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dccp: Feature negotiation for minimum-checksum-coverage

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This provides feature negotiation for server minimum checksum coverage
which so far has been missing.

Since sender/receiver coverage values range only from 0...15, their
type has also been reduced in size from u16 to u4.

Feature-negotiation options are now generated for both sender and receiver
coverage, i.e. when the peer has `forgotten' to enable partial coverage
then feature negotiation will automatically enable (negotiate) the partial
coverage value for this connection.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
This commit is contained in:
Gerrit Renker 2008-09-04 07:30:19 +02:00
parent 668144f7b4
commit 20f41eee82
2 changed files with 42 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/dccp.h
View File

@ -527,8 +527,8 @@ struct dccp_sock {
__u32 dccps_timestamp_time;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
__u16 dccps_pcslen;
__u16 dccps_pcrlen;
__u8 dccps_pcslen:4;
__u8 dccps_pcrlen:4;
__u64 dccps_ndp_count:48;
unsigned long dccps_rate_last;
struct dccp_minisock dccps_minisock;

53
net/dccp/proto.c
View File

@ -470,6 +470,42 @@ static int dccp_setsockopt_service(struct sock *sk, const __be32 service,
return 0;
}
static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
{
u8 *list, len;
int i, rc;
if (cscov < 0 || cscov > 15)
return -EINVAL;
/*
* Populate a list of permissible values, in the range cscov...15. This
* is necessary since feature negotiation of single values only works if
* both sides incidentally choose the same value. Since the list starts
* lowest-value first, negotiation will pick the smallest shared value.
*/
if (cscov == 0)
return 0;
len = 16 - cscov;
list = kmalloc(len, GFP_KERNEL);
if (list == NULL)
return -ENOBUFS;
for (i = 0; i < len; i++)
list[i] = cscov++;
rc = dccp_feat_register_sp(sk, DCCPF_MIN_CSUM_COVER, rx, list, len);
if (rc == 0) {
if (rx)
dccp_sk(sk)->dccps_pcrlen = cscov;
else
dccp_sk(sk)->dccps_pcslen = cscov;
}
kfree(list);
return rc;
}
static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, int optlen)
{
@ -502,20 +538,11 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
else
dp->dccps_server_timewait = (val != 0);
break;
case DCCP_SOCKOPT_SEND_CSCOV: /* sender side, RFC 4340, sec. 9.2 */
if (val < 0 || val > 15)
err = -EINVAL;
else
dp->dccps_pcslen = val;
case DCCP_SOCKOPT_SEND_CSCOV:
err = dccp_setsockopt_cscov(sk, val, false);
break;
case DCCP_SOCKOPT_RECV_CSCOV: /* receiver side, RFC 4340 sec. 9.2.1 */
if (val < 0 || val > 15)
err = -EINVAL;
else {
dp->dccps_pcrlen = val;
/* FIXME: add feature negotiation,
* ChangeL(MinimumChecksumCoverage, val) */
}
case DCCP_SOCKOPT_RECV_CSCOV:
err = dccp_setsockopt_cscov(sk, val, true);
break;
default:
err = -ENOPROTOOPT;