mirror of
https://github.com/matrix-construct/construct
synced 2024-12-28 00:14:07 +01:00
212380e3f4
+ branches/release-2.1 -> 2.2 base + 3.0 -> branches/cxxconversion + backport some immediate 3.0 functionality for 2.2 + other stuff
330 lines
15 KiB
Text
330 lines
15 KiB
Text
Protocol changes for +TSora
|
|
---------------------------
|
|
|
|
|
|
Note:
|
|
|
|
The protocols described here implement TimeStamps on IRC channels and
|
|
nicks. The idea of IRC TimeStamps was started on Undernet, and first
|
|
implemented by Run <carlo@runaway.xs4all.nl>. The protocols used here
|
|
are not exactly the same as the ones used on Undernet; the nick-kill
|
|
handling is very similar and must be credited to Run, while the
|
|
"TimeStamped channel description" protocol is quite different.
|
|
|
|
|
|
|
|
TSora servers keep track of which version of the TS protocol (if any)
|
|
their neighboring servers are using, and take it into account when
|
|
sending messages to them. This allows for seamless integration of TS
|
|
servers into a non-TS net, and for upgrades of the protocol.
|
|
|
|
Each server knows which is the lowest and the highest version of the
|
|
TS protocol it can interact with; currently both of these are set to 1:
|
|
|
|
#define TS_CURRENT 1 /* the highest TS ver we can do */
|
|
#define TS_MIN 1 /* the lowest TS ver we can do */
|
|
|
|
|
|
Timings and TS versions:
|
|
========================
|
|
|
|
. Keep a 'delta' value to be added to the result of all calls to time(),
|
|
initially 0.
|
|
|
|
. Send a second argument to the PASS command, ending in the 'TS' string.
|
|
|
|
. Send a
|
|
|
|
SVINFO <TS_CURRENT> <TS_MIN> <STANDALONE> :<UTC-TIME>
|
|
|
|
just after "SERVER", where <STANDALONE> is 1 if we're connected to
|
|
more TSora servers, and 0 if not, and <UTC-TIME> is our idea of the
|
|
current UTC time, fixed with the delta.
|
|
|
|
. When we receive a "SVINFO <x> <y> <z> :<t>" line from a connecting
|
|
server, we ignore it if TS_CURRENT<y or x<TS_MIN, otherwise we
|
|
set a flag remembering that that server is TS-aware, remember the TS
|
|
version to use with it (min(TS_CURRENT, x)). Additionally, if this is
|
|
our first connected TS server, we set our delta to t-<OUR_UTC> if
|
|
z==0, and to (t-<OUR_UTC>)/2 if z!=0. The SVINFO data is kept around
|
|
until the server has effectively registered with SERVER, and used
|
|
*after* sending our own SVINFO to that server.
|
|
|
|
|
|
Explanations:
|
|
|
|
Servers will always know which of their directly-linked servers can do
|
|
TS, and will use the TS protocol only with servers that do understand
|
|
it. This makes it possible to switch to full TS in just one
|
|
code-replacement step, without incompatibilities.
|
|
|
|
As long as not all servers are TS-aware, the net will be divided into
|
|
"zones" of linked TS-aware servers. Channel modes will be kept
|
|
synchronized at least within the zone in which the channel was
|
|
created, and nick collisions between servers in the same zone will
|
|
result in only one client being killed.
|
|
|
|
Time synchronization ensures that servers have the same idea of the
|
|
current time, and achieves this purpose as long as TS servers are
|
|
introduced one by one within the same 'zone'. The merging of two zones
|
|
cannot synchronize them completely, but it is to be expected that
|
|
within each zone the effective time will be very close to the real
|
|
time.
|
|
|
|
By sending TSINFO after SERVER rather than before, we avoid the extra
|
|
lag created by the identd check on the server. To be able to send
|
|
immediately a connect burst of either type (TS or not), we need to
|
|
know before that if the server does TS or not, so we send that
|
|
information with PASS as an extra argument. And to avoid being
|
|
incompatible with 2.9 servers, which check that this second argument
|
|
begins with "2.9", we check that it *ends* with "TS".
