[OpenWrt-Devel] [PATCH v2] ubus: use network order in ubus message header fields

[Felix Fietkau]

On 2016-02-15 05:09, Eyal Birger wrote:
> Changing the ubus message header fields from 'host' order to 'network' order
> allows passing ubus messages between hosts with different endianity.
> 
> Example use (creating a ubus proxy):
> 
> on host A (e.g. big endian router already running ubusd), run:
> $ socat TCP-LISTEN:5699,fork UNIX:/var/run/ubus.sock &
> 
> On host B (e.g. little endian development PC) run:
> $ socat UNIX-LISTEN:/var/run/ubus.sock,fork TCP:<host A IP>:5699 &
> 
> Now ubus applications can be run on host B and seamlessly interact with ubus
> applications on host A.
> 
> Signed-off-by: Eyal Birger <eyal.birger at gmail.com>
> 
> ----
> v2:
> 	Applied change to ubusd too. Thanks Felix!
> ---
>  libubus-io.c |  7 +++++--
>  ubusd.c      | 14 ++++++++++++--
>  2 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/ubusd.c b/ubusd.c
> index f1f8ac7..7279a70 100644
> --- a/ubusd.c
> +++ b/ubusd.c
> @@ -110,8 +110,15 @@ static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
>  	}
>  
>  	if (offset < sizeof(ub->hdr)) {
> -		iov[0].iov_base = ((char *) &ub->hdr) + offset;
> -		iov[0].iov_len = sizeof(ub->hdr) - offset;
> +		struct ubus_msghdr hdr;
> +
> +		hdr.version = ub->hdr.version;
> +		hdr.type = ub->hdr.type;
> +		hdr.seq = cpu_to_be16(ub->hdr.seq);
> +		hdr.peer = cpu_to_be32(ub->hdr.peer);
> +
> +		iov[0].iov_base = ((char *) &hdr) + offset;
> +		iov[0].iov_len = sizeof(hdr) - offset;
>  		iov[1].iov_base = (char *) ub->data;
>  		iov[1].iov_len = ub->len;
>  
This has some broken corner cases, because reads can be partial. I'd
prefer endian conversion on access instead of on receive/send, even
though it touches a few more lines.

- Felix
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