Re: [PATCH v2 2/3] Set net_<interface>_client{id, uuid} variables from DHCP options

[Javier Martinez Canillas]

Hello Daniel,

On 10/21/19 4:40 PM, Daniel Kiper wrote:
> On Fri, Oct 18, 2019 at 09:59:09AM +0200, Javier Martinez Canillas wrote:
>> From: Paulo Flabiano Smorigo <address@hidden>
>>
>> This patch sets a net_<interface>_clientid and net_<interface>_clientuuid
>> GRUB environment variables, using the DHCP client ID and UUID options if
>> these are found.
>>
>> In the same way than net_<interface>_<option> variables are set for other
>> options such domain name, boot file, next server, etc.
>>
>> Signed-off-by: Paulo Flabiano Smorigo <address@hidden>
>> Signed-off-by: Javier Martinez Canillas <address@hidden>
>> Reviewed-by: Daniel Kiper <address@hidden>
> 
> It seems to me that this RB should land in patch #3. Does not it?

Ups, sorry about that.

> Anyway, Reviewed-by: Daniel Kiper <address@hidden> :-)
> except one thing...
> 
>> ---
>>
>> Changes in v2:
>> - Use the existing grub_env_set_net_property() and remove duplicated code.
>>
>>  grub-core/net/bootp.c | 48 +++++++++++++++++++++++++++++++++++--------
>>  include/grub/net.h    |  2 ++
>>  2 files changed, 42 insertions(+), 8 deletions(-)
>>
>> diff --git a/grub-core/net/bootp.c b/grub-core/net/bootp.c
>> index 04cfbb04504..377006da938 100644
>> --- a/grub-core/net/bootp.c
>> +++ b/grub-core/net/bootp.c
>> @@ -95,6 +95,14 @@ enum
>>  /* Max timeout when waiting for BOOTP/DHCP reply */
>>  #define GRUB_DHCP_MAX_PACKET_TIMEOUT 32
>>
>> +static char
>> +hexdigit (grub_uint8_t val)
>> +{
>> +  if (val < 10)
>> +    return val + '0';
>> +  return val + 'a' - 10;
>> +}
>> +
>>  static const void *
>>  find_dhcp_option (const struct grub_net_bootp_packet *bp, grub_size_t size,
>>                grub_uint8_t opt_code, grub_uint8_t *opt_len)
>> @@ -152,6 +160,9 @@ again:
>>        if (i + taglength >= size)
>>      return NULL;
>>
>> +      grub_dprintf("net", "DHCP option %u (0x%02x) found with length %u.\n",
>> +                   tagtype, tagtype, taglength);
>> +
>>        /* FIXME RFC 3396 options concatentation */
>>        if (tagtype == opt_code)
>>      {
>> @@ -406,6 +417,35 @@ grub_net_configure_by_dhcp_ack (const char *name,
>>    if (opt && opt_len)
>>      grub_env_set_net_property (name, "extensionspath", (const char *) opt, 
>> opt_len);
>>
>> +  opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_CLIENT_ID, &opt_len);
>> +  if (opt && opt_len)
>> +    grub_env_set_net_property (name, "clientid", (const char *) opt, 
>> opt_len);
>> +
>> +  opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_CLIENT_UUID, &opt_len);
>> +  if (opt && opt_len == 17)
>> +    {
>> +      /* The format is 9cfe245e-d0c8-bd45-a79f-54ea5fbd3d97 */
>> +
>> +      opt += 1;
>> +      opt_len -= 1;
>> +
>> +      char *val = grub_malloc (2 * opt_len + 4 + 1);
>> +      int i = 0;
>> +      int j = 0;
>> +      for (i = 0; i < opt_len; i++)
>> +        {
>> +          val[2 * i + j] = hexdigit (opt[i] >> 4);
>> +          val[2 * i + 1 + j] = hexdigit (opt[i] & 0xf);
>> +
>> +          if ((i == 3) || (i == 5) || (i == 7) || (i == 9))
>> +            {
>> +              j++;
>> +              val[2 * i + 1+ j] = '-';
>> +            }
>> +        }
>> +      grub_env_set_net_property (name, "clientuuid", (char *) val, 2 * 
>> opt_len + 4);
>> +    }
>> +
>>    inter->dhcp_ack = grub_malloc (size);
>>    if (inter->dhcp_ack)
>>      {
>> @@ -631,14 +671,6 @@ grub_net_process_dhcp (struct grub_net_buff *nb,
>>      }
>>  }
>>
>> -static char
>> -hexdigit (grub_uint8_t val)
>> -{
>> -  if (val < 10)
>> -    return val + '0';
>> -  return val + 'a' - 10;
>> -}
>> -
>>  static grub_err_t
>>  grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
>>                int argc, char **args)
>> diff --git a/include/grub/net.h b/include/grub/net.h
>> index 4a9069a1474..556c54e579f 100644
>> --- a/include/grub/net.h
>> +++ b/include/grub/net.h
>> @@ -462,6 +462,8 @@ enum
>>      GRUB_NET_BOOTP_DOMAIN = 0x0f,
>>      GRUB_NET_BOOTP_ROOT_PATH = 0x11,
>>      GRUB_NET_BOOTP_EXTENSIONS_PATH = 0x12,
>> +    GRUB_NET_BOOTP_CLIENT_ID = 0x3d,
>> +    GRUB_NET_BOOTP_CLIENT_UUID = 0x61,
>>      GRUB_NET_DHCP_REQUESTED_IP_ADDRESS = 50,
>>      GRUB_NET_DHCP_OVERLOAD = 52,
>>      GRUB_NET_DHCP_MESSAGE_TYPE = 53,
> 
> I have just realized that this enum is a mixture of decimals and hexes.
> This is a mess. Could you add a patch before that patch changing all
> decimals to hexes and sort them properly?
> 

Sure. I'll do that.

I also noticed that we have a patch that adds documentation about the
netboot grub.cfg selection order so I'll also include that patch in v3.

> Daniel
> 

Best regards,
-- 
Javier Martinez Canillas
Software Engineer - Desktop Hardware Enablement
Red Hat