Annotation of embedaddon/dnsmasq/src/bpf.c, revision 1.1
1.1 ! misho 1: /* dnsmasq is Copyright (c) 2000-2013 Simon Kelley
! 2:
! 3: This program is free software; you can redistribute it and/or modify
! 4: it under the terms of the GNU General Public License as published by
! 5: the Free Software Foundation; version 2 dated June, 1991, or
! 6: (at your option) version 3 dated 29 June, 2007.
! 7:
! 8: This program is distributed in the hope that it will be useful,
! 9: but WITHOUT ANY WARRANTY; without even the implied warranty of
! 10: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
! 11: GNU General Public License for more details.
! 12:
! 13: You should have received a copy of the GNU General Public License
! 14: along with this program. If not, see <http://www.gnu.org/licenses/>.
! 15: */
! 16:
! 17: #include "dnsmasq.h"
! 18:
! 19: #if defined(HAVE_BSD_NETWORK) || defined(HAVE_SOLARIS_NETWORK)
! 20: #include <ifaddrs.h>
! 21:
! 22: #if defined(HAVE_BSD_NETWORK) && !defined(__APPLE__)
! 23: #include <sys/param.h>
! 24: #include <sys/sysctl.h>
! 25: #include <net/route.h>
! 26: #include <net/if_dl.h>
! 27: #include <netinet/if_ether.h>
! 28:
! 29: #ifndef SA_SIZE
! 30: #define SA_SIZE(sa) \
! 31: ( (!(sa) || ((struct sockaddr *)(sa))->sa_len == 0) ? \
! 32: sizeof(long) : \
! 33: 1 + ( (((struct sockaddr *)(sa))->sa_len - 1) | (sizeof(long) - 1) ) )
! 34: #endif
! 35:
! 36: int arp_enumerate(void *parm, int (*callback)())
! 37: {
! 38: int mib[6];
! 39: size_t needed;
! 40: char *next;
! 41: struct rt_msghdr *rtm;
! 42: struct sockaddr_inarp *sin2;
! 43: struct sockaddr_dl *sdl;
! 44: struct iovec buff;
! 45: int rc;
! 46:
! 47: buff.iov_base = NULL;
! 48: buff.iov_len = 0;
! 49:
! 50: mib[0] = CTL_NET;
! 51: mib[1] = PF_ROUTE;
! 52: mib[2] = 0;
! 53: mib[3] = AF_INET;
! 54: mib[4] = NET_RT_FLAGS;
! 55: #ifdef RTF_LLINFO
! 56: mib[5] = RTF_LLINFO;
! 57: #else
! 58: mib[5] = 0;
! 59: #endif
! 60: if (sysctl(mib, 6, NULL, &needed, NULL, 0) == -1 || needed == 0)
! 61: return 0;
! 62:
! 63: while (1)
! 64: {
! 65: if (!expand_buf(&buff, needed))
! 66: return 0;
! 67: if ((rc = sysctl(mib, 6, buff.iov_base, &needed, NULL, 0)) == 0 ||
! 68: errno != ENOMEM)
! 69: break;
! 70: needed += needed / 8;
! 71: }
! 72: if (rc == -1)
! 73: return 0;
! 74:
! 75: for (next = buff.iov_base ; next < (char *)buff.iov_base + needed; next += rtm->rtm_msglen)
! 76: {
! 77: rtm = (struct rt_msghdr *)next;
! 78: sin2 = (struct sockaddr_inarp *)(rtm + 1);
! 79: sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
! 80: if (!(*callback)(AF_INET, &sin2->sin_addr, LLADDR(sdl), sdl->sdl_alen, parm))
! 81: return 0;
! 82: }
! 83:
! 84: return 1;
! 85: }
! 86: #endif
! 87:
! 88:
! 89: int iface_enumerate(int family, void *parm, int (*callback)())
! 90: {
! 91: struct ifaddrs *head, *addrs;
! 92: int errsav, ret = 0;
! 93:
! 94: if (family == AF_UNSPEC)
! 95: #if defined(HAVE_BSD_NETWORK) && !defined(__APPLE__)
! 96: return arp_enumerate(parm, callback);
! 97: #else
! 98: return 0; /* need code for Solaris and MacOS*/
! 99: #endif
! 100:
! 101: /* AF_LINK doesn't exist in Linux, so we can't use it in our API */
! 102: if (family == AF_LOCAL)
! 103: family = AF_LINK;
! 104:
! 105: if (getifaddrs(&head) == -1)
! 106: return 0;
! 107:
! 108: for (addrs = head; addrs; addrs = addrs->ifa_next)
! 109: {
! 110: if (addrs->ifa_addr->sa_family == family)
! 111: {
! 112: int iface_index = if_nametoindex(addrs->ifa_name);
