+/* vi: set sw=4 ts=4: */
/* clientpacket.c
*
* Packet generation and dispatching functions for the DHCP client.
*
* Russ Dill <Russ.Dill@asu.edu> July 2001
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-#include <string.h>
-#include <sys/socket.h>
#include <features.h>
-#if __GLIBC__ >=2 && __GLIBC_MINOR >= 1
+#if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION
#include <netpacket/packet.h>
#include <net/ethernet.h>
#else
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#endif
-#include <stdlib.h>
-#include <time.h>
-#include <unistd.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <fcntl.h>
-
+#include "common.h"
#include "dhcpd.h"
-#include "clientpacket.h"
-#include "options.h"
#include "dhcpc.h"
-#include "common.h"
+#include "options.h"
/* Create a random xid */
-unsigned long random_xid(void)
+uint32_t random_xid(void)
{
- static int initialized;
- if (!initialized) {
- int fd;
- unsigned long seed;
+ static smallint initialized;
- fd = open("/dev/urandom", 0);
- if (fd < 0 || read(fd, &seed, sizeof(seed)) < 0) {
- LOG(LOG_WARNING, "Could not load seed from /dev/urandom: %m");
- seed = time(0);
- }
- if (fd >= 0) close(fd);
- srand(seed);
- initialized++;
+ if (!initialized) {
+ srand(monotonic_us());
+ initialized = 1;
}
return rand();
}
/* initialize a packet with the proper defaults */
static void init_packet(struct dhcpMessage *packet, char type)
{
- init_header(packet, type);
+ udhcp_init_header(packet, type);
memcpy(packet->chaddr, client_config.arp, 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);
- add_option_string(packet->options, client_config.vendorclass);
+ 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))
+ 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_requests(struct dhcpMessage *packet)
+static void add_param_req_option(struct dhcpMessage *packet)
{
+ uint8_t c;
int end = end_option(packet->options);
int i, len = 0;
packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
- for (i = 0; dhcp_options[i].code; i++)
- if (dhcp_options[i].flags & OPTION_REQ)
- packet->options[end + OPT_DATA + len++] = dhcp_options[i].code;
+ for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
+ if ((dhcp_options[i].flags & OPTION_REQ)
+ || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
+ ) {
+ packet->options[end + OPT_DATA + len] = c;
+ len++;
+ }
+ }
packet->options[end + OPT_LEN] = len;
packet->options[end + OPT_DATA + len] = DHCP_END;
-
}
+#if ENABLE_FEATURE_UDHCPC_ARPING
+/* Unicast a DHCP decline message */
+int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
+{
+ struct dhcpMessage 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 udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
+}
+#endif
+
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
-int send_discover(unsigned long xid, unsigned long requested)
+int send_discover(uint32_t xid, uint32_t requested)
{
struct dhcpMessage packet;
if (requested)
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
- add_requests(&packet);
- LOG(LOG_DEBUG, "Sending discover...");
- return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
- SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
+ /* 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 udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
/* Broadcasts a DHCP request message */
-int send_selecting(unsigned long xid, unsigned long server, unsigned long requested)
+int send_selecting(uint32_t xid, uint32_t server, uint32_t requested)
{
struct dhcpMessage packet;
struct in_addr addr;
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
- add_requests(&packet);
+ add_param_req_option(&packet);
addr.s_addr = requested;
- LOG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr));
- return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ bb_info_msg("Sending select for %s...", inet_ntoa(addr));
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
/* Unicasts or broadcasts a DHCP renew message */
-int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr)
+int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
{
struct dhcpMessage packet;
- int ret = 0;
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
packet.ciaddr = ciaddr;
- add_requests(&packet);
- LOG(LOG_DEBUG, "Sending renew...");
+ add_param_req_option(&packet);
+ bb_info_msg("Sending renew...");
if (server)
- ret = kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
- else ret = raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
- return ret;
}
/* Unicasts a DHCP release message */
-int send_release(unsigned long server, unsigned long ciaddr)
+int send_release(uint32_t server, uint32_t ciaddr)
{
struct dhcpMessage packet;
packet.xid = random_xid();
packet.ciaddr = ciaddr;
- add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
- LOG(LOG_DEBUG, "Sending release...");
- return kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+ bb_info_msg("Sending release...");
+ return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
}
-/* return -1 on errors that are fatal for the socket, -2 for those that aren't */
+/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
int get_raw_packet(struct dhcpMessage *payload, int fd)
{
int bytes;
struct udp_dhcp_packet packet;
- uint32_t source, dest;
uint16_t check;
- memset(&packet, 0, sizeof(struct udp_dhcp_packet));
- bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet));
+ memset(&packet, 0, sizeof(packet));
+ bytes = safe_read(fd, &packet, sizeof(packet));
if (bytes < 0) {
- DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring");
- usleep(500000); /* possible down interface, looping condition */
- return -1;
+ DEBUG("Cannot read on raw listening socket - ignoring");
+ sleep(1); /* possible down interface, looping condition */
+ return bytes; /* returns -1 */
}
- if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) {
- DEBUG(LOG_INFO, "message too short, ignoring");
+ if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
+ DEBUG("Packet is too short, ignoring");
return -2;
}
if (bytes < ntohs(packet.ip.tot_len)) {
- DEBUG(LOG_INFO, "Truncated packet");
+ /* packet is bigger than sizeof(packet), we did partial read */
+ DEBUG("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(struct udp_dhcp_packet) ||
- ntohs(packet.udp.len) != (uint16_t) (bytes - sizeof(packet.ip))) {
- DEBUG(LOG_INFO, "unrelated/bogus packet");
+ /* 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))
+ ) {
+ DEBUG("Unrelated/bogus packet");
return -2;
}
- /* check IP checksum */
+ /* verify IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
- if (check != checksum(&(packet.ip), sizeof(packet.ip))) {
- DEBUG(LOG_INFO, "bad IP header checksum, ignoring");
- return -1;
+ if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
+ DEBUG("Bad IP header checksum, ignoring");
+ return -2;
}
- /* verify the UDP checksum by replacing the header with a psuedo header */
- source = packet.ip.saddr;
- dest = packet.ip.daddr;
+ /* 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;
- memset(&packet.ip, 0, sizeof(packet.ip));
-
- packet.ip.protocol = IPPROTO_UDP;
- packet.ip.saddr = source;
- packet.ip.daddr = dest;
- packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */
- if (check && check != checksum(&packet, bytes)) {
- DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring");
+ if (check && check != udhcp_checksum(&packet, bytes)) {
+ bb_error_msg("packet with bad UDP checksum received, ignoring");
return -2;
}
- memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
+ memcpy(payload, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
- if (ntohl(payload->cookie) != DHCP_MAGIC) {
- LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring");
+ if (payload->cookie != htonl(DHCP_MAGIC)) {
+ bb_error_msg("received bogus message (bad magic), ignoring");
return -2;
}
- DEBUG(LOG_INFO, "oooooh!!! got some!");
+ DEBUG("Got valid DHCP packet");
return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
-
}