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authorDenys Vlasenko2010-03-22 13:43:12 +0100
committerDenys Vlasenko2010-03-22 13:43:12 +0100
commit501e35c47441722c69c62bd52841a9a6fd64932c (patch)
treeb44be8066c38222867175586ef5084a4fc662223 /networking/udhcp/dhcpc.c
parent6b24d5354bc166f6962b6b42de4ab9c7e6470225 (diff)
downloadbusybox-501e35c47441722c69c62bd52841a9a6fd64932c.zip
busybox-501e35c47441722c69c62bd52841a9a6fd64932c.tar.gz
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>
Diffstat (limited to 'networking/udhcp/dhcpc.c')
-rw-r--r--networking/udhcp/dhcpc.c245
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)
{