/* vi: set sw=4 ts=4: */
-/* dhcpd.c
- *
- * udhcp Server
+/*
+ * udhcp server
* Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
* Chris Trew <ctrew@moreton.com.au>
*
* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * 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.
*/
+//usage:#define udhcpd_trivial_usage
+//usage: "[-fS]" IF_FEATURE_UDHCP_PORT(" [-P N]") " [CONFFILE]"
+//usage:#define udhcpd_full_usage "\n\n"
+//usage: "DHCP server\n"
+//usage: "\n -f Run in foreground"
+//usage: "\n -S Log to syslog too"
+//usage: IF_FEATURE_UDHCP_PORT(
+//usage: "\n -P N Use port N (default 67)"
+//usage: )
+
#include <syslog.h>
#include "common.h"
#include "dhcpc.h"
#include "dhcpd.h"
-#include "options.h"
+
+
+/* Send a packet to a specific mac address and ip address by creating our own ip packet */
+static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
+{
+ const uint8_t *chaddr;
+ uint32_t ciaddr;
+
+ // Was:
+ //if (force_broadcast) { /* broadcast */ }
+ //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ }
+ //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
+ //else { /* unicast to dhcp_pkt->yiaddr */ }
+ // But this is wrong: yiaddr is _our_ idea what client's IP is
+ // (for example, from lease file). Client may not know that,
+ // and may not have UDP socket listening on that IP!
+ // We should never unicast to dhcp_pkt->yiaddr!
+ // dhcp_pkt->ciaddr, OTOH, comes from client's request packet,
+ // and can be used.
+
+ if (force_broadcast
+ || (dhcp_pkt->flags & htons(BROADCAST_FLAG))
+ || dhcp_pkt->ciaddr == 0
+ ) {
+ log1("Broadcasting packet to client");
+ ciaddr = INADDR_BROADCAST;
+ chaddr = MAC_BCAST_ADDR;
+ } else {
+ log1("Unicasting packet to client ciaddr");
+ ciaddr = dhcp_pkt->ciaddr;
+ chaddr = dhcp_pkt->chaddr;
+ }
+
+ udhcp_send_raw_packet(dhcp_pkt,
+ /*src*/ server_config.server_nip, SERVER_PORT,
+ /*dst*/ ciaddr, CLIENT_PORT, chaddr,
+ server_config.ifindex);
+}
+
+/* Send a packet to gateway_nip using the kernel ip stack */
+static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
+{
+ log1("Forwarding packet to relay");
+
+ udhcp_send_kernel_packet(dhcp_pkt,
+ server_config.server_nip, SERVER_PORT,
+ dhcp_pkt->gateway_nip, SERVER_PORT);
+}
+
+static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
+{
+ if (dhcp_pkt->gateway_nip)
+ send_packet_to_relay(dhcp_pkt);
+ else
+ send_packet_to_client(dhcp_pkt, force_broadcast);
+}
+
+static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
+{
+ /* Sets op, htype, hlen, cookie fields
+ * and adds DHCP_MESSAGE_TYPE option */
+ udhcp_init_header(packet, type);
+
+ packet->xid = oldpacket->xid;
+ memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
+ packet->flags = oldpacket->flags;
+ packet->gateway_nip = oldpacket->gateway_nip;
+ packet->ciaddr = oldpacket->ciaddr;
+ udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
+}
+
+/* Fill options field, siaddr_nip, and sname and boot_file fields.
+ * TODO: teach this code to use overload option.
