This implements the larger-initial-windows feature for CCID 3, as described in
section 5 of RFC 4342. When the first feedback packet arrives, the sender can
send up to 2..4 packets per RTT, instead of just one.
The patch further
* reduces the number of timestamping calls by passing the timestamp value
(which is computed in one of the calling functions anyway) as argument
* renames one constant with a very long name into one which is shorter and
resembles the one in RFC 3448 (t_mbi)
* simplifies some of the min_t/max_t cases where both `x', `y' have the same
type
Commiter note: renamed TFRC_t_mbi to TFRC_T_MBI, to follow Linux coding style.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
To reflect the fact that this now is of no effect, not making apps
stop working, just be warned in the system log.
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This removes and cleans up unused variables and structures which have become
unnecessary following the introduction of the EWMA patch to automatically track
the CCID 3 receiver/sender packet sizes `s'.
It deprecates the PACKET_SIZE socket option by returning an error code and
printing a deprecation warning if an application tries to read or write this
socket option.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This corrects the setting of the nofeedback timer with regard to RFC
3448 - previously it was not set to max(4*R, 2*s/X) as specified. Using
the maximum of 1 second as upper bound (as it was done before) can have
detrimental effects, especially if R is small.
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This is in response to a request sent earlier by Eric W. Biederman
and replaces all sysctl numbers for net.dccp.default with CTL_UNNUMBERED.
It has been tested to compile and to work.
Commiter note: I've removed the use of CTL_UNNUMBERED, not setting .ctl_name
sets it to 0, that is the what CTL_UNNUMBERED is, reason is
to avoid unneeded source code cluttering.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch
* removes setting t_RTO in ccid3_hc_tx_init (per [RFC 3448, 4.2], t_RTO is
undefined until feedback has been received);
* makes some trivial changes (updates of comments);
* performs a small optimisation by exploiting that the feedback timeout
uses the value of t_ipi. The way it is done is safe, because the timeouts
appear after the changes to t_ipi, ensuring that up-to-date values are used;
* in ccid3_hc_tx_packet_recv, moves the t_rto statement closer to the calculation
of the next_tmout. This makes the code clearer to read and is also safe, since
t_rto is not updated until the next call of ccid3_hc_tx_packet_recv, and is not
read by the functions called via ccid_wait_for_ccid();
* removes a `max' statement in sk_reset_timer, this is not needed since the timeout
value is always greater than 1E6 microseconds.
* adds `XXX'es to highlight that currently the nofeedback timer is set
in a non-standard way
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch:
* consolidates updating of parameters (t_nom, t_ipi, t_delta) which
need to be updated at the same time, since they are inter-dependent
* removes two inline functions which are no longer needed as a result of
the above consolidation
* resolves a FIXME regarding the re-calculation of t_ipi within the nofeedback
timer, in the state where no feedback has previously been received
* ties updating these parameters to updating the sending rate X, exploiting
that all three parameters in turn depend on X; and using a small optimisation
which can reduce the number of required instructions: only update the three
parameters when X really changes
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch concerns updating the value of the nofeedback timer when no feedback
has been received so far.
Since in this case the value of R is still undefined according to [RFC 3448,
4.2], we can not perform step (3) of [RFC 3448, 4.3]. A clarification is
provided in [RFC 4342, sec. 5], which states that in these cases the nofeedback
timer (still) expires "after two seconds".
Many thanks to Ian McDonald for pointing this out and providing the
clarification.
The patch
* implements [RFC 4342, sec. 5] with regard to the above case
* consolidates handling timer restart by
- adding an appropriate jump label and
- initialising the timeout value
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This considers the case - ACK received while no packet has been sent
so far. Resolved by printing a (rate-limited) warning message.
