Last foru commits: function old new delta option_to_env 621 791 +170 .rodata 168351 168505 +154 attach_option 431 506 +75 add_d6_client_options 112 167 +55 d6_option_strings 30 84 +54 udhcp_str2optset 644 660 +16 d6_optflags 12 20 +8 udhcpc6_main 2590 2596 +6 udhcpc_main 2648 2651 +3 read_optset 15 18 +3 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 10/0 up/down: 544/0) Total: 544 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1197 lines
36 KiB
C
1197 lines
36 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* udhcp server
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* Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
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* Chris Trew <ctrew@moreton.com.au>
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*
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* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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//applet:IF_UDHCPD(APPLET(udhcpd, BB_DIR_USR_SBIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_UDHCPD) += common.o packet.o signalpipe.o socket.o
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//kbuild:lib-$(CONFIG_UDHCPD) += dhcpd.o arpping.o
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//kbuild:lib-$(CONFIG_FEATURE_UDHCP_RFC3397) += domain_codec.o
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//usage:#define udhcpd_trivial_usage
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//usage: "[-fS] [-I ADDR]" IF_FEATURE_UDHCP_PORT(" [-P N]") " [CONFFILE]"
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//usage:#define udhcpd_full_usage "\n\n"
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//usage: "DHCP server\n"
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//usage: "\n -f Run in foreground"
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//usage: "\n -S Log to syslog too"
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//usage: "\n -I ADDR Local address"
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//usage: "\n -a MSEC Timeout for ARP ping (default 2000)"
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//usage: IF_FEATURE_UDHCP_PORT(
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//usage: "\n -P N Use port N (default 67)"
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//usage: )
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#include <netinet/ether.h>
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#include <syslog.h>
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#include "common.h"
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#include "dhcpc.h"
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#include "dhcpd.h"
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/* globals */
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#define g_leases ((struct dyn_lease*)ptr_to_globals)
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/* struct server_config_t server_config is in bb_common_bufsiz1 */
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/* Takes the address of the pointer to the static_leases linked list,
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* address to a 6 byte mac address,
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* 4 byte IP address */
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static void add_static_lease(struct static_lease **st_lease_pp,
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uint8_t *mac,
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uint32_t nip)
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{
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struct static_lease *st_lease;
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/* Find the tail of the list */
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while ((st_lease = *st_lease_pp) != NULL) {
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st_lease_pp = &st_lease->next;
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}
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/* Add new node */
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*st_lease_pp = st_lease = xzalloc(sizeof(*st_lease));
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memcpy(st_lease->mac, mac, 6);
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st_lease->nip = nip;
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/*st_lease->next = NULL;*/
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}
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/* Find static lease IP by mac */
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static uint32_t get_static_nip_by_mac(struct static_lease *st_lease, void *mac)
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{
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while (st_lease) {
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if (memcmp(st_lease->mac, mac, 6) == 0)
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return st_lease->nip;
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st_lease = st_lease->next;
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}
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return 0;
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}
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static int is_nip_reserved(struct static_lease *st_lease, uint32_t nip)
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{
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while (st_lease) {
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if (st_lease->nip == nip)
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return 1;
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st_lease = st_lease->next;
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}
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return 0;
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}
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#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
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/* Print out static leases just to check what's going on */
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/* Takes the address of the pointer to the static_leases linked list */
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static void log_static_leases(struct static_lease **st_lease_pp)
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{
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struct static_lease *cur;
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if (dhcp_verbose < 2)
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return;
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cur = *st_lease_pp;
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while (cur) {
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bb_error_msg("static lease: mac:%02x:%02x:%02x:%02x:%02x:%02x nip:%x",
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cur->mac[0], cur->mac[1], cur->mac[2],
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cur->mac[3], cur->mac[4], cur->mac[5],
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cur->nip
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);
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cur = cur->next;
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}
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}
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#else
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# define log_static_leases(st_lease_pp) ((void)0)
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#endif
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/* Find the oldest expired lease, NULL if there are no expired leases */
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static struct dyn_lease *oldest_expired_lease(void)
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{
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struct dyn_lease *oldest_lease = NULL;
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leasetime_t oldest_time = time(NULL);
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unsigned i;
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/* Unexpired leases have g_leases[i].expires >= current time
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* and therefore can't ever match */
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for (i = 0; i < server_config.max_leases; i++) {
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if (g_leases[i].expires == 0 /* empty entry */
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|| g_leases[i].expires < oldest_time
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) {
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oldest_time = g_leases[i].expires;
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oldest_lease = &g_leases[i];
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}
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}
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return oldest_lease;
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}
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/* Clear out all leases with matching nonzero chaddr OR yiaddr.
