[DCCP]: Provide feature negotiation for minimum-checksum-coverage
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 <[EMAIL PROTECTED]>
---
include/linux/dccp.h | 4 +--
net/dccp/proto.c | 52 ++++++++++++++++++++++++++++++++++++++-------------
2 files changed, 41 insertions(+), 15 deletions(-)
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -545,8 +545,8 @@ struct dccp_sock {
struct dccp_ts_echo *dccps_tstamp;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
- __u16 dccps_pcslen;
- __u16 dccps_pcrlen;
+ __u8 dccps_pcslen:4;
+ __u8 dccps_pcrlen:4;
unsigned long dccps_ndp_count;
__u32 dccps_mss_cache;
unsigned long dccps_rate_last;
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -469,6 +469,41 @@ static int dccp_setsockopt_change(struct
return rc;
}
+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;
+
+ if (rx)
+ dccp_sk(sk)->dccps_pcrlen = cscov;
+ else
+ dccp_sk(sk)->dccps_pcslen = cscov;
+ /*
+ * 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_change(sk, DCCPF_MIN_CSUM_COVER, rx, list, len);
+
+ kfree(list);
+ return rc;
+}
+
static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, int optlen)
{
@@ -502,20 +537,11 @@ static int do_dccp_setsockopt(struct soc
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;
-
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