):
+    def handle_LDAP_BIND_REQUEST(self, request, controls, reply):
+        if request.dn:
+            user_dn = str(request.dn)
+            try:
+                username = user_dn.split(',')[0].split('=')[1]
+                user = User.objects.get(username=username)
+                e = DjangoUserEntry(user)
+            except ObjectDoesNotExist:
+                return defer.fail(ldaperrors.LDAPInvalidCredentials())
+
+            d = e.bind(request.auth)
+            d.addCallbacks(reply, reply.handle_LDAPError)
+            return d
+
+        elif request.sasl:
+            if request.sasl.mechanism == "PLAIN":
+                authzid, authcid, password = request.sasl.credentials.split('\x00')
+                e = DjangoUserEntry(user)
+                d = defer.succeed(e)
+                d.addCallbacks(reply, reply.handle_LDAPError)
+                return d
+            else:
+                return defer.fail(ldaperrors.LDAPInvalidCredentials())
+        else:
+            return defer.fail(ldaperrors.LDAPInvalidCredentials())
+
+    def handle_LDAP_SEARCH_REQUEST(self, request, reply):
+        if not self.boundUser:
+            return defer.fail(ldaperrors.LDAPUnwillingToPerform())
+
+        search_filter = request.filter
+        f = request.filter.asText()
+
+        try:
+            user = User.objects.get(username=self.boundUser)
+            e = DjangoUserEntry(user)
+        except ObjectDoesNotExist:
+            return defer.fail(ldaperrors.LDAPNoSuchObject())
+
+        if search_filter.present("objectClass") and request.scope == ldapclient.SCOPE_BASE:
+            entries = [e]
+        else:
+            entries = []
+
+        reply(entries)
+        return defer.succeed(())
+
+
+
+    def handleUnknown(self, op):
+        # Ignore requests we don't support
+        return defer.succeed(None)
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
index d61718b..f06eeca 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,6 +8,7 @@ django-autosecretkey
 
 cryptography
 pysaml2
+ldaptor
 pyotp
 django-timezone-field
 django-phonenumber-field[phonenumbers]