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* If chaddr == NULL, this is a conflict lease.
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*/
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static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
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{
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unsigned i;
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for (i = 0; i < server_config.max_leases; i++) {
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if ((chaddr && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
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|| (yiaddr && g_leases[i].lease_nip == yiaddr)
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) {
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memset(&g_leases[i], 0, sizeof(g_leases[i]));
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}
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}
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}
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/* Add a lease into the table, clearing out any old ones.
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* If chaddr == NULL, this is a conflict lease.
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*/
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static struct dyn_lease *add_lease(
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const uint8_t *chaddr, uint32_t yiaddr,
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leasetime_t leasetime,
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const char *hostname, int hostname_len)
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{
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struct dyn_lease *oldest;
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/* clean out any old ones */
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clear_leases(chaddr, yiaddr);
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oldest = oldest_expired_lease();
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if (oldest) {
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memset(oldest, 0, sizeof(*oldest));
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if (hostname) {
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char *p;
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hostname_len++; /* include NUL */
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if (hostname_len > sizeof(oldest->hostname))
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hostname_len = sizeof(oldest->hostname);
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p = safe_strncpy(oldest->hostname, hostname, hostname_len);
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/*
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* Sanitization (s/bad_char/./g).
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* The intent is not to allow only "DNS-valid" hostnames,
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* but merely make dumpleases output safe for shells to use.
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* We accept "0-9A-Za-z._-", all other chars turn to dots.
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*/
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while (*p) {
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if (!isalnum(*p) && *p != '-' && *p != '_')
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*p = '.';
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p++;
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}
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}
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if (chaddr)
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memcpy(oldest->lease_mac, chaddr, 6);
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oldest->lease_nip = yiaddr;
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oldest->expires = time(NULL) + leasetime;
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}
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return oldest;
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}
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/* True if a lease has expired */
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static int is_expired_lease(struct dyn_lease *lease)
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{
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return (lease->expires < (leasetime_t) time(NULL));
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}
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/* Find the first lease that matches MAC, NULL if no match */
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static struct dyn_lease *find_lease_by_mac(const uint8_t *mac)
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{
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unsigned i;
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for (i = 0; i < server_config.max_leases; i++)
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if (memcmp(g_leases[i].lease_mac, mac, 6) == 0)
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return &g_leases[i];
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return NULL;
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}
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/* Find the first lease that matches IP, NULL is no match */
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static struct dyn_lease *find_lease_by_nip(uint32_t nip)
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{
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unsigned i;
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for (i = 0; i < server_config.max_leases; i++)
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if (g_leases[i].lease_nip == nip)
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return &g_leases[i];
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return NULL;
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}
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/* Check if the IP is taken; if it is, add it to the lease table */
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static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac, unsigned arpping_ms)
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{
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struct in_addr temp;
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int r;
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r = arpping(nip, safe_mac,
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server_config.server_nip,
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server_config.server_mac,
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server_config.interface,
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arpping_ms);
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if (r)
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return r;
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temp.s_addr = nip;
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bb_error_msg("%s belongs to someone, reserving it for %u seconds",
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inet_ntoa(temp), (unsigned)server_config.conflict_time);
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add_lease(NULL, nip, server_config.conflict_time, NULL, 0);
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return 0;
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}
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/* Find a new usable (we think) address */
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static uint32_t find_free_or_expired_nip(const uint8_t *safe_mac, unsigned arpping_ms)
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{
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uint32_t addr;
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struct dyn_lease *oldest_lease = NULL;
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#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
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uint32_t stop;
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unsigned i, hash;
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/* hash hwaddr: use the SDBM hashing algorithm. Seems to give good
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* dispersal even with similarly-valued "strings".
