/* vi: set sw=4 ts=4: */
/*
- * udhcp Server
+ * udhcp server
* Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
* Chris Trew <ctrew@moreton.com.au>
*
* 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 */
if (force_broadcast
|| (dhcp_pkt->flags & htons(BROADCAST_FLAG))
- || !dhcp_pkt->ciaddr
+ || dhcp_pkt->ciaddr == 0
) {
log1("Broadcasting packet to client");
ciaddr = INADDR_BROADCAST;
packet->flags = oldpacket->flags;
packet->gateway_nip = oldpacket->gateway_nip;
packet->ciaddr = oldpacket->ciaddr;
- add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip);
+ udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
}
/* Fill options field, siaddr_nip, and sname and boot_file fields.
while (curr) {
if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
- add_option_string(packet->options, curr->data);
+ udhcp_add_binary_option(packet, curr->data);
curr = curr->next;
}
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 = get_option(packet, DHCP_LEASE_TIME);
+ 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);
}
/* We got a DHCP DISCOVER. Send an OFFER. */
-static void send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease)
+/* 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;
if (!static_lease_nip) {
/* We have no static lease for client's chaddr */
uint32_t req_nip;
- uint8_t *req_ip_opt;
const char *p_host_name;
if (lease) {
packet.yiaddr = lease->lease_nip;
}
/* Or: if client has requested an IP */
- else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
+ else if (requested_ip_opt != NULL
/* (read IP) */
- && (move_from_unaligned32(req_nip, req_ip_opt), 1)
+ && (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
return;
}
/* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
- p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
+ 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,
}
lease_time_sec = select_lease_time(oldpacket);
- add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
+ udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet);
addr.s_addr = packet.yiaddr;
send_packet(&packet, /*force_bcast:*/ 0);
}
-static void send_NAK(struct dhcp_packet *oldpacket)
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_NAK(struct dhcp_packet *oldpacket)
{
struct dhcp_packet packet;
send_packet(&packet, /*force_bcast:*/ 1);
}
-static void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
+/* 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;
packet.yiaddr = yiaddr;
lease_time_sec = select_lease_time(oldpacket);
- add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
+ udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet);
bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
send_packet(&packet, /*force_bcast:*/ 0);
- p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
+ p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
add_lease(packet.chaddr, packet.yiaddr,
lease_time_sec,
p_host_name,
}
}
-static void send_inform(struct dhcp_packet *oldpacket)
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE void send_inform(struct dhcp_packet *oldpacket)
{
struct dhcp_packet packet;
- /* "The server responds to a DHCPINFORM message by sending a DHCPACK
+ /* "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);
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 dhcp_packet packet;
uint8_t *state;
- uint32_t static_lease_nip;
unsigned timeout_end;
unsigned num_ips;
unsigned opt;
struct option_set *option;
- struct dyn_lease *lease, fake_lease;
IF_FEATURE_UDHCP_PORT(char *str_P;)
#if ENABLE_FEATURE_UDHCP_PORT
#endif
opt = getopt32(argv, "fSv"
IF_FEATURE_UDHCP_PORT("P:", &str_P)
-#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
- , &dhcp_verbose
-#endif
+ IF_UDHCP_VERBOSE(, &dhcp_verbose)
);
- argv += optind;
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;
}
bb_info_msg("%s (v"BB_VER") started", applet_name);
- option = find_option(server_config.options, DHCP_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.max_lease_sec, option->data + OPT_DATA);
/* 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_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) {
log1("Error on select");
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;
bb_error_msg("not a REQUEST, ignoring packet");
continue;
}
- state = get_option(&packet, DHCP_MESSAGE_TYPE);
+ 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;
}
+ /* 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;
+ }
+ }
+
/* Look for a static/dynamic lease */
static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
if (static_lease_nip) {
lease = find_lease_by_mac(packet.chaddr);
}
- /* Get REQUESTED_IP and SERVER_ID if present */
- server_id_opt = get_option(&packet, DHCP_SERVER_ID);
- if (server_id_opt) {
- uint32_t server_id_net;
- move_from_unaligned32(server_id_net, server_id_opt);
- if (server_id_net != server_config.server_nip) {
- /* client talks to somebody else */
- log1("server ID doesn't match, ignoring");
- continue;
- }
- }
- requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
- if (requested_opt) {
- move_from_unaligned32(requested_nip, requested_opt);
+ /* 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:
log1("Received DISCOVER");
- send_offer(&packet, static_lease_nip, lease);
+ send_offer(&packet, static_lease_nip, lease, requested_ip_opt);
break;
case DHCPREQUEST:
log1("Received REQUEST");
-
- /* RFC 2131: "The REQUESTED_IP option MUST be set
- * to the value of 'yiaddr' in the DHCPOFFER message
- * from the server." */
- if (!requested_opt) {
- log1("no requested IP, ignoring");
- break;
+/* 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 requests IP which matches the lease.
+ /* client requested or configured IP matches the lease.
* ACK it, and bump lease expiration time. */
send_ACK(&packet, lease->lease_nip);
break;
}
- if (server_id_opt) {
- /* client was talking specifically to us.
- * "No, we don't have this IP for you". */
+ /* No lease for this MAC, or lease IP != requested IP */
+
+ 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 */
+
break;
case DHCPDECLINE:
*/
log1("Received DECLINE");
if (server_id_opt
- && requested_opt
+ && requested_ip_opt
&& lease /* chaddr matches this lease */
&& requested_nip == lease->lease_nip
) {
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