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      1  1.1   pooka /*
      2  1.1   pooka  * dhcpcd - DHCP client daemon
      3  1.1   pooka  * Copyright (c) 2006-2010 Roy Marples <roy (at) marples.name>
      4  1.1   pooka  * All rights reserved
      5  1.1   pooka 
      6  1.1   pooka  * Redistribution and use in source and binary forms, with or without
      7  1.1   pooka  * modification, are permitted provided that the following conditions
      8  1.1   pooka  * are met:
      9  1.1   pooka  * 1. Redistributions of source code must retain the above copyright
     10  1.1   pooka  *    notice, this list of conditions and the following disclaimer.
     11  1.1   pooka  * 2. Redistributions in binary form must reproduce the above copyright
     12  1.1   pooka  *    notice, this list of conditions and the following disclaimer in the
     13  1.1   pooka  *    documentation and/or other materials provided with the distribution.
     14  1.1   pooka  *
     15  1.1   pooka  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     16  1.1   pooka  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  1.1   pooka  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18  1.1   pooka  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  1.1   pooka  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  1.1   pooka  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     21  1.1   pooka  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  1.1   pooka  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  1.1   pooka  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  1.1   pooka  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  1.1   pooka  * SUCH DAMAGE.
     26  1.1   pooka  */
     27  1.1   pooka 
     28  1.1   pooka #include <sys/types.h>
     29  1.1   pooka #include <sys/ioctl.h>
     30  1.1   pooka #include <sys/param.h>
     31  1.1   pooka #include <sys/socket.h>
     32  1.1   pooka #include <sys/time.h>
     33  1.1   pooka 
     34  1.1   pooka #include <arpa/inet.h>
     35  1.1   pooka #include <net/if.h>
     36  1.1   pooka #include <net/if_arp.h>
     37  1.1   pooka #ifdef AF_LINK
     38  1.1   pooka #  include <net/if_dl.h>
     39  1.1   pooka #  include <net/if_types.h>
     40  1.1   pooka #endif
     41  1.1   pooka #include <netinet/in_systm.h>
     42  1.1   pooka #include <netinet/in.h>
     43  1.1   pooka #include <netinet/ip.h>
     44  1.1   pooka #define __FAVOR_BSD /* Nasty glibc hack so we can use BSD semantics for UDP */
     45  1.1   pooka #include <netinet/udp.h>
     46  1.1   pooka #undef __FAVOR_BSD
     47  1.1   pooka #ifdef AF_PACKET
     48  1.1   pooka #  include <netpacket/packet.h>
     49  1.1   pooka #endif
     50  1.1   pooka #ifdef SIOCGIFMEDIA
     51  1.1   pooka #  include <net/if_media.h>
     52  1.1   pooka #endif
     53  1.1   pooka 
     54  1.1   pooka #include <ctype.h>
     55  1.1   pooka #include <errno.h>
     56  1.1   pooka #include <ifaddrs.h>
     57  1.1   pooka #include <fnmatch.h>
     58  1.1   pooka #include <stddef.h>
     59  1.1   pooka #include <stdio.h>
