[U-Boot] [PATCH 5/5] net: sandbox-raw: Allow interface to be specified by index

[Heinrich Schuchardt]

On 06/26/2018 11:19 PM, Joe Hershberger wrote:
> With systemd stable interface names, eth0 will almost never exist.
> Instead of using that name in the sandbox.dts, use index 2 (the first
> interface after "lo"). Enumerate the interfaces on the system to choose
> a valid interace name.
> 
> Signed-off-by: Joe Hershberger <joe.hershberger at ni.com>

Hello Joe,

thanks for addressing this issue.

On my laptop the raw interfaces are currently called:
1 - lo - loopback
2 - enp0s25 - wired ethernet
3 - wlp12s0 - WLAN

But this list is not static:

It is allowable to define multiple loopback interfaces. Additional
bridges, tap and tun interfaces may be defined. A computer may also have
multiple wired and wireless interfaces. And of cause I may choose to
plug in an additional ethernet adapter while my computer is running.

The interface index does not tell which interface is actually connected
to the network. My laptop uses wpl12s0 (index = 3) for sending out this
mail. So, please, do not replace one invalid assumption (eth0) by
another (index = 2).

I doubt there is a guarantee that index 1 is a loopback interface on
POSIX systems. If you need a special treatment of loopback devices you
could analyze the properties of each interface to detect which one is a
loopback interface.

There is no need for using the device tree for the specification of
interfaces. Instead a raw ethernet device can be set up for each
interface. Let the user choose at runtime which device he wants to use
for testing.

Best regards

Heinrich

> ---
> 
>  arch/sandbox/cpu/eth-raw-os.c         | 28 ++++++++++++++++++++++++++++
>  arch/sandbox/dts/sandbox.dts          |  2 +-
>  arch/sandbox/include/asm/eth-raw-os.h |  4 +++-
>  drivers/net/sandbox-raw.c             |  8 +++++++-
>  4 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/sandbox/cpu/eth-raw-os.c b/arch/sandbox/cpu/eth-raw-os.c
> index 61f23ed210..11b5271f31 100644
> --- a/arch/sandbox/cpu/eth-raw-os.c
> +++ b/arch/sandbox/cpu/eth-raw-os.c
> @@ -150,6 +150,34 @@ int sandbox_eth_raw_os_start(const char *ifname, unsigned char *ethmac,
>  		return _raw_packet_start(ifname, ethmac, priv);
>  }
>  
> +int sandbox_eth_raw_os_start_idx(unsigned int ifindex, unsigned char *ethmac,
> +				 struct eth_sandbox_raw_priv *priv)
> +{
> +	int ret;
> +	struct if_nameindex *ni, *i;
> +	const char *ifname = NULL;
> +
> +	ni = if_nameindex();
> +	if (!ni)
> +		return -EINVAL;
> +
> +	for (i = ni; !(i->if_index == 0 && !i->if_name); i++) {
> +		if (ifindex == i->if_index) {
> +			ifname = i->if_name;
> +			printf("(%s)\n", ifname);
> +			break;
> +		}
> +	}
> +	/* Don't bother supporting 'lo' by index. Just use the name in DTS */
> +	if (ifname)
> +		ret = _raw_packet_start(ifname, ethmac, priv);
> +	else
> +		ret = -EINVAL;
> +
> +	if_freenameindex(ni);
> +	return ret;
> +}
> +
>  int sandbox_eth_raw_os_send(void *packet, int length,
>  			    struct eth_sandbox_raw_priv *priv)
>  {
> diff --git a/arch/sandbox/dts/sandbox.dts b/arch/sandbox/dts/sandbox.dts
> index 0ea2452742..e7f6c194d0 100644
> --- a/arch/sandbox/dts/sandbox.dts
> +++ b/arch/sandbox/dts/sandbox.dts
> @@ -56,7 +56,7 @@
>  	eth at 80000000 {
>  		compatible = "sandbox,eth-raw";
>  		reg = <0x80000000 0x1000>;
> -		host-raw-interface = "eth0";
> +		host-raw-interface-idx = <2>;
>  	};
>  
>  	eth at 90000000 {
> diff --git a/arch/sandbox/include/asm/eth-raw-os.h b/arch/sandbox/include/asm/eth-raw-os.h
> index f986d3142d..70b29b4508 100644
> --- a/arch/sandbox/include/asm/eth-raw-os.h
> +++ b/arch/sandbox/include/asm/eth-raw-os.h
> @@ -29,7 +29,9 @@ struct eth_sandbox_raw_priv {
>  };
>  
>  int sandbox_eth_raw_os_start(const char *ifname, unsigned char *ethmac,
> -			    struct eth_sandbox_raw_priv *priv);
> +			     struct eth_sandbox_raw_priv *priv);
> +int sandbox_eth_raw_os_start_idx(unsigned int ifindex, unsigned char *ethmac,
> +				 struct eth_sandbox_raw_priv *priv);
>  int sandbox_eth_raw_os_send(void *packet, int length,
>  			    struct eth_sandbox_raw_priv *priv);
>  int sandbox_eth_raw_os_recv(void *packet, int *length,
> diff --git a/drivers/net/sandbox-raw.c b/drivers/net/sandbox-raw.c
> index f835a6a7f3..3bde8d84ce 100644
> --- a/drivers/net/sandbox-raw.c
> +++ b/drivers/net/sandbox-raw.c
> @@ -22,6 +22,7 @@ static int sb_eth_raw_start(struct udevice *dev)
>  	struct eth_sandbox_raw_priv *priv = dev_get_priv(dev);
>  	struct eth_pdata *pdata = dev_get_platdata(dev);
>  	const char *interface;
> +	u32 index;
>  
>  	debug("eth_sandbox_raw: Start\n");
>  
> @@ -37,7 +38,12 @@ static int sb_eth_raw_start(struct udevice *dev)
>  						priv);
>  	}
>  
> -	return -EINVAL;
> +	if (dev_read_u32(dev, "host-raw-interface-idx", &index) < 0)
> +		return -EINVAL;
> +
> +	printf("eth_sandbox_raw: Using interface index %d from DT ", index);
> +
> +	return sandbox_eth_raw_os_start_idx(index, pdata->enetaddr, priv);
>  }
>  
>  static int sb_eth_raw_send(struct udevice *dev, void *packet, int length)
>