udhcp: code shrink; disable time and log server options

function                                             old     new   delta
add_server_options                                     -     100    +100
udhcp_add_simple_option                               92      90      -2
nobody_responds_to_arp                                88      85      -3
dhcp_options                                          66      62      -4
udhcp_add_option_string                              104      94     -10
udhcp_run_script                                     665     654     -11
dhcp_option_strings                                  203     188     -15
static.blank_chaddr                                   16       -     -16
send_ACK                                             211     180     -31
add_bootp_options                                     61       -     -61
udhcpd_main                                         1925    1846     -79
------------------------------------------------------------------------------
(add/remove: 1/2 grow/shrink: 0/8 up/down: 100/-232)         Total: -132 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

7 files changed, 126 insertions, 127 deletions

diff --git a/examples/udhcp/udhcpd.conf b/examples/udhcp/udhcpd.conf
index 0ad982b55..a27a05357 100644
--- a/examples/udhcp/udhcpd.conf
+++ b/examples/udhcp/udhcpd.conf
@@ -77,7 +77,7 @@ option	lease	864000		# 10 days
 #opt domain     STRING      - client's domain name
 #opt search     STRING_LIST - search domains
 #opt nisdomain  STRING
-#opt timezone   NUM
+#opt timezone   NUM    - (localtime - UTC_time) in seconds. signed
 #opt tftp       STRING - TFTP server name
 #opt bootfile   STRING - file (kernel image) to load for booting
 #opt bootsize   NUM    - size of that file
@@ -89,10 +89,11 @@ option	lease	864000		# 10 days
 #opt dns        IP_LIST
 #opt wins       IP_LIST
 #opt nissrv     IP_LIST
-#opt namesrv    IP_LIST - obsolete, disabled
-#opt logsrv     IP_LIST
-#opt cookiesrv  IP_LIST - rarely (never?) used, disabled
+#opt ntpsrv     IP_LIST
 #opt lprsrv     IP_LIST
 #opt swapsrv    IP
-#opt timesrv    IP_LIST
-#opt ntpsrv     IP_LIST
+# Obsolete options, no longer supported
+#opt logsrv     IP_LIST - 704/UDP log server (not syslog!)
+#opt namesrv    IP_LIST - IEN 116 name server, obsolete (August 1979!!!)
+#opt cookiesrv  IP_LIST - RFC 865 "quote of the day" server, rarely (never?) used
+#opt timesrv    IP_LIST - RFC 868 time server, rarely (never?) used
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index e88cfb1c7..d7c874e5b 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -44,6 +44,10 @@ struct dhcp_packet {
 	uint32_t cookie;      /* fixed first four option bytes (99,130,83,99 dec) */
 	uint8_t options[DHCP_OPTIONS_BUFSIZE + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS];
 } PACKED;
+#define DHCP_PKT_SNAME_LEN      64
+#define DHCP_PKT_FILE_LEN      128
+#define DHCP_PKT_SNAME_LEN_STR "64"
+#define DHCP_PKT_FILE_LEN_STR "128"
 
 struct ip_udp_dhcp_packet {
 	struct iphdr ip;
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index d7887d914..cc4cb9280 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -75,7 +75,9 @@ static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadca
 		server_config.ifindex);
 }
 
-/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
+/* Send the dhcp packet.
+ * If force broadcast is set, the packet will be broadcast.
+ */
 static int send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
 {
 	if (dhcp_pkt->gateway_nip)
@@ -94,10 +96,21 @@ static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacke
 	add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip);
 }
 
-/* add in the bootp options */
-static void add_bootp_options(struct dhcp_packet *packet)
+/* Fill options field, siaddr_nip, and sname and boot_file fields.
+ * TODO: teach this code to use overload option.
+ */
+static void add_server_options(struct dhcp_packet *packet)
 {
+	struct option_set *curr = server_config.options;
+
+	while (curr) {
+		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+			add_option_string(packet->options, curr->data);
+		curr = curr->next;
+	}
+
 	packet->siaddr_nip = server_config.siaddr_nip;
+
 	if (server_config.sname)
 		strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
 	if (server_config.boot_file)
@@ -123,17 +136,17 @@ static uint32_t select_lease_time(struct dhcp_packet *packet)
 static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease)
 {
 	struct dhcp_packet packet;
-	uint32_t req_nip;
 	uint32_t lease_time_sec = server_config.max_lease_sec;
-	uint8_t *req_ip_opt;
 	const char *p_host_name;
-	struct option_set *curr;
 	struct in_addr addr;
 
 	init_packet(&packet, oldpacket, DHCPOFFER);
 
