udhcp: pass pointer to whole packet to "add option" functions

This is needed for "overflow option" support

function                                             old     new   delta
udhcp_find_option                                      -      34     +34
udhcp_add_binary_option                               94     106     +12
write_leases                                         227     223      -4
udhcp_init_header                                     86      82      -4
send_release                                         104      99      -5
init_packet                                           87      81      -6
add_client_options                                   160     154      -6
add_server_options                                   100      92      -8
udhcpd_main                                         1964    1954     -10
udhcpc_main                                         2859    2837     -22
find_option                                           34       -     -34
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/8 up/down: 46/-99)            Total: -53 bytes

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

8 files changed, 37 insertions, 34 deletions

diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index bc458ac..9316774 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -226,14 +226,16 @@ int FAST_FUNC udhcp_end_option(uint8_t *optionptr)
 /* Add an option (supplied in binary form) to the options.
  * Option format: [code][len][data1][data2]..[dataLEN]
  */
-void FAST_FUNC udhcp_add_binary_option(uint8_t *optionptr, uint8_t *addopt)
+void FAST_FUNC udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt)
 {
 	unsigned len;
+	uint8_t *optionptr = packet->options;
 	unsigned end = udhcp_end_option(optionptr);
 
-	/* end position + option code/length + addopt length + end option */
 	len = OPT_DATA + addopt[OPT_LEN];
+	/* end position + (option code/length + addopt length) + end option */
 	if (end + len + 1 >= DHCP_OPTIONS_BUFSIZE) {
+//TODO: learn how to use overflow option if we exhaust packet->options[]
 		bb_error_msg("option 0x%02x did not fit into the packet",
 				addopt[OPT_CODE]);
 		return;
@@ -243,8 +245,8 @@ void FAST_FUNC udhcp_add_binary_option(uint8_t *optionptr, uint8_t *addopt)
 	optionptr[end + len] = DHCP_END;
 }
 
-/* Add a one to four byte option to a packet */
-void FAST_FUNC udhcp_add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
+/* Add an one to four byte option to a packet */
+void FAST_FUNC udhcp_add_simple_option(struct dhcp_packet *packet, uint8_t code, uint32_t data)
 {
 	const struct dhcp_option *dh;
 
@@ -259,7 +261,7 @@ void FAST_FUNC udhcp_add_simple_option(uint8_t *optionptr, uint8_t code, uint32_
 				data <<= 8 * (4 - len);
 			/* Assignment is unaligned! */
 			move_to_unaligned32(&option[OPT_DATA], data);
-			udhcp_add_binary_option(optionptr, option);
+			udhcp_add_binary_option(packet, option);
 			return;
 		}
 	}
@@ -268,7 +270,7 @@ void FAST_FUNC udhcp_add_simple_option(uint8_t *optionptr, uint8_t code, uint32_
 }
 
 /* Find option 'code' in opt_list */
-struct option_set* FAST_FUNC find_option(struct option_set *opt_list, uint8_t code)
+struct option_set* FAST_FUNC udhcp_find_option(struct option_set *opt_list, uint8_t code)
 {
 	while (opt_list && opt_list->data[OPT_CODE] < code)
 		opt_list = opt_list->next;
@@ -307,7 +309,7 @@ static NOINLINE void attach_option(
 	char *allocated = NULL;
 #endif
 
-	existing = find_option(*opt_list, option->code);
+	existing = udhcp_find_option(*opt_list, option->code);
 	if (!existing) {
 		log2("Attaching option %02x to list", option->code);
 #if ENABLE_FEATURE_UDHCP_RFC3397
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index cc0cab6..bb7541f 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -172,13 +172,13 @@ extern const uint8_t dhcp_option_lengths[];
 
 uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC;
 int udhcp_end_option(uint8_t *optionptr) FAST_FUNC;
-void udhcp_add_binary_option(uint8_t *optionptr, uint8_t *addopt) FAST_FUNC;
-void udhcp_add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data) FAST_FUNC;
+void udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) FAST_FUNC;
+void udhcp_add_simple_option(struct dhcp_packet *packet, 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;
 #endif
-struct option_set *find_option(struct option_set *opt_list, uint8_t code) FAST_FUNC;
+struct option_set *udhcp_find_option(struct option_set *opt_list, uint8_t code) FAST_FUNC;
 
 
 // RFC 2131  Table 5: Fields and options used by DHCP clients
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 2c76080..717c92c 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -319,22 +319,22 @@ static void init_packet(struct dhcp_packet *packet, char type)
 	udhcp_init_header(packet, type);
 	memcpy(packet->chaddr, client_config.client_mac, 6);
 	if (client_config.clientid)
-		udhcp_add_binary_option(packet->options, client_config.clientid);
+		udhcp_add_binary_option(packet, client_config.clientid);
 	if (client_config.hostname)
-		udhcp_add_binary_option(packet->options, client_config.hostname);
+		udhcp_add_binary_option(packet, client_config.hostname);
 	if (client_config.fqdn)
-		udhcp_add_binary_option(packet->options, client_config.fqdn);
+		udhcp_add_binary_option(packet, client_config.fqdn);
 	if (type != DHCPDECLINE
 	 && type != DHCPRELEASE
 	 && client_config.vendorclass
 	) {
-		udhcp_add_binary_option(packet->options, client_config.vendorclass);
+		udhcp_add_binary_option(packet, client_config.vendorclass);
 	}
 }
 
