Re: [PATCH v2 04/16] udp: Don't connect "forward" sockets for spliced flows

[Stefano Brivio <sbrivio@redhat.com>]

Nit:

On Thu, 24 Nov 2022 12:16:47 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> Currently we connect() the socket we use to forward spliced UDP flows.
> However, we now only ever use sendto() rather than send() on this socket
> so there's not actually any need to connect it.  Don't do so.
> 
> Rename a number of things that referred to "connect" or "conn" since that
> would now be misleading.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  udp.c | 85 ++++++++++++++++++++++++-----------------------------------
>  1 file changed, 35 insertions(+), 50 deletions(-)
> 
> diff --git a/udp.c b/udp.c
> index 1e78da5..ed095ec 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -45,23 +45,20 @@
>   *
>   * - from init to namespace:
>   *
> - *   - forward direction: 127.0.0.1:5000 -> 127.0.0.1:80 in init from bound
> - *     socket s, with epoll reference: index = 80, splice = UDP_TO_NS
> + *   - forward direction: 127.0.0.1:5000 -> 127.0.0.1:80 in init from socket s,
> + *     with epoll reference: index = 80, splice = UDP_TO_NS
>   *     - if udp_splice_to_ns[V4][5000].target_sock:
>   *       - send packet to udp_splice_to_ns[V4][5000].target_sock, with
>   *         destination port 80
>   *     - otherwise:
>   *       - create new socket udp_splice_to_ns[V4][5000].target_sock
>   *       - bind in namespace to 127.0.0.1:5000
> - *       - connect in namespace to 127.0.0.1:80 (note: this destination port
> - *         might be remapped to another port instead)
>   *       - add to epoll with reference: index = 5000, splice: UDP_BACK_TO_INIT
>   *       - set udp_splice_to_ns[V4][5000].orig_sock to s
>   *     - update udp_splice_to_ns[V4][5000].ts with current time
>   *
> - *   - reverse direction: 127.0.0.1:80 -> 127.0.0.1:5000 in namespace from
> - *     connected socket s, having epoll reference: index = 5000,
> - *     splice = UDP_BACK_TO_INIT
> + *   - reverse direction: 127.0.0.1:80 -> 127.0.0.1:5000 in namespace socket s,
> + *     having epoll reference: index = 5000, splice = UDP_BACK_TO_INIT
>   *     - if udp_splice_to_ns[V4][5000].orig_sock:
>   *       - send to udp_splice_to_ns[V4][5000].orig_sock, with destination port
>   *         5000
> @@ -69,7 +66,7 @@
>   *
>   * - from namespace to init:
>   *
> - *   - forward direction: 127.0.0.1:2000 -> 127.0.0.1:22 in namespace from bound
> + *   - forward direction: 127.0.0.1:2000 -> 127.0.0.1:22 in namespace from
>   *     socket s, with epoll reference: index = 22, splice = UDP_TO_INIT
>   *     - if udp4_splice_to_init[V4][2000].target_sock:
>   *       - send packet to udp_splice_to_init[V4][2000].target_sock, with
> @@ -77,14 +74,12 @@
>   *     - otherwise:
>   *       - create new socket udp_splice_to_init[V4][2000].target_sock
>   *       - bind in init to 127.0.0.1:2000
> - *       - connect in init to 127.0.0.1:22 (note: this destination port
> - *         might be remapped to another port instead)
>   *       - add to epoll with reference: index = 2000, splice = UDP_BACK_TO_NS
>   *       - set udp_splice_to_init[V4][2000].orig_sock to s
>   *     - update udp_splice_to_init[V4][2000].ts with current time
>   *
> - *   - reverse direction: 127.0.0.1:22 -> 127.0.0.1:2000 in init from connected
> - *     socket s, having epoll reference: index = 2000, splice = UDP_BACK_TO_NS
> + *   - reverse direction: 127.0.0.1:22 -> 127.0.0.1:2000 in init from socket s,
> + *     having epoll reference: index = 2000, splice = UDP_BACK_TO_NS
>   *   - if udp_splice_to_init[V4][2000].orig_sock:
>   *     - send to udp_splice_to_init[V4][2000].orig_sock, with destination port
>   *       2000
> @@ -144,8 +139,7 @@ struct udp_tap_port {
>   * @orig_sock:		Originating socket, bound to dest port in source ns of
>   *			originating datagram
>   * @target_sock:	Target socket, bound to source port of originating
> - *			datagram in dest ns, connected to dest port of
> - *			originating datagram in dest ns
> + *			datagram in dest ns
>   * @ts:			Activity timestamp
>   */
>  struct udp_splice_flow {
> @@ -163,8 +157,8 @@ static struct udp_splice_flow udp_splice_to_init[IP_VERSIONS][NUM_PORTS];
>  
>  enum udp_act_type {
>  	UDP_ACT_TAP,
> -	UDP_ACT_NS_CONN,
> -	UDP_ACT_INIT_CONN,
> +	UDP_ACT_SPLICE_NS,
> +	UDP_ACT_SPLICE_INIT,
>  	UDP_ACT_TYPE_MAX,
>  };
>  
> @@ -398,20 +392,19 @@ static void udp_sock6_iov_init(void)
>  }
>  
>  /**
> - * udp_splice_connect() - Create and connect socket for "spliced" binding
> + * udp_splice_new() - Create and prepare socket for "spliced" binding
>   * @c:		Execution context
> - * @v6:		Set for IPv6 connections
> + * @v6:		Set for IPv6 sockets
>   * @bound_sock:	Originating bound socket
>   * @src:	Source port of original connection, host order
> - * @dst:	Destination port of original connection, host order
>   * @splice:	UDP_BACK_TO_INIT from init, UDP_BACK_TO_NS from namespace
>   *
> - * Return: connected socket, negative error code on failure
> + * Return: Prepared socket, negative error code on failure

prepared

-- 
Stefano