Further removes an unnecessary BUG_ON in ccid3_hc_tx_packet_recv,
received feedback on a terminating connection is simply ignored.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch removes a switch statement which is redundant since,
* nothing is done in states TFRC_SSTATE_NO_SENT/TFRC_SSTATE_NO_FBACK
* it is impossible that the function is called in the state TFRC_SSTATE_TERM, since
--the function is called, in dccp_write_xmit, after ccid3_hc_tx_send_packet
--if ccid3_hc_tx_send_packet is called in state TFRC_SSTATE_TERM, it returns
-EINVAL, which means that ccid3_hc_tx_packet_sent will not be called
(compare dccp_write_xmit)
--> therefore, this case is logically impossible
* the remaining state is TFRC_SSTATE_FBACK which conditionally updates t_ipi, t_nom,
and t_delta. This is a no-op, since
--t_ipi only changes when feedback is received
--however, when feedback arrives via ccid3_hc_tx_packet_recv, there is an identical
code block which performs the same set of operations
--performing the same set of operations again in ccid3_hc_tx_packet_sent therefore
does not change anything, since between the time of receiving the last feedback
(and therefore update of t_ipi, t_nom, and t_delta), the value of t_ipi has not
changed
--since t_ipi has not changed, the values of t_delta and t_nom also do not change,
they depend fully on t_ipi
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This resolves an `XXX' in ccid3_hc_tx_send_packet().
The function is only called on Data and DataAck packets and returns a negative
result on zero-sized messages. This is a reasonable policy since CCID 3 is a
congestion-control module and congestion control on zero-sized Data(Ack)
packets is in a way pathological.
The patch uses a more suitable error code for this case, it returns the Posix.1
code `EBADMSG' ("Not a data message") instead of `ENOTCONN'.
As a result of ignoring zero-sized packets, a the condition for a warning
"First packet is data" in ccid3_hc_tx_packet_sent is always satisfied; this
message has been removed since it will always be printed.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This makes some logically equivalent simplifications, by replacing
rc - values plus goto's with direct return statements.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch performs a simplifying (performance) optimisation:
In each call of the inline function ccid3_calc_new_t_ipi(), the state is
tested against TFRC_SSTATE_NO_FBACK. This is expensive when the function
is called very often. A simpler solution, implemented by this patch, is
to adapt the control flow.
Background:
Now that we can stuff bigger ack vectors into options.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Ack vectors grow proportional to the window size. If an ack vector does not fit
into a single option, it must be spread across multiple options. This patch
will allow for windows to grow larger.
Committer note: Simplified the patch a bit, original algorithm kept.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Commiter note:
This was split from Andrea's original patch, in the process I changed the type
of the ackvec index fields to u16 instead of to int and haven't folded
dccp_ackvec_parse with dccp_ackvec_check_rcv_ackno.
Next patch will actually do the insertion of more than one ackvec per packet,
using, initially, up to a max of 2 ackvecs as per Andrea's original patch, then
I'll work on support for larger ackvecs, be it using a sysctl or using
setsockopt.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Commiter note: original patch was splitted.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This one got lost on the way from Ian to Gerrit to me, fix it.
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This removes a non-referenced variable.
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This makes the code of the dccp_probe module more portable.
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This adds documentation to the CCID 3 rx/tx socket fields, plus some
minor re-formatting.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This reaps the benefit of the earlier patch, which changed the type of
CCID 3 states to use enums, in that many conditions are now simplified
and the number of possible (unexpected) values is greatly reduced.
In a few instances, this also allowed to simplify pre-conditions; where
care has been taken to retain logical equivalence.
[DCCP]: Introduce a consistent BUG/WARN message scheme
This refines the existing set of DCCP messages so that
* BUG(), BUG_ON(), WARN_ON() have meaningful DCCP-specific counterparts
* DCCP_CRIT (for severe warnings) is not rate-limited
* DCCP_WARN() is introduced as rate-limited wrapper
Using these allows a faster and cleaner transition to their original
counterparts once the code has matured into a full DCCP implementation.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Previously the transmit queue was unbounded.
This patch:
* puts a limit on transmit queue length
and sends back EAGAIN if the buffer is full
* sets the TX queue length to a sensible default
* implements tx buffer sysctls for DCCP
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This adds a CCID3 debug option to the configuration menu
which is missing in Kconfig, but already used by the code.
