504 lines
11 KiB
C
504 lines
11 KiB
C
/*
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* dhcpcd - DHCP client daemon
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* Copyright (c) 2006-2010 Roy Marples <roy@marples.name>
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* All rights reserved
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <arpa/inet.h>
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#include <net/if.h>
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#include <net/if_arp.h>
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#ifdef AF_LINK
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# include <net/if_dl.h>
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# include <net/if_types.h>
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#endif
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#include <netinet/in_systm.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#define __FAVOR_BSD /* Nasty glibc hack so we can use BSD semantics for UDP */
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#include <netinet/udp.h>
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#undef __FAVOR_BSD
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#ifdef AF_PACKET
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# include <netpacket/packet.h>
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#endif
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#ifdef SIOCGIFMEDIA
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# include <net/if_media.h>
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#endif
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#include <ctype.h>
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#include <errno.h>
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#include <ifaddrs.h>
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#include <fnmatch.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "common.h"
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#include "dhcp.h"
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#include "if-options.h"
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#include "net.h"
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#include <rump/rump_syscalls.h>
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static char hwaddr_buffer[(HWADDR_LEN * 3) + 1];
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int socket_afnet = -1;
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int
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inet_ntocidr(struct in_addr address)
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{
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int cidr = 0;
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uint32_t mask = htonl(address.s_addr);
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while (mask) {
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cidr++;
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mask <<= 1;
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}
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return cidr;
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}
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int
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inet_cidrtoaddr(int cidr, struct in_addr *addr)
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{
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int ocets;
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if (cidr < 1 || cidr > 32) {
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errno = EINVAL;
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return -1;
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}
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ocets = (cidr + 7) / 8;
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addr->s_addr = 0;
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if (ocets > 0) {
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memset(&addr->s_addr, 255, (size_t)ocets - 1);
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memset((unsigned char *)&addr->s_addr + (ocets - 1),
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(256 - (1 << (32 - cidr) % 8)), 1);
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}
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return 0;
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}
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uint32_t
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get_netmask(uint32_t addr)
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{
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uint32_t dst;
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if (addr == 0)
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return 0;
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dst = htonl(addr);
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if (IN_CLASSA(dst))
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return ntohl(IN_CLASSA_NET);
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if (IN_CLASSB(dst))
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return ntohl(IN_CLASSB_NET);
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if (IN_CLASSC(dst))
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return ntohl(IN_CLASSC_NET);
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return 0;
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}
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char *
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hwaddr_ntoa(const unsigned char *hwaddr, size_t hwlen)
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{
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char *p = hwaddr_buffer;
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size_t i;
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for (i = 0; i < hwlen && i < HWADDR_LEN; i++) {
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if (i > 0)
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*p ++= ':';
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p += snprintf(p, 3, "%.2x", hwaddr[i]);
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}
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*p ++= '\0';
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return hwaddr_buffer;
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}
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size_t
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hwaddr_aton(unsigned char *buffer, const char *addr)
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{
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char c[3];
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const char *p = addr;
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unsigned char *bp = buffer;
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size_t len = 0;
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c[2] = '\0';
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while (*p) {
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c[0] = *p++;
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c[1] = *p++;
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/* Ensure that digits are hex */
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if (isxdigit((unsigned char)c[0]) == 0 ||
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isxdigit((unsigned char)c[1]) == 0)
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{
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errno = EINVAL;
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return 0;
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}
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/* We should have at least two entries 00:01 */
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if (len == 0 && *p == '\0') {
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errno = EINVAL;
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return 0;
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}
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/* Ensure that next data is EOL or a separator with data */
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if (!(*p == '\0' || (*p == ':' && *(p + 1) != '\0'))) {
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errno = EINVAL;
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return 0;
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}
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if (*p)
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p++;
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if (bp)
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*bp++ = (unsigned char)strtol(c, NULL, 16);
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len++;
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}
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return len;
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}
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struct interface *
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init_interface(const char *ifname)
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{
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struct ifreq ifr;
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struct interface *iface = NULL;
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memset(&ifr, 0, sizeof(ifr));
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strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
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if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
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goto eexit;
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iface = xzalloc(sizeof(*iface));
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strlcpy(iface->name, ifname, sizeof(iface->name));
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iface->flags = ifr.ifr_flags;
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/* We reserve the 100 range for virtual interfaces, if and when
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* we can work them out. */
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iface->metric = 200 + if_nametoindex(iface->name);
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if (getifssid(ifname, iface->ssid) != -1) {
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iface->wireless = 1;
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iface->metric += 100;
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}
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if (rump_sys_ioctl(socket_afnet, SIOCGIFMTU, &ifr) == -1)
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goto eexit;
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/* Ensure that the MTU is big enough for DHCP */
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if (ifr.ifr_mtu < MTU_MIN) {
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ifr.ifr_mtu = MTU_MIN;
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strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
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if (rump_sys_ioctl(socket_afnet, SIOCSIFMTU, &ifr) == -1)
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goto eexit;
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}
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/* 0 is a valid fd, so init to -1 */
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iface->raw_fd = -1;
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iface->udp_fd = -1;
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iface->arp_fd = -1;
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goto exit;
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eexit:
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free(iface);
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iface = NULL;
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exit:
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return iface;
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}
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int
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carrier_status(struct interface *iface)