|
|
|
|
The current time is only used when setting a TS on a new channel or
|
|
nick, and once such a TS is set, it is never modified because of
|
|
synchronization, as it is much more important that the TS for a
|
|
channel or nick stays the same across all servers than that it is
|
|
accurate to the second.
|
|
|
|
Note that Undernet's 2.8.x servers have no time synchronization at
|
|
all, and have had no problems because of it - all of this is more to
|
|
catch the occasional server with a way-off clock than anything.
|
|
|
|
|
|
NICK handling patches (anti-nick-collide + shorter connect burst):
|
|
==================================================================
|
|
|
|
. For each nick, store a TS value = the TS value received if any, or our
|
|
UTC+delta at the time we first heard of the nick. TS's are propagated
|
|
to TS-aware servers whenever sending a NICK command.
|
|
|
|
. Nick changes reset the TS to the current time.
|
|
|
|
. When sending a connect burst to another TS server, replace the
|
|
NICK/USER pair with only one NICK command containing the nick, the
|
|
hopcount, the TS, the umode, and all the USER information.
|
|
|
|
The format for a full NICK line is:
|
|
NICK <nick> <hops> <TS> <umode> <user> <host> <server> :<ircname>
|
|
|
|
The umode is a + followed by any applying usermodes.
|
|
|
|
The format for a nick-change NICK line is:
|
|
:<oldnick> NICK <newnick> :<TS>
|
|
|
|
. When a NICK is received from a TS server, that conflicts with an
|
|
existing nick:
|
|
+ if the userhosts differ or one is not known:
|
|
* if the timestamps are equal, kill ours and the old one if it
|
|
was a nick change
|
|
* if the incoming timestamp is older than ours, kill ours and
|
|
propagate the new one
|
|
* if the incoming timestamp is younger, ignore the line, but kill
|
|
the old nick if it was a nick change
|
|
+ if the userhosts are the same:
|
|
* if the timestamps are equal, kill ours and the old one if it
|
|
was a nick change
|
|
* if the incoming timestamp is younger, kill ours and propagate
|
|
the new one
|
|
* if the incoming timestamp is older, ignore the line but kill
|
|
the old nick if it was a nick change
|
|
|
|
. When a NICK is received from a non-TS server that conflicts with
|
|
an existing nick, kill both.
|
|
|
|
. Do not send "Fake Prefix" kills in response to lines coming from TS
|
|
servers; the sanitization works anyway, and this allows the "newer
|
|
nick overruled" case to work.
|
|
|
|
Explanations:
|
|
|
|
The modified nick-introduction syntax allows for a slightly shorter
|
|
connect-burst, and most importantly lets the server compare
|
|
user@host's when determining which nick to kill: if the user@host
|
|
is the same, then the older nick must be killed rather than the
|
|
newer.
|
|
|
|
When talking to a non-TS server, we need to behave exactly like one
|
|
because it expects us to. When talkign to a TS server, we don't kill
|
|
the nicks it's introducing, as we know it'll be smart enough to do it
|
|
itself when seeing our own introduced nick.
|
|
|
|
When we see a nick arriving from a non-TS server, it won't have a TS,
|
|
but it's safe enough to give it the current time rather than keeping
|
|
it 0; such TS's won't be the same all across the network (as long as
|
|
there is more than one TS zone), and when there's a collision, the TS
|
|
used will be the one in the zone the collision occurs in.
|
|
|
|
Also, it is important to note that by the time a server sees (and
|
|
chooses to ignore) a nick introduction, the introducing server has
|
|
also had the time to put umode changes for that nick on its queue, so
|
|
we must ignore them too... so we need to ignore fake-prefix lines
|
|
rather than sending kills for them. This is safe enough, as the rest
|
|
of the protocol ensures that they'll get killed anyway (and the
|
|
Undernet does it too, so it's been more than enough tested). Just for
|
|
an extra bit of compatibility, we still kill fake prefixes coming from
|
|
non-TS servers.
|
|
|
|
This part of the TS protocol is almost exactly the same as the
|
|
Undernet's .anc (anti-nick-collide) patches, except that Undernet
|
|
servers don't add usermodes to the NICK line.
