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 a03e25ca4..d51d8b82f 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)
 {