 	/* ADDME: if static, short circuit */
 	if (!static_lease_nip) {
+		uint32_t req_nip;
+		uint8_t *req_ip_opt;
+
 		/* The client is in our lease/offered table */
 		if (lease) {
 			packet.yiaddr = lease->lease_nip;
@@ -145,10 +158,10 @@ static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip,
 		 /* and the IP is in the lease range */
 		 && ntohl(req_nip) >= server_config.start_ip
 		 && ntohl(req_nip) <= server_config.end_ip
-		 /* and is not already taken/offered */
-		 && (!(lease = find_lease_by_nip(req_nip))
-			/* or its taken, but expired */
-			|| is_expired_lease(lease))
+		 /* and */
+		 && (  !(lease = find_lease_by_nip(req_nip)) /* is not already taken */
+		    || is_expired_lease(lease) /* or is taken, but expired */
+		    )
 		) {
 			packet.yiaddr = req_nip;
 		}
@@ -178,19 +191,11 @@ static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip,
 	}
 
 	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
-
-	curr = server_config.options;
-	while (curr) {
-		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
-			add_option_string(packet.options, curr->data);
-		curr = curr->next;
-	}
-
-	add_bootp_options(&packet);
+	add_server_options(&packet);
 
 	addr.s_addr = packet.yiaddr;
 	bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
-	return send_packet(&packet, 0);
+	return send_packet(&packet, /*force_bcast:*/ 0);
 }
 
 static int send_NAK(struct dhcp_packet *oldpacket)
@@ -200,13 +205,12 @@ static int send_NAK(struct dhcp_packet *oldpacket)
 	init_packet(&packet, oldpacket, DHCPNAK);
 
 	log1("Sending NAK");
-	return send_packet(&packet, 1);
+	return send_packet(&packet, /*force_bcast:*/ 1);
 }
 
 static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
 {
 	struct dhcp_packet packet;
-	struct option_set *curr;
 	uint32_t lease_time_sec;
 	struct in_addr addr;
 	const char *p_host_name;
@@ -217,20 +221,12 @@ static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
 	lease_time_sec = select_lease_time(oldpacket);
 
 	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
-
-	curr = server_config.options;
-	while (curr) {
-		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
-			add_option_string(packet.options, curr->data);
-		curr = curr->next;
-	}
-
-	add_bootp_options(&packet);
+	add_server_options(&packet);
 
 	addr.s_addr = packet.yiaddr;
 	bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
 
-	if (send_packet(&packet, 0) < 0)
+	if (send_packet(&packet, /*force_bcast:*/ 0) < 0)
 		return -1;
 
 	p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
@@ -250,20 +246,11 @@ static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
 static int send_inform(struct dhcp_packet *oldpacket)
 {
 	struct dhcp_packet packet;
-	struct option_set *curr;
 
 	init_packet(&packet, oldpacket, DHCPACK);
+	add_server_options(&packet);
 
-	curr = server_config.options;
-	while (curr) {
-		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
-			add_option_string(packet.options, curr->data);
-		curr = curr->next;
-	}
-
-	add_bootp_options(&packet);
-
-	return send_packet(&packet, 0);
+	return send_packet(&packet, /*force_bcast:*/ 0);
 }
 
 
diff --git a/networking/udhcp/leases.c b/networking/udhcp/leases.c
index 78b0d0ade..efe67cf5d 100644
--- a/networking/udhcp/leases.c
+++ b/networking/udhcp/leases.c
@@ -29,16 +29,15 @@ static struct dyn_lease *oldest_expired_lease(void)
 }
 
 
-/* Clear every lease out that chaddr OR yiaddr matches and is nonzero */
-static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
+/* Clear out all leases with matching nonzero chaddr OR yiaddr.
+ * If chaddr == NULL, this is a conflict lease.
+ */
+static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
 {
-	unsigned i, j;
-
-	for (j = 0; j < 16 && !chaddr[j]; j++)
-		continue;
+	unsigned i;
 
 	for (i = 0; i < server_config.max_leases; i++) {
-		if ((j != 16 && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
+		if ((chaddr && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
 		 || (yiaddr && g_leases[i].lease_nip == yiaddr)
 		) {
 			memset(&g_leases[i], 0, sizeof(g_leases[i]));
@@ -47,7 +46,9 @@ static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
 }
 
