/*
* dhcpcd - DHCP client daemon
* Copyright 2006-2008 Roy Marples <roy@marples.name>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include <netinet/in_systm.h>
#ifdef __linux__
#include <netinet/ether.h>
#include <netpacket/packet.h>
#endif
#include <netinet/in.h>
#include <netinet/ip.h>
#define __FAVOR_BSD /* Nasty glibc hack so we can use BSD semantics for UDP */
#include <netinet/udp.h>
#undef __FAVOR_BSD
#ifdef SIOCGIFMEDIA
#include <net/if_media.h>
#endif
#include <arpa/inet.h>
#ifdef AF_LINK
# include <net/if_dl.h>
#endif
#include <ctype.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "config.h"
#include "common.h"
#include "dhcp.h"
#include "logger.h"
#include "net.h"
#include "signals.h"
int
inet_ntocidr(struct in_addr address)
{
int cidr = 0;
uint32_t mask = htonl(address.s_addr);
while (mask) {
cidr++;
mask <<= 1;
}
return cidr;
}
int
inet_cidrtoaddr(int cidr, struct in_addr *addr)
{
int ocets;
if (cidr < 0 || cidr > 32) {
errno = EINVAL;
return -1;
}
ocets = (cidr + 7) / 8;
addr->s_addr = 0;
if (ocets > 0) {
memset(&addr->s_addr, 255, (size_t)ocets - 1);
memset((unsigned char *)&addr->s_addr + (ocets - 1),
(256 - (1 << (32 - cidr) % 8)), 1);
}
return 0;
}
uint32_t
get_netmask(uint32_t addr)
{
uint32_t dst;
if (addr == 0)
return 0;
dst = htonl(addr);
if (IN_CLASSA(dst))
return ntohl(IN_CLASSA_NET);
if (IN_CLASSB (dst))
return ntohl(IN_CLASSB_NET);
if (IN_CLASSC (dst))
return ntohl(IN_CLASSC_NET);
return 0;
}
char *
hwaddr_ntoa(const unsigned char *hwaddr, size_t hwlen)
{
static char buffer[(HWADDR_LEN * 3) + 1];
char *p = buffer;
size_t i;
for (i = 0; i < hwlen && i < HWADDR_LEN; i++) {
if (i > 0)
*p ++= ':';
p += snprintf(p, 3, "%.2x", hwaddr[i]);
}
*p ++= '\0';
return buffer;
}
size_t
hwaddr_aton(unsigned char *buffer, const char *addr)
{
char c[3];
const char *p = addr;
unsigned char *bp = buffer;
size_t len = 0;
c[2] = '\0';
while (*p) {
c[0] = *p++;
c[1] = *p++;
/* Ensure that digits are hex */
if (isxdigit((unsigned char)c[0]) == 0 ||
isxdigit((unsigned char)c[1]) == 0)
{
errno = EINVAL;
return 0;
}
/* We should have at least two entries 00:01 */
if (len == 0 && *p == '\0') {
errno = EINVAL;
return 0;
}
/* Ensure that next data is EOL or a seperator with data */
if (!(*p == '\0' || (*p == ':' && *(p + 1) != '\0'))) {
errno = EINVAL;
return 0;
}
if (*p)
p++;
if (bp)
*bp++ = (unsigned char)strtol(c, NULL, 16);
len++;
}
return len;
}
int
do_interface(const char *ifname,
_unused unsigned char *hwaddr, _unused size_t *hwlen,
struct in_addr *addr, struct in_addr *net, int get)
{
int s;
struct ifconf ifc;
int retval = 0, found = 0;
int len = 10 * sizeof(struct ifreq);
int lastlen = 0;
char *p;
union {
char *buffer;
struct ifreq *ifr;
} ifreqs;
struct sockaddr_in address;
struct ifreq *ifr;
struct sockaddr_in netmask;
#ifdef AF_LINK
struct sockaddr_dl *sdl;
#endif
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
return -1;
/* Not all implementations return the needed buffer size for
* SIOGIFCONF so we loop like so for all until it works */
memset(&ifc, 0, sizeof(ifc));
for (;;) {
ifc.ifc_len = len;
ifc.ifc_buf = xmalloc((size_t)len);
if (ioctl(s, SIOCGIFCONF, &ifc) == -1) {
if (errno != EINVAL || lastlen != 0) {
close(s);
free(ifc.ifc_buf);
return -1;
}
} else {
if (ifc.ifc_len == lastlen)
break;
lastlen = ifc.ifc_len;
}
free(ifc.ifc_buf);
ifc.ifc_buf = NULL;
len *= 2;
}
for (p = (char *)ifc.ifc_buf; p < (char *)ifc.ifc_buf + ifc.ifc_len;) {
