[ADD/UNTESTED] Finalise step 5.2 of auth rules.

Next up is the invite membership(5.3).

src/Room.c

@@ -220,6 +220,26 @@ RoomStateGetID(Room * room, char *event_id)
         JsonFree(name); \
     } \
     return ret
+static bool
+RoomIsJoinRule(Room * room, char *e_id, char *jr)
+{
+    HashMap *state_point;
+    HashMap *joinrule = NULL;
+    char *id_joinrule = NULL;
+    bool ret = false;
+
+    if (!room || !e_id || !jr)
+    {
+        return false;
+    }
+
+    PrepareState(room, e_id, "m.room.join_rules", "", joinrule);
+    ret = StrEquals(
+        JsonValueAsString(JsonGet(joinrule, 1, "join_rule")),
+        jr);
+finish:
+    FinishState(joinrule);
+}
 /* Verifies if user has a specific membership before [e_id] in the room. */
 static bool
 RoomUserHasMembership(Room * room, char *e_id, char *user, char *mbr)
@@ -577,6 +597,14 @@ AuthoriseAliasV1(PduV1 pdu)
     return true;
 }
 static bool
+AuthorizeInviteMembershipV1(Room * room, PduV1 pdu)
+{
+    /* TODO */
+    (void) room;
+    (void) pdu;
+    return false;
+}
+static bool
 AuthorizeJoinMembershipV1(Room * room, PduV1 pdu)
 {
     /* Step 5.2.1: If the only previous event is an m.room.create and the 
@@ -609,10 +637,24 @@ AuthorizeJoinMembershipV1(Room * room, PduV1 pdu)
         return false;
     }
     /* Step 5.2.3: If the sender is banned, reject. */
-    /* TODO */
+    if (RoomUserHasMembership(room, pdu.event_id, pdu.sender, "ban"))
+    {
+        return false;
+    }
 
     /* Step 5.2.4: If the join_rule is invite then allow if membership 
      * state is invite or join. */
+    if (RoomIsJoinRule(room, pdu.event_id, "invite") &&
+        (RoomUserHasMembership(room, pdu.event_id, pdu.sender, "invite") ||
+         RoomUserHasMembership(room, pdu.event_id, pdu.sender, "join")))
+    {
+        return true;
+    }
+    /* Step 5.2.5: If the join_rule is public, allow. */
+    if (RoomIsJoinRule(room, pdu.event_id, "public"))
+    {
+        return true;
+    }
     /* Step 5.2.6: Otherwise, reject. */
     return false;
 }
@@ -645,8 +687,11 @@ AuthoriseMemberV1(Room * room, PduV1 pdu)
     /* Step 5.2: If membership is join. */
     JumpIfMembership("join", AuthorizeJoinMembershipV1);
 
-    /* Step 4.3: Otherwise, allow. */
+    /* Step 5.3: If membership is invite. */
-    return true;
+    JumpIfMembership("invite", AuthorizeInviteMembershipV1);
+    
+    /* Step 5.6: Otherwise, the membership is unknown. Reject. */
+    return false;
 #undef JumpIfMembership
 }
 static bool