|
|
|
|
|
|
TimeStamped channel descriptions (avoiding hacked ops and desynchs):
|
|
====================================================================
|
|
|
|
. For each channel, keep a timestamp, set to the current time when the
|
|
channel is created by a client on the local server, or to the received
|
|
value if the channel has been propagated from a TS server, or to 0
|
|
otherwise. This value will have the semantics of "the time of creation
|
|
of the current ops on the channel", and 0 will mean that the channel
|
|
is in non-TS mode.
|
|
|
|
A new server protocol command is introduced, SJOIN, which introduces
|
|
a full channel description: a timestamp, all the modes (except bans),
|
|
and the list of channel members with their ops and voices. This
|
|
command will be used instead of JOIN and of (most) MODEs both in
|
|
connect bursts and when propagating channel creations among TS
|
|
servers. SJOIN will never be accepted from or sent to users.
|
|
|
|
The syntax for the command is:
|
|
|
|
SJOIN <TS> #<channel> <modes> :[@][+]<nick_1> ... [@][+]<nick_n>
|
|
|
|
The fields have the following meanings:
|
|
|
|
* <TS> is the timestamp for the channel
|
|
|
|
* <modes> is the list of global channel modes, starting with a +
|
|
and a letter for each of the active modes (spmntkil), followed
|
|
by an argument for +l if there is a limit, and an argument for
|
|
+k if there's a key (in the same order they were mentioned in
|
|
the string of letters).
|
|
|
|
A channel with no modes will have a "+" in that field.
|
|
|
|
A special value of "0" means that the server does not specify the
|
|
modes, and will be used when more than one SJOIN line is needed
|
|
to completely describe a channel, or when propagating a SJOIN
|
|
the modes of which were rejected.
|
|
|
|
* Each nick is preceded by a "@" if the user has ops, and a "+" if
|
|
the user has a voice. For mode +ov, both flags are used.
|
|
|
|
SJOINs will be propagated (when appropriate) to neighboring TS
|
|
servers, and converted to JOINs and MODEs for neighboring non-TS
|
|
servers.
|
|
|
|
To propagate channels for which not all users fit in one
|
|
SJOIN line, several SJOINs will be sent consecutively, only the first
|
|
one including actual information in the <mode> field.
|
|
|
|
An extra ad-hoc restriction is imposed on SJOIN messages, to simplify
|
|
processing: if a channel has ops, then the first <nick> of the first
|
|
SJOIN sent to propagate that channel must be one of the ops.
|
|
|
|
Servers will never attempt to reconstruct a SJOIN from JOIN/MODE
|
|
information being received at the moment from other servers.
|
|
|
|
. For each user on a channel, keep an extra flag (like ops and voice)
|
|
that is set when the user has received channel ops from another
|
|
server (in a SJOIN channel description), which we rejected (ignored).
|
|
Mode changes (but NOT kicks) coming from a TS server and from someone
|
|
with this flag set will be ignored. The flag will be reset when the
|
|
user gets ops from another user or server.
|
|
|
|
. On deops done by non-local users, coming from TS servers, on channels
|
|
with a non-zero TS, do not check that the user has ops but check that
|
|
their 'deopped' flag is not set. For kicks coming from a TS server, do
|
|
not check either. This will avoid desynchs, and 'bad' modechanges are
|
|
avoided anyway. Other mode changes will still only be taken into
|
|
account and propagated when done by users that are seen as having ops.
|
|
|
|
. When a MODE change that ops someone is received from a server for a
|
|
channel, that channel's TS is set to 0, and the mode change is
|
|
propagated.
|
|
|
|
. When a SJOIN is received for a channel, deal with it in this way:
|
|
* received-TS = 0:
|
|
+ if we have ops or the SJOIN doesn't op anyone, SJOIN propagated
|
|
with our own TS.
|
|
+ otherwise, TS set to 0 and SJOIN propagated with 0.
|
|
* received-TS > 0, own-TS = 0:
|
|
+ if the SJOIN ops someone or we don't have ops, set our TS to the
|
|
received TS and propagate.