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*/
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hash = 0;
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for (i = 0; i < 6; i++)
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hash += safe_mac[i] + (hash << 6) + (hash << 16) - hash;
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/* pick a seed based on hwaddr then iterate until we find a free address. */
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addr = server_config.start_ip
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+ (hash % (1 + server_config.end_ip - server_config.start_ip));
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stop = addr;
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#else
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addr = server_config.start_ip;
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#define stop (server_config.end_ip + 1)
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#endif
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do {
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uint32_t nip;
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struct dyn_lease *lease;
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/* ie, 192.168.55.0 */
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if ((addr & 0xff) == 0)
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goto next_addr;
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/* ie, 192.168.55.255 */
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if ((addr & 0xff) == 0xff)
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goto next_addr;
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nip = htonl(addr);
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/* skip our own address */
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if (nip == server_config.server_nip)
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goto next_addr;
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/* is this a static lease addr? */
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if (is_nip_reserved(server_config.static_leases, nip))
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goto next_addr;
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lease = find_lease_by_nip(nip);
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if (!lease) {
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//TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
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if (nobody_responds_to_arp(nip, safe_mac, arpping_ms))
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return nip;
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} else {
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if (!oldest_lease || lease->expires < oldest_lease->expires)
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oldest_lease = lease;
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}
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next_addr:
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addr++;
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#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
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if (addr > server_config.end_ip)
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addr = server_config.start_ip;
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#endif
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} while (addr != stop);
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if (oldest_lease
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&& is_expired_lease(oldest_lease)
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&& nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac, arpping_ms)
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) {
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return oldest_lease->lease_nip;
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}
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return 0;
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}
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/* On these functions, make sure your datatype matches */
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static int FAST_FUNC read_str(const char *line, void *arg)
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{
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char **dest = arg;
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free(*dest);
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*dest = xstrdup(line);
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return 1;
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}
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static int FAST_FUNC read_u32(const char *line, void *arg)
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{
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*(uint32_t*)arg = bb_strtou32(line, NULL, 10);
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return errno == 0;
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}
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static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
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{
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char *line;
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char *mac_string;
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char *ip_string;
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struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
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uint32_t nip;
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/* Read mac */
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line = (char *) const_line;
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mac_string = strtok_r(line, " \t", &line);
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if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
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return 0;
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/* Read ip */
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ip_string = strtok_r(NULL, " \t", &line);
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if (!ip_string || !udhcp_str2nip(ip_string, &nip))
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return 0;
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add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
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log_static_leases(arg);
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return 1;
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}
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static int FAST_FUNC read_optset(const char *line, void *arg) {
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return udhcp_str2optset(line, arg,
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dhcp_optflags, dhcp_option_strings,
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/*dhcpv6:*/ 0
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);
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}
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struct config_keyword {
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const char *keyword;
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int (*handler)(const char *line, void *var) FAST_FUNC;
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unsigned ofs;
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const char *def;
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};
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#define OFS(field) offsetof(struct server_config_t, field)
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static const struct config_keyword keywords[] = {
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/* keyword handler variable address default */
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{"start" , udhcp_str2nip , OFS(start_ip ), "192.168.0.20"},
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{"end" , udhcp_str2nip , OFS(end_ip ), "192.168.0.254"},
