net/dhcp: Replace parse_dhcp_vendor() with find_dhcp_option()
For proper DHCP support we will need to parse DHCP options from a packet more often and at various places. Refactor the option parsing into a new function, which will scan a packet to find *a particular* option field. Use that new function in places where we were dealing with DHCP options before. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Andrei Borzenkov
Vincent Batts
parent
526fa11df7
commit
6c38b920c8
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@ -43,25 +43,41 @@ static grub_uint8_t grub_userclass[] = {0x4D, 0x06, 0x05, 'G', 'R', 'U', 'B', '2
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static grub_uint8_t grub_dhcpdiscover[] = {0x35, 0x01, 0x01};
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static grub_uint8_t grub_dhcptime[] = {0x33, 0x04, 0x00, 0x00, 0x0e, 0x10};
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static void
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parse_dhcp_vendor (const char *name, const void *vend, int limit, int *mask)
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static const void *
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find_dhcp_option (const struct grub_net_bootp_packet *bp, grub_size_t size,
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grub_uint8_t opt_code, grub_uint8_t *opt_len)
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{
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const grub_uint8_t *ptr, *ptr0;
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const grub_uint8_t *ptr;
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grub_size_t i;
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ptr = ptr0 = vend;
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if (opt_len)
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*opt_len = 0;
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/* Is the packet big enough to hold at least the magic cookie? */
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if (size < sizeof (*bp) + sizeof (grub_uint32_t))
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return NULL;
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/*
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* Pointer arithmetic to point behind the common stub packet, where
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* the options start.
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*/
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ptr = (grub_uint8_t *) (bp + 1);
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if (ptr[0] != GRUB_NET_BOOTP_RFC1048_MAGIC_0
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|| ptr[1] != GRUB_NET_BOOTP_RFC1048_MAGIC_1
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|| ptr[2] != GRUB_NET_BOOTP_RFC1048_MAGIC_2
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|| ptr[3] != GRUB_NET_BOOTP_RFC1048_MAGIC_3)
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return;
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ptr = ptr + sizeof (grub_uint32_t);
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while (ptr - ptr0 < limit)
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return NULL;
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size -= sizeof (*bp);
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i = sizeof (grub_uint32_t);
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while (i < size)
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{
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grub_uint8_t tagtype;
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grub_uint8_t taglength;
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tagtype = *ptr++;
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tagtype = ptr[i++];
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/* Pad tag. */
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if (tagtype == GRUB_NET_BOOTP_PAD)
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@ -69,81 +85,27 @@ parse_dhcp_vendor (const char *name, const void *vend, int limit, int *mask)
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/* End tag. */
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if (tagtype == GRUB_NET_BOOTP_END)
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return;
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break;
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taglength = *ptr++;
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if (i >= size)
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return NULL;
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switch (tagtype)
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taglength = ptr[i++];
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if (i + taglength >= size)
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return NULL;
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/* FIXME RFC 3396 options concatentation */
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if (tagtype == opt_code)
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{
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case GRUB_NET_BOOTP_NETMASK:
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if (taglength == 4)
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{
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int i;
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for (i = 0; i < 32; i++)
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if (!(ptr[i / 8] & (1 << (7 - (i % 8)))))
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break;
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*mask = i;
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}
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break;
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case GRUB_NET_BOOTP_ROUTER:
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if (taglength == 4)
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{
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grub_net_network_level_netaddress_t target;
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grub_net_network_level_address_t gw;
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char *rname;
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target.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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target.ipv4.base = 0;
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target.ipv4.masksize = 0;
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gw.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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grub_memcpy (&gw.ipv4, ptr, sizeof (gw.ipv4));
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rname = grub_xasprintf ("%s:default", name);
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if (rname)
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grub_net_add_route_gw (rname, target, gw, NULL);
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grub_free (rname);
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}
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break;
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case GRUB_NET_BOOTP_DNS:
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{
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int i;
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for (i = 0; i < taglength / 4; i++)
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{
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struct grub_net_network_level_address s;
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s.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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s.ipv4 = grub_get_unaligned32 (ptr);
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s.option = DNS_OPTION_PREFER_IPV4;
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grub_net_add_dns_server (&s);
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ptr += 4;
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}
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}
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continue;
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case GRUB_NET_BOOTP_HOSTNAME:
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grub_env_set_net_property (name, "hostname", (const char *) ptr,
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taglength);
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break;
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case GRUB_NET_BOOTP_DOMAIN:
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grub_env_set_net_property (name, "domain", (const char *) ptr,
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taglength);
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break;
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case GRUB_NET_BOOTP_ROOT_PATH:
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grub_env_set_net_property (name, "rootpath", (const char *) ptr,
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taglength);
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break;
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case GRUB_NET_BOOTP_EXTENSIONS_PATH:
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grub_env_set_net_property (name, "extensionspath", (const char *) ptr,
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taglength);
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break;
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/* If you need any other options please contact GRUB
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development team. */
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if (opt_len)
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*opt_len = taglength;
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return &ptr[i];
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}
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ptr += taglength;
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i += taglength;
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}
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return NULL;
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}
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#define OFFSET_OF(x, y) ((grub_size_t)((grub_uint8_t *)((y)->x) - (grub_uint8_t *)(y)))
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@ -161,6 +123,8 @@ grub_net_configure_by_dhcp_ack (const char *name,
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struct grub_net_network_level_interface *inter;
