dhcp.c

DHCP服务器源码

		    find_lease_by_hw_addr
			    (&seek, lease -> hardware_addr.hbuf,
			     lease -> hardware_addr.hlen, MDL);
		    if (!seek)
			    break;
		    if (seek == lease && !seek -> n_hw) {
			    lease_dereference (&seek, MDL);
			    break;
		    }
		    next = (struct lease *)0;
		    while (seek) {
			if (seek -> n_hw)
			    lease_reference (&next, seek -> n_hw, MDL);
			if (seek != lease &&
			    seek -> binding_state != FTS_RELEASED &&
			    seek -> binding_state != FTS_EXPIRED &&
			    seek -> binding_state != FTS_RESET &&
			    seek -> binding_state != FTS_FREE &&
			    seek -> binding_state != FTS_BACKUP)
				break;
			lease_dereference (&seek, MDL);
			if (next) {
			    lease_reference (&seek, next, MDL);
			    lease_dereference (&next, MDL);
			}
		    }
		    if (next)
			lease_dereference (&next, MDL);
		    if (seek) {
			release_lease (seek, packet);
			lease_dereference (&seek, MDL);
		    } else
			break;
		} while (1);
	    }
	}
	

	/* Make sure this packet satisfies the configured minimum
	   number of seconds. */
	memset (&d1, 0, sizeof d1);
	if (offer == DHCPOFFER &&
	    (oc = lookup_option (&server_universe, state -> options,
				 SV_MIN_SECS))) {
		if (evaluate_option_cache (&d1, packet, lease,
					   (struct client_state *)0,
					   packet -> options, state -> options,
					   &lease -> scope, oc, MDL)) {
			if (d1.len &&
			    ntohs (packet -> raw -> secs) < d1.data [0]) {
				log_info ("%s: %d secs < %d", msg,
					  ntohs (packet -> raw -> secs),
					  d1.data [0]);
				data_string_forget (&d1, MDL);
				free_lease_state (state, MDL);
				return;
			}
			data_string_forget (&d1, MDL);
		}
	}

	/* Try to find a matching host declaration for this lease. */
	if (!lease -> host) {
		struct host_decl *hp = (struct host_decl *)0;
		struct host_decl *h;

		/* Try to find a host_decl that matches the client
		   identifier or hardware address on the packet, and
		   has no fixed IP address.   If there is one, hang
		   it off the lease so that its option definitions
		   can be used. */
		oc = lookup_option (&dhcp_universe, packet -> options,
				    DHO_DHCP_CLIENT_IDENTIFIER);
		if (oc &&
		    evaluate_option_cache (&d1, packet, lease,
					   (struct client_state *)0,
					   packet -> options, state -> options,
					   &lease -> scope, oc, MDL)) {
			find_hosts_by_uid (&hp, d1.data, d1.len, MDL);
			data_string_forget (&d1, MDL);
			if (hp)
				host_reference (&lease -> host, hp, MDL);
		}
		if (!hp) {
			find_hosts_by_haddr (&hp,
					     packet -> raw -> htype,
					     packet -> raw -> chaddr,
					     packet -> raw -> hlen,
					     MDL);
			for (h = hp; h; h = h -> n_ipaddr) {
				if (!h -> fixed_addr)
					break;
			}
			if (h)
				host_reference (&lease -> host, h, MDL);
		}
		if (hp)
			host_dereference (&hp, MDL);
	}

	/* If we have a host_decl structure, run the options associated
	   with its group.  Wether the host decl struct is old or not. */
	if (lease -> host)
		execute_statements_in_scope ((struct binding_value **)0,
					     packet, lease,
					     (struct client_state *)0,
					     packet -> options,
					     state -> options, &lease -> scope,
					     lease -> host -> group,
					     (lease -> pool
					      ? lease -> pool -> group
					      : lease -> subnet -> group));

	/* Drop the request if it's not allowed for this client.   By
	   default, unknown clients are allowed. */
	if (!lease -> host &&
	    (oc = lookup_option (&server_universe, state -> options,
				 SV_BOOT_UNKNOWN_CLIENTS)) &&
	    !evaluate_boolean_option_cache (&ignorep,
					    packet, lease,
					    (struct client_state *)0,
					    packet -> options,
					    state -> options,
					    &lease -> scope, oc, MDL)) {
		if (!ignorep)
			log_info ("%s: unknown client", msg);
		free_lease_state (state, MDL);
		return;
	} 

	/* Drop the request if it's not allowed for this client. */
	if (!offer &&
	    (oc = lookup_option (&server_universe, state -> options,
				   SV_ALLOW_BOOTP)) &&
	    !evaluate_boolean_option_cache (&ignorep,
					    packet, lease,
					    (struct client_state *)0,
					    packet -> options,
					    state -> options,
					    &lease -> scope, oc, MDL)) {
		if (!ignorep)
			log_info ("%s: bootp disallowed", msg);
		free_lease_state (state, MDL);
		return;
	} 

