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net/dhcp: Use DHCP options for name and bootfile

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The BOOTP RFC describes the boot file name and the server name as being part
of the integral BOOTP data structure, with some limits on the size of them.
DHCP extends this by allowing them to be separate DHCP options, which is more
flexible.

Teach the code dealing with those fields to check for those DHCP options first
and use this information, if provided. We fall back to using the BOOTP
information if those options are not used.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Andrei Borzenkov 2019-03-07 15:14:13 +00:00 committed by Vincent Batts
parent 6767cde642
commit 1157a45292
2 changed files with 54 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
grub-core/net/bootp.c
View file

@ -186,7 +186,9 @@ grub_net_configure_by_dhcp_ack (const char *name,
int mask = -1;
char server_ip[sizeof ("xxx.xxx.xxx.xxx")];
const grub_uint8_t *opt;
grub_uint8_t opt_len;
grub_uint8_t opt_len, overload = 0;
const char *boot_file = 0, *server_name = 0;
grub_size_t boot_file_len, server_name_len;
addr.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
addr.ipv4 = bp->your_ip;
@ -205,9 +207,36 @@ grub_net_configure_by_dhcp_ack (const char *name,
if (!inter)
return 0;
if (size > OFFSET_OF (boot_file, bp))
grub_env_set_net_property (name, "boot_file", bp->boot_file,
sizeof (bp->boot_file));
opt = find_dhcp_option (bp, size, GRUB_NET_DHCP_OVERLOAD, &opt_len);
if (opt && opt_len == 1)
overload = *opt;
opt = find_dhcp_option (bp, size, GRUB_NET_DHCP_TFTP_SERVER_NAME, &opt_len);
if (opt && opt_len)
{
server_name = (const char *) opt;
server_name_len = opt_len;
}
else if (size > OFFSET_OF (server_name, bp) && !(overload & GRUB_DHCP_OPT_OVERLOAD_SNAME) &&
bp->server_name[0])
{
server_name = bp->server_name;
server_name_len = sizeof (bp->server_name);
}
opt = find_dhcp_option (bp, size, GRUB_NET_DHCP_BOOTFILE_NAME, &opt_len);
if (opt && opt_len)
{
boot_file = (const char *) opt;
boot_file_len = opt_len;
}
else if (size > OFFSET_OF (boot_file, bp) && !(overload && GRUB_DHCP_OPT_OVERLOAD_FILE) &&
bp->boot_file[0])
{
boot_file = bp->boot_file;
boot_file_len = sizeof (bp->boot_file);
}
if (bp->server_ip)
{
grub_snprintf (server_ip, sizeof (server_ip), "%d.%d.%d.%d",
@ -238,26 +267,28 @@ grub_net_configure_by_dhcp_ack (const char *name,
*device = grub_xasprintf ("tftp,%s", server_ip);
grub_print_error ();
}
if (size > OFFSET_OF (server_name, bp)
&& bp->server_name[0])
if (server_name)
{
grub_env_set_net_property (name, "dhcp_server_name", bp->server_name,
sizeof (bp->server_name));
grub_env_set_net_property (name, "dhcp_server_name", server_name, server_name_len);
if (is_def && !grub_net_default_server)
{
grub_net_default_server = grub_strdup (bp->server_name);
grub_net_default_server = grub_strdup (server_name);
grub_print_error ();
}
if (device && !*device)
{
*device = grub_xasprintf ("tftp,%s", bp->server_name);
*device = grub_xasprintf ("tftp,%s", server_name);
grub_print_error ();
}
}
if (size > OFFSET_OF (boot_file, bp) && path)
if (boot_file)
{
*path = grub_strndup (bp->boot_file, sizeof (bp->boot_file));
grub_env_set_net_property (name, "boot_file", boot_file, boot_file_len);
if (path)
{
*path = grub_strndup (boot_file, boot_file_len);
grub_print_error ();
if (*path)
{
@ -269,6 +300,7 @@ grub_net_configure_by_dhcp_ack (const char *name,
**path = 0;
}
}
}
opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_NETMASK, &opt_len);
if (opt && opt_len == 4)

2
include/grub/net.h
View file

@ -461,6 +461,8 @@ enum
GRUB_NET_BOOTP_ROOT_PATH = 0x11,
GRUB_NET_BOOTP_EXTENSIONS_PATH = 0x12,
GRUB_NET_DHCP_OVERLOAD = 52,
GRUB_NET_DHCP_TFTP_SERVER_NAME = 66,
GRUB_NET_DHCP_BOOTFILE_NAME = 67,
GRUB_NET_BOOTP_END = 0xff
};