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int mask = -1;
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char server_ip[sizeof ("xxx.xxx.xxx.xxx")];
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const grub_uint8_t *opt;
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grub_uint8_t opt_len;
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addr.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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addr.ipv4 = bp->your_ip;
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@ -243,9 +207,69 @@ grub_net_configure_by_dhcp_ack (const char *name,
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**path = 0;
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}
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}
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if (size > OFFSET_OF (vendor, bp))
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parse_dhcp_vendor (name, &bp->vendor, size - OFFSET_OF (vendor, bp), &mask);
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_NETMASK, &opt_len);
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if (opt && opt_len == 4)
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{
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int i;
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for (i = 0; i < 32; i++)
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if (!(opt[i / 8] & (1 << (7 - (i % 8)))))
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break;
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mask = i;
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}
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grub_net_add_ipv4_local (inter, mask);
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/* We do not implement dead gateway detection and the first entry SHOULD
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be preferred one */
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_ROUTER, &opt_len);
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if (opt && opt_len && !(opt_len & 3))
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{
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grub_net_network_level_netaddress_t target;
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grub_net_network_level_address_t gw;
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char *rname;
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target.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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target.ipv4.base = 0;
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target.ipv4.masksize = 0;
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gw.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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gw.ipv4 = grub_get_unaligned32 (opt);
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rname = grub_xasprintf ("%s:default", name);
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if (rname)
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grub_net_add_route_gw (rname, target, gw, 0);
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grub_free (rname);
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}
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_DNS, &opt_len);
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if (opt && opt_len && !(opt_len & 3))
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{
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int i;
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for (i = 0; i < opt_len / 4; i++)
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{
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struct grub_net_network_level_address s;
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s.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4;
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s.ipv4 = grub_get_unaligned32 (opt);
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s.option = DNS_OPTION_PREFER_IPV4;
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grub_net_add_dns_server (&s);
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opt += 4;
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}
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}
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_HOSTNAME, &opt_len);
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if (opt && opt_len)
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grub_env_set_net_property (name, "hostname", (const char *) opt, opt_len);
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_DOMAIN, &opt_len);
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if (opt && opt_len)
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grub_env_set_net_property (name, "domain", (const char *) opt, opt_len);
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_ROOT_PATH, &opt_len);
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if (opt && opt_len)
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grub_env_set_net_property (name, "rootpath", (const char *) opt, opt_len);
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opt = find_dhcp_option (bp, size, GRUB_NET_BOOTP_EXTENSIONS_PATH, &opt_len);
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if (opt && opt_len)
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grub_env_set_net_property (name, "extensionspath", (const char *) opt, opt_len);
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inter->dhcp_ack = grub_malloc (size);
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if (inter->dhcp_ack)
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@ -304,8 +328,8 @@ grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
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int argc, char **args)
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{
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struct grub_net_network_level_interface *inter;
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int num;
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grub_uint8_t *ptr;
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unsigned num;
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const grub_uint8_t *ptr;
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grub_uint8_t taglength;
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if (argc < 4)
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@ -323,44 +347,27 @@ grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
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if (!inter->dhcp_ack)
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return grub_error (GRUB_ERR_IO, N_("no DHCP info found"));
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if (inter->dhcp_acklen <= OFFSET_OF (vendor, inter->dhcp_ack))
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ptr = inter->dhcp_ack->vendor;
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/* This duplicates check in find_dhcp_option to preserve previous error return */
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if (inter->dhcp_acklen < OFFSET_OF (vendor, inter->dhcp_ack) + sizeof (grub_uint32_t)
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|| ptr[0] != GRUB_NET_BOOTP_RFC1048_MAGIC_0
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|| ptr[1] != GRUB_NET_BOOTP_RFC1048_MAGIC_1
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|| ptr[2] != GRUB_NET_BOOTP_RFC1048_MAGIC_2
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|| ptr[3] != GRUB_NET_BOOTP_RFC1048_MAGIC_3)
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return grub_error (GRUB_ERR_IO, N_("no DHCP options found"));
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num = grub_strtoul (args[2], 0, 0);
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if (grub_errno)
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return grub_errno;
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ptr = inter->dhcp_ack->vendor;
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/* Exclude PAD (0) and END (255) option codes */
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if (num == 0 || num > 254)
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid DHCP option code"));
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if (ptr[0] != GRUB_NET_BOOTP_RFC1048_MAGIC_0
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|| ptr[1] != GRUB_NET_BOOTP_RFC1048_MAGIC_1
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|| ptr[2] != GRUB_NET_BOOTP_RFC1048_MAGIC_2
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|| ptr[3] != GRUB_NET_BOOTP_RFC1048_MAGIC_3)
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return grub_error (GRUB_ERR_IO, N_("no DHCP options found"));
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ptr = ptr + sizeof (grub_uint32_t);
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while (1)
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{
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grub_uint8_t tagtype;
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if (ptr >= ((grub_uint8_t *) inter->dhcp_ack) + inter->dhcp_acklen)
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return grub_error (GRUB_ERR_IO, N_("no DHCP option %d found"), num);
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tagtype = *ptr++;
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/* Pad tag. */
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if (tagtype == 0)
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continue;
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/* End tag. */
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if (tagtype == 0xff)
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return grub_error (GRUB_ERR_IO, N_("no DHCP option %d found"), num);
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taglength = *ptr++;
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if (tagtype == num)
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break;
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ptr += taglength;
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}
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ptr = find_dhcp_option (inter->dhcp_ack, inter->dhcp_acklen, num, &taglength);
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if (!ptr)
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return grub_error (GRUB_ERR_IO, N_("no DHCP option %u found"), num);
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if (grub_strcmp (args[3], "string") == 0)
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{
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