[H.323 Helper 1/3]: Add support for Call Forwarding

[Jing Min Zhao]

Thank you, Patrick. This patch is very important. It can also be used
by the future H.450 features. I'd like to make these code a general
function. I'll do this when I come back in 3 days.


----- Original Message ----- 
From: "Patrick McHardy" <kaber at trash.net>
To: "Jing Min Zhao" <zhaojingmin at users.sourceforge.net>
Cc: <netfilter-devel at lists.netfilter.org>
Sent: Friday, May 19, 2006 11:23 PM
Subject: Re: [H.323 Helper 1/3]: Add support for Call Forwarding


> Patrick McHardy wrote:
>> Jing Min Zhao wrote:
>>
>>>WARNING: "ip_fib_main_table" [net/ipv4/netfilter/ip_conntrack_h323.ko] 
>>>undefined!
>>>WARNING: "ip_fib_local_table" [net/ipv4/netfilter/ip_conntrack_h323.ko] 
>>>undefined!
>>>WARNING: "free_fib_info" [net/ipv4/netfilter/ip_conntrack_h323.ko] 
>>>undefined!
>>
>>
>> Oops .. these aren't exported. Just drop the patch, I'll send you a
>> better one this weekend.
>
> Sorry for the delay, but here it is :) I've already queued your patch
> for 2.6.18, if there are no problems I'll just add this one on top.
> The saved_ip conversion can happen latter, currently it would conflict
> with a bunch of other patches.
>


--------------------------------------------------------------------------------


> [NETFILTER]: H.323 helper: replace internal_net_addr parameter by 
> routing-based heuristic
>
> Call Forwarding doesn't need to create an expectation if both peers can
> reach each other without our help. The internal_net_addr parameter
> lets the user explicitly specify a single network where this is true,
> but is not very flexible and even fails in the common case that calls
> will both be forwarded to outside parties and inside parties. Use an
> optional heuristic based on routing instead, the assumption is that
> if bpth the outgoing device and the gateway are equal, both peers can
> reach each other directly.
>
> Signed-off-by: Patrick McHardy <kaber at trash.net>
>
> ---
> commit 19d2680b3e7afec4258525d4ca13079bea4e4d7b
> tree 67a780d51c8e8bde8234abc17d497177d53a2299
> parent 165f6194cc61940a2277b0f0dde84695e598aebe
> author Patrick McHardy <kaber at trash.net> Sat, 20 May 2006 05:16:47 +0200
> committer Patrick McHardy <kaber at trash.net> Sat, 20 May 2006 05:16:47 
> +0200
>
> net/ipv4/netfilter/ip_conntrack_helper_h323.c |   57 
> ++++++++++++-------------
> 1 files changed, 27 insertions(+), 30 deletions(-)
>
> diff --git a/net/ipv4/netfilter/ip_conntrack_helper_h323.c 
> b/net/ipv4/netfilter/ip_conntrack_helper_h323.c
> index 3052468..0665674 100644
> --- a/net/ipv4/netfilter/ip_conntrack_helper_h323.c
> +++ b/net/ipv4/netfilter/ip_conntrack_helper_h323.c
> @@ -40,12 +40,11 @@ static int gkrouted_only = 1;
> module_param(gkrouted_only, int, 0600);
> MODULE_PARM_DESC(gkrouted_only, "only accept calls from gatekeeper");
>
> -static char *internal_net = NULL;
> -static u_int32_t internal_net_addr = 0;
> -static u_int32_t internal_net_mask = 0;
> -module_param(internal_net, charp, 0600);
> -MODULE_PARM_DESC(internal_net, "specify your internal network using 
> format "
> - "address/mask. this is used by call forwarding support");
> +static int callforward_filter = 1;
> +module_param(callforward_filter, bool, 0600);
> +MODULE_PARM_DESC(callforward_filter, "only create call forwarding 
> expectations "
> +                      "if both endpoints are on different sides "
> +      "(determined by routing information)");
>
> /* Hooks for NAT */
> int (*set_h245_addr_hook) (struct sk_buff ** pskb,
> @@ -721,12 +720,28 @@ static int expect_callforwarding(struct
>
>  /* If the calling party is on the same side of the forward-to party,
>  * we don't need to track the second call */
> - if (internal_net &&
> -     ((ip & internal_net_mask) == internal_net_addr) ==
> -     ((ct->tuplehash[!dir].tuple.src.ip & internal_net_mask) ==
> -      internal_net_addr)) {
> - DEBUGP("ip_ct_q931: Call Forwarding not tracked\n");
> - return 0;
> + if (callforward_filter) {
> + struct rtable *rt1, *rt2;
> + struct flowi fl1 = {
> + .fl4_dst = ip,
> + };
> + struct flowi fl2 = {
> + .fl4_dst = ct->tuplehash[!dir].tuple.src.ip,
> + };
> +
> + if (ip_route_output_key(&rt1, &fl1) == 0) {
> + if (ip_route_output_key(&rt2, &fl2) == 0) {
> + if (rt1->rt_gateway == rt2->rt_gateway &&
> +     rt1->u.dst.dev  == rt2->u.dst.dev)
> + ret = 1;
> + dst_release(&rt2->u.dst);
> + }
> + dst_release(&rt1->u.dst);
> + }
> + if (ret) {
> + DEBUGP("ip_ct_q931: Call Forwarding not tracked\n");
> + return 0;
> + }
>  }
>
>  /* Create expect for the second call leg */
> @@ -1762,7 +1777,6 @@ static void fini(void)
> static int __init init(void)
> {
>  int ret;
> - char *p;
>
>  h323_buffer = kmalloc(65536, GFP_KERNEL);
>  if (!h323_buffer)
> @@ -1772,23 +1786,6 @@ static int __init init(void)
>  fini();
>  return ret;
>  }
> -
> - if (internal_net) {
> - if ((p = strchr(internal_net, '/')))
> - *p++ = 0;
> - if (isdigit(internal_net[0])) {
> - internal_net_addr = in_aton(internal_net);
> - if (p && isdigit(p[0]))
> - internal_net_mask = in_aton(p);
> - else
> - internal_net_mask = 0xffffffff;
> - internal_net_addr &= internal_net_mask;
> - }
> - DEBUGP("ip_ct_h323: internal_net = %u.%u.%u.%u/%u.%u.%u.%u\n",
> -        NIPQUAD(internal_net_addr),
> -        NIPQUAD(internal_net_mask));
> - }
> -
>  DEBUGP("ip_ct_h323: init success\n");
>  return 0;
> }
>