	/* Drop the request if booting is specifically denied. */
	oc = lookup_option (&server_universe, state -> options,
			    SV_ALLOW_BOOTING);
	if (oc &&
	    !evaluate_boolean_option_cache (&ignorep,
					    packet, lease,
					    (struct client_state *)0,
					    packet -> options,
					    state -> options,
					    &lease -> scope, oc, MDL)) {
		if (!ignorep)
			log_info ("%s: booting disallowed", msg);
		free_lease_state (state, MDL);
		return;
	}

	/* If we are configured to do per-class billing, do it. */
	if (have_billing_classes && !(lease -> flags & STATIC_LEASE)) {
		/* See if the lease is currently being billed to a
		   class, and if so, whether or not it can continue to
		   be billed to that class. */
		if (lease -> billing_class) {
			for (i = 0; i < packet -> class_count; i++)
				if (packet -> classes [i] ==
				    lease -> billing_class)
					break;
			if (i == packet -> class_count)
				unbill_class (lease, lease -> billing_class);
		}
		
		/* If we don't have an active billing, see if we need
		   one, and if we do, try to do so. */
		if (!lease -> billing_class) {
			for (i = 0; i < packet -> class_count; i++) {
				if (packet -> classes [i] -> lease_limit)
					break;
			}
			if (i != packet -> class_count) {
				for (i = 0; i < packet -> class_count; i++)
					if ((packet -> 
					     classes [i] -> lease_limit) &&
					    bill_class (lease,
							packet -> classes [i]))
						break;
				if (i == packet -> class_count) {
					log_info ("%s: no available billing",
						  msg);
					free_lease_state (state, MDL);
					/* XXX probably not necessary: */
					return;
				}
			}
		}
	}

	/* Figure out the filename. */
	oc = lookup_option (&server_universe, state -> options, SV_FILENAME);
	if (oc)
		evaluate_option_cache (&state -> filename, packet, lease,
				       (struct client_state *)0,
				       packet -> options, state -> options,
				       &lease -> scope, oc, MDL);

	/* Choose a server name as above. */
	oc = lookup_option (&server_universe, state -> options,
			    SV_SERVER_NAME);
	if (oc)
		evaluate_option_cache (&state -> server_name, packet, lease,
				       (struct client_state *)0,
				       packet -> options, state -> options,
				       &lease -> scope, oc, MDL);

	/* At this point, we have a lease that we can offer the client.
	   Now we construct a lease structure that contains what we want,
	   and call supersede_lease to do the right thing with it. */
	lt = (struct lease *)0;
	result = lease_allocate (&lt, MDL);
	if (result != ISC_R_SUCCESS) {
		log_info ("%s: can't allocate temporary lease structure: %s",
			  msg, isc_result_totext (result));
		free_lease_state (state, MDL);
		return;
	}
		
	/* Use the ip address of the lease that we finally found in
	   the database. */
	lt -> ip_addr = lease -> ip_addr;

	/* Start now. */
	lt -> starts = cur_time;

	/* Figure out how long a lease to assign.    If this is a
	   dynamic BOOTP lease, its duration must be infinite. */
	if (offer) {
		default_lease_time = DEFAULT_DEFAULT_LEASE_TIME;
		if ((oc = lookup_option (&server_universe, state -> options,
					 SV_DEFAULT_LEASE_TIME))) {
			if (evaluate_option_cache (&d1, packet, lease,
						   (struct client_state *)0,
						   packet -> options,
						   state -> options,
						   &lease -> scope, oc, MDL)) {
				if (d1.len == sizeof (u_int32_t))
					default_lease_time =
						getULong (d1.data);
				data_string_forget (&d1, MDL);
			}
		}

		if ((oc = lookup_option (&dhcp_universe, packet -> options,
					 DHO_DHCP_LEASE_TIME)))
			s1 = evaluate_option_cache (&d1, packet, lease,
						    (struct client_state *)0,
						    packet -> options,
						    state -> options,
						    &lease -> scope, oc, MDL);
		else
			s1 = 0;
		if (s1 && d1.len == sizeof (u_int32_t)) {
			lease_time = getULong (d1.data);
			data_string_forget (&d1, MDL);
		} else {
			if (s1)
				data_string_forget (&d1, MDL);
			lease_time = default_lease_time;
		}
		