 
-/* Add a lease into the table, clearing out any old ones */
+/* Add a lease into the table, clearing out any old ones
+ * If chaddr == NULL, this is a conflict lease.
+ */
 struct dyn_lease* FAST_FUNC add_lease(
 		const uint8_t *chaddr, uint32_t yiaddr,
 		leasetime_t leasetime,
@@ -56,12 +57,12 @@ struct dyn_lease* FAST_FUNC add_lease(
 	struct dyn_lease *oldest;
 
 	/* clean out any old ones */
-	clear_lease(chaddr, yiaddr);
+	clear_leases(chaddr, yiaddr);
 
 	oldest = oldest_expired_lease();
 
 	if (oldest) {
-		oldest->hostname[0] = '\0';
+		memset(oldest, 0, sizeof(*oldest));
 		if (hostname) {
 			char *p;
 			if (hostname_len > sizeof(oldest->hostname))
@@ -74,7 +75,8 @@ struct dyn_lease* FAST_FUNC add_lease(
 				p++;
 			}
 		}
-		memcpy(oldest->lease_mac, chaddr, 6);
+		if (chaddr)
+			memcpy(oldest->lease_mac, chaddr, 6);
 		oldest->lease_nip = yiaddr;
 		oldest->expires = time(NULL) + leasetime;
 	}
@@ -119,10 +121,6 @@ struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
 /* Check if the IP is taken; if it is, add it to the lease table */
 static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
 {
-	/* 16 zero bytes */
-	static const uint8_t blank_chaddr[16] = { 0 };
-	/* = { 0 } helps gcc to put it in rodata, not bss */
-
 	struct in_addr temp;
 	int r;
 
@@ -136,7 +134,7 @@ static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
 	temp.s_addr = nip;
 	bb_info_msg("%s belongs to someone, reserving it for %u seconds",
 		inet_ntoa(temp), (unsigned)server_config.conflict_time);
-	add_lease(blank_chaddr, nip, server_config.conflict_time, NULL, 0);
+	add_lease(NULL, nip, server_config.conflict_time, NULL, 0);
 	return 0;
 }
 
@@ -173,7 +171,8 @@ uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
 		}
 	}
 
-	if (oldest_lease && is_expired_lease(oldest_lease)
+	if (oldest_lease
+	 && is_expired_lease(oldest_lease)
 	 && nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac)
 	) {
 		return oldest_lease->lease_nip;
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c
index 09d31c69b..5bef985bc 100644
--- a/networking/udhcp/options.c
+++ b/networking/udhcp/options.c
@@ -20,10 +20,10 @@ const struct dhcp_option dhcp_options[] = {
 	{ OPTION_IP                   | OPTION_REQ, 0x01 }, /* DHCP_SUBNET        */
 	{ OPTION_S32                              , 0x02 }, /* DHCP_TIME_OFFSET   */
 	{ OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x03 }, /* DHCP_ROUTER        */
-	{ OPTION_IP | OPTION_LIST                 , 0x04 }, /* DHCP_TIME_SERVER   */
+//	{ OPTION_IP | OPTION_LIST                 , 0x04 }, /* DHCP_TIME_SERVER   */
 //	{ OPTION_IP | OPTION_LIST                 , 0x05 }, /* DHCP_NAME_SERVER   */