+ */
+static void add_server_options(struct dhcp_packet *packet)
+{
+ struct option_set *curr = server_config.options;
+
+ while (curr) {
+ if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+ udhcp_add_binary_option(packet, curr->data);
+ curr = curr->next;
+ }
+
+ packet->siaddr_nip = server_config.siaddr_nip;
+
+ if (server_config.sname)
+ strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
+ if (server_config.boot_file)
+ strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
+}
+
+static uint32_t select_lease_time(struct dhcp_packet *packet)
+{
+ uint32_t lease_time_sec = server_config.max_lease_sec;
+ uint8_t *lease_time_opt = udhcp_get_option(packet, DHCP_LEASE_TIME);
+ if (lease_time_opt) {
+ move_from_unaligned32(lease_time_sec, lease_time_opt);
+ lease_time_sec = ntohl(lease_time_sec);
+ if (lease_time_sec > server_config.max_lease_sec)
+ lease_time_sec = server_config.max_lease_sec;
+ if (lease_time_sec < server_config.min_lease_sec)
+ lease_time_sec = server_config.min_lease_sec;
+ }
+ return lease_time_sec;
+}
+
+/* We got a DHCP DISCOVER. Send an OFFER. */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
+ uint32_t static_lease_nip,
+ struct dyn_lease *lease,
+ uint8_t *requested_ip_opt)
+{
+ struct dhcp_packet packet;
+ uint32_t lease_time_sec;
+ struct in_addr addr;
+
+ init_packet(&packet, oldpacket, DHCPOFFER);
+
+ /* If it is a static lease, use its IP */
+ packet.yiaddr = static_lease_nip;
+ /* Else: */
+ if (!static_lease_nip) {
+ /* We have no static lease for client's chaddr */
+ uint32_t req_nip;
+ const char *p_host_name;
+
+ if (lease) {
+ /* We have a dynamic lease for client's chaddr.
+ * Reuse its IP (even if lease is expired).
+ * Note that we ignore requested IP in this case.
+ */
+ packet.yiaddr = lease->lease_nip;
+ }
+ /* Or: if client has requested an IP */
+ else if (requested_ip_opt != NULL
+ /* (read IP) */
+ && (move_from_unaligned32(req_nip, requested_ip_opt), 1)
+ /* and the IP is in the lease range */
+ && ntohl(req_nip) >= server_config.start_ip
+ && ntohl(req_nip) <= server_config.end_ip
+ /* and */
+ && ( !(lease = find_lease_by_nip(req_nip)) /* is not already taken */
+ || is_expired_lease(lease) /* or is taken, but expired */
+ )
+ ) {
+ packet.yiaddr = req_nip;
+ }
+ else {
+ /* Otherwise, find a free IP */
+ packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
+ }
+
+ if (!packet.yiaddr) {
+ bb_error_msg("no free IP addresses. OFFER abandoned");
+ return;
+ }
+ /* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
+ p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
+ lease = add_lease(packet.chaddr, packet.yiaddr,
+ server_config.offer_time,
+ p_host_name,
+ p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
+ );
+ if (!lease) {
+ bb_error_msg("no free IP addresses. OFFER abandoned");
+ return;
+ }
+ }
+
+ lease_time_sec = select_lease_time(oldpacket);
+ udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
+ add_server_options(&packet);
+
+ addr.s_addr = packet.yiaddr;
+ bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
+ /* send_packet emits error message itself if it detects failure */
+ send_packet(&packet, /*force_bcast:*/ 0);
+}
+
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_NAK(struct dhcp_packet *oldpacket)
+{
+ struct dhcp_packet packet;
+
+ init_packet(&packet, oldpacket, DHCPNAK);
+
+ log1("Sending NAK");
+ send_packet(&packet, /*force_bcast:*/ 1);
+}
+
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
+{
+ struct dhcp_packet packet;
+ uint32_t lease_time_sec;
+ struct in_addr addr;
+ const char *p_host_name;
+
+ init_packet(&packet, oldpacket, DHCPACK);
+ packet.yiaddr = yiaddr;
+
+ lease_time_sec = select_lease_time(oldpacket);
+ udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
+
+ add_server_options(&packet);
+
+ addr.s_addr = yiaddr;
+ bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
+ send_packet(&packet, /*force_bcast:*/ 0);
+
+ p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
+ add_lease(packet.chaddr, packet.yiaddr,
+ lease_time_sec,
+ p_host_name,
+ p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
+ );
+ if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
+ /* rewrite the file with leases at every new acceptance */
+ write_leases();
+ }
+}
+
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_inform(struct dhcp_packet *oldpacket)
+{
+ struct dhcp_packet packet;
+
+ /* "If a client has obtained a network address through some other means
+ * (e.g., manual configuration), it may use a DHCPINFORM request message
+ * to obtain other local configuration parameters. Servers receiving a
+ * DHCPINFORM message construct a DHCPACK message with any local
+ * configuration parameters appropriate for the client without:
+ * allocating a new address, checking for an existing binding, filling
+ * in 'yiaddr' or including lease time parameters. The servers SHOULD
+ * unicast the DHCPACK reply to the address given in the 'ciaddr' field
+ * of the DHCPINFORM message.