		/* See if there's a maximum lease time. */
		max_lease_time = DEFAULT_MAX_LEASE_TIME;
		if ((oc = lookup_option (&server_universe, state -> options,
					 SV_MAX_LEASE_TIME))) {
			if (evaluate_option_cache (&d1, packet, lease,
						   (struct client_state *)0,
						   packet -> options,
						   state -> options,
						   &lease -> scope, oc, MDL)) {
				if (d1.len == sizeof (u_int32_t))
					max_lease_time =
						getULong (d1.data);
				data_string_forget (&d1, MDL);
			}
		}

		/* Enforce the maximum lease length. */
		if (lease_time < 0 /* XXX */
		    || lease_time > max_lease_time)
			lease_time = max_lease_time;
			
		min_lease_time = DEFAULT_MIN_LEASE_TIME;
		if (min_lease_time > max_lease_time)
			min_lease_time = max_lease_time;

		if ((oc = lookup_option (&server_universe, state -> options,
					 SV_MIN_LEASE_TIME))) {
			if (evaluate_option_cache (&d1, packet, lease,
						   (struct client_state *)0,
						   packet -> options,
						   state -> options,
						   &lease -> scope, oc, MDL)) {
				if (d1.len == sizeof (u_int32_t))
					min_lease_time = getULong (d1.data);
				data_string_forget (&d1, MDL);
			}
		}

		if (lease_time < min_lease_time) {
			if (min_lease_time)
				lease_time = min_lease_time;
			else
				lease_time = default_lease_time;
		}

#if defined (FAILOVER_PROTOCOL)
		/* Okay, we know the lease duration.   Now check the
		   failover state, if any. */
		if (lease -> tsfp) {
			lt ->tsfp = lease ->tsfp;
		}
		if (lease -> pool && lease -> pool -> failover_peer) {
			dhcp_failover_state_t *peer =
			    lease -> pool -> failover_peer;

			/* If the lease time we arrived at exceeds what
			   the peer has, we can only issue a lease of
			   peer -> mclt, but we can tell the peer we
			   want something longer in the future. */
			/* XXX This may result in updates that only push
			   XXX the peer's expiry time for this lease up
			   XXX by a few seconds - think about this again
			   XXX later. */
			if (lease_time > peer -> mclt &&
			    cur_time + lease_time > lease -> tsfp) {
				/* Here we're assuming that if we don't have
				   to update tstp, there's already an update
				   queued.   May want to revisit this.  */
				if (peer -> me.state != partner_down &&
				    cur_time + lease_time > lease -> tstp)
					lt -> tstp = (cur_time + lease_time +
						      peer -> mclt / 2);

				/* Now choose a lease time that is either
				   MCLT, for a lease that's never before been
				   assigned, or TSFP + MCLT for a lease that
				   has.
				   XXX Note that TSFP may be < cur_time.
				   XXX What do we do in this case?
				   XXX should the expiry timer on the lease
				   XXX set tsfp and tstp to zero? */
				if (lease -> tsfp < cur_time) {
					lease_time = peer -> mclt;
				} else {
					lease_time = (lease -> tsfp  - cur_time
						      + peer -> mclt);
				}
			} else {
				if (cur_time + lease_time > lease -> tsfp &&
				    lease_time > peer -> mclt / 2) {
					lt -> tstp = (cur_time + lease_time +
						      peer -> mclt / 2);
				} else { 
					lt -> tstp = (cur_time + lease_time +
						      lease_time / 2);
				}
			}

			lt -> cltt = cur_time;
		}
#endif /* FAILOVER_PROTOCOL */

		/* If the lease duration causes the time value to wrap,
		   use the maximum expiry time. */
		if (cur_time + lease_time < cur_time)
			state -> offered_expiry = MAX_TIME - 1;
		else
			state -> offered_expiry = cur_time + lease_time;
		if (when)
			lt -> ends = when;
		else
			lt -> ends = state -> offered_expiry;

		/* Don't make lease active until we actually get a
		   DHCPREQUEST. */
		if (offer == DHCPACK)
			lt -> next_binding_state = FTS_ACTIVE;
		else
			lt -> next_binding_state = lease -> binding_state;
	} else {
		lease_time = MAX_TIME - cur_time;

		if ((oc = lookup_option (&server_universe, state -> options,
					 SV_BOOTP_LEASE_LENGTH))) {
			if (evaluate_option_cache (&d1, packet, lease,
						   (struct client_state *)0,
						   packet -> options,
						   state -> options,
						   &lease -> scope, oc, MDL)) {
				if (d1.len == sizeof (u_int32_t))
					lease_time = getULong (d1.data);
				data_string_forget (&d1, MDL);
			}
		}

		if ((oc = lookup_option (&server_universe, state -> options,
					 SV_BOOTP_LEASE_CUTOFF))) {
			if (evaluate_option_cache (&d1, packet, lease,
						   (struct client_state *)0,
						   packet -> options,
						   state -> options,
						   &lease -> scope,