 	{ OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER    */
-	{ OPTION_IP | OPTION_LIST                 , 0x07 }, /* DHCP_LOG_SERVER    */
+//	{ OPTION_IP | OPTION_LIST                 , 0x07 }, /* DHCP_LOG_SERVER    */
 //	{ OPTION_IP | OPTION_LIST                 , 0x08 }, /* DHCP_COOKIE_SERVER */
 	{ OPTION_IP | OPTION_LIST                 , 0x09 }, /* DHCP_LPR_SERVER    */
 	{ OPTION_STRING               | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
@@ -34,23 +34,23 @@ const struct dhcp_option dhcp_options[] = {
 	{ OPTION_U8                               , 0x17 }, /* DHCP_IP_TTL        */
 	{ OPTION_U16                              , 0x1a }, /* DHCP_MTU           */
 	{ OPTION_IP                   | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST     */
-	{ OPTION_STRING                           , 0x28 }, /* nisdomain          */
-	{ OPTION_IP | OPTION_LIST                 , 0x29 }, /* nissrv             */
+	{ OPTION_STRING                           , 0x28 }, /* DHCP_NIS_DOMAIN    */
+	{ OPTION_IP | OPTION_LIST                 , 0x29 }, /* DHCP_NIS_SERVER    */
 	{ OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER    */
 	{ OPTION_IP | OPTION_LIST                 , 0x2c }, /* DHCP_WINS_SERVER   */
 	{ OPTION_U32                              , 0x33 }, /* DHCP_LEASE_TIME    */
 	{ OPTION_IP                               , 0x36 }, /* DHCP_SERVER_ID     */
-	{ OPTION_STRING                           , 0x38 }, /* DHCP_MESSAGE       */
-	{ OPTION_STRING                           , 0x42 }, /* tftp               */
-	{ OPTION_STRING                           , 0x43 }, /* bootfile           */
+	{ OPTION_STRING                           , 0x38 }, /* DHCP_ERR_MESSAGE   */
+//TODO: must be combined with 'sname' and 'file' handling:
+	{ OPTION_STRING                           , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
+	{ OPTION_STRING                           , 0x43 }, /* DHCP_BOOT_FILE     */
 //TODO: not a string, but a set of LASCII strings:
-//	{ OPTION_STRING                           , 0x4D }, /* userclass          */
+//	{ OPTION_STRING                           , 0x4D }, /* DHCP_USER_CLASS    */
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	{ OPTION_STR1035 | OPTION_LIST            , 0x77 }, /* search             */
+	{ OPTION_STR1035 | OPTION_LIST            , 0x77 }, /* DHCP_DOMAIN_SEARCH */
 #endif
 	{ OPTION_STATIC_ROUTES                    , 0x79 }, /* DHCP_STATIC_ROUTES */
-	/* MSIE's "Web Proxy Autodiscovery Protocol" support */
-	{ OPTION_STRING                           , 0xfc }, /* wpad               */
+	{ OPTION_STRING                           , 0xfc }, /* DHCP_WPAD          */
 