+ * ...
+ * The server responds to a DHCPINFORM message by sending a DHCPACK
+ * message directly to the address given in the 'ciaddr' field
+ * of the DHCPINFORM message. The server MUST NOT send a lease
+ * expiration time to the client and SHOULD NOT fill in 'yiaddr'."
+ */
+//TODO: do a few sanity checks: is ciaddr set?
+//Better yet: is ciaddr == IP source addr?
+ init_packet(&packet, oldpacket, DHCPACK);
+ add_server_options(&packet);
+
+ send_packet(&packet, /*force_bcast:*/ 0);
+}
/* globals */
-struct dhcpOfferedAddr *leases;
+struct dyn_lease *g_leases;
/* struct server_config_t server_config is in bb_common_bufsiz1 */
int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int udhcpd_main(int argc UNUSED_PARAM, char **argv)
{
- fd_set rfds;
int server_socket = -1, retval, max_sock;
- struct dhcpMessage packet;
- uint8_t *state, *server_id, *requested;
- uint32_t server_id_aligned = server_id_aligned; /* for compiler */
- uint32_t requested_aligned = requested_aligned;
- uint32_t static_lease_ip;
+ uint8_t *state;
unsigned timeout_end;
unsigned num_ips;
unsigned opt;
struct option_set *option;
- struct dhcpOfferedAddr *lease, static_lease;
IF_FEATURE_UDHCP_PORT(char *str_P;)
#if ENABLE_FEATURE_UDHCP_PORT
CLIENT_PORT = 68;
#endif
- opt = getopt32(argv, "fS" IF_FEATURE_UDHCP_PORT("P:", &str_P));
- argv += optind;
+#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
+ opt_complementary = "vv";
+#endif
+ opt = getopt32(argv, "fSv"
+ IF_FEATURE_UDHCP_PORT("P:", &str_P)
+ IF_UDHCP_VERBOSE(, &dhcp_verbose)
+ );
if (!(opt & 1)) { /* no -f */
bb_daemonize_or_rexec(0, argv);
logmode = LOGMODE_NONE;
}
+ /* update argv after the possible vfork+exec in daemonize */
+ argv += optind;
if (opt & 2) { /* -S */
openlog(applet_name, LOG_PID, LOG_DAEMON);
logmode |= LOGMODE_SYSLOG;
}
#if ENABLE_FEATURE_UDHCP_PORT
- if (opt & 4) { /* -P */
+ if (opt & 8) { /* -P */
SERVER_PORT = xatou16(str_P);
CLIENT_PORT = SERVER_PORT + 1;
}
/* Create pidfile */
write_pidfile(server_config.pidfile);
- /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
+ /* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
bb_info_msg("%s (v"BB_VER") started", applet_name);
- option = find_option(server_config.options, DHCP_LEASE_TIME);
- server_config.lease = 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.lease, option->data + 2);
- server_config.lease = ntohl(server_config.lease);
+ move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
+ server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
}
/* Sanity check */
server_config.max_leases = num_ips;
}
- leases = xzalloc(server_config.max_leases * sizeof(*leases));
+ g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
read_leases(server_config.lease_file);
- if (udhcp_read_interface(server_config.interface, &server_config.ifindex,
- &server_config.server_nip, server_config.arp)) {
+ if (udhcp_read_interface(server_config.interface,
+ &server_config.ifindex,
+ &server_config.server_nip,
+ server_config.server_mac)
+ ) {
retval = 1;
goto ret;
}
/* Setup the signal pipe */
udhcp_sp_setup();
+ continue_with_autotime:
timeout_end = monotonic_sec() + server_config.auto_time;
while (1) { /* loop until universe collapses */
+ fd_set rfds;
+ struct dhcp_packet packet;
int bytes;
struct timeval tv;
+ uint8_t *server_id_opt;
+ uint8_t *requested_ip_opt;
+ uint32_t requested_nip = requested_nip; /* for compiler */
+ uint32_t static_lease_nip;
+ struct dyn_lease *lease, fake_lease;
if (server_socket < 0) {
server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
}
if (retval == 0) {
write_leases();
- timeout_end = monotonic_sec() + server_config.auto_time;
