+++ /dev/null
-/* db.c
-
- IP Address Allocation database... */
-
-/*
- * Copyright (c) 1995 The Internet Software Consortium. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of The Internet Software Consortium nor the names
- * of its contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
- * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * This software has been written for the Internet Software Consortium
- * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
- * Enterprises. To learn more about the Internet Software Consortium,
- * see ``http://www.vix.com/isc''. To learn more about Vixie
- * Enterprises, see ``http://www.vix.com''.
- */
-
-#ifndef lint
-static char copyright[] =
-"@(#) Copyright (c) 1995 The Internet Software Consortium. All rights reserved.\n";
-#endif /* not lint */
-
-#include "dhcpd.h"
-
-/*
- The IP Address Allocation Database tracks addresses that have been
- allocated from the free pool as specified in dhcpd.conf. The
- database is maintained in two parts to maintain integrity: the
- journal file and the data file.
-
- Both files are free-form flat files similar to dhcpd.conf, but with
- a more limited syntax - all that can be specified are leases and
- who they belong to.
-
- When dhcpd starts up, it reads the entire data file into memory.
- It then reads the journal file into memory and makes corrections to
- the data based on journal entries.
-
- While dhcpd is running, it periodically records the current time,
- forks (if possible) and dumps the recorded time and its internal
- database of temporarily assigned addresses into a temporary file.
- It then removes any existing backup file, renames the existing file
- with the backup filename, and then renames the new temporary file
- with the real data file name. The link syscall is not present on
- most systems, so a synchronous ``rename'' that guarantees that
- exactly one file will be the master database may not be possible.
- Therefore the recovery routine needs to know what to do if it finds
- a backup and a temporary file, but no database file.
-
- Whenever a client requests that an address be allocated to it, or
- requests a lease renewal, and the server is able to satisfy the
- request, it writes a record into the journal file indicating what
- has been requested and waits for that information to reach the
- disk. Once the file's dirty buffers have been flushed, the server
- responds to the request, and logs another record in the journal
- indicating that it has done so.
-
- Entries in the journal file are logged along with the time at which
- the logging occurred. When the server forks to dump the database,
- it records the current time before forking. The copy of the server
- that writes out the database records the time read prior to forking
- in the new data file. The copy of the server that continues to
- serve DHCP requests ensures that any journal entries subsequent to
- the fork have time stamps that are greater than the time read
- before forking. When recovering from a crash, the server discards
- any entries in the journal which have time stamps earlier than the
- time stamp on the data file.
-
- When recovering from a crash, dhcpd may find a journal entry for a
- request, but no entry indicating that it was satisfied. There is
- no automatic way to recover from this, since the server may have
- sent out a response, so in this case the server must notify
- sysadmin of the problem and leave it to them to solve it.
-
- In addition to the actual data files, we also keep a running log of
- ``interesting'' events, which we mail to the dhcp-admin alias every
- morning at 7:00 AM. This log can be tailed by paranoid sysadmins
- or in times of network trouble. */
-
-/* Initialize the internal database, perform crash recovery as needed. */
-
-void dbinit ()
-{
- FILE *dbfile;
-
- /* We are assuming that on entry, there is no other dhcpd
- running on this machine. If there were, there would be the
- potential for serious database corruption. The main code
- currently assures that there is only one server running by
- listening on the bootps port with INADDR_ANY. Unices that
- I'm familiar with will only allow one process to do this,
- even if the SO_REUSEADDR option is set. 'twouldn't surprise
- me terribly, though, if this didn't work for some other
- operating system. Beware. XXX */
-
- /* Look for a file under the official database name.
- Failing that, look for a file under the backup name.
- If we find neither, we assume that the database is empty. */
-
- if ((dbfile = fopen (_PATH_DHCP_DB, "r")) != NULL
- (dbfile = fopen (_PATH_DHCP_DB_BACKUP, "r") != NULL)) {
-
- /* Read in the data file, making a list of assigned
- addresses that have been removed from dhcpd.conf. */
-
- }
-
- /* Open the journal file and read through any entries which
- are out of date. */
-
- /* Now read entries that postdate the last database sync,
- keeping track of incomplete entries (when we're done, there
- should never be more than one such entry. */
-
- /* Now expire any leases that have lapsed since we last ran. */
-
- /* ...and we're done... */
-}
+++ /dev/null
-/* db.c
-
- IP Address Allocation database... */
-
-/*
- * Copyright (c) 1995 The Internet Software Consortium. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of The Internet Software Consortium nor the names
- * of its contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
- * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * This software has been written for the Internet Software Consortium
- * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
- * Enterprises. To learn more about the Internet Software Consortium,
- * see ``http://www.vix.com/isc''. To learn more about Vixie
- * Enterprises, see ``http://www.vix.com''.
