From 6079a463cf95fafcc704a4e5e92a4da12444bd3c Mon Sep 17 00:00:00 2001 From: Wei Yongjun Date: Tue, 27 May 2008 06:22:38 -0700 Subject: dccp: Fix to handle short sequence numbers packet correctly RFC4340 said: 8.5. Pseudocode ... If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet has short sequence numbers), drop packet and return But DCCP has some mistake to handle short sequence numbers packet, now it drop packet only if P.type is Data, Ack, or DataAck and P.X == 0. Signed-off-by: Wei Yongjun Acked-by: Gerrit Renker Acked-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/ipv4.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/dccp') diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index b348dd70c685..c22a3780c14e 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -739,8 +739,8 @@ int dccp_invalid_packet(struct sk_buff *skb) * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet * has short sequence numbers), drop packet and return */ - if (dh->dccph_type >= DCCP_PKT_DATA && - dh->dccph_type <= DCCP_PKT_DATAACK && dh->dccph_x == 0) { + if ((dh->dccph_type < DCCP_PKT_DATA || + dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", dccp_packet_name(dh->dccph_type)); return 1; -- cgit v1.2.2 From 825de27d9e40b3117b29a79d412b7a4b78c5d815 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Tue, 27 May 2008 06:33:54 -0700 Subject: dccp ccid-3: Fix "t_ipi explosion" bug The identification of this bug is thanks to Cheng Wei and Tomasz Grobelny. To avoid divide-by-zero, the implementation previously ignored RTTs smaller than 4 microseconds when performing integer division RTT/4. When the RTT reached a value less than 4 microseconds (as observed on loopback), this prevented the Window Counter CCVal value from advancing. As a result, the receiver stopped sending feedback. This in turn caused non-ending expiries of the nofeedback timer at the sender, so that the sending rate was progressively reduced until reaching the minimum of one packet per 64 seconds. The patch fixes this bug by handling integer division more intelligently. Due to consistent use of dccp_sample_rtt(), divide-by-zero-RTT is avoided. Signed-off-by: Gerrit Renker Signed-off-by: David S. Miller --- net/dccp/ccids/ccid3.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'net/dccp') diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index cd61dea2eea1..f813077234b7 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -193,22 +193,17 @@ static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len) /* * Update Window Counter using the algorithm from [RFC 4342, 8.1]. - * The algorithm is not applicable if RTT < 4 microseconds. + * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt(). */ static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx, ktime_t now) { - u32 quarter_rtts; - - if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */ - return; - - quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count); - quarter_rtts /= hctx->ccid3hctx_rtt / 4; + u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count), + quarter_rtts = (4 * delta) / hctx->ccid3hctx_rtt; if (quarter_rtts > 0) { hctx->ccid3hctx_t_last_win_count = now; - hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5); + hctx->ccid3hctx_last_win_count += min(quarter_rtts, 5U); hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */ } } -- cgit v1.2.2