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/**
* Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License v2 as published by
* the Free Software Foundation.
*
* 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.
*
*/
#include <time.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <resolv.h>
#include <getopt.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdbool.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/ip6.h>
#include <netpacket/packet.h>
#include <linux/rtnetlink.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/syscall.h>
#include <libubox/uloop.h>
#include "odhcpd.h"
static int ioctl_sock;
static int rtnl_socket = -1;
static int rtnl_seq = 0;
static int urandom_fd = -1;
static void sighandler(_unused int signal)
{
uloop_end();
}
int main()
{
openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
setlogmask(LOG_UPTO(LOG_WARNING));
uloop_init();
if (getuid() != 0) {
syslog(LOG_ERR, "Must be run as root!");
return 2;
}
ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
if ((rtnl_socket = odhcpd_open_rtnl()) < 0) {
syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno));
return 2;
}
if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
return 4;
signal(SIGUSR1, SIG_IGN);
signal(SIGINT, sighandler);
signal(SIGTERM, sighandler);
if (init_router())
return 4;
if (init_dhcpv6())
return 4;
if (init_ndp())
return 4;
if (init_dhcpv4())
return 4;
odhcpd_run();
return 0;
}
int odhcpd_open_rtnl(void)
{
int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
// Connect to the kernel netlink interface
struct sockaddr_nl nl = {.nl_family = AF_NETLINK};
if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) {
syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s",
strerror(errno));
return -1;
}
return sock;
}
// Read IPv6 MTU for interface
int odhcpd_get_interface_mtu(const char *ifname)
{
char buf[64];
const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu";
snprintf(buf, sizeof(buf), sysctl_pattern, ifname);
int fd = open(buf, O_RDONLY);
ssize_t len = read(fd, buf, sizeof(buf) - 1);
close(fd);
if (len < 0)
return -1;
buf[len] = 0;
return atoi(buf);
}
// Read IPv6 MAC for interface
int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
{
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
return -1;
memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
return 0;
}
// Forwards a packet on a specific interface
ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
struct iovec *iov, size_t iov_len,
const struct interface *iface)
{
// Construct headers
uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
struct msghdr msg = {(void*)dest, sizeof(*dest), iov, iov_len,
cmsg_buf, sizeof(cmsg_buf), 0};
// Set control data (define destination interface)
struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
chdr->cmsg_level = IPPROTO_IPV6;
chdr->cmsg_type = IPV6_PKTINFO;
chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
pktinfo->ipi6_ifindex = iface->ifindex;
// Also set scope ID if link-local
if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
|| IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
dest->sin6_scope_id = iface->ifindex;
// IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
if (dest->sin6_port == 0) {
msg.msg_control = NULL;
msg.msg_controllen = 0;
}
char ipbuf[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
if (sent < 0)
syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)",
ipbuf, iface->ifname, strerror(errno));
else
syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s",
(long)sent, ipbuf, iface->ifname);
return sent;
}
// Detect an IPV6-address currently assigned to the given interface
ssize_t odhcpd_get_interface_addresses(int ifindex,
struct odhcpd_ipaddr *addrs, size_t cnt)
{
struct {
struct nlmsghdr nhm;
struct ifaddrmsg ifa;
} req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
return 0;
uint8_t buf[8192];
ssize_t len = 0, ret = 0;
for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
len = recv(rtnl_socket, buf, sizeof(buf), 0);
nhm = (struct nlmsghdr*)buf;
if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
if (errno == EINTR)
continue;
else
return ret;
}
}
if (nhm->nlmsg_type != RTM_NEWADDR)
break;
// Skip address but keep clearing socket buffer
if (ret >= (ssize_t)cnt)
continue;
struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
(ifindex && ifa->ifa_index != (unsigned)ifindex))
continue;
struct rtattr *rta = (struct rtattr*)&ifa[1];
size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
memset(&addrs[ret], 0, sizeof(addrs[ret]));
addrs[ret].prefix = ifa->ifa_prefixlen;
while (RTA_OK(rta, alen)) {
if (rta->rta_type == IFA_ADDRESS) {
memcpy(&addrs[ret].addr, RTA_DATA(rta),
sizeof(struct in6_addr));
} else if (rta->rta_type == IFA_CACHEINFO) {
struct ifa_cacheinfo *ifc = RTA_DATA(rta);
addrs[ret].preferred = ifc->ifa_prefered;
addrs[ret].valid = ifc->ifa_valid;
}
rta = RTA_NEXT(rta, alen);
}
if (ifa->ifa_flags & IFA_F_DEPRECATED)
addrs[ret].preferred = 0;
addrs[ret].has_class = false;