- */
-
-#ifndef lint
-static char copyright[] =
-"@(#) Copyright (c) 1995 The Internet Software Consortium. All rights reserved.\n";
-#endif /* not lint */
-
-#include "dhcpd.h"
-
-/*
- The IP Address Allocation Database tracks addresses that have been
- allocated from the free pool as specified in dhcpd.conf. The
- database is maintained in two parts to maintain integrity: the
- journal file and the data file.
-
- Both files are free-form flat files similar to dhcpd.conf, but with
- a more limited syntax - all that can be specified are leases and
- who they belong to.
-
- When dhcpd starts up, it reads the entire data file into memory.
- It then reads the journal file into memory and makes corrections to
- the data based on journal entries.
-
- While dhcpd is running, it periodically records the current time,
- forks (if possible) and dumps the recorded time and its internal
- database of temporarily assigned addresses into a temporary file.
- It then removes any existing backup file, renames the existing file
- with the backup filename, and then renames the new temporary file
- with the real data file name. The link syscall is not present on
- most systems, so a synchronous ``rename'' that guarantees that
- exactly one file will be the master database may not be possible.
- Therefore the recovery routine needs to know what to do if it finds
- a backup and a temporary file, but no database file.
-
- Whenever a client requests that an address be allocated to it, or
- requests a lease renewal, and the server is able to satisfy the
- request, it writes a record into the journal file indicating what
- has been requested and waits for that information to reach the
- disk. Once the file's dirty buffers have been flushed, the server
- responds to the request, and logs another record in the journal
- indicating that it has done so.
-
- Entries in the journal file are logged along with the time at which
- the logging occurred. When the server forks to dump the database,
- it records the current time before forking. The copy of the server
- that writes out the database records the time read prior to forking
- in the new data file. The copy of the server that continues to
- serve DHCP requests ensures that any journal entries subsequent to
- the fork have time stamps that are greater than the time read
- before forking. When recovering from a crash, the server discards
- any entries in the journal which have time stamps earlier than the
- time stamp on the data file.
-
- When recovering from a crash, dhcpd may find a journal entry for a
- request, but no entry indicating that it was satisfied. There is
- no automatic way to recover from this, since the server may have
- sent out a response, so in this case the server must notify
- sysadmin of the problem and leave it to them to solve it.
-
- In addition to the actual data files, we also keep a running log of
- ``interesting'' events, which we mail to the dhcp-admin alias every
- morning at 7:00 AM. This log can be tailed by paranoid sysadmins
- or in times of network trouble. */
-
-/* Initialize the internal database, perform crash recovery as needed. */
-
-void dbinit ()
-{
- FILE *dbfile;
-
- /* We are assuming that on entry, there is no other dhcpd
- running on this machine. If there were, there would be the
- potential for serious database corruption. The main code
- currently assures that there is only one server running by
- listening on the bootps port with INADDR_ANY. Unices that
- I'm familiar with will only allow one process to do this,
- even if the SO_REUSEADDR option is set. 'twouldn't surprise
- me terribly, though, if this didn't work for some other
- operating system. Beware. XXX */
-
- /* Look for a file under the official database name.
- Failing that, look for a file under the backup name.
- If we find neither, we assume that the database is empty. */
-
- if ((dbfile = fopen (_PATH_DHCP_DB, "r")) != NULL
- (dbfile = fopen (_PATH_DHCP_DB_BACKUP, "r") != NULL)) {
-
- /* Read in the data file, making a list of assigned
- addresses that have been removed from dhcpd.conf. */
-
- }
-
- /* Open the journal file and read through any entries which
- are out of date. */
-
- /* Now read entries that postdate the last database sync,
- keeping track of incomplete entries (when we're done, there
- should never be more than one such entry. */
-
- /* Now expire any leases that have lapsed since we last ran. */
-
- /* ...and we're done... */
-}
projects / thirdparty / dhcp.git / commitdiff
