Fix for the "Don't allow block placement inside player, exce

diff -rupN minetest_orig/src/server.cpp minetest_modified/src/server.cpp
--- minetest_orig/src/server.cpp    2011-11-12 17:17:42.000000000 +0100
+++ minetest_modified/src/server.cpp    2011-11-24 15:53:37.762770923 +0100
@@ -2671,6 +2671,43 @@ void Server::ProcessData(u8 *data, u32 d
                        client->SetBlockNotSent(blockpos);
                        return;
                    }
+
+                   if ((g_settings->getBool("free_move") == false) &&
+                       (content_features(((MaterialItem*)item)->getMaterial()).air_equivalent == false))
+                   {
+                       float distance;
+                       core::list<Player*> players = m_env.getPlayers();
+                       core::list<Player*>::Iterator ip;
+
+                       for(ip = players.begin(); ip != players.end(); ip++) {
+                           Player *p = *ip;
+                           v3f player_pos = p->getPosition();
+                           v3f player_eye_pos = p->getEyePosition();
+
+                           // this is strange. I would expect that (p->touching_ground == false) prevents a block
+                           // to be placed at the current players "legs" but it doesn't. Seems that standing on
+                           // something doesn't mean to touch ground? Not a big problem here IMHO.
+                           if((p == player) && (p->touching_ground == false)) {
+                               distance = BS*0.4;
+                           } else {
+                               distance = BS*0.9;
+                           }
+
+                           if((player_pos.getDistanceFrom(intToFloat(p_over, BS)) <= distance) ||
+                               (player_eye_pos.getDistanceFrom(intToFloat(p_over, BS)) <= distance))
+                           {
+                               infostream  << "Client "<<peer_id<<" tried to place"
+                                           << " block on a player position;"
+                                           << " setting MapBlock not sent."<<std::endl;
+
+                               RemoteClient *client = getClient(peer_id);
+                               v3s16 blockpos = getNodeBlockPos(p_over);
+                               client->SetBlockNotSent(blockpos);
+                               return;
+                           }
+                       }
+                   }
+
                }
                catch(InvalidPositionException &e)
                {