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{
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int ret;
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struct ifreq ifr;
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#ifdef SIOCGIFMEDIA
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struct ifmediareq ifmr;
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#endif
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#ifdef __linux__
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char *p;
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#endif
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memset(&ifr, 0, sizeof(ifr));
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strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
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#ifdef __linux__
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/* We can only test the real interface up */
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if ((p = strchr(ifr.ifr_name, ':')))
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*p = '\0';
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#endif
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if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
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return -1;
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iface->flags = ifr.ifr_flags;
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ret = -1;
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#ifdef SIOCGIFMEDIA
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memset(&ifmr, 0, sizeof(ifmr));
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strlcpy(ifmr.ifm_name, iface->name, sizeof(ifmr.ifm_name));
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if (rump_sys_ioctl(socket_afnet, SIOCGIFMEDIA, &ifmr) != -1 &&
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ifmr.ifm_status & IFM_AVALID)
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ret = (ifmr.ifm_status & IFM_ACTIVE) ? 1 : 0;
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#endif
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if (ret == -1)
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ret = (ifr.ifr_flags & IFF_RUNNING) ? 1 : 0;
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return ret;
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}
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int
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up_interface(struct interface *iface)
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{
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struct ifreq ifr;
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int retval = -1;
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#ifdef __linux__
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char *p;
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#endif
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memset(&ifr, 0, sizeof(ifr));
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strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
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#ifdef __linux__
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/* We can only bring the real interface up */
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if ((p = strchr(ifr.ifr_name, ':')))
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*p = '\0';
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#endif
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if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == 0) {
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if ((ifr.ifr_flags & IFF_UP))
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retval = 0;
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else {
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ifr.ifr_flags |= IFF_UP;
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if (rump_sys_ioctl(socket_afnet, SIOCSIFFLAGS, &ifr) == 0)
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retval = 0;
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}
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iface->flags = ifr.ifr_flags;
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}
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return retval;
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}
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int
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do_address(const char *ifname,
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struct in_addr *addr, struct in_addr *net, struct in_addr *dst, int act)
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{
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struct ifaddrs *ifaddrs, *ifa;
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const struct sockaddr_in *a, *n, *d;
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int retval;
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if (getifaddrs(&ifaddrs) == -1)
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return -1;
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retval = 0;
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for (ifa = ifaddrs; ifa; ifa = ifa->ifa_next) {
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if (ifa->ifa_addr == NULL ||
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ifa->ifa_addr->sa_family != AF_INET ||
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strcmp(ifa->ifa_name, ifname) != 0)
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continue;
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a = (const struct sockaddr_in *)(void *)ifa->ifa_addr;
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n = (const struct sockaddr_in *)(void *)ifa->ifa_netmask;
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if (ifa->ifa_flags & IFF_POINTOPOINT)
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d = (const struct sockaddr_in *)(void *)
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ifa->ifa_dstaddr;
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else
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d = NULL;
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if (act == 1) {
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addr->s_addr = a->sin_addr.s_addr;
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net->s_addr = n->sin_addr.s_addr;
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if (dst) {
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if (ifa->ifa_flags & IFF_POINTOPOINT)
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dst->s_addr = d->sin_addr.s_addr;
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else
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dst->s_addr = INADDR_ANY;
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}
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retval = 1;
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break;
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}
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if (addr->s_addr == a->sin_addr.s_addr &&
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(net == NULL || net->s_addr == n->sin_addr.s_addr))
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{
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retval = 1;
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break;
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}
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}
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freeifaddrs(ifaddrs);
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return retval;
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}
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int
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do_mtu(const char *ifname, short int mtu)
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{
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struct ifreq ifr;
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int r;
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memset(&ifr, 0, sizeof(ifr));
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strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
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ifr.ifr_mtu = mtu;
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r = rump_sys_ioctl(socket_afnet, mtu ? SIOCSIFMTU : SIOCGIFMTU, &ifr);
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if (r == -1)
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return -1;
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return ifr.ifr_mtu;
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}
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void
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free_routes(struct rt *routes)
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{
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struct rt *r;
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while (routes) {
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r = routes->next;
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free(routes);
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routes = r;
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}
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}
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struct udp_dhcp_packet
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{
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struct ip ip;
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struct udphdr udp;
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struct dhcp_message dhcp;
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};
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const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);
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static uint16_t
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checksum(const void *data, uint16_t len)
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{
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const uint8_t *addr = data;
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uint32_t sum = 0;
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while (len > 1) {
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sum += addr[0] * 256 + addr[1];
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addr += 2;
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len -= 2;
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}
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if (len == 1)
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sum += *addr * 256;
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sum = (sum >> 16) + (sum & 0xffff);
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sum += (sum >> 16);
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sum = htons(sum);
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return ~sum;
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}
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ssize_t
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make_udp_packet(uint8_t **packet, const uint8_t *data, size_t length,
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struct in_addr source, struct in_addr dest)
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{
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struct udp_dhcp_packet *udpp;
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struct ip *ip;
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struct udphdr *udp;
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udpp = xzalloc(sizeof(*udpp));
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ip = &udpp->ip;
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udp = &udpp->udp;
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/* OK, this is important :)
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* We copy the data to our packet and then create a small part of the
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* ip structure and an invalid ip_len (basically udp length).