 	/* Options below have no match in dhcp_option_strings[],
 	 * are not passed to dhcpc scripts, and cannot be specified
@@ -62,8 +62,9 @@ const struct dhcp_option dhcp_options[] = {
 	{ OPTION_IP                               , 0x32 }, /* DHCP_REQUESTED_IP  */
 	{ OPTION_U8                               , 0x35 }, /* DHCP_MESSAGE_TYPE  */
 	{ OPTION_U16                              , 0x39 }, /* DHCP_MAX_SIZE      */
-	{ OPTION_STRING                           , 0x3C }, /* DHCP_VENDOR        */
-	{ OPTION_STRING                           , 0x3D }, /* DHCP_CLIENT_ID     */
+	{ OPTION_STRING                           , 0x3c }, /* DHCP_VENDOR        */
+//FIXME: handling of this option is not exactly correct:
+	{ OPTION_STRING                           , 0x3d }, /* DHCP_CLIENT_ID     */
 	{ 0, 0 } /* zeroed terminating entry */
 };
 
@@ -76,10 +77,10 @@ const char dhcp_option_strings[] ALIGN1 =
 	"subnet" "\0"      /* DHCP_SUBNET         */
 	"timezone" "\0"    /* DHCP_TIME_OFFSET    */
 	"router" "\0"      /* DHCP_ROUTER         */
-	"timesrv" "\0"     /* DHCP_TIME_SERVER    */
+//	"timesrv" "\0"     /* DHCP_TIME_SERVER    */
 //	"namesrv" "\0"     /* DHCP_NAME_SERVER    */
 	"dns" "\0"         /* DHCP_DNS_SERVER     */
-	"logsrv" "\0"      /* DHCP_LOG_SERVER     */
+//	"logsrv" "\0"      /* DHCP_LOG_SERVER     */
 //	"cookiesrv" "\0"   /* DHCP_COOKIE_SERVER  */
 	"lprsrv" "\0"      /* DHCP_LPR_SERVER     */
 	"hostname" "\0"    /* DHCP_HOST_NAME      */
@@ -90,24 +91,24 @@ const char dhcp_option_strings[] ALIGN1 =
 	"ipttl" "\0"       /* DHCP_IP_TTL         */
 	"mtu" "\0"         /* DHCP_MTU            */
 	"broadcast" "\0"   /* DHCP_BROADCAST      */
-	"nisdomain" "\0"   /*                     */
-	"nissrv" "\0"      /*                     */
+	"nisdomain" "\0"   /* DHCP_NIS_DOMAIN     */
+	"nissrv" "\0"      /* DHCP_NIS_SERVER     */
 	"ntpsrv" "\0"      /* DHCP_NTP_SERVER     */
 	"wins" "\0"        /* DHCP_WINS_SERVER    */
 	"lease" "\0"       /* DHCP_LEASE_TIME     */
 	"serverid" "\0"    /* DHCP_SERVER_ID      */
-	"message" "\0"     /* DHCP_MESSAGE        */
-	"tftp" "\0"
-	"bootfile" "\0"
-//	"userclass" "\0"
+	"message" "\0"     /* DHCP_ERR_MESSAGE    */
+	"tftp" "\0"        /* DHCP_TFTP_SERVER_NAME */
+	"bootfile" "\0"    /* DHCP_BOOT_FILE      */
+//	"userclass" "\0"   /* DHCP_USER_CLASS     */
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	"search" "\0"
+	"search" "\0"      /* DHCP_DOMAIN_SEARCH  */
 #endif
 // "staticroutes" is only used to set udhcpc environment, it doesn't work
-// in udhcpd.conf since OPTION_STATIC_ROUTES is not handled yet:
-	"staticroutes" "\0" /* DHCP_STATIC_ROUTES  */
-	/* MSIE's "Web Proxy Autodiscovery Protocol" support */
-	"wpad" "\0"
+// in udhcpd.conf since OPTION_STATIC_ROUTES is not handled yet
+// by "string->option" conversion code:
+	"staticroutes" "\0"/* DHCP_STATIC_ROUTES */
+	"wpad" "\0"        /* DHCP_WPAD          */
 	;
 
 
@@ -225,7 +226,7 @@ int FAST_FUNC end_option(uint8_t *optionptr)
 
 /* add an option string to the options */
 /* option bytes: [code][len][data1][data2]..[dataLEN] */
-int FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string)
+void FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string)
 {
 	int end = end_option(optionptr);
 
@@ -233,17 +234,16 @@ int FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string)
 	if (end + string[OPT_LEN] + 2 + 1 >= DHCP_OPTIONS_BUFSIZE) {
 		bb_error_msg("option 0x%02x did not fit into the packet",
 				string[OPT_CODE]);
-		return 0;
+		return;
 	}
 	log_option("Adding option", string);
 	memcpy(optionptr + end, string, string[OPT_LEN] + 2);
 	optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
-	return string[OPT_LEN] + 2;
 }
 
 
 /* add a one to four byte option to a packet */
-int FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
+void FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
 {
 	const struct dhcp_option *dh;
 
@@ -258,10 +258,10 @@ int FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
 				data <<= 8 * (4 - len);
 			/* Assignment is unaligned! */
 			move_to_unaligned32(&option[OPT_DATA], data);
-			return add_option_string(optionptr, option);
+			add_option_string(optionptr, option);
+			return;
 		}
 	}
 
 	bb_error_msg("can't add option 0x%02x", code);
-	return 0;
 }
diff --git a/networking/udhcp/options.h b/networking/udhcp/options.h
index 75087fa35..b7c9d8f8d 100644
--- a/networking/udhcp/options.h
+++ b/networking/udhcp/options.h
@@ -32,45 +32,55 @@ enum {
 /* Do not modify below here unless you know what you are doing!! */
 /*****************************************************************/
 
-/* DHCP protocol -- see RFC 2131 */
+/* DHCP protocol. See RFC 2131 */
 #define DHCP_MAGIC		0x63825363
 
