| /* dnsmasq is Copyright (c) 2000-2017 Simon Kelley |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; version 2 dated June, 1991, or |
| (at your option) version 3 dated 29 June, 2007. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "dnsmasq.h" |
| |
| /* Time between forced re-loads from kernel. */ |
| #define INTERVAL 90 |
| |
| #define ARP_MARK 0 |
| #define ARP_FOUND 1 /* Confirmed */ |
| #define ARP_NEW 2 /* Newly created */ |
| #define ARP_EMPTY 3 /* No MAC addr */ |
| |
| struct arp_record { |
| unsigned short hwlen, status; |
| int family; |
| unsigned char hwaddr[DHCP_CHADDR_MAX]; |
| struct all_addr addr; |
| struct arp_record *next; |
| }; |
| |
| static struct arp_record *arps = NULL, *old = NULL, *freelist = NULL; |
| static time_t last = 0; |
| |
| static int filter_mac(int family, char *addrp, char *mac, size_t maclen, void *parmv) |
| { |
| struct arp_record *arp; |
| |
| (void)parmv; |
| |
| if (maclen > DHCP_CHADDR_MAX) |
| return 1; |
| |
| #ifndef HAVE_IPV6 |
| if (family != AF_INET) |
| return 1; |
| #endif |
| |
| /* Look for existing entry */ |
| for (arp = arps; arp; arp = arp->next) |
| { |
| if (family != arp->family || arp->status == ARP_NEW) |
| continue; |
| |
| if (family == AF_INET) |
| { |
| if (arp->addr.addr.addr4.s_addr != ((struct in_addr *)addrp)->s_addr) |
| continue; |
| } |
| #ifdef HAVE_IPV6 |
| else |
| { |
| if (!IN6_ARE_ADDR_EQUAL(&arp->addr.addr.addr6, (struct in6_addr *)addrp)) |
| continue; |
| } |
| #endif |
| |
| if (arp->status == ARP_EMPTY) |
| { |
| /* existing address, was negative. */ |
| arp->status = ARP_NEW; |
| arp->hwlen = maclen; |
| memcpy(arp->hwaddr, mac, maclen); |
| } |
| else if (arp->hwlen == maclen && memcmp(arp->hwaddr, mac, maclen) == 0) |
| /* Existing entry matches - confirm. */ |
| arp->status = ARP_FOUND; |
| else |
| continue; |
| |
| break; |
| } |
| |
| if (!arp) |
| { |
| /* New entry */ |
| if (freelist) |
| { |
| arp = freelist; |
| freelist = freelist->next; |
| } |
| else if (!(arp = whine_malloc(sizeof(struct arp_record)))) |
| return 1; |
| |
| arp->next = arps; |
| arps = arp; |
| arp->status = ARP_NEW; |
| arp->hwlen = maclen; |
| arp->family = family; |
| memcpy(arp->hwaddr, mac, maclen); |
| if (family == AF_INET) |
| arp->addr.addr.addr4.s_addr = ((struct in_addr *)addrp)->s_addr; |
| #ifdef HAVE_IPV6 |
| else |
| memcpy(&arp->addr.addr.addr6, addrp, IN6ADDRSZ); |
| #endif |
| } |
| |
| return 1; |
| } |
| |
| /* If in lazy mode, we cache absence of ARP entries. */ |
| int find_mac(union mysockaddr *addr, unsigned char *mac, int lazy, time_t now) |
| { |
| struct arp_record *arp, *tmp, **up; |
| int updated = 0; |
| |
| again: |
| |
| /* If the database is less then INTERVAL old, look in there */ |
| if (difftime(now, last) < INTERVAL) |
| { |
| /* addr == NULL -> just make cache up-to-date */ |
| if (!addr) |
| return 0; |
| |
| for (arp = arps; arp; arp = arp->next) |
| { |
| if (addr->sa.sa_family != arp->family) |
| continue; |
| |
| if (arp->family == AF_INET && |
| arp->addr.addr.addr4.s_addr != addr->in.sin_addr.s_addr) |
| continue; |
| |
| #ifdef HAVE_IPV6 |
| if (arp->family == AF_INET6 && |
| !IN6_ARE_ADDR_EQUAL(&arp->addr.addr.addr6, &addr->in6.sin6_addr)) |
| continue; |
| #endif |
| |
| /* Only accept positive entries unless in lazy mode. */ |
| if (arp->status != ARP_EMPTY || lazy || updated) |
| { |
| if (mac && arp->hwlen != 0) |
| memcpy(mac, arp->hwaddr, arp->hwlen); |
| return arp->hwlen; |
| } |
| } |
| } |
| |
| /* Not found, try the kernel */ |
| if (!updated) |
| { |
| updated = 1; |
| last = now; |
| |
| /* Mark all non-negative entries */ |
| for (arp = arps; arp; arp = arp->next) |
| if (arp->status != ARP_EMPTY) |
| arp->status = ARP_MARK; |
| |
| iface_enumerate(AF_UNSPEC, NULL, filter_mac); |
| |
| /* Remove all unconfirmed entries to old list. */ |
| for (arp = arps, up = &arps; arp; arp = tmp) |
| { |
| tmp = arp->next; |
| |
| if (arp->status == ARP_MARK) |
| { |
| *up = arp->next; |
| arp->next = old; |
| old = arp; |
| } |
| else |
| up = &arp->next; |
| } |
| |
| goto again; |
| } |
| |
| /* record failure, so we don't consult the kernel each time |
| we're asked for this address */ |
| if (freelist) |
| { |
| arp = freelist; |
| freelist = freelist->next; |
| } |
| else |
| arp = whine_malloc(sizeof(struct arp_record)); |
| |
| if (arp) |
| { |
| arp->next = arps; |
| arps = arp; |
| arp->status = ARP_EMPTY; |
| arp->family = addr->sa.sa_family; |
| arp->hwlen = 0; |
| |
| if (addr->sa.sa_family == AF_INET) |
| arp->addr.addr.addr4.s_addr = addr->in.sin_addr.s_addr; |
| #ifdef HAVE_IPV6 |
| else |
| memcpy(&arp->addr.addr.addr6, &addr->in6.sin6_addr, IN6ADDRSZ); |
| #endif |
| } |
| |
| return 0; |
| } |
| |
| int do_arp_script_run(void) |
| { |
| struct arp_record *arp; |
| |
| /* Notify any which went, then move to free list */ |
| if (old) |
| { |
| #ifdef HAVE_SCRIPT |
| if (option_bool(OPT_SCRIPT_ARP)) |
| queue_arp(ACTION_ARP_DEL, old->hwaddr, old->hwlen, old->family, &old->addr); |
| #endif |
| arp = old; |
| old = arp->next; |
| arp->next = freelist; |
| freelist = arp; |
| return 1; |
| } |
| |
| for (arp = arps; arp; arp = arp->next) |
| if (arp->status == ARP_NEW) |
| { |
| #ifdef HAVE_SCRIPT |
| if (option_bool(OPT_SCRIPT_ARP)) |
| queue_arp(ACTION_ARP, arp->hwaddr, arp->hwlen, arp->family, &arp->addr); |
| #endif |
| arp->status = ARP_FOUND; |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| |