dccp: 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 <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
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@ -527,8 +527,8 @@ struct dccp_sock {
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__u32 dccps_timestamp_time;
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__u16 dccps_l_ack_ratio;
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__u16 dccps_r_ack_ratio;
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__u16 dccps_pcslen;
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__u16 dccps_pcrlen;
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__u8 dccps_pcslen:4;
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__u8 dccps_pcrlen:4;
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__u64 dccps_ndp_count:48;
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unsigned long dccps_rate_last;
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struct dccp_minisock dccps_minisock;
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@ -470,6 +470,42 @@ static int dccp_setsockopt_service(struct sock *sk, const __be32 service,
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return 0;
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}
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static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
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{
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u8 *list, len;
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int i, rc;
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if (cscov < 0 || cscov > 15)
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return -EINVAL;
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/*
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* Populate a list of permissible values, in the range cscov...15. This
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* is necessary since feature negotiation of single values only works if
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* both sides incidentally choose the same value. Since the list starts
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* lowest-value first, negotiation will pick the smallest shared value.
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*/
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if (cscov == 0)
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return 0;
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len = 16 - cscov;
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list = kmalloc(len, GFP_KERNEL);
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if (list == NULL)
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return -ENOBUFS;
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for (i = 0; i < len; i++)
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list[i] = cscov++;
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rc = dccp_feat_register_sp(sk, DCCPF_MIN_CSUM_COVER, rx, list, len);
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if (rc == 0) {
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if (rx)
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dccp_sk(sk)->dccps_pcrlen = cscov;
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else
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dccp_sk(sk)->dccps_pcslen = cscov;
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}
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kfree(list);
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return rc;
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}
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static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
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char __user *optval, int optlen)
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{
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@ -502,20 +538,11 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
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else
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dp->dccps_server_timewait = (val != 0);
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break;
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case DCCP_SOCKOPT_SEND_CSCOV: /* sender side, RFC 4340, sec. 9.2 */
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if (val < 0 || val > 15)
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err = -EINVAL;
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else
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dp->dccps_pcslen = val;
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case DCCP_SOCKOPT_SEND_CSCOV:
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err = dccp_setsockopt_cscov(sk, val, false);
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break;
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case DCCP_SOCKOPT_RECV_CSCOV: /* receiver side, RFC 4340 sec. 9.2.1 */
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if (val < 0 || val > 15)
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err = -EINVAL;
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else {
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dp->dccps_pcrlen = val;
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/* FIXME: add feature negotiation,
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* ChangeL(MinimumChecksumCoverage, val) */
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}
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case DCCP_SOCKOPT_RECV_CSCOV:
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err = dccp_setsockopt_cscov(sk, val, true);
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break;
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default:
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err = -ENOPROTOOPT;
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