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{"interface" , read_str , OFS(interface ), "eth0"},
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/* Avoid "max_leases value not sane" warning by setting default
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* to default_end_ip - default_start_ip + 1: */
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{"max_leases" , read_u32 , OFS(max_leases ), "235"},
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{"auto_time" , read_u32 , OFS(auto_time ), "7200"},
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{"decline_time" , read_u32 , OFS(decline_time ), "3600"},
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{"conflict_time", read_u32 , OFS(conflict_time), "3600"},
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{"offer_time" , read_u32 , OFS(offer_time ), "60"},
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{"min_lease" , read_u32 , OFS(min_lease_sec), "60"},
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{"lease_file" , read_str , OFS(lease_file ), LEASES_FILE},
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{"pidfile" , read_str , OFS(pidfile ), "/var/run/udhcpd.pid"},
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{"siaddr" , udhcp_str2nip , OFS(siaddr_nip ), "0.0.0.0"},
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/* keywords with no defaults must be last! */
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{"option" , read_optset , OFS(options ), ""},
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{"opt" , read_optset , OFS(options ), ""},
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{"notify_file" , read_str , OFS(notify_file ), NULL},
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{"sname" , read_str , OFS(sname ), NULL},
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{"boot_file" , read_str , OFS(boot_file ), NULL},
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{"static_lease" , read_staticlease, OFS(static_leases), ""},
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};
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enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
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static NOINLINE void read_config(const char *file)
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{
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parser_t *parser;
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const struct config_keyword *k;
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unsigned i;
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char *token[2];
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for (i = 0; i < KWS_WITH_DEFAULTS; i++)
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keywords[i].handler(keywords[i].def, (char*)&server_config + keywords[i].ofs);
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parser = config_open(file);
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while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
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for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
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if (strcasecmp(token[0], k->keyword) == 0) {
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if (!k->handler(token[1], (char*)&server_config + k->ofs)) {
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bb_error_msg("can't parse line %u in %s",
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parser->lineno, file);
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/* reset back to the default value */
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k->handler(k->def, (char*)&server_config + k->ofs);
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}
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break;
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}
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}
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}
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config_close(parser);
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server_config.start_ip = ntohl(server_config.start_ip);
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server_config.end_ip = ntohl(server_config.end_ip);
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}
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static void write_leases(void)
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{
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int fd;
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unsigned i;
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leasetime_t curr;
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int64_t written_at;
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fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
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if (fd < 0)
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return;
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curr = written_at = time(NULL);
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written_at = SWAP_BE64(written_at);
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full_write(fd, &written_at, sizeof(written_at));
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for (i = 0; i < server_config.max_leases; i++) {
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leasetime_t tmp_time;
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if (g_leases[i].lease_nip == 0)
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continue;
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/* Screw with the time in the struct, for easier writing */
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tmp_time = g_leases[i].expires;
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g_leases[i].expires -= curr;
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if ((signed_leasetime_t) g_leases[i].expires < 0)
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g_leases[i].expires = 0;
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g_leases[i].expires = htonl(g_leases[i].expires);
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/* No error check. If the file gets truncated,
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* we lose some leases on restart. Oh well. */
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full_write(fd, &g_leases[i], sizeof(g_leases[i]));
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/* Then restore it when done */
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g_leases[i].expires = tmp_time;
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}
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close(fd);
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if (server_config.notify_file) {
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|
char *argv[3];
|
|
argv[0] = server_config.notify_file;
|
|
argv[1] = server_config.lease_file;
|
|
argv[2] = NULL;
|
|
spawn_and_wait(argv);
|
|
}
|
|
}
|
|
|
|
static NOINLINE void read_leases(const char *file)
|
|
{
|
|
struct dyn_lease lease;
|
|
int64_t written_at, time_passed;
|
|
int fd;
|
|
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
|
|
unsigned i = 0;
|
|
#endif
|
|
|
|
fd = open_or_warn(file, O_RDONLY);
|
|
if (fd < 0)
|
|
return;
|
|
|
|
if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
|
|
goto ret;
|
|
written_at = SWAP_BE64(written_at);
|
|
|
|
time_passed = time(NULL) - written_at;
|
|
/* Strange written_at, or lease file from old version of udhcpd
|
|
* which had no "written_at" field? */
|
|
if ((uint64_t)time_passed > 12 * 60 * 60)
|
|
goto ret;
|
|
|
|
while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
|
|
uint32_t y = ntohl(lease.lease_nip);
|
|
if (y >= server_config.start_ip && y <= server_config.end_ip) {
|
|
signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
|
|
uint32_t static_nip;
|
|
|
|
if (expires <= 0)
|
|
/* We keep expired leases: add_lease() will add
|
|
* a lease with 0 seconds remaining.