     60  1.1   pooka #include <stdlib.h>
     61  1.1   pooka #include <string.h>
     62  1.1   pooka #include <unistd.h>
     63  1.1   pooka 
     64  1.1   pooka #include "common.h"
     65  1.1   pooka #include "dhcp.h"
     66  1.1   pooka #include "if-options.h"
     67  1.1   pooka #include "net.h"
     68  1.1   pooka 
     69  1.1   pooka #include <rump/rump_syscalls.h>
     70  1.1   pooka 
     71  1.1   pooka static char hwaddr_buffer[(HWADDR_LEN * 3) + 1];
     72  1.1   pooka 
     73  1.1   pooka int socket_afnet = -1;
     74  1.1   pooka 
     75  1.1   pooka int
     76  1.1   pooka inet_ntocidr(struct in_addr address)
     77  1.1   pooka {
     78  1.1   pooka 	int cidr = 0;
     79  1.1   pooka 	uint32_t mask = htonl(address.s_addr);
     80  1.1   pooka 
     81  1.1   pooka 	while (mask) {
     82  1.1   pooka 		cidr++;
     83  1.1   pooka 		mask <<= 1;
     84  1.1   pooka 	}
     85  1.1   pooka 	return cidr;
     86  1.1   pooka }
     87  1.1   pooka 
     88  1.1   pooka int
     89  1.1   pooka inet_cidrtoaddr(int cidr, struct in_addr *addr)
     90  1.1   pooka {
     91  1.1   pooka 	int ocets;
     92  1.1   pooka 
     93  1.1   pooka 	if (cidr < 1 || cidr > 32) {
     94  1.1   pooka 		errno = EINVAL;
     95  1.1   pooka 		return -1;
     96  1.1   pooka 	}
     97  1.1   pooka 	ocets = (cidr + 7) / 8;
     98  1.1   pooka 
     99  1.1   pooka 	addr->s_addr = 0;
    100  1.1   pooka 	if (ocets > 0) {
    101  1.1   pooka 		memset(&addr->s_addr, 255, (size_t)ocets - 1);
    102  1.1   pooka 		memset((unsigned char *)&addr->s_addr + (ocets - 1),
    103  1.1   pooka 		    (256 - (1 << (32 - cidr) % 8)), 1);
    104  1.1   pooka 	}
    105  1.1   pooka 
    106  1.1   pooka 	return 0;
    107  1.1   pooka }
    108  1.1   pooka 
    109  1.1   pooka uint32_t
    110  1.1   pooka get_netmask(uint32_t addr)
    111  1.1   pooka {
    112  1.1   pooka 	uint32_t dst;
    113  1.1   pooka 
    114  1.1   pooka 	if (addr == 0)
    115  1.1   pooka 		return 0;
    116  1.1   pooka 
    117  1.1   pooka 	dst = htonl(addr);
    118  1.1   pooka 	if (IN_CLASSA(dst))
    119  1.1   pooka 		return ntohl(IN_CLASSA_NET);
    120  1.1   pooka 	if (IN_CLASSB(dst))
    121  1.1   pooka 		return ntohl(IN_CLASSB_NET);
    122  1.1   pooka 	if (IN_CLASSC(dst))
    123  1.1   pooka 		return ntohl(IN_CLASSC_NET);
    124  1.1   pooka 
    125  1.1   pooka 	return 0;
    126  1.1   pooka }
    127  1.1   pooka 
    128  1.1   pooka char *
    129  1.1   pooka hwaddr_ntoa(const unsigned char *hwaddr, size_t hwlen)
    130  1.1   pooka {
    131  1.1   pooka 	char *p = hwaddr_buffer;
    132  1.1   pooka 	size_t i;
    133  1.1   pooka 
    134  1.1   pooka 	for (i = 0; i < hwlen && i < HWADDR_LEN; i++) {
    135  1.1   pooka 		if (i > 0)
    136  1.1   pooka 			*p ++= ':';
    137  1.1   pooka 		p += snprintf(p, 3, "%.2x", hwaddr[i]);
    138  1.1   pooka 	}
    139  1.1   pooka 
    140  1.1   pooka 	*p ++= '\0';
    141  1.1   pooka 
    142  1.1   pooka 	return hwaddr_buffer;
    143  1.1   pooka }
    144  1.1   pooka 
