From 95f4981dec59a8d8d307041ed8289d0633f7b601 Mon Sep 17 00:00:00 2001
From: Stefano Pigozzi <me@steffo.eu>
Date: Thu, 15 Apr 2021 17:14:28 +0200
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20Properly=20check=20permissions=20fo?=
 =?UTF-8?q?r=20Projects?=
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---
 sophon/core/models.py      | 38 +++++++++++++++++++++-----------------
 sophon/core/permissions.py | 18 ++++++++++++++++++
 sophon/core/views.py       | 12 ++++++------
 3 files changed, 45 insertions(+), 23 deletions(-)
 create mode 100644 sophon/core/permissions.py

diff --git a/sophon/core/models.py b/sophon/core/models.py
index 32ba696..ca5c6af 100644
--- a/sophon/core/models.py
+++ b/sophon/core/models.py
@@ -9,19 +9,6 @@ import json
 import abc
 
 
-class RelatedToProject(metaclass=abc.ABCMeta):
-    """
-    A model which is related to :class:`.Project` in some way.
-    """
-
-    @abc.abstractmethod
-    def get_project(self) -> "Project":
-        """
-        :return: The project this object is related to.
-        """
-        raise NotImplementedError()
-
-
 class DataSource(models.Model):
     """
     A :class:`.DataSource` is a web service which provides access to statistical information sourced by multiple data
@@ -312,15 +299,12 @@ class DataFlow(models.Model):
         return f"[{self.datasource}] {self.id}"
 
 
-class Project(models.Model, RelatedToProject):
+class Project(models.Model):
     """
     A research :class:`.Project` is a work which may use zero or more :class:`.DataSource`\\ s to prove or disprove an
     hypothesis.
     """
 
-    def get_project(self):
-        return self
-
     slug = models.SlugField(
         "Slug",
         help_text="Unique alphanumeric string which identifies the project.",
@@ -349,6 +333,7 @@ class Project(models.Model, RelatedToProject):
             ("PRIVATE", "🔒 Private"),
         ],
         default="INTERNAL",
+        max_length=16,
     )
 
     owner = models.ForeignKey(
@@ -371,5 +356,24 @@ class Project(models.Model, RelatedToProject):
         blank=True,
     )
 
+    def get_contributors(self):
+        return {self.owner, *self.collaborators.values()}
+
+    def can_be_viewed_by(self, user):
+        if self.visibility == "PUBLIC":
+            return True
+        elif self.visibility == "INTERNAL":
+            return not user.is_anonymous()
+        elif self.visibility == "PRIVATE":
+            return user in self.get_contributors()
+        else:
+            raise ValueError(f"Unknown visibility value: {self.visibility}")
+
+    def can_be_edited_by(self, user):
+        return user in self.get_contributors()
+
+    def can_be_administrated_by(self, user):
+        return user == self.owner
+
     def __str__(self):
         return self.slug
diff --git a/sophon/core/permissions.py b/sophon/core/permissions.py
new file mode 100644
index 0000000..035146d
--- /dev/null
+++ b/sophon/core/permissions.py
@@ -0,0 +1,18 @@
+import logging
+from rest_framework import permissions
+
+log = logging.getLogger(__name__)
+
+
+class ProjectPermissions(permissions.BasePermission):
+    def has_object_permission(self, request, view, obj):
+        if view.action == "retrieve":
+            return obj.can_be_viewed_by(request.user)
+        elif view.action == "update":
+            return obj.can_be_edited_by(request.user)
+        elif view.action == "partial_update":
+            return obj.can_be_edited_by(request.user)
+        elif view.action == "destroy":
+            return obj.can_be_administrated_by(request.user)
+        log.warning(f"Rejecting permissions for unknown action: {view.action}")
+        return False
diff --git a/sophon/core/views.py b/sophon/core/views.py
index abcbb1c..23b3cfe 100644
--- a/sophon/core/views.py
+++ b/sophon/core/views.py
@@ -1,5 +1,5 @@
-from rest_framework import viewsets, decorators, response
-from . import models, serializers
+from rest_framework import viewsets, decorators, response, permissions
+from . import models, serializers, permissions as custom_permissions
 from datetime import datetime
 from logging import getLogger
 
@@ -12,7 +12,7 @@ class ProjectViewSet(viewsets.ModelViewSet):
     """
     queryset = models.Project.objects.all()
     serializer_class = serializers.ProjectSerializer
-    permission_classes = []
+    permission_classes = [custom_permissions.ProjectPermissions]
 
 
 class DataFlowViewSet(viewsets.ModelViewSet):
@@ -21,7 +21,7 @@ class DataFlowViewSet(viewsets.ModelViewSet):
     """
     queryset = models.DataFlow.objects.all()
     serializer_class = serializers.DataFlowSerializer
-    permission_classes = []
+    permission_classes = [permissions.DjangoModelPermissionsOrAnonReadOnly]
 
 
 class DataSourceViewSet(viewsets.ModelViewSet):
@@ -30,10 +30,10 @@ class DataSourceViewSet(viewsets.ModelViewSet):
     """
     queryset = models.DataSource.objects.all()
     serializer_class = serializers.DataSourceSerializer
-    permission_classes = []
+    permission_classes = [permissions.DjangoModelPermissionsOrAnonReadOnly]
 
     @decorators.action(methods=["post"], detail=True)
-    def sync(self, request, pk):
+    def sync(self, request, *args, **kwargs):
         """
         Syncronize the :class:`.models.DataFlow`\\ s with the ones stored in the server of the
         :class:`.models.DataSource`\\ .