/* Cast the ifc buffer to an ifreq cleanly */
ifreqs.buffer = p;
ifr = ifreqs.ifr;
#ifndef __linux__
if (ifr->ifr_addr.sa_len > sizeof(ifr->ifr_ifru))
p += offsetof(struct ifreq, ifr_ifru) +
ifr->ifr_addr.sa_len;
else
#endif
p += sizeof(*ifr);
if (strcmp(ifname, ifr->ifr_name) != 0)
continue;
found = 1;
#ifdef AF_LINK
if (hwaddr && hwlen && ifr->ifr_addr.sa_family == AF_LINK) {
sdl = xmalloc(ifr->ifr_addr.sa_len);
memcpy(sdl, &ifr->ifr_addr, ifr->ifr_addr.sa_len);
*hwlen = sdl->sdl_alen;
memcpy(hwaddr, LLADDR(sdl), *hwlen);
free(sdl);
retval = 1;
break;
}
#endif
if (ifr->ifr_addr.sa_family == AF_INET) {
memcpy(&address, &ifr->ifr_addr, sizeof(address));
if (ioctl(s, SIOCGIFNETMASK, ifr) == -1)
continue;
memcpy(&netmask, &ifr->ifr_addr, sizeof(netmask));
if (get) {
addr->s_addr = address.sin_addr.s_addr;
net->s_addr = netmask.sin_addr.s_addr;
retval = 1;
break;
} else {
if (address.sin_addr.s_addr == addr->s_addr &&
(!net ||
netmask.sin_addr.s_addr == net->s_addr))
{
retval = 1;
break;
}
}
}
}
if (!found)
errno = ENXIO;
close(s);
free(ifc.ifc_buf);
return retval;
}
int
up_interface(const char *ifname)
{
int s;
struct ifreq ifr;
int retval = -1;
#ifdef __linux__
char *p;
#endif
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
return -1;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
#ifdef __linux__
/* We can only bring the real interface up */
if ((p = strchr(ifr.ifr_name, ':')))
*p = '\0';
#endif
if (ioctl(s, SIOCGIFFLAGS, &ifr) == 0) {
if ((ifr.ifr_flags & IFF_UP))
retval = 0;
else {
ifr.ifr_flags |= IFF_UP;
if (ioctl(s, SIOCSIFFLAGS, &ifr) == 0)
retval = 0;
}
}
close(s);
return retval;
}
int
carrier_status(const char *ifname)
{
int s;
struct ifreq ifr;
int retval = -1;
#ifdef SIOCGIFMEDIA
struct ifmediareq ifmr;
#endif
#ifdef __linux__
char *p;
#endif
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
return -1;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
#ifdef __linux__
/* We can only test the real interface up */
if ((p = strchr(ifr.ifr_name, ':')))
*p = '\0';
#endif
if ((retval = ioctl(s, SIOCGIFFLAGS, &ifr)) == 0) {
if (ifr.ifr_flags & IFF_UP && ifr.ifr_flags & IFF_RUNNING)
retval = 1;
else
retval = 0;
}
#ifdef SIOCGIFMEDIA
if (retval == 1) {
memset(&ifmr, 0, sizeof(ifmr));
strncpy(ifmr.ifm_name, ifr.ifr_name, sizeof(ifmr.ifm_name));
if (ioctl(s, SIOCGIFMEDIA, &ifmr) != -1 &&
ifmr.ifm_status & IFM_AVALID)
{
if (!(ifmr.ifm_status & IFM_ACTIVE))
retval = 0;
}
}
#endif
close(s);
return retval;
}
struct interface *
read_interface(const char *ifname, _unused int metric)
{
int s;
struct ifreq ifr;
struct interface *iface = NULL;
unsigned char *hwaddr = NULL;
size_t hwlen = 0;
sa_family_t family = 0;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
return NULL;
#ifdef __linux__
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(s, SIOCGIFHWADDR, &ifr) == -1)
goto eexit;
switch (ifr.ifr_hwaddr.sa_family) {
case ARPHRD_ETHER:
case ARPHRD_IEEE802:
hwlen = ETHER_ADDR_LEN;
break;
case ARPHRD_IEEE1394:
hwlen = EUI64_ADDR_LEN;
case ARPHRD_INFINIBAND:
hwlen = INFINIBAND_ADDR_LEN;
break;
}
hwaddr = xmalloc(sizeof(unsigned char) * HWADDR_LEN);
memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, hwlen);
family = ifr.ifr_hwaddr.sa_family;
#else
ifr.ifr_metric = metric;
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(s, SIOCSIFMETRIC, &ifr) == -1)
goto eexit;
hwaddr = xmalloc(sizeof(unsigned char) * HWADDR_LEN);