    145  1.1   pooka size_t
    146  1.1   pooka hwaddr_aton(unsigned char *buffer, const char *addr)
    147  1.1   pooka {
    148  1.1   pooka 	char c[3];
    149  1.1   pooka 	const char *p = addr;
    150  1.1   pooka 	unsigned char *bp = buffer;
    151  1.1   pooka 	size_t len = 0;
    152  1.1   pooka 
    153  1.1   pooka 	c[2] = '\0';
    154  1.1   pooka 	while (*p) {
    155  1.1   pooka 		c[0] = *p++;
    156  1.1   pooka 		c[1] = *p++;
    157  1.1   pooka 		/* Ensure that digits are hex */
    158  1.1   pooka 		if (isxdigit((unsigned char)c[0]) == 0 ||
    159  1.1   pooka 		    isxdigit((unsigned char)c[1]) == 0)
    160  1.1   pooka 		{
    161  1.1   pooka 			errno = EINVAL;
    162  1.1   pooka 			return 0;
    163  1.1   pooka 		}
    164  1.1   pooka 		/* We should have at least two entries 00:01 */
    165  1.1   pooka 		if (len == 0 && *p == '\0') {
    166  1.1   pooka 			errno = EINVAL;
    167  1.1   pooka 			return 0;
    168  1.1   pooka 		}
    169  1.2  andvar 		/* Ensure that next data is EOL or a separator with data */
    170  1.1   pooka 		if (!(*p == '\0' || (*p == ':' && *(p + 1) != '\0'))) {
    171  1.1   pooka 			errno = EINVAL;
    172  1.1   pooka 			return 0;
    173  1.1   pooka 		}
    174  1.1   pooka 		if (*p)
    175  1.1   pooka 			p++;
    176  1.1   pooka 		if (bp)
    177  1.1   pooka 			*bp++ = (unsigned char)strtol(c, NULL, 16);
    178  1.1   pooka 		len++;
    179  1.1   pooka 	}
    180  1.1   pooka 	return len;
    181  1.1   pooka }
    182  1.1   pooka 
    183  1.1   pooka struct interface *
    184  1.1   pooka init_interface(const char *ifname)
    185  1.1   pooka {
    186  1.1   pooka 	struct ifreq ifr;
    187  1.1   pooka 	struct interface *iface = NULL;
    188  1.1   pooka 
    189  1.1   pooka 	memset(&ifr, 0, sizeof(ifr));
    190  1.1   pooka 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    191  1.1   pooka 	if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
    192  1.1   pooka 		goto eexit;
    193  1.1   pooka 
    194  1.1   pooka 	iface = xzalloc(sizeof(*iface));
    195  1.1   pooka 	strlcpy(iface->name, ifname, sizeof(iface->name));
    196  1.1   pooka 	iface->flags = ifr.ifr_flags;
    197  1.1   pooka 	/* We reserve the 100 range for virtual interfaces, if and when
    198  1.1   pooka 	 * we can work them out. */
    199  1.1   pooka 	iface->metric = 200 + if_nametoindex(iface->name);
    200  1.1   pooka 	if (getifssid(ifname, iface->ssid) != -1) {
    201  1.1   pooka 		iface->wireless = 1;
    202  1.1   pooka 		iface->metric += 100;
    203  1.1   pooka 	}
    204  1.1   pooka 
    205  1.1   pooka 	if (rump_sys_ioctl(socket_afnet, SIOCGIFMTU, &ifr) == -1)
    206  1.1   pooka 		goto eexit;
    207  1.1   pooka 	/* Ensure that the MTU is big enough for DHCP */
    208  1.1   pooka 	if (ifr.ifr_mtu < MTU_MIN) {
    209  1.1   pooka 		ifr.ifr_mtu = MTU_MIN;
    210  1.1   pooka 		strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    211  1.1   pooka 		if (rump_sys_ioctl(socket_afnet, SIOCSIFMTU, &ifr) == -1)
    212  1.1   pooka 			goto eexit;