|
|
* Fewer IP address changes this way for mass reboot scenario.
|
|
*/
|
|
expires = 0;
|
|
|
|
/* Check if there is a different static lease for this IP or MAC */
|
|
static_nip = get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
|
|
if (static_nip) {
|
|
/* NB: we do not add lease even if static_nip == lease.lease_nip.
|
|
*/
|
|
continue;
|
|
}
|
|
if (is_nip_reserved(server_config.static_leases, lease.lease_nip))
|
|
continue;
|
|
|
|
/* NB: add_lease takes "relative time", IOW,
|
|
* lease duration, not lease deadline. */
|
|
if (add_lease(lease.lease_mac, lease.lease_nip,
|
|
expires,
|
|
lease.hostname, sizeof(lease.hostname)
|
|
) == 0
|
|
) {
|
|
bb_error_msg("too many leases while loading %s", file);
|
|
break;
|
|
}
|
|
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
|
|
i++;
|
|
#endif
|
|
}
|
|
}
|
|
log1("read %d leases", i);
|
|
ret:
|
|
close(fd);
|
|
}
|
|
|
|
/* 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,
|
|
/*send_flags:*/ 0
|
|
);
|
|
}
|
|
|
|
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,
|
|
unsigned arpping_ms)
|
|
{
|
|
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, arpping_ms);
|
|
}
|
|
|
|
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_error_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 %s", "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_error_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);
|
|
}
|
|
|
|
int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
|
int udhcpd_main(int argc UNUSED_PARAM, char **argv)
|
|
{
|
|
int server_socket = -1, retval;
|
|
uint8_t *state;
|
|
unsigned timeout_end;
|
|
unsigned num_ips;
|
|
unsigned opt;
|
|
struct option_set *option;
|
|
char *str_I = str_I;
|
|
const char *str_a = "2000";
|
|
unsigned arpping_ms;
|
|
IF_FEATURE_UDHCP_PORT(char *str_P;)
|
|
|
|
setup_common_bufsiz();
|
|
|
|
IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
|
|
IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
|
|
|
|
opt = getopt32(argv, "^"
|
|
"fSI:va:"IF_FEATURE_UDHCP_PORT("P:")
|
|
"\0"
|
|
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
|
|
"vv"
|
|
#endif
|
|
, &str_I
|
|
, &str_a
|
|
IF_FEATURE_UDHCP_PORT(, &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 (opt & 4) { /* -I */
|
|
len_and_sockaddr *lsa = xhost_and_af2sockaddr(str_I, 0, AF_INET);
|
|
server_config.server_nip = lsa->u.sin.sin_addr.s_addr;
|
|
free(lsa);
|
|
}
|
|
#if ENABLE_FEATURE_UDHCP_PORT
|
|
if (opt & 32) { /* -P */
|
|
SERVER_PORT = xatou16(str_P);
|
|
CLIENT_PORT = SERVER_PORT + 1;
|
|
}
|
|
#endif
|
|
arpping_ms = xatou(str_a);
|
|
|
|
/* Would rather not do read_config before daemonization -
|
|
* otherwise NOMMU machines will parse config twice */
|
|
read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
|
|
/* prevent poll timeout overflow */
|
|
if (server_config.auto_time > INT_MAX / 1000)
|
|
server_config.auto_time = INT_MAX / 1000;
|
|
|
|
/* Make sure fd 0,1,2 are open */
|
|
bb_sanitize_stdio();
|
|
|
|
/* Create pidfile */
|
|
write_pidfile(server_config.pidfile);
|
|
/* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
|
|
|
|
bb_error_msg("started, v"BB_VER);
|
|
|
|
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);
|
|
server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
|
|
}
|
|
|
|
/* Sanity check */
|
|
