diff options
Diffstat (limited to 'net/dccp/output.c')
| -rw-r--r-- | net/dccp/output.c | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/net/dccp/output.c b/net/dccp/output.c index 5589a5e581f..3b763db3d86 100644 --- a/net/dccp/output.c +++ b/net/dccp/output.c @@ -133,15 +133,31 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) return -ENOBUFS; } +/** + * dccp_determine_ccmps - Find out about CCID-specfic packet-size limits + * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.), + * since the RX CCID is restricted to feedback packets (Acks), which are small + * in comparison with the data traffic. A value of 0 means "no current CCMPS". + */ +static u32 dccp_determine_ccmps(const struct dccp_sock *dp) +{ + const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid; + + if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL) + return 0; + return tx_ccid->ccid_ops->ccid_ccmps; +} + unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) { struct inet_connection_sock *icsk = inet_csk(sk); struct dccp_sock *dp = dccp_sk(sk); - int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len - - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext)); + u32 ccmps = dccp_determine_ccmps(dp); + int cur_mps = ccmps ? min(pmtu, ccmps) : pmtu; - /* Now subtract optional transport overhead */ - mss_now -= icsk->icsk_ext_hdr_len; + /* Account for header lengths and IPv4/v6 option overhead */ + cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len + + sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext)); /* * FIXME: this should come from the CCID infrastructure, where, say, @@ -151,13 +167,13 @@ unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) * make it a multiple of 4 */ - mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; + cur_mps -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; /* And store cached results */ icsk->icsk_pmtu_cookie = pmtu; - dp->dccps_mss_cache = mss_now; + dp->dccps_mss_cache = cur_mps; - return mss_now; + return cur_mps; } EXPORT_SYMBOL_GPL(dccp_sync_mss); |