    213  1.1   pooka 	}
    214  1.1   pooka 
    215  1.1   pooka 	/* 0 is a valid fd, so init to -1 */
    216  1.1   pooka 	iface->raw_fd = -1;
    217  1.1   pooka 	iface->udp_fd = -1;
    218  1.1   pooka 	iface->arp_fd = -1;
    219  1.1   pooka 	goto exit;
    220  1.1   pooka 
    221  1.1   pooka eexit:
    222  1.1   pooka 	free(iface);
    223  1.1   pooka 	iface = NULL;
    224  1.1   pooka exit:
    225  1.1   pooka 	return iface;
    226  1.1   pooka }
    227  1.1   pooka 
    228  1.1   pooka int
    229  1.1   pooka carrier_status(struct interface *iface)
    230  1.1   pooka {
    231  1.1   pooka 	int ret;
    232  1.1   pooka 	struct ifreq ifr;
    233  1.1   pooka #ifdef SIOCGIFMEDIA
    234  1.1   pooka 	struct ifmediareq ifmr;
    235  1.1   pooka #endif
    236  1.1   pooka #ifdef __linux__
    237  1.1   pooka 	char *p;
    238  1.1   pooka #endif
    239  1.1   pooka 
    240  1.1   pooka 	memset(&ifr, 0, sizeof(ifr));
    241  1.1   pooka 	strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
    242  1.1   pooka #ifdef __linux__
    243  1.1   pooka 	/* We can only test the real interface up */
    244  1.1   pooka 	if ((p = strchr(ifr.ifr_name, ':')))
    245  1.1   pooka 		*p = '\0';
    246  1.1   pooka #endif
    247  1.1   pooka 
    248  1.1   pooka 	if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
    249  1.1   pooka 		return -1;
    250  1.1   pooka 	iface->flags = ifr.ifr_flags;
    251  1.1   pooka 
    252  1.1   pooka 	ret = -1;
    253  1.1   pooka #ifdef SIOCGIFMEDIA
    254  1.1   pooka 	memset(&ifmr, 0, sizeof(ifmr));
    255  1.1   pooka 	strlcpy(ifmr.ifm_name, iface->name, sizeof(ifmr.ifm_name));
    256  1.1   pooka 	if (rump_sys_ioctl(socket_afnet, SIOCGIFMEDIA, &ifmr) != -1 &&
    257  1.1   pooka 	    ifmr.ifm_status & IFM_AVALID)
    258  1.1   pooka 		ret = (ifmr.ifm_status & IFM_ACTIVE) ? 1 : 0;
    259  1.1   pooka #endif
    260  1.1   pooka 	if (ret == -1)
    261  1.1   pooka 		ret = (ifr.ifr_flags & IFF_RUNNING) ? 1 : 0;
    262  1.1   pooka 	return ret;
    263  1.1   pooka }
    264  1.1   pooka 
    265  1.1   pooka int
    266  1.1   pooka up_interface(struct interface *iface)
    267  1.1   pooka {
    268  1.1   pooka 	struct ifreq ifr;
    269  1.1   pooka 	int retval = -1;
    270  1.1   pooka #ifdef __linux__
    271  1.1   pooka 	char *p;
    272  1.1   pooka #endif
    273  1.1   pooka 
    274  1.1   pooka 	memset(&ifr, 0, sizeof(ifr));
    275  1.1   pooka 	strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
    276  1.1   pooka #ifdef __linux__
    277  1.1   pooka 	/* We can only bring the real interface up */
    278  1.1   pooka 	if ((p = strchr(ifr.ifr_name, ':')))
    279  1.1   pooka 		*p = '\0';
    280  1.1   pooka #endif
    281  1.1   pooka 	if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == 0) {
    282  1.1   pooka 		if ((ifr.ifr_flags & IFF_UP))
    283  1.1   pooka 			retval = 0;
    284  1.1   pooka 		else {
    285  1.1   pooka 			ifr.ifr_flags |= IFF_UP;
    286  1.1   pooka 			if (rump_sys_ioctl(socket_afnet, SIOCSIFFLAGS, &ifr) == 0)