|
|
+ otherwise, propagate with TS = 0.
|
|
* received-TS = own-TS: propagate.
|
|
* received-TS < own-TS:
|
|
+ if the SJOIN ops someone, remove *all* modes (except bans) from
|
|
the channel and propagate these mode changes to all neighboring
|
|
non-TS servers, and copy the received TS and propagate the SJOIN.
|
|
+ if the SJOIN does not op anyone and we have ops, propagate
|
|
with our own TS.
|
|
+ otherwise, copy the received TS and propagate the SJOIN.
|
|
* received-TS > own-TS:
|
|
+ if the SJOIN does not introduce any ops, process and propagate
|
|
with our own TS.
|
|
+ if we have ops: for each person the mode change would op, set the
|
|
'deopped' flag; process all the JOINs ignoring the '@' and '+'
|
|
flags; propagate without the flags and with our TS.
|
|
+ if we don't have ops: set our TS to the received one, propagate
|
|
with the flags.
|
|
|
|
|
|
Explanations:
|
|
|
|
This part of the protocol is the one that is most different (and
|
|
incompatible) with the Undernet's: we never timestamp MODE changes,
|
|
but instead we introduce the concept of time-stamped channel
|
|
descriptions. This way each server can determine, based on its state
|
|
and the received description, what the correct modes for a channel
|
|
are, and deop its own users if necessary. With this protocol, there is
|
|
*never* the need to reverse and bounce back a mode change. This is
|
|
both faster and more bandwith-effective.
|
|
|
|
The end goal is to have a protocol will eventually protect channels
|
|
against hacked ops, while minimizing the impact on a mixed-server net.
|
|
In order to do this, whenever there is a conflict between a TS server
|
|
and a non-TS one, the non-TS one's idea of the whole situation
|
|
prevails. This means that channels will only have a TS when they have
|
|
been created on a TS-aware server, and will lose it whenever a server
|
|
op comes from a non-TS server. Also, at most one 'zone' will have a TS
|
|
for any given channel at any given time, ensuring that there won't be
|
|
any deops when zones are merged. However, when TS zones are merged, if
|
|
the side that has a TS also has ops, then the TS is kept across the
|
|
whole new zone. Effective protection will only be ensured once all
|
|
servers run TS patches and channels have been re-created, as there is
|
|
no way servers can assign a TS to a channel they are not creating
|
|
(like they do with nicks) without having unwanted deops later.
|
|
|
|
The visible effects of this timestamped channel-description protocol
|
|
are that when a split rejoins, and one side has hacked ops, the other
|
|
side doesn't see any server mode changes (just like with Undernet's
|
|
TS), but the side that has hacked ops sees:
|
|
|
|
* first the first server on the other side deopping and devoicing
|
|
everyone, and fixing the +spmntkli modes
|
|
* then other users joining, and getting server ops and voices
|
|
|
|
The less obvious part of this protocol is its behavior in the case
|
|
that the younger side of a rejoin has servers that are lagged with
|
|
each other. In such a situation, a SJOIN that clears all modes and
|
|
sets the legitimate ones is being propagated from one server, and
|
|
lagged illegitimate mode changes and kicks are being propagated in the
|
|
opposite direction. In this case, a kick done by someone who is being
|
|
deopped by the SJOIN must be taken into account to keep the name list
|
|
in sync (and since it can only be kicking someone who also was on the
|
|
younger side), while a deop does not matter (and will be ignored by
|
|
the first server on the other side), and an opping *needs* to be
|
|
discareded to avoid hacked ops.
|
|
|
|
The main property of timestamped channel descriptions that makes them
|
|
a very stable protocol even with lag and splits, is that they leave a
|
|
server in the same final state, independently of the order in which
|
|
channel descriptions coming from different servers are received. Even
|
|
when SJOINs and MODEs for the same channel are being propagated in
|
|
different direction because of several splits rejoining, the final
|
|
state will be the same, independently of the exact order in which each
|
|
server received the SJOINs, and will be the same across all the
|
|
servers in the same zone.
|
|
|
|
|