- continue;
+ goto continue_with_autotime;
}
if (retval < 0 && errno != EINTR) {
- DEBUG("error on select");
+ log1("Error on select");
continue;
}
switch (udhcp_sp_read(&rfds)) {
case SIGUSR1:
- bb_info_msg("Received a SIGUSR1");
+ bb_info_msg("Received SIGUSR1");
write_leases();
/* why not just reset the timeout, eh */
- timeout_end = monotonic_sec() + server_config.auto_time;
- continue;
+ goto continue_with_autotime;
case SIGTERM:
- bb_info_msg("Received a SIGTERM");
+ bb_info_msg("Received SIGTERM");
+ write_leases();
goto ret0;
- case 0: /* no signal: read a packet */
+ case 0: /* no signal: read a packet */
break;
default: /* signal or error (probably EINTR): back to select */
continue;
if (bytes < 0) {
/* bytes can also be -2 ("bad packet data") */
if (bytes == -1 && errno != EINTR) {
- DEBUG("error on read, %s, reopening socket", strerror(errno));
+ log1("Read error: %s, reopening socket", strerror(errno));
close(server_socket);
server_socket = -1;
}
continue;
}
-
- state = get_option(&packet, DHCP_MESSAGE_TYPE);
- if (state == NULL) {
- bb_error_msg("cannot get option from packet, ignoring");
+ if (packet.hlen != 6) {
+ bb_error_msg("MAC length != 6, ignoring packet");
+ continue;
+ }
+ if (packet.op != BOOTREQUEST) {
+ bb_error_msg("not a REQUEST, ignoring packet");
+ continue;
+ }
+ state = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
+ if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) {
+ bb_error_msg("no or bad message type option, ignoring packet");
continue;
}
- /* Look for a static lease */
- static_lease_ip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
- if (static_lease_ip) {
- bb_info_msg("Found static lease: %x", static_lease_ip);
-
- memcpy(&static_lease.lease_mac16, &packet.chaddr, 16);
- static_lease.lease_nip = static_lease_ip;
- static_lease.expires = 0;
+ /* Get SERVER_ID if present */
+ server_id_opt = udhcp_get_option(&packet, DHCP_SERVER_ID);
+ if (server_id_opt) {
+ uint32_t server_id_network_order;
+ move_from_unaligned32(server_id_network_order, server_id_opt);
+ if (server_id_network_order != server_config.server_nip) {
+ /* client talks to somebody else */
+ log1("server ID doesn't match, ignoring");
+ continue;
+ }
+ }
- lease = &static_lease;
+ /* Look for a static/dynamic lease */
+ static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
+ if (static_lease_nip) {
+ bb_info_msg("Found static lease: %x", static_lease_nip);
+ memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
+ fake_lease.lease_nip = static_lease_nip;
+ fake_lease.expires = 0;
+ lease = &fake_lease;
} else {
- lease = find_lease_by_chaddr(packet.chaddr);
+ lease = find_lease_by_mac(packet.chaddr);
+ }
+
+ /* Get REQUESTED_IP if present */
+ requested_ip_opt = udhcp_get_option(&packet, DHCP_REQUESTED_IP);
+ if (requested_ip_opt) {
+ move_from_unaligned32(requested_nip, requested_ip_opt);
}
switch (state[0]) {
+
case DHCPDISCOVER:
- DEBUG("Received DISCOVER");
+ log1("Received DISCOVER");
- if (send_offer(&packet) < 0) {
- bb_error_msg("send OFFER failed");
- }
+ send_offer(&packet, static_lease_nip, lease, requested_ip_opt);
break;
+
case DHCPREQUEST:
- DEBUG("received REQUEST");
-
- requested = get_option(&packet, DHCP_REQUESTED_IP);
- server_id = get_option(&packet, DHCP_SERVER_ID);
-
- if (requested)
- move_from_unaligned32(requested_aligned, requested);
- if (server_id)
- move_from_unaligned32(server_id_aligned, server_id);
-
- if (lease) {
- if (server_id) {
- /* SELECTING State */
- DEBUG("server_id = %08x", ntohl(server_id_aligned));
- if (server_id_aligned == server_config.server_nip