addrs[ret].class = 0;
#ifdef WITH_UBUS
struct interface *iface = odhcpd_get_interface_by_index(ifindex);
if (iface)
addrs[ret].has_class = ubus_get_class(iface->ifname,
&addrs[ret].addr, &addrs[ret].class);
#endif
++ret;
}
return ret;
}
int odhcpd_get_preferred_interface_address(int ifindex, struct in6_addr *addr)
{
struct odhcpd_ipaddr ipaddrs[8];
ssize_t ip_cnt = odhcpd_get_interface_addresses(ifindex, ipaddrs, ARRAY_SIZE(ipaddrs));
uint32_t preferred = 0;
int ret = 0;
for (ssize_t i = 0; i < ip_cnt; i++) {
struct odhcpd_ipaddr *ipaddr = &ipaddrs[i];
if (ipaddr->preferred > preferred || !preferred) {
preferred = ipaddr->preferred;
*addr = ipaddr->addr;
ret = 1;
}
}
return ret;
}
struct interface* odhcpd_get_interface_by_index(int ifindex)
{
struct interface *iface;
list_for_each_entry(iface, &interfaces, head)
if (iface->ifindex == ifindex)
return iface;
return NULL;
}
struct interface* odhcpd_get_interface_by_name(const char *name)
{
struct interface *iface;
list_for_each_entry(iface, &interfaces, head)
if (!strcmp(iface->ifname, name))
return iface;
return NULL;
}
struct interface* odhcpd_get_master_interface(void)
{
struct interface *iface;
list_for_each_entry(iface, &interfaces, head)
if (iface->master)
return iface;
return NULL;
}
// Convenience function to receive and do basic validation of packets
static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
{
struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128];
union {
struct sockaddr_in6 in6;
struct sockaddr_in in;
struct sockaddr_ll ll;
struct sockaddr_nl nl;
} addr;
while (true) {
struct iovec iov = {data_buf, sizeof(data_buf)};
struct msghdr msg = {&addr, sizeof(addr), &iov, 1,
cmsg_buf, sizeof(cmsg_buf), 0};
ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN)
break;
else
continue;
}
// Extract destination interface
int destiface = 0;
int *hlim = NULL;
void *dest = NULL;
struct in6_pktinfo *pktinfo;
struct in_pktinfo *pkt4info;
for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) {
if (ch->cmsg_level == IPPROTO_IPV6 &&
ch->cmsg_type == IPV6_PKTINFO) {
pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
destiface = pktinfo->ipi6_ifindex;
dest = &pktinfo->ipi6_addr;
} else if (ch->cmsg_level == IPPROTO_IP &&
ch->cmsg_type == IP_PKTINFO) {
pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
destiface = pkt4info->ipi_ifindex;
dest = &pkt4info->ipi_addr;
} else if (ch->cmsg_level == IPPROTO_IPV6 &&
ch->cmsg_type == IPV6_HOPLIMIT) {
hlim = (int*)CMSG_DATA(ch);
}
}
// Check hoplimit if received
if (hlim && *hlim != 255)
continue;
// Detect interface for packet sockets
if (addr.ll.sll_family == AF_PACKET)
destiface = addr.ll.sll_ifindex;
struct interface *iface =
odhcpd_get_interface_by_index(destiface);
if (!iface && addr.nl.nl_family != AF_NETLINK)
continue;
char ipbuf[INET6_ADDRSTRLEN] = "kernel";
if (addr.ll.sll_family == AF_PACKET &&
len >= (ssize_t)sizeof(struct ip6_hdr))
inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
else if (addr.in6.sin6_family == AF_INET6)
inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
else if (addr.in.sin_family == AF_INET)
inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
syslog(LOG_DEBUG, "--");
syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
ipbuf, (iface) ? iface->ifname : "netlink");
e->handle_dgram(&addr, data_buf, len, iface, dest);
}
}
// Register events for the multiplexer
int odhcpd_register(struct odhcpd_event *event)
{
event->uloop.cb = odhcpd_receive_packets;
return uloop_fd_add(&event->uloop, ULOOP_READ);
}
void odhcpd_process(struct odhcpd_event *event)
{
odhcpd_receive_packets(&event->uloop, 0);
}
void odhcpd_urandom(void *data, size_t len)
{
read(urandom_fd, data, len);
}
time_t odhcpd_time(void)
{
struct timespec ts;
syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
return ts.tv_sec;
}
static const char hexdigits[] = "0123456789abcdef";
static const int8_t hexvals[] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
{
size_t c;
for (c = 0; c < len && src[0] && src[1]; ++c) {
int8_t x = (int8_t)*src++;
int8_t y = (int8_t)*src++;
if (x < 0 || (x = hexvals[x]) < 0
|| y < 0 || (y = hexvals[y]) < 0)
return -1;
dst[c] = x << 4 | y;
while (((int8_t)*src) < 0 ||
(*src && hexvals[(uint8_t)*src] < 0))
src++;
}
return c;
}
void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
{
for (size_t i = 0; i < len; ++i) {
*dst++ = hexdigits[src[i] >> 4];
*dst++ = hexdigits[src[i] & 0x0f];
}
*dst = 0;
}
int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits)
{
const uint8_t *a = av, *b = bv;
size_t bytes = bits / 8;
bits %= 8;
int res = memcmp(a, b, bytes);
if (res == 0 && bits > 0)
res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits));
return res;
}
void odhcpd_bmemcpy(void *av, const void *bv, size_t bits)
{
uint8_t *a = av;
const uint8_t *b = bv;
size_t bytes = bits / 8;
bits %= 8;
memcpy(a, b, bytes);
if (bits > 0) {
uint8_t mask = (1 << (8 - bits)) - 1;
a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]);
}
}
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