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* We then fill the udp structure and put the checksum
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* of the whole packet into the udp checksum.
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* Finally we complete the ip structure and ip checksum.
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* If we don't do the ordering like so then the udp checksum will be
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* broken, so find another way of doing it! */
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memcpy(&udpp->dhcp, data, length);
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ip->ip_p = IPPROTO_UDP;
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ip->ip_src.s_addr = source.s_addr;
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if (dest.s_addr == 0)
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ip->ip_dst.s_addr = INADDR_BROADCAST;
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else
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ip->ip_dst.s_addr = dest.s_addr;
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udp->uh_sport = htons(DHCP_CLIENT_PORT);
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udp->uh_dport = htons(DHCP_SERVER_PORT);
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udp->uh_ulen = htons(sizeof(*udp) + length);
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ip->ip_len = udp->uh_ulen;
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udp->uh_sum = checksum(udpp, sizeof(*udpp));
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ip->ip_v = IPVERSION;
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ip->ip_hl = sizeof(*ip) >> 2;
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ip->ip_id = arc4random() & UINT16_MAX;
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ip->ip_ttl = IPDEFTTL;
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ip->ip_len = htons(sizeof(*ip) + sizeof(*udp) + length);
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ip->ip_sum = checksum(ip, sizeof(*ip));
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*packet = (uint8_t *)udpp;
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return sizeof(*ip) + sizeof(*udp) + length;
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}
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ssize_t
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get_udp_data(const uint8_t **data, const uint8_t *udp)
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{
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struct udp_dhcp_packet packet;
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memcpy(&packet, udp, sizeof(packet));
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*data = udp + offsetof(struct udp_dhcp_packet, dhcp);
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return ntohs(packet.ip.ip_len) -
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sizeof(packet.ip) -
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sizeof(packet.udp);
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}
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int
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valid_udp_packet(const uint8_t *data, size_t data_len, struct in_addr *from)
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{
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struct udp_dhcp_packet packet;
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uint16_t bytes, udpsum;
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if (data_len < sizeof(packet.ip)) {
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if (from)
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from->s_addr = INADDR_ANY;
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errno = EINVAL;
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return -1;
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}
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memcpy(&packet, data, MIN(data_len, sizeof(packet)));
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if (from)
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from->s_addr = packet.ip.ip_src.s_addr;
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if (data_len > sizeof(packet)) {
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errno = EINVAL;
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return -1;
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}
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if (checksum(&packet.ip, sizeof(packet.ip)) != 0) {
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errno = EINVAL;
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return -1;
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}
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bytes = ntohs(packet.ip.ip_len);
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if (data_len < bytes) {
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errno = EINVAL;
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return -1;
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}
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udpsum = packet.udp.uh_sum;
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packet.udp.uh_sum = 0;
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packet.ip.ip_hl = 0;
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packet.ip.ip_v = 0;
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packet.ip.ip_tos = 0;
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packet.ip.ip_len = packet.udp.uh_ulen;
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packet.ip.ip_id = 0;
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packet.ip.ip_off = 0;
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packet.ip.ip_ttl = 0;
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packet.ip.ip_sum = 0;
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if (udpsum && checksum(&packet, bytes) != udpsum) {
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errno = EINVAL;
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return -1;
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}
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return 0;
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}
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