udhcp: merge clientpacket.c into dhcpc.c

function                                             old     new   delta
udhcpc_main                                         2569    2855    +286
perform_release                                      122     124      +2
client_background                                     31      32      +1
init_packet                                          156      88     -68
send_decline                                         114       -    -114
send_discover                                        121       -    -121
send_select                                          130       -    -130
------------------------------------------------------------------------------
(add/remove: 0/4 grow/shrink: 3/1 up/down: 289/-433)         Total: -144 bytes

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

1 files changed, 239 insertions, 6 deletions

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index a03e25c..d51d8b8 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -63,6 +63,245 @@ static smallint state;
 /* struct client_config_t client_config is in bb_common_bufsiz1 */
 
 
+/* Create a random xid */
+static uint32_t random_xid(void)
+{
+	static smallint initialized;
+
+	if (!initialized) {
+		srand(monotonic_us());
+		initialized = 1;
+	}
+	return rand();
+}
+
+/* Initialize the packet with the proper defaults */
+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)
+		add_option_string(packet->options, client_config.clientid);
+	if (client_config.hostname)
+		add_option_string(packet->options, client_config.hostname);
+	if (client_config.fqdn)
+		add_option_string(packet->options, client_config.fqdn);
+	if (type != DHCPDECLINE
+	 && type != DHCPRELEASE
+	 && client_config.vendorclass
+	) {
+		add_option_string(packet->options, client_config.vendorclass);
+	}
+}
+
+/* Add a parameter request list for stubborn DHCP servers. Pull the data
+ * from the struct in options.c. Don't do bounds checking here because it
+ * goes towards the head of the packet. */
+static void add_param_req_option(struct dhcp_packet *packet)
+{
+	uint8_t c;
+	int end = end_option(packet->options);
+	int i, len = 0;
+
+	for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
+		if ((   (dhcp_options[i].flags & OPTION_REQ)
+		     && !client_config.no_default_options
+		    )
+		 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
+		) {
+			packet->options[end + OPT_DATA + len] = c;
+			len++;
+		}
+	}
+	if (len) {
+		packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+		packet->options[end + OPT_LEN] = len;
+		packet->options[end + OPT_DATA + len] = DHCP_END;
+	}
+}
+
+/* RFC 2131
+ * 4.4.4 Use of broadcast and unicast
+ *
+ * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
+ * messages, unless the client knows the address of a DHCP server.
+ * The client unicasts DHCPRELEASE messages to the server. Because
+ * the client is declining the use of the IP address supplied by the server,
+ * the client broadcasts DHCPDECLINE messages.
+ *
+ * When the DHCP client knows the address of a DHCP server, in either
+ * INIT or REBOOTING state, the client may use that address
+ * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
+ * The client may also use unicast to send DHCPINFORM messages
+ * to a known DHCP server. If the client receives no response to DHCP
+ * messages sent to the IP address of a known DHCP server, the DHCP
+ * client reverts to using the IP broadcast address.
+ */
+
+static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
+{
+	return udhcp_send_raw_packet(packet,
+		/*src*/ INADDR_ANY, CLIENT_PORT,
+		/*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
+		client_config.ifindex);
+}
+
+/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
+static int send_discover(uint32_t xid, uint32_t requested)
+{
+	struct dhcp_packet packet;
+
+	init_packet(&packet, DHCPDISCOVER);
+	packet.xid = xid;
+	if (requested)
+		add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+	/* Explicitly saying that we want RFC-compliant packets helps
+	 * some buggy DHCP servers to NOT send bigger packets */
+	add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
+	add_param_req_option(&packet);
+
+	bb_info_msg("Sending discover...");
+	return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+/* Broadcast a DHCP request message */
+/* RFC 2131 3.1 paragraph 3:
+ * "The client _broadcasts_ a DHCPREQUEST message..."
+ */
+static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
+{
+	struct dhcp_packet packet;
+	struct in_addr addr;
+
+	init_packet(&packet, DHCPREQUEST);
+	packet.xid = xid;
+	add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+	add_simple_option(packet.options, DHCP_SERVER_ID, server);