    287  1.1   pooka 				retval = 0;
    288  1.1   pooka 		}
    289  1.1   pooka 		iface->flags = ifr.ifr_flags;
    290  1.1   pooka 	}
    291  1.1   pooka 	return retval;
    292  1.1   pooka }
    293  1.1   pooka 
    294  1.1   pooka int
    295  1.1   pooka do_address(const char *ifname,
    296  1.1   pooka     struct in_addr *addr, struct in_addr *net, struct in_addr *dst, int act)
    297  1.1   pooka {
    298  1.1   pooka 	struct ifaddrs *ifaddrs, *ifa;
    299  1.1   pooka 	const struct sockaddr_in *a, *n, *d;
    300  1.1   pooka 	int retval;
    301  1.1   pooka 
    302  1.1   pooka 	if (getifaddrs(&ifaddrs) == -1)
    303  1.1   pooka 		return -1;
    304  1.1   pooka 
    305  1.1   pooka 	retval = 0;
    306  1.1   pooka 	for (ifa = ifaddrs; ifa; ifa = ifa->ifa_next) {
    307  1.1   pooka 		if (ifa->ifa_addr == NULL ||
    308  1.1   pooka 		    ifa->ifa_addr->sa_family != AF_INET ||
    309  1.1   pooka 		    strcmp(ifa->ifa_name, ifname) != 0)
    310  1.1   pooka 			continue;
    311  1.1   pooka 		a = (const struct sockaddr_in *)(void *)ifa->ifa_addr;
    312  1.1   pooka 		n = (const struct sockaddr_in *)(void *)ifa->ifa_netmask;
    313  1.1   pooka 		if (ifa->ifa_flags & IFF_POINTOPOINT)
    314  1.1   pooka 			d = (const struct sockaddr_in *)(void *)
    315  1.1   pooka 			    ifa->ifa_dstaddr;
    316  1.1   pooka 		else
    317  1.1   pooka 			d = NULL;
    318  1.1   pooka 		if (act == 1) {
    319  1.1   pooka 			addr->s_addr = a->sin_addr.s_addr;
    320  1.1   pooka 			net->s_addr = n->sin_addr.s_addr;
    321  1.1   pooka 			if (dst) {
    322  1.1   pooka 				if (ifa->ifa_flags & IFF_POINTOPOINT)
    323  1.1   pooka 					dst->s_addr = d->sin_addr.s_addr;
    324  1.1   pooka 				else
    325  1.1   pooka 					dst->s_addr = INADDR_ANY;
    326  1.1   pooka 			}
    327  1.1   pooka 			retval = 1;
    328  1.1   pooka 			break;
    329  1.1   pooka 		}
    330  1.1   pooka 		if (addr->s_addr == a->sin_addr.s_addr &&
    331  1.1   pooka 		    (net == NULL || net->s_addr == n->sin_addr.s_addr))
    332  1.1   pooka 		{
    333  1.1   pooka 			retval = 1;
    334  1.1   pooka 			break;
    335  1.1   pooka 		}
    336  1.1   pooka 	}
    337  1.1   pooka 	freeifaddrs(ifaddrs);
    338  1.1   pooka 	return retval;
    339  1.1   pooka }
    340  1.1   pooka 
    341  1.1   pooka int
    342  1.1   pooka do_mtu(const char *ifname, short int mtu)
    343  1.1   pooka {
    344  1.1   pooka 	struct ifreq ifr;
    345  1.1   pooka 	int r;
    346  1.1   pooka 
    347  1.1   pooka 	memset(&ifr, 0, sizeof(ifr));
    348  1.1   pooka 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    349  1.1   pooka 	ifr.ifr_mtu = mtu;
    350  1.1   pooka 	r = rump_sys_ioctl(socket_afnet, mtu ? SIOCSIFMTU : SIOCGIFMTU, &ifr);
    351  1.1   pooka 	if (r == -1)
    352  1.1   pooka 		return -1;
    353  1.1   pooka 	return ifr.ifr_mtu;
    354  1.1   pooka }
    355  1.1   pooka 
    356  1.1   pooka void
    357  1.1   pooka free_routes(struct rt *routes)
    358  1.1   pooka {
    359  1.1   pooka 	struct rt *r;
    360  1.1   pooka 