if (do_interface(ifname, hwaddr, &hwlen, NULL, NULL, 0) != 1)
goto eexit;
family = ARPHRD_ETHER;
#endif
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(s, SIOCGIFMTU, &ifr) == -1)
goto eexit;
/* Ensure that the MTU is big enough for DHCP */
if (ifr.ifr_mtu < MTU_MIN) {
ifr.ifr_mtu = MTU_MIN;
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(s, SIOCSIFMTU, &ifr) == -1)
goto eexit;
}
if (up_interface(ifname) != 0)
goto eexit;
iface = xzalloc(sizeof(*iface));
strlcpy(iface->name, ifname, IF_NAMESIZE);
snprintf(iface->leasefile, PATH_MAX, LEASEFILE, ifname);
memcpy(&iface->hwaddr, hwaddr, hwlen);
iface->hwlen = hwlen;
iface->family = family;
iface->arpable = !(ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK));
/* 0 is a valid fd, so init to -1 */
iface->raw_fd = -1;
iface->udp_fd = -1;
iface->arp_fd = -1;
iface->link_fd = -1;
eexit:
close(s);
free(hwaddr);
return iface;
}
int
do_mtu(const char *ifname, short int mtu)
{
struct ifreq ifr;
int r;
int s;
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
return -1;
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
ifr.ifr_mtu = mtu;
r = ioctl(s, mtu ? SIOCSIFMTU : SIOCGIFMTU, &ifr);
close(s);
if (r == -1)
return -1;
return ifr.ifr_mtu;
}
void
free_routes(struct rt *routes)
{
struct rt *r;
while (routes) {
r = routes->next;
free(routes);
routes = r;
}
}
int
open_udp_socket(struct interface *iface)
{
int s;
union sockunion {
struct sockaddr sa;
struct sockaddr_in sin;
} su;
int n;
#ifdef SO_BINDTODEVICE
struct ifreq ifr;
#endif
if ((s = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
return -1;
n = 1;
if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &n, sizeof(n)) == -1)
goto eexit;
#ifdef SO_BINDTODEVICE
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr)) == -1)
goto eexit;
#endif
/* As we don't use this socket for receiving, set the
* receive buffer to 1 */
n = 1;
if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n)) == -1)
goto eexit;
memset(&su, 0, sizeof(su));
su.sin.sin_family = AF_INET;
su.sin.sin_port = htons(DHCP_CLIENT_PORT);
su.sin.sin_addr.s_addr = iface->addr.s_addr;
if (bind(s, &su.sa, sizeof(su)) == -1)
goto eexit;
iface->udp_fd = s;
set_cloexec(s);
return 0;
eexit:
close(s);
return -1;
}
ssize_t
send_packet(const struct interface *iface, struct in_addr to,
const uint8_t *data, ssize_t len)
{
union sockunion {
struct sockaddr sa;
struct sockaddr_in sin;
} su;
memset(&su, 0, sizeof(su));
su.sin.sin_family = AF_INET;
su.sin.sin_addr.s_addr = to.s_addr;
su.sin.sin_port = htons(DHCP_SERVER_PORT);
return sendto(iface->udp_fd, data, len, 0, &su.sa, sizeof(su));
}
struct udp_dhcp_packet
{
struct ip ip;
struct udphdr udp;
struct dhcp_message dhcp;
};
const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);
static uint16_t
checksum(const void *data, uint16_t len)
{
const uint8_t *addr = data;
uint32_t sum = 0;
while (len > 1) {
sum += addr[0] * 256 + addr[1];
addr += 2;
len -= 2;
}
if (len == 1)
sum += *addr * 256;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
sum = htons(sum);
return ~sum;
}
ssize_t
make_udp_packet(uint8_t **packet, const uint8_t *data, size_t length,
struct in_addr source, struct in_addr dest)
{
struct udp_dhcp_packet *udpp;
struct ip *ip;
struct udphdr *udp;
udpp = xzalloc(sizeof(*udpp));
ip = &udpp->ip;
udp = &udpp->udp;
/* OK, this is important :)
* We copy the data to our packet and then create a small part of the
* ip structure and an invalid ip_len (basically udp length).