- && requested
- && requested_aligned == lease->lease_nip
- ) {
- send_ACK(&packet, lease->lease_nip);
- }
- } else if (requested) {
- /* INIT-REBOOT State */
- if (lease->lease_nip == requested_aligned)
- send_ACK(&packet, lease->lease_nip);
- else
- send_NAK(&packet);
- } else if (lease->lease_nip == packet.ciaddr) {
- /* RENEWING or REBINDING State */
- send_ACK(&packet, lease->lease_nip);
- } else { /* don't know what to do!!!! */
- send_NAK(&packet);
+ log1("Received REQUEST");
+/* RFC 2131:
+
+o DHCPREQUEST generated during SELECTING state:
+
+ Client inserts the address of the selected server in 'server
+ identifier', 'ciaddr' MUST be zero, 'requested IP address' MUST be
+ filled in with the yiaddr value from the chosen DHCPOFFER.
+
+ Note that the client may choose to collect several DHCPOFFER
+ messages and select the "best" offer. The client indicates its
+ selection by identifying the offering server in the DHCPREQUEST
+ message. If the client receives no acceptable offers, the client
+ may choose to try another DHCPDISCOVER message. Therefore, the
+ servers may not receive a specific DHCPREQUEST from which they can
+ decide whether or not the client has accepted the offer.
+
+o DHCPREQUEST generated during INIT-REBOOT state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST be filled in with client's notion of its previously
+ assigned address. 'ciaddr' MUST be zero. The client is seeking to
+ verify a previously allocated, cached configuration. Server SHOULD
+ send a DHCPNAK message to the client if the 'requested IP address'
+ is incorrect, or is on the wrong network.
+
+ Determining whether a client in the INIT-REBOOT state is on the
+ correct network is done by examining the contents of 'giaddr', the
+ 'requested IP address' option, and a database lookup. If the DHCP
+ server detects that the client is on the wrong net (i.e., the
+ result of applying the local subnet mask or remote subnet mask (if
+ 'giaddr' is not zero) to 'requested IP address' option value
+ doesn't match reality), then the server SHOULD send a DHCPNAK
+ message to the client.
+
+ If the network is correct, then the DHCP server should check if
+ the client's notion of its IP address is correct. If not, then the
+ server SHOULD send a DHCPNAK message to the client. If the DHCP
+ server has no record of this client, then it MUST remain silent,
+ and MAY output a warning to the network administrator. This
+ behavior is necessary for peaceful coexistence of non-
+ communicating DHCP servers on the same wire.
+
+ If 'giaddr' is 0x0 in the DHCPREQUEST message, the client is on
+ the same subnet as the server. The server MUST broadcast the
+ DHCPNAK message to the 0xffffffff broadcast address because the
+ client may not have a correct network address or subnet mask, and
+ the client may not be answering ARP requests.
+
+ If 'giaddr' is set in the DHCPREQUEST message, the client is on a
+ different subnet. The server MUST set the broadcast bit in the
+ DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
+ client, because the client may not have a correct network address
+ or subnet mask, and the client may not be answering ARP requests.
+
+o DHCPREQUEST generated during RENEWING state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ client's IP address. In this situation, the client is completely
+ configured, and is trying to extend its lease. This message will
+ be unicast, so no relay agents will be involved in its
+ transmission. Because 'giaddr' is therefore not filled in, the
+ DHCP server will trust the value in 'ciaddr', and use it when
+ replying to the client.