CCID 2 already provides such an entry.
To enable debugging, set CONFIG_IP_DCCP_CCID3_DEBUG=y
NOTE: The use of ccid3_{t,r}x_state_name is safe, since
now only enum values can appear.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch
* makes debugging (when configured) work both for static / module build
* provides generic debugging macros for use in other DCCP / CCID modules
* adds missing information about debug parameters to Kconfig
* performs some code tidy-up
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
These are code optimizations which are relevant when dealing with large
windows. They are not coded the way I would like to, but they do the job for
the short-term. This patch should be more neat.
Commiter note: Changed the seqno comparisions to use {after,before}48 to handle
wrapping.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Spotted by Ian McDonald, tentatively fixed by Gerrit Renker:
http://www.mail-archive.com/dccp%40vger.kernel.org/msg00599.html
Rewritten not to unroll sk_receive_skb, in the common case, i.e. no lock
debugging, its optimized away.
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch tackles the following problem:
* the ccid3_hc_{t,r}x_sock define ccid3hc{t,r}x_state as `u8', but
in reality there can only be a few, pre-defined enum names
* this necessitates addiditional checking for unexpected values
which would otherwise be caught by the compiler
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Do not traverse the list of ack vector records [proportional to window size]
when we know we will not find what we are looking for. This is especially
useful because ack vectors are checked twice:
1) Upon parsing of options.
2) Upon notification of a new ack.
All of the work will occur during check #1. Therefore, when check #2 is
performed, no new work will be done. This is now "detected" and there is no
performance hit when doing #2.
Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch does not change code; it performs some trivial clean/tidy-ups:
* removal of a `debug_prefix' string in favour of the
already existing dccp_role(sk)
* add documentation of structures and constants
* separated out the cases for invalid packets (step 1
of the packet validation)
* removing duplicate statements
* combining declaration & initialisation
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch replaces cryptic feature negotiation messages of type
Oct 31 15:42:20 kernel: dccp_feat_change: feat change type=32 feat=1
Oct 31 15:42:21 kernel: dccp_feat_change: feat change type=34 feat=1
Oct 31 15:42:21 kernel: dccp_feat_change: feat change type=32 feat=5
into ones of type:
Nov 2 13:54:45 kernel: dccp_feat_change: ChangeL(CCID (1), 3)
Nov 2 13:54:45 kernel: dccp_feat_change: ChangeR(CCID (1), 3)
Nov 2 13:54:45 kernel: dccp_feat_change: ChangeL(Ack Ratio (5), 2)
Also,
* completed the feature number list wrt RFC 4340 sec. 6.4
* annotating which ones have been implemented so far
* implemented rudimentary sanity checking in feat.c (FIXMEs)
* some minor fixes
Commiter note: uninlined dccp_feat_name and dccp_feat_typename, for
consistency with dccp_{state,packet}_name, that, BTW,
should be compiled only if CONFIG_IP_DCCP_DEBUG is
selected, leaving this to another cset tho. Also
shortened dccp_feat_negotiation_debug to dccp_feat_debug.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Resolves the problem that if IPv6 was configured `y' and DCCP `m' then
dccp_ipv6 was not built as a module. With this change, dccp_ipv6 is built
as a module whenever DCCP *OR* IPv6 are configured as modules; it will be
built-in only if both DCCP = `y' and IPV6 = `y'.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Throughout the TCP/DCCP (and tunnelling) code, it often happens that the
return code of a transmit function needs to be tested against NET_XMIT_CN
which is a value that does not indicate a strict error condition.
This patch uses a macro for these recurring situations which is consistent
with the already existing macro net_xmit_errno, saving on duplicated code.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This
* resolves a FIXME - DCCPv6 connections started all with
an initial sequence number of 1;
* provides a redirection `secure_dccpv6_sequence_number'
in case the init_sequence_v6 code should be updated later;
* concentrates the update of S.GAR into dccp_connect_init();
* removes a duplicate dccp_update_gss() in ipv4.c;
* uses inet->dport instead of usin->sin_port, due to the
following assignment in dccp_v4_connect():
inet->dport = usin->sin_port;
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch removes the following redundancies:
1) The test skb->protocol == htons(ETH_P_IPV6) in dccp_v6_init_sequence
is always true since
* dccp_v6_conn_request() is the only calling function
* dccp_v6_conn_request() redirects all skb's with ETH_P_IP to
dccp_v4_conn_request()
2) The first argument, `struct sock *sk', of dccp_v{4,6}_init_sequence()
is never used.
