[DCCP]: Handle timestamps on Request/Response exchange separately
In DCCP, timestamps can occur on packets anytime, CCID3 uses a timestamp(/echo) on the Request/Response
exchange. This patch addresses the following situation:
* timestamps are recorded on the listening socket;
* Responses are sent from dccp_request_sockets;
* suppose two connections reach the listening socket with very small time in between:
* the first timestamp value gets overwritten by the second connection request.
This is not really good, so this patch separates timestamps into
* those which are received by the server during the initial handshake (on dccp_request_sock);
* those which are received by the client or the client after connection establishment.
As before, a timestamp of 0 is regarded as indicating that no (meaningful) timestamp has been
received (in addition, a warning message is printed if hosts send 0-valued timestamps).
The timestamp-echoing now works as follows:
* when a timestamp is present on the initial Request, it is placed into dreq, due to the
call to dccp_parse_options in dccp_v{4,6}_conn_request;
* when a timestamp is present on the Ack leading from RESPOND => OPEN, it is copied over
from the request_sock into the child cocket in dccp_create_openreq_child;
* timestamps received on an (established) dccp_sock are treated as before.
Since Elapsed Time is measured in hundredths of milliseconds (13.2), the new dccp_timestamp()
function is used, as it is expected that the time between receiving the timestamp and
sending the timestamp echo will be very small against the wrap-around time. As a byproduct,
this allows smaller timestamping-time fields.
Furthermore, inserting the Timestamp Echo option has been taken out of the block starting with
'!dccp_packet_without_ack()', since Timestamp Echo can be carried on any packet (5.8 and 13.3).
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@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index b1d5da6..027d181 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -117,11 +117,13 @@
struct dccp_sock *newdp = dccp_sk(newsk);
struct dccp_minisock *newdmsk = dccp_msk(newsk);
- newdp->dccps_role = DCCP_ROLE_SERVER;
- newdp->dccps_hc_rx_ackvec = NULL;
- newdp->dccps_service_list = NULL;
- newdp->dccps_service = dreq->dreq_service;
- newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
+ newdp->dccps_role = DCCP_ROLE_SERVER;
+ newdp->dccps_hc_rx_ackvec = NULL;
+ newdp->dccps_service_list = NULL;
+ newdp->dccps_service = dreq->dreq_service;
+ newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
+ newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
+ newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
if (dccp_feat_clone(sk, newsk))
goto out_free;
@@ -303,9 +305,12 @@
void dccp_reqsk_init(struct request_sock *req, struct sk_buff *skb)
{
- inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
- inet_rsk(req)->acked = 0;
- req->rcv_wnd = sysctl_dccp_feat_sequence_window;
+ struct dccp_request_sock *dreq = dccp_rsk(req);
+
+ inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
+ inet_rsk(req)->acked = 0;
+ req->rcv_wnd = sysctl_dccp_feat_sequence_window;
+ dreq->dreq_timestamp_echo = 0;
}
EXPORT_SYMBOL_GPL(dccp_reqsk_init);