dhcpd: remember and record hostnames; optimize get_option

dumpleases: show hostnames

function                                             old     new   delta
add_lease                                            230     292     +62
send_offer                                           403     421     +18
send_ACK                                             232     249     +17
read_leases                                          249     258      +9
dumpleases_main                                      604     609      +5
nobody_responds_to_arp                                84      86      +2
udhcp_end_option                                      32      30      -2
udhcp_get_option                                     222     171     -51
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 6/2 up/down: 113/-53)            Total: 60 bytes

1 files changed, 60 insertions, 63 deletions

diff --git a/networking/udhcp/options.h b/networking/udhcp/options.h
index d18a353d0..87440c30c 100644
--- a/networking/udhcp/options.h
+++ b/networking/udhcp/options.h
@@ -7,7 +7,7 @@
 # pragma GCC visibility push(hidden)
 #endif
 
-#define TYPE_MASK	0x0F
+#define TYPE_MASK       0x0F
 
 enum {
 	OPTION_IP = 1,
@@ -24,8 +24,8 @@ enum {
 	OPTION_S32
 };
 
-#define OPTION_REQ	0x10 /* have the client request this option */
-#define OPTION_LIST	0x20 /* There can be a list of 1 or more of these */
+#define OPTION_REQ      0x10 /* have the client request this option */
+#define OPTION_LIST     0x20 /* There can be a list of 1 or more of these */
 
 /*****************************************************************/
 /* Do not modify below here unless you know what you are doing!! */
@@ -34,67 +34,64 @@ enum {
 /* DHCP protocol -- see RFC 2131 */
 #define DHCP_MAGIC		0x63825363
 
-
 /* DHCP option codes (partial list) */
-#define DHCP_PADDING		0x00
-#define DHCP_SUBNET		0x01
-#define DHCP_TIME_OFFSET	0x02
-#define DHCP_ROUTER		0x03
-#define DHCP_TIME_SERVER	0x04
-#define DHCP_NAME_SERVER	0x05
-#define DHCP_DNS_SERVER		0x06
-#define DHCP_LOG_SERVER		0x07
-#define DHCP_COOKIE_SERVER	0x08
-#define DHCP_LPR_SERVER		0x09
-#define DHCP_HOST_NAME		0x0c
-#define DHCP_BOOT_SIZE		0x0d
-#define DHCP_DOMAIN_NAME	0x0f
-#define DHCP_SWAP_SERVER	0x10
-#define DHCP_ROOT_PATH		0x11
-#define DHCP_IP_TTL		0x17
-#define DHCP_MTU		0x1a
-#define DHCP_BROADCAST		0x1c
-#define DHCP_NTP_SERVER		0x2a
-#define DHCP_WINS_SERVER	0x2c
-#define DHCP_REQUESTED_IP	0x32
-#define DHCP_LEASE_TIME		0x33
-#define DHCP_OPTION_OVER	0x34
-#define DHCP_MESSAGE_TYPE	0x35
-#define DHCP_SERVER_ID		0x36
-#define DHCP_PARAM_REQ		0x37
-#define DHCP_MESSAGE		0x38
-#define DHCP_MAX_SIZE		0x39
-#define DHCP_T1			0x3a
-#define DHCP_T2			0x3b
-#define DHCP_VENDOR		0x3c
-#define DHCP_CLIENT_ID		0x3d
-#define DHCP_FQDN		0x51
-#define DHCP_END		0xFF
-
-
-#define BOOTREQUEST		1
-#define BOOTREPLY		2
-
-#define ETH_10MB		1
-#define ETH_10MB_LEN		6
-
-#define DHCPDISCOVER		1 /* client -> server */
-#define DHCPOFFER		2 /* client <- server */
-#define DHCPREQUEST		3 /* client -> server */
-#define DHCPDECLINE		4 /* client -> server */
-#define DHCPACK			5 /* client <- server */
-#define DHCPNAK			6 /* client <- server */
-#define DHCPRELEASE		7 /* client -> server */
-#define DHCPINFORM		8 /* client -> server */
-
-#define OPTION_FIELD		0
-#define FILE_FIELD		1
-#define SNAME_FIELD		2
-
-/* miscellaneous defines */
-#define OPT_CODE 0
-#define OPT_LEN 1
-#define OPT_DATA 2
+#define DHCP_PADDING            0x00
+#define DHCP_SUBNET             0x01
+#define DHCP_TIME_OFFSET        0x02
+#define DHCP_ROUTER             0x03
+#define DHCP_TIME_SERVER        0x04
+#define DHCP_NAME_SERVER        0x05
+#define DHCP_DNS_SERVER         0x06
+#define DHCP_LOG_SERVER         0x07
+#define DHCP_COOKIE_SERVER      0x08
+#define DHCP_LPR_SERVER         0x09
+#define DHCP_HOST_NAME          0x0c
+#define DHCP_BOOT_SIZE          0x0d
+#define DHCP_DOMAIN_NAME        0x0f
+#define DHCP_SWAP_SERVER        0x10
+#define DHCP_ROOT_PATH          0x11
+#define DHCP_IP_TTL             0x17
+#define DHCP_MTU                0x1a
+#define DHCP_BROADCAST          0x1c
+#define DHCP_NTP_SERVER         0x2a
+#define DHCP_WINS_SERVER        0x2c
+#define DHCP_REQUESTED_IP       0x32
+#define DHCP_LEASE_TIME         0x33
+#define DHCP_OPTION_OVERLOAD    0x34
+#define DHCP_MESSAGE_TYPE       0x35
+#define DHCP_SERVER_ID          0x36
+#define DHCP_PARAM_REQ          0x37
+#define DHCP_MESSAGE            0x38
+#define DHCP_MAX_SIZE           0x39
+#define DHCP_T1                 0x3a
+#define DHCP_T2                 0x3b
+#define DHCP_VENDOR             0x3c
+#define DHCP_CLIENT_ID          0x3d
+#define DHCP_FQDN               0x51
+#define DHCP_END                0xFF
+/* Offsets in option byte sequence */
+#define OPT_CODE                0
+#define OPT_LEN                 1
+#define OPT_DATA                2
+/* Bits in "overload" option */
+#define OPTION_FIELD            0
+#define FILE_FIELD              1
+#define SNAME_FIELD             2
+
+#define BOOTREQUEST             1
+#define BOOTREPLY               2
+
+#define ETH_10MB                1
+#define ETH_10MB_LEN            6
+
+#define DHCPDISCOVER            1 /* client -> server */
+#define DHCPOFFER               2 /* client <- server */
+#define DHCPREQUEST             3 /* client -> server */
+#define DHCPDECLINE             4 /* client -> server */
+#define DHCPACK                 5 /* client <- server */
+#define DHCPNAK                 6 /* client <- server */
+#define DHCPRELEASE             7 /* client -> server */
+#define DHCPINFORM              8 /* client -> server */
 
 struct dhcp_option {
 	uint8_t flags;