 static void add_client_options(struct dhcp_packet *packet)
 {
-	/* Add am "param req" option with the list of options we'd like to have
+	/* Add a "param req" option with the list of options we'd like to have
 	 * from stubborn DHCP servers. Pull the data from the struct in common.c.
 	 * No bounds checking because it goes towards the head of the packet. */
 	uint8_t c;
@@ -361,7 +361,7 @@ static void add_client_options(struct dhcp_packet *packet)
 	{
 		struct option_set *curr = client_config.options;
 		while (curr) {
-			udhcp_add_binary_option(packet->options, curr->data);
+			udhcp_add_binary_option(packet, curr->data);
 			curr = curr->next;
 		}
 //		if (client_config.sname)
@@ -405,10 +405,10 @@ static int send_discover(uint32_t xid, uint32_t requested)
 	init_packet(&packet, DHCPDISCOVER);
 	packet.xid = xid;
 	if (requested)
-		udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+		udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 	/* Explicitly saying that we want RFC-compliant packets helps
 	 * some buggy DHCP servers to NOT send bigger packets */
-	udhcp_add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
+	udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
 	add_client_options(&packet);
 
 	bb_info_msg("Sending discover...");
@@ -426,8 +426,8 @@ static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
 
 	init_packet(&packet, DHCPREQUEST);
 	packet.xid = xid;
-	udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
-	udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
+	udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 	add_client_options(&packet);
 
 	addr.s_addr = requested;
@@ -461,8 +461,8 @@ static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
 
 	init_packet(&packet, DHCPDECLINE);
 	packet.xid = xid;
-	udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
-	udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
+	udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 
 	bb_info_msg("Sending decline...");
 	return raw_bcast_from_client_config_ifindex(&packet);
@@ -478,7 +478,7 @@ static int send_release(uint32_t server, uint32_t ciaddr)
 	packet.xid = random_xid();
 	packet.ciaddr = ciaddr;
 
-	udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
+	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 
 	bb_info_msg("Sending release...");
 	return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 32f351f..4ab32de 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -93,7 +93,7 @@ static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacke
 	packet->flags = oldpacket->flags;
 	packet->gateway_nip = oldpacket->gateway_nip;
 	packet->ciaddr = oldpacket->ciaddr;
-	udhcp_add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip);
+	udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
 }
 
 /* Fill options field, siaddr_nip, and sname and boot_file fields.
@@ -105,7 +105,7 @@ static void add_server_options(struct dhcp_packet *packet)
 
 	while (curr) {
 		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
-			udhcp_add_binary_option(packet->options, curr->data);
+			udhcp_add_binary_option(packet, curr->data);
 		curr = curr->next;
 	}
 
@@ -194,7 +194,7 @@ static void send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip,
 	}
 
 	lease_time_sec = select_lease_time(oldpacket);
-	udhcp_add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
+	udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
 	add_server_options(&packet);
 
 	addr.s_addr = packet.yiaddr;
@@ -224,7 +224,7 @@ static void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
 	packet.yiaddr = yiaddr;
 
 	lease_time_sec = select_lease_time(oldpacket);
-	udhcp_add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
+	udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
 
 	add_server_options(&packet);
 
@@ -324,7 +324,7 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
 
 	bb_info_msg("%s (v"BB_VER") started", applet_name);
 
-	option = find_option(server_config.options, DHCP_LEASE_TIME);
+	option = udhcp_find_option(server_config.options, DHCP_LEASE_TIME);
 	server_config.max_lease_sec = DEFAULT_LEASE_TIME;
 	if (option) {
 		move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
diff --git a/networking/udhcp/files.c b/networking/udhcp/files.c
index 1f25bb1..cf55a6b 100644
--- a/networking/udhcp/files.c
+++ b/networking/udhcp/files.c
@@ -167,10 +167,11 @@ void FAST_FUNC write_leases(void)
 	close(fd);
 
 	if (server_config.notify_file) {
-// TODO: vfork-based child creation
-		char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
-		system(cmd);
-		free(cmd);
+		char *argv[3];
+		argv[0] = server_config.notify_file;
+		argv[1] = server_config.lease_file;
+		argv[2] = NULL;
+		spawn_and_wait(argv);
 	}
 }
 
diff --git a/networking/udhcp/leases.c b/networking/udhcp/leases.c
index efe67cf..81acb99 100644
--- a/networking/udhcp/leases.c
+++ b/networking/udhcp/leases.c
@@ -163,6 +163,7 @@ uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
 
 		lease = find_lease_by_nip(nip);
 		if (!lease) {
+//TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
 			if (nobody_responds_to_arp(nip, safe_mac))
 				return nip;
 		} else {
diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 5b113bc..ecdbec7 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -33,7 +33,7 @@ void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
 	packet->cookie = htonl(DHCP_MAGIC);
 	if (DHCP_END != 0)
 		packet->options[0] = DHCP_END;
-	udhcp_add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
+	udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type);
 }
 
 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
diff --git a/networking/udhcp/socket.c b/networking/udhcp/socket.c
index a0ffbf8..469b362 100644
--- a/networking/udhcp/socket.c
+++ b/networking/udhcp/socket.c
@@ -24,7 +24,6 @@
  */
 
 #include <net/if.h>
-//#include <features.h>
 #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION
 #include <netpacket/packet.h>
 #include <net/ethernet.h>