+
+ A client MAY choose to renew or extend its lease prior to T1. The
+ server may choose not to extend the lease (as a policy decision by
+ the network administrator), but should return a DHCPACK message
+ regardless.
+
+o DHCPREQUEST generated during REBINDING state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ client's IP address. In this situation, the client is completely
+ configured, and is trying to extend its lease. This message MUST
+ be broadcast to the 0xffffffff IP broadcast address. The DHCP
+ server SHOULD check 'ciaddr' for correctness before replying to
+ the DHCPREQUEST.
+
+ The DHCPREQUEST from a REBINDING client is intended to accommodate
+ sites that have multiple DHCP servers and a mechanism for
+ maintaining consistency among leases managed by multiple servers.
+ A DHCP server MAY extend a client's lease only if it has local
+ administrative authority to do so.
+*/
+ if (!requested_ip_opt) {
+ requested_nip = packet.ciaddr;
+ if (requested_nip == 0) {
+ log1("no requested IP and no ciaddr, ignoring");
+ break;
}
+ }
+ if (lease && requested_nip == lease->lease_nip) {
+ /* client requested or configured IP matches the lease.
+ * ACK it, and bump lease expiration time. */
+ send_ACK(&packet, lease->lease_nip);
+ break;
+ }
+ /* No lease for this MAC, or lease IP != requested IP */
- /* what to do if we have no record of the client */
- } else if (server_id) {
- /* SELECTING State */
-
- } else if (requested) {
- /* INIT-REBOOT State */
- lease = find_lease_by_yiaddr(requested_aligned);
- if (lease) {
- if (lease_expired(lease)) {
- /* probably best if we drop this lease */
- memset(lease->lease_mac16, 0, 16);
- } else {
- /* make some contention for this address */
- send_NAK(&packet);
- }
- } else {
- uint32_t r = ntohl(requested_aligned);
- if (r < server_config.start_ip
- || r > server_config.end_ip
- ) {
- send_NAK(&packet);
- }
- /* else remain silent */
- }
+ if (server_id_opt /* client is in SELECTING state */
+ || requested_ip_opt /* client is in INIT-REBOOT state */
+ ) {
+ /* "No, we don't have this IP for you" */
+ send_NAK(&packet);
+ } /* else: client is in RENEWING or REBINDING, do not answer */
- } else {
- /* RENEWING or REBINDING State */
- }
break;
+
case DHCPDECLINE:
- DEBUG("Received DECLINE");
- if (lease) {
- memset(lease->lease_mac16, 0, 16);
+ /* RFC 2131:
+ * "If the server receives a DHCPDECLINE message,
+ * the client has discovered through some other means
+ * that the suggested network address is already
+ * in use. The server MUST mark the network address
+ * as not available and SHOULD notify the local
+ * sysadmin of a possible configuration problem."
+ *
+ * SERVER_ID must be present,
+ * REQUESTED_IP must be present,
+ * chaddr must be filled in,
+ * ciaddr must be 0 (we do not check this)
+ */
+ log1("Received DECLINE");
+ if (server_id_opt
+ && requested_ip_opt
+ && lease /* chaddr matches this lease */
+ && requested_nip == lease->lease_nip
+ ) {
+ memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
lease->expires = time(NULL) + server_config.decline_time;
}
break;
+
case DHCPRELEASE:
- DEBUG("Received RELEASE");
- if (lease)
+ /* "Upon receipt of a DHCPRELEASE message, the server
+ * marks the network address as not allocated."
+ *
+ * SERVER_ID must be present,
+ * REQUESTED_IP must not be present (we do not check this),
+ * chaddr must be filled in,
+ * ciaddr must be filled in
+ */
+ log1("Received RELEASE");
+ if (server_id_opt
+ && lease /* chaddr matches this lease */
+ && packet.ciaddr == lease->lease_nip
+ ) {
lease->expires = time(NULL);
+ }
break;
+
case DHCPINFORM:
- DEBUG("Received INFORM");
+ log1("Received INFORM");
send_inform(&packet);
break;
- default:
- bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
}
}
ret0:
projects / oweals / busybox.git / blobdiff