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author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2007-12-13 14:37:19 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2008-01-28 22:57:51 (GMT) |
commit | b4d4f7c70fd3361c6c889752e08ea9be304cf5f4 (patch) | |
tree | b84c712184dfcdde4b68980f4eff21bcaefbfcf3 /include | |
parent | 8109616e2ef978d142ea45850efd4f102b9bdce4 (diff) | |
download | linux-b4d4f7c70fd3361c6c889752e08ea9be304cf5f4.tar.xz |
[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>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/dccp.h | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/include/linux/dccp.h b/include/linux/dccp.h index 7214031..484e45c 100644 --- a/include/linux/dccp.h +++ b/include/linux/dccp.h @@ -407,11 +407,23 @@ struct dccp_opt_pend { extern void dccp_minisock_init(struct dccp_minisock *dmsk); +/** + * struct dccp_request_sock - represent DCCP-specific connection request + * @dreq_inet_rsk: structure inherited from + * @dreq_iss: initial sequence number sent on the Response (RFC 4340, 7.1) + * @dreq_isr: initial sequence number received on the Request + * @dreq_service: service code present on the Request (there is just one) + * The following two fields are analogous to the ones in dccp_sock: + * @dreq_timestamp_echo: last received timestamp to echo (13.1) + * @dreq_timestamp_echo: the time of receiving the last @dreq_timestamp_echo + */ struct dccp_request_sock { struct inet_request_sock dreq_inet_rsk; __u64 dreq_iss; __u64 dreq_isr; __be32 dreq_service; + __u32 dreq_timestamp_echo; + __u32 dreq_timestamp_time; }; static inline struct dccp_request_sock *dccp_rsk(const struct request_sock *req) @@ -477,8 +489,8 @@ struct dccp_ackvec; * @dccps_gar - greatest valid ack number received on a non-Sync; initialized to %dccps_iss * @dccps_service - first (passive sock) or unique (active sock) service code * @dccps_service_list - second .. last service code on passive socket - * @dccps_timestamp_time - time of latest TIMESTAMP option * @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option + * @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo * @dccps_l_ack_ratio - feature-local Ack Ratio * @dccps_r_ack_ratio - feature-remote Ack Ratio * @dccps_pcslen - sender partial checksum coverage (via sockopt) @@ -514,8 +526,8 @@ struct dccp_sock { __u64 dccps_gar; __be32 dccps_service; struct dccp_service_list *dccps_service_list; - ktime_t dccps_timestamp_time; __u32 dccps_timestamp_echo; + __u32 dccps_timestamp_time; __u16 dccps_l_ack_ratio; __u16 dccps_r_ack_ratio; __u16 dccps_pcslen; |