num_ips = server_config.end_ip - server_config.start_ip + 1;
|
|
if (server_config.max_leases > num_ips) {
|
|
bb_error_msg("max_leases=%u is too big, setting to %u",
|
|
(unsigned)server_config.max_leases, num_ips);
|
|
server_config.max_leases = num_ips;
|
|
}
|
|
|
|
/* this sets g_leases */
|
|
SET_PTR_TO_GLOBALS(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 == 0 ? &server_config.server_nip : NULL),
|
|
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 */
|
|
struct pollfd pfds[2];
|
|
struct dhcp_packet packet;
|
|
int bytes;
|
|
int 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,
|
|
server_config.interface);
|
|
}
|
|
|
|
udhcp_sp_fd_set(pfds, server_socket);
|
|
|
|
new_tv:
|
|
tv = -1;
|
|
if (server_config.auto_time) {
|
|
tv = timeout_end - monotonic_sec();
|
|
if (tv <= 0) {
|
|
write_leases:
|
|
write_leases();
|
|
goto continue_with_autotime;
|
|
}
|
|
tv *= 1000;
|
|
}
|
|
|
|
/* Block here waiting for either signal or packet */
|
|
retval = poll(pfds, 2, tv);
|
|
if (retval <= 0) {
|
|
if (retval == 0)
|
|
goto write_leases;
|
|
if (errno == EINTR)
|
|
goto new_tv;
|
|
/* < 0 and not EINTR: should not happen */
|
|
bb_perror_msg_and_die("poll");
|
|
}
|
|
|
|
if (pfds[0].revents) switch (udhcp_sp_read()) {
|
|
case SIGUSR1:
|
|
bb_error_msg("received %s", "SIGUSR1");
|
|
write_leases();
|
|
/* why not just reset the timeout, eh */
|
|
goto continue_with_autotime;
|
|
case SIGTERM:
|
|
bb_error_msg("received %s", "SIGTERM");
|
|
write_leases();
|
|
goto ret0;
|
|
}
|
|
|
|
/* Is it a packet? */
|
|
if (!pfds[1].revents)
|
|
continue; /* no */
|
|
|
|
/* Note: we do not block here, we block on poll() instead.
|
|
* Blocking here would prevent SIGTERM from working:
|
|
* socket read inside this call is restarted on caught signals.
|
|
*/
|
|
bytes = udhcp_recv_kernel_packet(&packet, server_socket);
|
|
if (bytes < 0) {
|
|
/* bytes can also be -2 ("bad packet data") */
|
|
if (bytes == -1 && errno != EINTR) {
|
|
log1("read error: "STRERROR_FMT", reopening socket" STRERROR_ERRNO);
|
|
close(server_socket);
|
|
server_socket = -1;
|
|
}
|
|
continue;
|
|
}
|
|
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;
|
|
}
|
|
|
|
/* 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) {
|
|
bb_error_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_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:
|
|
log1("received %s", "DISCOVER");
|
|
|
|
send_offer(&packet, static_lease_nip, lease, requested_ip_opt, arpping_ms);
|
|
break;
|
|
|
|
case DHCPREQUEST:
|
|
log1("received %s", "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 */
|
|
|
|
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:
|
|
/* 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 %s", "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:
|
|
/* "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 %s", "RELEASE");
|
|
if (server_id_opt
|
|
&& lease /* chaddr matches this lease */
|
|
&& packet.ciaddr == lease->lease_nip
|
|
) {
|
|
lease->expires = time(NULL);
|
|
}
|
|
break;
|
|
|
|
case DHCPINFORM:
|
|
log1("received %s", "INFORM");
|
|
send_inform(&packet);
|
|
break;
|
|
}
|
|
}
|
|
ret0:
|
|
retval = 0;
|
|
ret:
|
|
/*if (server_config.pidfile) - server_config.pidfile is never NULL */
|
|
remove_pidfile(server_config.pidfile);
|
|
return retval;
|
|
}
|