    361  1.1   pooka 	while (routes) {
    362  1.1   pooka 		r = routes->next;
    363  1.1   pooka 		free(routes);
    364  1.1   pooka 		routes = r;
    365  1.1   pooka 	}
    366  1.1   pooka }
    367  1.1   pooka 
    368  1.1   pooka struct udp_dhcp_packet
    369  1.1   pooka {
    370  1.1   pooka 	struct ip ip;
    371  1.1   pooka 	struct udphdr udp;
    372  1.1   pooka 	struct dhcp_message dhcp;
    373  1.1   pooka };
    374  1.1   pooka const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);
    375  1.1   pooka 
    376  1.1   pooka static uint16_t
    377  1.1   pooka checksum(const void *data, uint16_t len)
    378  1.1   pooka {
    379  1.1   pooka 	const uint8_t *addr = data;
    380  1.1   pooka 	uint32_t sum = 0;
    381  1.1   pooka 
    382  1.1   pooka 	while (len > 1) {
    383  1.1   pooka 		sum += addr[0] * 256 + addr[1];
    384  1.1   pooka 		addr += 2;
    385  1.1   pooka 		len -= 2;
    386  1.1   pooka 	}
    387  1.1   pooka 
    388  1.1   pooka 	if (len == 1)
    389  1.1   pooka 		sum += *addr * 256;
    390  1.1   pooka 
    391  1.1   pooka 	sum = (sum >> 16) + (sum & 0xffff);
    392  1.1   pooka 	sum += (sum >> 16);
    393  1.1   pooka 
    394  1.1   pooka 	sum = htons(sum);
    395  1.1   pooka 
    396  1.1   pooka 	return ~sum;
    397  1.1   pooka }
    398  1.1   pooka 
    399  1.1   pooka ssize_t
    400  1.1   pooka make_udp_packet(uint8_t **packet, const uint8_t *data, size_t length,
    401  1.1   pooka     struct in_addr source, struct in_addr dest)
    402  1.1   pooka {
    403  1.1   pooka 	struct udp_dhcp_packet *udpp;
    404  1.1   pooka 	struct ip *ip;
    405  1.1   pooka 	struct udphdr *udp;
    406  1.1   pooka 
    407  1.1   pooka 	udpp = xzalloc(sizeof(*udpp));
    408  1.1   pooka 	ip = &udpp->ip;
    409  1.1   pooka 	udp = &udpp->udp;
    410  1.1   pooka 
    411  1.1   pooka 	/* OK, this is important :)
    412  1.1   pooka 	 * We copy the data to our packet and then create a small part of the
    413  1.1   pooka 	 * ip structure and an invalid ip_len (basically udp length).
    414  1.1   pooka 	 * We then fill the udp structure and put the checksum
    415  1.1   pooka 	 * of the whole packet into the udp checksum.
    416  1.1   pooka 	 * Finally we complete the ip structure and ip checksum.
    417  1.1   pooka 	 * If we don't do the ordering like so then the udp checksum will be
    418  1.1   pooka 	 * broken, so find another way of doing it! */
    419  1.1   pooka 
    420  1.1   pooka 	memcpy(&udpp->dhcp, data, length);
    421  1.1   pooka 
    422  1.1   pooka 	ip->ip_p = IPPROTO_UDP;
    423  1.1   pooka 	ip->ip_src.s_addr = source.s_addr;
    424  1.1   pooka 	if (dest.s_addr == 0)
    425  1.1   pooka 		ip->ip_dst.s_addr = INADDR_BROADCAST;
    426  1.1   pooka 	else
    427  1.1   pooka 		ip->ip_dst.s_addr = dest.s_addr;
    428  1.1   pooka 
    429  1.1   pooka 	udp->uh_sport = htons(DHCP_CLIENT_PORT);
    430  1.1   pooka 	udp->uh_dport = htons(DHCP_SERVER_PORT);
    431  1.1   pooka 	udp->uh_ulen = htons(sizeof(*udp) + length);
