Fixes a bug where packet reordering made the server give the
client two peer ids instead of one. This in turn confused
reliable packet sending and made connecting to the server fail.
The client usually sends three packets at init: one "dummy"
packet consisting of two 0 bytes, and the init packet as well as
its legacy counterpart. The last one can be turned off since commit
af30183124, but this is of lower
relevance for the bug. The relevant part here is that network
packet reorder (which is a normal occurence) can make the packets
reach the server in different order.
If reorder puts the dummy packet further behind, the following
would happen before the patch:
1. The server will get one of the init packets on channel 1 and
assign the client a peer id, as the packet will have zero as
peer id.
2. The server sends a CONTROLTYPE_SET_PEER_ID packet to inform
the client of the peer id.
3. The next packet from the client will contain the peer id set by
the server.
4. The server sets the m_has_sent_with_id member for the client's
peer structure to true.
5. Now the dummy packet arrives. It has a peer id of zero, therefore
the server searches whether it already has a peer id for the
address the packet was sent from. The search fails because
m_has_sent_with_id was set to true and the server only searched
for peers with m_has_sent_with_id set to false.
6. In a working setup, the server would assign the dummy packet to
the correct peer id. However the server instead now assigns a
second peer id and peer structure to the peer, and assign the
packet to that new peer.
7. In order to inform the peer of its peer id, the server sends a
CONTROLTYPE_SET_PEER_ID command packet, reliably, to the peer.
This packet uses the new peer id.
8. The client sends an ack to that packet, not with the new peer id
but with the peer id sent in 2.
9. This packet reaches the server, but it drops the ACK as the peer
id does not map to any un-ACK-ed packets with that seqnum. The
same time, the server still waits for an ACK with the new peer
id, which of course won't come. This causes the server to
periodically re-try sending that packet, and the client ACKing it
each time.
Steps 7-9 cause annoyances and erroneous output, but don't cause
the connection failure itself.
The actual mistake that causes the connection failure happens in 6:
The server does not assign the dummy packet to the correct peer, but
to a newly created one.
Therefore, all further packets sent by the client on channel 0 are
now buffered by the server as it waits for the dummy packet to reach
the peer, which of course doesn't happen as the server assigned
that packet to the second peer it created for the client.
This makes the connection code indefinitely buffer the
TOSERVER_CLIENT_READY packet, not passing it to higher level code,
which stalls the continuation of the further init process
indefinitely and causes the actual bug.
Maybe this can be caused by reordered init packets as well, the only
studied case was where network has reliably reordered the dummy
packet to get sent after the init packets.
The patch fixes the bug by not ignoring peers where
m_has_sent_with_id has been set anymore. The other changes of the
patch are just cleanups of unused methods and fields and additional
explanatory comments.
One could think of alternate ways to fix the bug:
* The client could simply take the new peer id and continue
communicating with that. This is however worse than the fix as
it requires the peer id set command to be sent reliably (which
currently happens, but it cant be changed anymore). Also, such a
change would require both server and client to be patched in order
for the bug to be fixed, as right now the client ignores peer id
set commands after the peer id is different from
PEER_ID_INEXISTENT and the server requires modification too to
change the peer id internally.
And, most importantly, right now we guarantee higher level server
code that the peer id for a certain peer does not change. This
guarantee would have to be broken, and it would require much
larger changes to the server than this patch means.
* One could stop sending the dummy packet. One may be unsure whether
this is a good idea, as the meaning of the dummy packet is not
known (it might be there for something important), and as it is
possible that the init packets may cause this problem as well
(although it may be possible too that they can't cause this).
Thanks to @auouymous who had originally reported this bug and who
has helped patiently in finding its cause.
Version 1.8.2 of irrlicht changed the way that IGUIStaticText::getTextHeight() works and since that release properly deals with newlines.
From irrlicht changes.txt for 1.8.2, "IGUIStaticText::getTextHeight returns now the correct height for texts with newlines even WordWrap is not set."
* Remove the copy from db::loadBlock by using a pointer to the destination
* cleanup db backend, the child backend doesn't have to set their functions as virtual
The path finding code works fairly well except that it considers
anythin not CONTENT_AIR to be "above the surface". This results in
paths that are unwalkable for entities since e.g. plants are not
walkable. The path would force them to jump on top of grass plants,
etc..
The obvious solution is not to use CONTENT_AIR as a criteria, but
instead distinguish between walkable and non-walkable nodes. This
results in paths that properly walk through grass nodes.
This was extensively tested by a flock of electric sheep.
Note that for underwater purposes this changes the behaviour from
"the surface is walkable" to "ignore water entirely" making the
path go across the water bottom, and pathing fail likely from the
water surface. This is intentional.
Before, the GridNodes were stored in vector<vector<vector<T>>>,
and initialized in advance. Putting three vectors inside each other
puts lots of unneccessary stress onto the allocator, costs more memory,
and has worse cache locality than a flat vector<T>.
For larger search distances, an the array getting initialized means
essentially O(distance^3) complexity in both time and memory,
which makes the current path search a joke. In order to really
profit from the dijkstra/A* algorithms, other data structures
need to be used for larger distances.
For shorter distances, a map based GridNode storage may be slow as
it requires lots of levels of indirection, which is bad for things like
cache locality, and an array based storage may be faster.
This commit does:
1. remove the vector<vector<vector<T>>> based GridNodes storage that
is allocated and initialized in advance and for the whole
possible area.
2. Add a vector<T> based GridNodes storage that is allocated and
initialized in advance for the whole possible area.
3. Add a map<P,T> based GridNodes storage whose elements are
allocated and initialized, when the path search code
demands it.
4. Add code to decide between approach 2 and 3,
based on the length of the path.
5. Remove the unused "surfaces" member of the PathGridnode class.
Setting this isn't as easy anymore for the
map based GridNodes storage.
* Fix naming style for methods and classes:
Use camelCase for methods and PascalCase for classes as
code style demands it. And use sneak_case for methods that
are not member of a class.
* Replace "* " with " *" for Pointers
* Same for references
* Put function body opening braces on new line
* Other misc minor non functional style improvements
There is no need to put them into the header, they are solely used
inside the pathfinder.
Another advantage of this change is that only the pathfinder.cpp has
to be compiled if PATHFINDER_DEBUG gets defined or undefined, not
all files including the .h.
This commit moves the pathfinder classes to the cpp file without
modifications.
Also, the PATHFINDER_DEBUG macro gets moved to the cpp file and
the PATHFINDER_CALC_TIME macro gets moved to a plce where it
actually does work.
Previously, race conditions occurred inside logging, that caused
segfaults because a thread was trying to use an old pointer that
was freed when the string was reallocated. Using a fixed-length buffer
avoids this, at the cost of cutting too long messages over seveal lines.
The shadow bug at y = 63 was caused by dark air being placed as dust,
when the biome dust was unspecified it was falling back to 'air'
In dustTopNodes only dust == 'ignore' will disable dust placement
Previous mountain terrain generation was by necessity placing
stone in air, this was removing air from any overgenerated
structures such as tunnels, dungeons and large caves
Moving it into the base terrain generation loop ensures that
only 'ignore' is replaced
generateRidgeTerrain: only return if node_max.Y < water_level - 16
Previously, if water level was set a few nodes above a mapchunk
border the river channel was only partially excavated
ShadowNinja
Craig Robbins
Ekdohibs
est31
Loic Blot
kwolekr
SmallJoker
paramat
gregorycu
Kahrl
Maksim Gamarnik
Auke Kok
obneq
Xunto
Xunto
TriBlade9
rubenwardy