[U-Boot] [PATCH 1/2] net: Add option to prefer bootp/dhcp serverip

[Joe Hershberger]

On Wed, Jun 6, 2018 at 7:32 AM, Alexander Graf <agraf at suse.de> wrote:
> Currently we can choose between 2 different types of behavior for the
> serverip variable:
>
>   1) Always overwrite it with the DHCP server IP address (default)
>   2) Ignore what the DHCP server says (CONFIG_BOOTP_SERVERIP)
>
> This patch adds a 3rd option:
>
>   3) Use serverip from DHCP if no serverip is given
>      (CONFIG_BOOTP_PREFER_SERVERIP)
>
> With this new option, we can have the default case that a boot file gets
> loaded from the DHCP provided TFTP server work while allowing users to
> specify their own serverip variable to explicitly use a different tftp
> server.
>
> Signed-off-by: Alexander Graf <agraf at suse.de>
> ---
>  README      | 5 +++++
>  cmd/Kconfig | 9 +++++++++
>  net/bootp.c | 7 ++++++-
>  3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/README b/README
> index fb331f910d..d8a99281ca 100644
> --- a/README
> +++ b/README
> @@ -1511,10 +1511,15 @@ The following options need to be configured:
>                 CONFIG_BOOTP_TIMEOFFSET
>                 CONFIG_BOOTP_VENDOREX
>                 CONFIG_BOOTP_MAY_FAIL
> +               CONFIG_BOOTP_PREFER_SERVERIP
>
>                 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
>                 environment variable, not the BOOTP server.
>
> +               CONFIG_BOOTP_PREFER_SERVERIP - TFTP server will be the
> +               serverip environment variable if previously unset, otherwise

I think you mean "previously set" here.

Also, I don't think we are putting descriptions in the README if the
help is already in the Kconfig. Right, Tom?

> +               the DHCP provided serverip is used.
> +
>                 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
>                 after the configured retry count, the call will fail
>                 instead of starting over.  This can be used to fail over
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index e283cb9a8a..e77a4131b3 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -1121,6 +1121,15 @@ config BOOTP_HOSTNAME
>         help
>           The name may or may not be qualified with the local domain name.
>
> +config BOOTP_PREFER_SERVERIP
> +       bool "Leave serverip variable in place if existing"

I think this would be clearer if it were "serverip variable in the
environment takes precedent over DHCP server IP."

> +       default n
> +       depends on CMD_BOOTP
> +       help
> +         By default a BOOTP/DHCP reply will overwrite the tftp target ip

Use the actual variable name here... "serverip"

> +         address. With this option enabled, it will leave it alone if

Too many "it"s.

"With this option enabled, the 'serverip' variable in the environment
takes precedence over DHCP server IP and will only be set by the DHCP
server if not already set in the environment."

> +         already specified, but populate it if no serverip is specified.
> +
>  config BOOTP_SUBNETMASK
>         bool "Request & store 'netmask' from BOOTP/DHCP server"
>         default y
> diff --git a/net/bootp.c b/net/bootp.c
> index 9d7cb5d30c..91de4cd426 100644
> --- a/net/bootp.c
> +++ b/net/bootp.c
> @@ -147,9 +147,14 @@ static void store_net_params(struct bootp_hdr *bp)
>  {
>  #if !defined(CONFIG_BOOTP_SERVERIP)
>         struct in_addr tmp_ip;
> +       bool overwrite_serverip = true;
> +
> +#if defined(CONFIG_BOOTP_PREFER_SERVERIP)
> +       overwrite_serverip = false;
> +#endif
>
>         net_copy_ip(&tmp_ip, &bp->bp_siaddr);
> -       if (tmp_ip.s_addr != 0)
> +       if (tmp_ip.s_addr != 0 && (overwrite_serverip || !net_server_ip.s_addr))
>                 net_copy_ip(&net_server_ip, &bp->bp_siaddr);
>         memcpy(net_server_ethaddr,
>                ((struct ethernet_hdr *)net_rx_packet)->et_src, 6);
> --
> 2.12.3
>
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