    432  1.1   pooka 	ip->ip_len = udp->uh_ulen;
    433  1.1   pooka 	udp->uh_sum = checksum(udpp, sizeof(*udpp));
    434  1.1   pooka 
    435  1.1   pooka 	ip->ip_v = IPVERSION;
    436  1.1   pooka 	ip->ip_hl = sizeof(*ip) >> 2;
    437  1.1   pooka 	ip->ip_id = arc4random() & UINT16_MAX;
    438  1.1   pooka 	ip->ip_ttl = IPDEFTTL;
    439  1.1   pooka 	ip->ip_len = htons(sizeof(*ip) + sizeof(*udp) + length);
    440  1.1   pooka 	ip->ip_sum = checksum(ip, sizeof(*ip));
    441  1.1   pooka 
    442  1.1   pooka 	*packet = (uint8_t *)udpp;
    443  1.1   pooka 	return sizeof(*ip) + sizeof(*udp) + length;
    444  1.1   pooka }
    445  1.1   pooka 
    446  1.1   pooka ssize_t
    447  1.1   pooka get_udp_data(const uint8_t **data, const uint8_t *udp)
    448  1.1   pooka {
    449  1.1   pooka 	struct udp_dhcp_packet packet;
    450  1.1   pooka 
    451  1.1   pooka 	memcpy(&packet, udp, sizeof(packet));
    452  1.1   pooka 	*data = udp + offsetof(struct udp_dhcp_packet, dhcp);
    453  1.1   pooka 	return ntohs(packet.ip.ip_len) -
    454  1.1   pooka 	    sizeof(packet.ip) -
    455  1.1   pooka 	    sizeof(packet.udp);
    456  1.1   pooka }
    457  1.1   pooka 
    458  1.1   pooka int
    459  1.1   pooka valid_udp_packet(const uint8_t *data, size_t data_len, struct in_addr *from)
    460  1.1   pooka {
    461  1.1   pooka 	struct udp_dhcp_packet packet;
    462  1.1   pooka 	uint16_t bytes, udpsum;
    463  1.1   pooka 
    464  1.1   pooka 	if (data_len < sizeof(packet.ip)) {
    465  1.1   pooka 		if (from)
    466  1.1   pooka 			from->s_addr = INADDR_ANY;
    467  1.1   pooka 		errno = EINVAL;
    468  1.1   pooka 		return -1;
    469  1.1   pooka 	}
    470  1.1   pooka 	memcpy(&packet, data, MIN(data_len, sizeof(packet)));
    471  1.1   pooka 	if (from)
    472  1.1   pooka 		from->s_addr = packet.ip.ip_src.s_addr;
    473  1.1   pooka 	if (data_len > sizeof(packet)) {
    474  1.1   pooka 		errno = EINVAL;
    475  1.1   pooka 		return -1;
    476  1.1   pooka 	}
    477  1.1   pooka 	if (checksum(&packet.ip, sizeof(packet.ip)) != 0) {
    478  1.1   pooka 		errno = EINVAL;
    479  1.1   pooka 		return -1;
    480  1.1   pooka 	}
    481  1.1   pooka 
    482  1.1   pooka 	bytes = ntohs(packet.ip.ip_len);
    483  1.1   pooka 	if (data_len < bytes) {
    484  1.1   pooka 		errno = EINVAL;
    485  1.1   pooka 		return -1;
    486  1.1   pooka 	}
    487  1.1   pooka 	udpsum = packet.udp.uh_sum;
    488  1.1   pooka 	packet.udp.uh_sum = 0;
    489  1.1   pooka 	packet.ip.ip_hl = 0;
    490  1.1   pooka 	packet.ip.ip_v = 0;
    491  1.1   pooka 	packet.ip.ip_tos = 0;
    492  1.1   pooka 	packet.ip.ip_len = packet.udp.uh_ulen;
    493  1.1   pooka 	packet.ip.ip_id = 0;
    494  1.1   pooka 	packet.ip.ip_off = 0;
    495  1.1   pooka 	packet.ip.ip_ttl = 0;
    496  1.1   pooka 	packet.ip.ip_sum = 0;
    497  1.1   pooka 	if (udpsum && checksum(&packet, bytes) != udpsum) {
    498  1.1   pooka 		errno = EINVAL;
    499  1.1   pooka 		return -1;
    500  1.1   pooka 	}
    501  1.1   pooka 
    502  1.1   pooka 	return 0;
    503  1.1   pooka }
    504