+	add_param_req_option(&packet);
+
+	addr.s_addr = requested;
+	bb_info_msg("Sending select for %s...", inet_ntoa(addr));
+	return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+/* Unicast or broadcast a DHCP renew message */
+static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
+{
+	struct dhcp_packet packet;
+
+	init_packet(&packet, DHCPREQUEST);
+	packet.xid = xid;
+	packet.ciaddr = ciaddr;
+	add_param_req_option(&packet);
+
+	bb_info_msg("Sending renew...");
+	if (server)
+		return udhcp_send_kernel_packet(&packet,
+			ciaddr, CLIENT_PORT,
+			server, SERVER_PORT);
+	return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+#if ENABLE_FEATURE_UDHCPC_ARPING
+/* Broadcast a DHCP decline message */
+static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
+{
+	struct dhcp_packet packet;
+
+	init_packet(&packet, DHCPDECLINE);
+	packet.xid = xid;
+	add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+	add_simple_option(packet.options, DHCP_SERVER_ID, server);
+
+	bb_info_msg("Sending decline...");
+	return raw_bcast_from_client_config_ifindex(&packet);
+}
+#endif
+
+/* Unicast a DHCP release message */
+static int send_release(uint32_t server, uint32_t ciaddr)
+{
+	struct dhcp_packet packet;
+
+	init_packet(&packet, DHCPRELEASE);
+	packet.xid = random_xid();
+	packet.ciaddr = ciaddr;
+
+	add_simple_option(packet.options, DHCP_SERVER_ID, server);
+
+	bb_info_msg("Sending release...");
+	return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+}
+
+/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
+static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
+{
+	int bytes;
+	struct ip_udp_dhcp_packet packet;
+	uint16_t check;
+
+	memset(&packet, 0, sizeof(packet));
+	bytes = safe_read(fd, &packet, sizeof(packet));
+	if (bytes < 0) {
+		log1("Packet read error, ignoring");
+		/* NB: possible down interface, etc. Caller should pause. */
+		return bytes; /* returns -1 */
+	}
+
+	if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
+		log1("Packet is too short, ignoring");
+		return -2;
+	}
+
+	if (bytes < ntohs(packet.ip.tot_len)) {
+		/* packet is bigger than sizeof(packet), we did partial read */
+		log1("Oversized packet, ignoring");
+		return -2;
+	}
+
+	/* ignore any extra garbage bytes */
+	bytes = ntohs(packet.ip.tot_len);
+
+	/* make sure its the right packet for us, and that it passes sanity checks */
+	if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
+	 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
+	 || packet.udp.dest != htons(CLIENT_PORT)
+	/* || bytes > (int) sizeof(packet) - can't happen */
+	 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
+	) {
+		log1("Unrelated/bogus packet, ignoring");
+		return -2;
+	}
+
+	/* verify IP checksum */
+	check = packet.ip.check;
+	packet.ip.check = 0;
+	if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
+		log1("Bad IP header checksum, ignoring");
+		return -2;
+	}
+
+	/* verify UDP checksum. IP header has to be modified for this */
+	memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
+	/* ip.xx fields which are not memset: protocol, check, saddr, daddr */
+	packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
+	check = packet.udp.check;
+	packet.udp.check = 0;
+	if (check && check != udhcp_checksum(&packet, bytes)) {
+		log1("Packet with bad UDP checksum received, ignoring");
+		return -2;
+	}
+
+	memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
+
+	if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
+		bb_info_msg("Packet with bad magic, ignoring");
+		return -2;
+	}
+	log1("Got valid DHCP packet");
+	udhcp_dump_packet(dhcp_pkt);
+	return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
+}
 
 static int udhcp_raw_socket(int ifindex)
 {
@@ -135,7 +374,6 @@ static int udhcp_raw_socket(int ifindex)
 	return fd;
 }
 
-
 /* just a little helper */
 static void change_listen_mode(int new_mode)
 {
@@ -157,7 +395,6 @@ static void change_listen_mode(int new_mode)
 	/* else LISTEN_NONE: sockfd stays closed */
 }
 
-
 /* perform a renew */
 static void perform_renew(void)
 {
@@ -181,7 +418,6 @@ static void perform_renew(void)
 	}
 }
 
-
 /* perform a release */
 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
 {
@@ -204,7 +440,6 @@ static void perform_release(uint32_t requested_ip, uint32_t server_addr)
 	state = RELEASED;
 }
 
-
 #if BB_MMU
 static void client_background(void)
 {
@@ -215,7 +450,6 @@ static void client_background(void)
 }
 #endif
 
-
 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 {
 	uint8_t *storage;
@@ -227,7 +461,6 @@ static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 	return storage;
 }
 
-
 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 {