* We then fill the udp structure and put the checksum
* of the whole packet into the udp checksum.
* Finally we complete the ip structure and ip checksum.
* If we don't do the ordering like so then the udp checksum will be
* broken, so find another way of doing it! */
memcpy(&udpp->dhcp, data, length);
ip->ip_p = IPPROTO_UDP;
ip->ip_src.s_addr = source.s_addr;
if (dest.s_addr == 0)
ip->ip_dst.s_addr = INADDR_BROADCAST;
else
ip->ip_dst.s_addr = dest.s_addr;
udp->uh_sport = htons(DHCP_CLIENT_PORT);
udp->uh_dport = htons(DHCP_SERVER_PORT);
udp->uh_ulen = htons(sizeof(*udp) + length);
ip->ip_len = udp->uh_ulen;
udp->uh_sum = checksum(udpp, sizeof(*udpp));
ip->ip_v = IPVERSION;
ip->ip_hl = 5;
ip->ip_id = 0;
ip->ip_tos = IPTOS_LOWDELAY;
ip->ip_len = htons (sizeof(*ip) + sizeof(*udp) + length);
ip->ip_id = 0;
ip->ip_off = htons(IP_DF); /* Don't fragment */
ip->ip_ttl = IPDEFTTL;
ip->ip_sum = checksum(ip, sizeof(*ip));
*packet = (uint8_t *)udpp;
return sizeof(*ip) + sizeof(*udp) + length;
}
ssize_t
get_udp_data(const uint8_t **data, const uint8_t *udp)
{
struct udp_dhcp_packet packet;
memcpy(&packet, udp, sizeof(packet));
*data = udp + offsetof(struct udp_dhcp_packet, dhcp);
return ntohs(packet.ip.ip_len) - sizeof(packet.ip) - sizeof(packet.udp);
}
int
valid_udp_packet(const uint8_t *data)
{
struct udp_dhcp_packet packet;
uint16_t bytes;
uint16_t ipsum;
uint16_t iplen;
uint16_t udpsum;
struct in_addr source;
struct in_addr dest;
int retval = 0;
memcpy(&packet, data, sizeof(packet));
bytes = ntohs(packet.ip.ip_len);
ipsum = packet.ip.ip_sum;
iplen = packet.ip.ip_len;
udpsum = packet.udp.uh_sum;
if (0 != checksum(&packet.ip, sizeof(packet.ip))) {
errno = EINVAL;
return -1;
}
packet.ip.ip_sum = 0;
memcpy(&source, &packet.ip.ip_src, sizeof(packet.ip.ip_src));
memcpy(&dest, &packet.ip.ip_dst, sizeof(packet.ip.ip_dst));
memset(&packet.ip, 0, sizeof(packet.ip));
packet.udp.uh_sum = 0;
packet.ip.ip_p = IPPROTO_UDP;
memcpy(&packet.ip.ip_src, &source, sizeof(packet.ip.ip_src));
memcpy(&packet.ip.ip_dst, &dest, sizeof(packet.ip.ip_dst));
packet.ip.ip_len = packet.udp.uh_ulen;
if (udpsum && udpsum != checksum(&packet, bytes)) {
errno = EINVAL;
retval = -1;
}
return retval;
}
int
send_arp(const struct interface *iface, int op, in_addr_t sip, in_addr_t tip)
{
struct arphdr *arp;
size_t arpsize;
uint8_t *p;
int retval;
arpsize = sizeof(*arp) + 2 * iface->hwlen + 2 * sizeof(sip);
arp = xmalloc(arpsize);
arp->ar_hrd = htons(iface->family);
arp->ar_pro = htons(ETHERTYPE_IP);
arp->ar_hln = iface->hwlen;
arp->ar_pln = sizeof(sip);
arp->ar_op = htons(op);
p = (uint8_t *)arp;
p += sizeof(*arp);
memcpy(p, iface->hwaddr, iface->hwlen);
p += iface->hwlen;
memcpy(p, &sip, sizeof(sip));
p += sizeof(sip);
/* ARP requests should ignore this */
retval = iface->hwlen;
while (retval--)
*p++ = '\0';
memcpy(p, &tip, sizeof(tip));
p += sizeof(tip);
retval = send_raw_packet(iface, ETHERTYPE_ARP, arp, arpsize);
free(arp);
return retval;
}