(This is similar for tcp_v{4,6}_init_sequence, an analogous patch has been
submitted to netdev and merged.)
By the way - are the `sport' / `dport' arguments in the right order?
I have made them consistent among calls but they seem to be in the
reverse order.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This removes 3 forward declarations by reordering 2 functions.
No code change at all.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
In order to make their function clearer and obtain a consistent naming
scheme to identify sysctls, all existing DCCP sysctls have been prefixed
with `sysctl_dccp', following the same convention as used by TCP.
Feature-specific sysctls retain the `feat' in the middle, although the
`default' has been dropped, since it is obvious from use.
Also removed a duplicate `dccp_feat_default_sequence_window' in ipv4.c.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This adds 3 sysctls which govern the retransmission behaviour of DCCP control
packets (3way handshake, feature negotiation).
It removes 4 FIXMEs from the code.
The close resemblance of sysctl variables to their TCP analogues is emphasised
not only by their name, but also by giving them the same initial values.
This is useful since there is not much practical experience with DCCP yet.
Furthermore, with regard to the previous patch, it is now possible to limit
the number of keepalive-Responses by setting net.dccp.default.request_retries
(also a bit like in TCP).
Lastly, added documentation of all existing DCCP sysctls.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This updates program documentation: spell out precise conditions about
which packets are eligible for retransmission (which is actually quite
hard to extract from RFC 4340).
It is based on the following table derived from RFC 4340:
+-----------+---------------------------------+---------------------+
| Type | Retransmit? | Remark |
+-----------+---------------------------------+---------------------+
| Request | in client-REQUEST state | sec. 8.1.1 |
| Response | NEVER | SHOULD NOT, 8.1.3 |
| Data | NEVER | unreliable protocol |
| Ack | possible in client-PARTOPEN | sec. 8.1.5 |
| DataAck | NEVER | unreliable protocol |
| CloseReq | only in server-CLOSEREQ state | MUST, sec. 8.3 |
| Close | in node-CLOSING state | MUST, sec. 8.3 |
+-----------+-------------------------------------------------------+
| Reset | only in response to other packets |
| Sync | only in response to sequence-invalid packets (7.5.4) |
| SyncAck | only in response to Sync packets |
+-----------+-------------------------------------------------------+
Hence the only packets eligible for retransmission are:
* Requests in client-REQUEST state (sec. 8.1.1)
* Acks in client-PARTOPEN state (sec. 8.1.5)
* CloseReq in server-CLOSEREQ state (sec. 8.3)
* Close in node-CLOSING state (sec. 8.3)
I had meant to put in a check for these types too, but have left that
for later.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This patch does the following:
a) introduces variable-length checksums as specified in [RFC 4340, sec. 9.2]
b) provides necessary socket options and documentation as to how to use them
c) basic support and infrastructure for the Minimum Checksum Coverage feature
[RFC 4340, sec. 9.2.1]: acceptability tests, user notification and user
interface
In addition, it
(1) fixes two bugs in the DCCPv4 checksum computation:
* pseudo-header used checksum_len instead of skb->len
* incorrect checksum coverage calculation based on dccph_x
(2) removes dccp_v4_verify_checksum() since it reduplicates code of the
checksum computation; code calling this function is updated accordingly.
(3) now uses skb_checksum(), which is safer than checksum_partial() if the
sk_buff has is a non-linear buffer (has pages attached to it).
(4) fixes an outstanding TODO item:
* If P.CsCov is too large for the packet size, drop packet and return.
The code has been tested with applications, the latest version of tcpdump now
comes with support for partial DCCP checksums.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
