On 05/22/2012 11:58 AM, Eric Dumazet wrote:
On Tue, 2012-05-22 at 11:30 +0530, Jagdish Motwani wrote:
The nat_rtp_rtcp hook takes two separate parameters port and rtp_port.
port is expected to be the real h245 address(found inside the packet).
rtp_port is the even number closest to port (RTP ports are even and
RTCP ports are odd)
However currently, both port and rtp_port are having same value(both are
rounded to nearest even numbers).
This works well in case of openlogicalchannel with media (RTP/even) port.
But in case of openlogicalchannel for media control (RTCP/odd) port,
h245 address in the packet is wrongly modified to have an even port.
I am attaching a pcap demonstrating the problem, for any further analysis.
This behavior was introduced around v2.6.19 while rewriting the helper.
Signed-off-by: Jagdish Motwani<jagdish.motwani@xxxxxxxxxxxxx>
Signed-off-by: Sanket Shah<sanket.shah@xxxxxxxxxxxxx>
--
diff --git a/net/netfilter/nf_conntrack_h323_main.c
b/net/netfilter/nf_conntrack_h323_main.c
index 46d69d7..7f0de36 100644
--- a/net/netfilter/nf_conntrack_h323_main.c
+++ b/net/netfilter/nf_conntrack_h323_main.c
@@ -270,9 +270,8 @@ static int expect_rtp_rtcp(struct sk_buff *skb,
struct nf_conn *ct,
return 0;
/* RTP port is even */
- port&= htons(~1);
- rtp_port = port;
- rtcp_port = htons(ntohs(port) + 1);
+ rtp_port = port& htons(~1);
+ rtcp_port = htons(ntohs(rtp_port) + 1);
seems better to use :
rtp_port = port& ~htons(1);
rtcp_port = port | htons(1);
Thanks. Updating the patch
--
diff --git a/net/netfilter/nf_conntrack_h323_main.c
b/net/netfilter/nf_conntrack_h323_main.c
index 46d69d7..31f50bc 100644
--- a/net/netfilter/nf_conntrack_h323_main.c
+++ b/net/netfilter/nf_conntrack_h323_main.c
@@ -270,9 +270,8 @@ static int expect_rtp_rtcp(struct sk_buff *skb,
struct nf_conn *ct,
return 0;
/* RTP port is even */
- port &= htons(~1);
- rtp_port = port;
- rtcp_port = htons(ntohs(port) + 1);
+ rtp_port = port & ~htons(1);
+ rtcp_port = port | htons(1);
/* Create expect for RTP */
if ((rtp_exp = nf_ct_expect_alloc(ct)) == NULL)
--
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