-/* DHCP option codes (partial list) */
+/* DHCP option codes (partial list). See RFC 2132.
+ * Commented out options are handled by common option machinery,
+ * uncommented ones have spacial cases (grep for them to see).
+ */
 #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 /* _really_ ancient kind of NS */
-#define DHCP_DNS_SERVER         0x06
-#define DHCP_LOG_SERVER         0x07
+//#define DHCP_TIME_OFFSET      0x02 /* (localtime - UTC_time) in seconds. signed */
+//#define DHCP_ROUTER           0x03
+//#define DHCP_TIME_SERVER      0x04 /* RFC 868 time server (32-bit, 0 = 1.1.1900) */
+//#define DHCP_NAME_SERVER      0x05 /* IEN 116 _really_ ancient kind of NS */
+//#define DHCP_DNS_SERVER       0x06
+//#define DHCP_LOG_SERVER       0x07 /* port 704 UDP log (not syslog)
 //#define DHCP_COOKIE_SERVER    0x08 /* "quote of the day" server */
-#define DHCP_LPR_SERVER         0x09
+//#define DHCP_LPR_SERVER       0x09
 #define DHCP_HOST_NAME          0x0c /* either client informs server or server gives name to client */
-#define DHCP_BOOT_SIZE          0x0d
-#define DHCP_DOMAIN_NAME        0x0f /* server gives domain suffix */
-#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_BOOT_SIZE        0x0d
+//#define DHCP_DOMAIN_NAME      0x0f /* server gives domain suffix */
+//#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_NIS_DOMAIN       0x28
+//#define DHCP_NIS_SERVER       0x29
+//#define DHCP_NTP_SERVER       0x2a
+//#define DHCP_WINS_SERVER      0x2c
 #define DHCP_REQUESTED_IP       0x32 /* sent by client if specific IP is wanted */
 #define DHCP_LEASE_TIME         0x33
 #define DHCP_OPTION_OVERLOAD    0x34
 #define DHCP_MESSAGE_TYPE       0x35
 #define DHCP_SERVER_ID          0x36 /* by default server's IP */
 #define DHCP_PARAM_REQ          0x37 /* list of options client wants */
-#define DHCP_MESSAGE            0x38 /* error message when sending NAK etc */
+//#define DHCP_ERR_MESSAGE      0x38 /* error message when sending NAK etc */
 #define DHCP_MAX_SIZE           0x39
-//#define DHCP_T1               0x3a
-//#define DHCP_T2               0x3b
 #define DHCP_VENDOR             0x3c /* client's vendor (a string) */
 #define DHCP_CLIENT_ID          0x3d /* by default client's MAC addr, but may be arbitrarily long */
+//#define DHCP_TFTP_SERVER_NAME 0x42 /* same as 'sname' field */
+//#define DHCP_BOOT_FILE        0x43 /* same as 'file' field */
+//#define DHCP_USER_CLASS       0x4d /* RFC 3004. set of LASCII strings. "I am a printer" etc */
 #define DHCP_FQDN               0x51 /* client asks to update DNS to map its FQDN to its new IP */
-#define DHCP_STATIC_ROUTES      0x79
-#define DHCP_END                0xFF
+//#define DHCP_DOMAIN_SEARCH    0x77 /* RFC 3397. set of ASCIZ string, DNS-style compressed */
+//#define DHCP_STATIC_ROUTES    0x79 /* RFC 3442. (mask,ip,router) tuples */
+//#define DHCP_WPAD             0xfc /* MSIE's Web Proxy Autodiscovery Protocol */
+#define DHCP_END                0xff
+
+
 /* Offsets in option byte sequence */
 #define OPT_CODE                0
 #define OPT_LEN                 1
@@ -106,8 +116,8 @@ extern const uint8_t dhcp_option_lengths[];
 
 uint8_t *get_option(struct dhcp_packet *packet, int code) FAST_FUNC;
 int end_option(uint8_t *optionptr) FAST_FUNC;
-int add_option_string(uint8_t *optionptr, uint8_t *string) FAST_FUNC;
-int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data) FAST_FUNC;
+void add_option_string(uint8_t *optionptr, uint8_t *string) FAST_FUNC;
+void add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data) FAST_FUNC;
 #if ENABLE_FEATURE_UDHCP_RFC3397
 char *dname_dec(const uint8_t *cstr, int clen, const char *pre) FAST_FUNC;
 uint8_t *dname_enc(const uint8_t *cstr, int clen, const char *src, int *retlen) FAST_FUNC;
diff --git a/networking/udhcp/script.c b/networking/udhcp/script.c
index 321b015e0..b4413fa16 100644
--- a/networking/udhcp/script.c
+++ b/networking/udhcp/script.c
@@ -244,14 +244,12 @@ static char **fill_envp(struct dhcp_packet *packet)
 	}
 	if (!(over & FILE_FIELD) && packet->file[0]) {
 		/* watch out for invalid packets */
-		packet->file[sizeof(packet->file) - 1] = '\0';
-		*curr = xasprintf("boot_file=%s", packet->file);
+		*curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 		putenv(*curr++);
 	}
 	if (!(over & SNAME_FIELD) && packet->sname[0]) {
 		/* watch out for invalid packets */
-		packet->sname[sizeof(packet->sname) - 1] = '\0';
-		*curr = xasprintf("sname=%s", packet->sname);
+		*curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 		putenv(*curr++);
 	}
 	return envp;