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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2007-12-13 17:37:19 +0300
committerDavid S. Miller <davem@davemloft.net>2008-01-29 01:57:51 +0300
commitb4d4f7c70fd3361c6c889752e08ea9be304cf5f4 (patch)
treeb84c712184dfcdde4b68980f4eff21bcaefbfcf3 /net/dccp/options.c
parent8109616e2ef978d142ea45850efd4f102b9bdce4 (diff)
downloadlinux-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 'net/dccp/options.c')
-rw-r--r--net/dccp/options.c56
1 files changed, 36 insertions, 20 deletions
diff --git a/net/dccp/options.c b/net/dccp/options.c
index f496d4dc7efc..0c996d8c79a3 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -166,16 +166,27 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
case DCCPO_TIMESTAMP:
if (len != 4)
goto out_invalid_option;
-
+ /*
+ * RFC 4340 13.1: "The precise time corresponding to
+ * Timestamp Value zero is not specified". We use
+ * zero to indicate absence of a meaningful timestamp.
+ */
opt_val = get_unaligned((__be32 *)value);
- opt_recv->dccpor_timestamp = ntohl(opt_val);
-
- /* FIXME: if dreq != NULL, don't store this on listening socket */
- dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
- dp->dccps_timestamp_time = ktime_get_real();
+ if (unlikely(opt_val == 0)) {
+ DCCP_WARN("Timestamp with zero value\n");
+ break;
+ }
+ if (dreq != NULL) {
+ dreq->dreq_timestamp_echo = ntohl(opt_val);
+ dreq->dreq_timestamp_time = dccp_timestamp();
+ } else {
+ opt_recv->dccpor_timestamp =
+ dp->dccps_timestamp_echo = ntohl(opt_val);
+ dp->dccps_timestamp_time = dccp_timestamp();
+ }
dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
- dccp_role(sk), opt_recv->dccpor_timestamp,
+ dccp_role(sk), ntohl(opt_val),
(unsigned long long)
DCCP_SKB_CB(skb)->dccpd_ack_seq);
break;
@@ -393,16 +404,24 @@ int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
-static int dccp_insert_option_timestamp_echo(struct sock *sk,
+static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
+ struct dccp_request_sock *dreq,
struct sk_buff *skb)
{
- struct dccp_sock *dp = dccp_sk(sk);
__be32 tstamp_echo;
- int len, elapsed_time_len;
unsigned char *to;
- const suseconds_t delta = ktime_us_delta(ktime_get_real(),
- dp->dccps_timestamp_time);
- u32 elapsed_time = delta / 10;
+ u32 elapsed_time, elapsed_time_len, len;
+
+ if (dreq != NULL) {
+ elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
+ tstamp_echo = htonl(dreq->dreq_timestamp_echo);
+ dreq->dreq_timestamp_echo = 0;
+ } else {
+ elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
+ tstamp_echo = htonl(dp->dccps_timestamp_echo);
+ dp->dccps_timestamp_echo = 0;
+ }
+
elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
len = 6 + elapsed_time_len;
@@ -415,7 +434,6 @@ static int dccp_insert_option_timestamp_echo(struct sock *sk,
*to++ = DCCPO_TIMESTAMP_ECHO;
*to++ = len;
- tstamp_echo = htonl(dp->dccps_timestamp_echo);
memcpy(to, &tstamp_echo, 4);
to += 4;
@@ -427,8 +445,6 @@ static int dccp_insert_option_timestamp_echo(struct sock *sk,
memcpy(to, &var32, 4);
}
- dp->dccps_timestamp_echo = 0;
- dp->dccps_timestamp_time = ktime_set(0, 0);
return 0;
}
@@ -537,10 +553,6 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
dccp_insert_option_ackvec(sk, skb))
return -1;
-
- if (dp->dccps_timestamp_echo != 0 &&
- dccp_insert_option_timestamp_echo(sk, skb))
- return -1;
}
if (dp->dccps_hc_rx_insert_options) {
@@ -564,6 +576,10 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
dccp_insert_option_timestamp(sk, skb))
return -1;
+ if (dp->dccps_timestamp_echo != 0 &&
+ dccp_insert_option_timestamp_echo(dp, NULL, skb))
+ return -1;
+
/* XXX: insert other options when appropriate */
if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {