From 327730c2c6621143f262d05a18c9eb856ccbb9d1 Mon Sep 17 00:00:00 2001
From: lda <lda@freetards.xyz>
Date: Sat, 18 May 2024 20:17:54 +0200
Subject: [PATCH] [ADD/WIP] Basic PDU depth system.

NOTE: This is *not* a good way to compute depth.
---
 src/Room.c         | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 src/include/Room.h |  6 +++++
 2 files changed, 63 insertions(+)

diff --git a/src/Room.c b/src/Room.c
index 8682b1c..652c083 100644
--- a/src/Room.c
+++ b/src/Room.c
@@ -91,6 +91,8 @@ RoomCreate(Db * db, User *user, RoomCreateRequest * req, ServerPart s)
     char *sender_str, *key;
     JsonValue *val;
     HashMap *override;
+    Array *initial_states;
+    size_t i;
     if (!db || !req || !user)
     {
         return NULL;
@@ -164,6 +166,21 @@ RoomCreate(Db * db, User *user, RoomCreateRequest * req, ServerPart s)
 
     /* TODO: Events set by the preset */
     /* TODO: Events in initial_state */
+    initial_states = req->initial_state;
+    for (i = 0; i < ArraySize(initial_states); i++)
+    {
+        RoomStateEvent *rse = ArrayGet(initial_states, i);
+        HashMap *rseObject = RoomStateEventToJson(rse);
+
+        if (!HashMapGet(rseObject, "state_key"))
+        {
+            HashMapSet(rseObject, "state_key", JsonValueString(""));
+        }
+        HashMapSet(rseObject, "sender", JsonValueString(sender_str));
+
+        JsonFree(RoomEventSend(room, rseObject));
+        JsonFree(rseObject);
+    }
     if (req->name)
     {
         content = HashMapCreate();
@@ -481,6 +498,7 @@ PopulateEventV1(Room * room, HashMap * event, PduV1 * pdu, ServerPart serv)
         JsonDuplicate(JsonValueAsObject(JsonGet(event, 1, "content")));
     pdu->room_id = StrDuplicate(room->id);
     pdu->signatures = HashMapCreate();
+    pdu->depth = RoomGetDepth(room) + 1; /* TODO: Clamp this value. */
 
     /* Create a random event ID for this PDU.
      * TODO: Optionally verify whenever it's already used, but that 
@@ -1661,3 +1679,42 @@ RoomEventCreate(char *sender, char *type, char *key, HashMap *c)
 
     return event;
 }
+
+/* TODO: This has it's fair share of problems, as a malicious 
+ * homserver could *easily* fake a PDU depth and put this 
+ * function to the depth limit. */
+uint64_t
+RoomGetDepth(Room *room)
+{
+    Array *leaves;
+    HashMap *pdu;
+    size_t i;
+    uint64_t max;
+    if (!room)
+    {
+        return 0;
+    }
+
+    leaves = RoomPrevEventsGet(room);
+    if (!leaves)
+    {
+        return 0;
+    }
+
+    max = 0;
+    for (i = 0; i < ArraySize(leaves); i++)
+    {
+        uint64_t depth;
+        pdu = JsonValueAsObject(ArrayGet(leaves, i));
+        
+        depth = JsonValueAsInteger(HashMapGet(pdu, "depth"));
+        if (depth > max)
+        {
+            max = depth;
+        }
+    }
+    (void) i;
+    (void) pdu;
+
+    return max;
+}
diff --git a/src/include/Room.h b/src/include/Room.h
index 7213916..feeec5a 100644
--- a/src/include/Room.h
+++ b/src/include/Room.h
@@ -170,4 +170,10 @@ extern bool RoomAddEventV1(Room *, PduV1);
  */
 extern HashMap * RoomEventCreate(char *, char *, char *, HashMap *);
 
+/**
+ * Computes an approximation of the PDU depth by looking at 
+ * the leaves stored in the room data.
+ */
+extern uint64_t RoomGetDepth(Room *);
+
 #endif /* TELODENDRIA_ROOM_H */