! 113:
! 114: if (iface_index == 0 || !addrs->ifa_addr || !addrs->ifa_netmask)
! 115: continue;
! 116:
! 117: if (family == AF_INET)
! 118: {
! 119: struct in_addr addr, netmask, broadcast;
! 120: addr = ((struct sockaddr_in *) addrs->ifa_addr)->sin_addr;
! 121: netmask = ((struct sockaddr_in *) addrs->ifa_netmask)->sin_addr;
! 122: if (addrs->ifa_broadaddr)
! 123: broadcast = ((struct sockaddr_in *) addrs->ifa_broadaddr)->sin_addr;
! 124: else
! 125: broadcast.s_addr = 0;
! 126: if (!((*callback)(addr, iface_index, netmask, broadcast, parm)))
! 127: goto err;
! 128: }
! 129: #ifdef HAVE_IPV6
! 130: else if (family == AF_INET6)
! 131: {
! 132: struct in6_addr *addr = &((struct sockaddr_in6 *) addrs->ifa_addr)->sin6_addr;
! 133: unsigned char *netmask = (unsigned char *) &((struct sockaddr_in6 *) addrs->ifa_netmask)->sin6_addr;
! 134: int scope_id = ((struct sockaddr_in6 *) addrs->ifa_addr)->sin6_scope_id;
! 135: int i, j, prefix = 0;
! 136:
! 137: for (i = 0; i < IN6ADDRSZ; i++, prefix += 8)
! 138: if (netmask[i] != 0xff)
! 139: break;
! 140:
! 141: if (i != IN6ADDRSZ && netmask[i])
! 142: for (j = 7; j > 0; j--, prefix++)
! 143: if ((netmask[i] & (1 << j)) == 0)
! 144: break;
! 145:
! 146: /* voodoo to clear interface field in address */
! 147: if (!option_bool(OPT_NOWILD) && IN6_IS_ADDR_LINKLOCAL(addr))
! 148: {
! 149: addr->s6_addr[2] = 0;
! 150: addr->s6_addr[3] = 0;
! 151: }
! 152:
! 153: /* preferred and valid times == forever until we known how to dtermine them. */
! 154: if (!((*callback)(addr, prefix, scope_id, iface_index, 0, -1, -1, parm)))
! 155: goto err;
! 156: }
! 157: #endif
! 158: #ifdef HAVE_DHCP6
! 159: else if (family == AF_LINK)
! 160: {
! 161: /* Assume ethernet again here */
! 162: struct sockaddr_dl *sdl = (struct sockaddr_dl *) addrs->ifa_addr;
! 163: if (sdl->sdl_alen != 0 &&
! 164: !((*callback)(iface_index, ARPHRD_ETHER, LLADDR(sdl), sdl->sdl_alen, parm)))
! 165: goto err;
! 166: }
! 167: #endif
! 168: }
! 169: }
! 170:
! 171: ret = 1;
! 172:
! 173: err:
! 174: errsav = errno;
! 175: freeifaddrs(head);
! 176: errno = errsav;
! 177:
! 178: return ret;
! 179: }
! 180: #endif
! 181:
! 182:
! 183: #if defined(HAVE_BSD_NETWORK) && defined(HAVE_DHCP)
! 184: #include <net/bpf.h>
! 185:
! 186: void init_bpf(void)
! 187: {
! 188: int i = 0;
! 189:
! 190: while (1)
! 191: {
! 192: sprintf(daemon->dhcp_buff, "/dev/bpf%d", i++);
! 193: if ((daemon->dhcp_raw_fd = open(daemon->dhcp_buff, O_RDWR, 0)) != -1)
! 194: return;
! 195:
! 196: if (errno != EBUSY)
! 197: die(_("cannot create DHCP BPF socket: %s"), NULL, EC_BADNET);
! 198: }
! 199: }
! 200:
! 201: void send_via_bpf(struct dhcp_packet *mess, size_t len,
! 202: struct in_addr iface_addr, struct ifreq *ifr)
! 203: {
! 204: /* Hairy stuff, packet either has to go to the
! 205: net broadcast or the destination can't reply to ARP yet,
! 206: but we do know the physical address.
! 207: Build the packet by steam, and send directly, bypassing
! 208: the kernel IP stack */
! 209:
! 210: struct ether_header ether;
! 211: struct ip ip;
! 212: struct udphdr {
! 213: u16 uh_sport; /* source port */
! 214: u16 uh_dport; /* destination port */
! 215: u16 uh_ulen; /* udp length */
! 216: u16 uh_sum; /* udp checksum */
! 217: } udp;
! 218:
! 219: u32 i, sum;
! 220: struct iovec iov[4];
! 221:
! 222: /* Only know how to do ethernet on *BSD */
! 223: if (mess->htype != ARPHRD_ETHER || mess->hlen != ETHER_ADDR_LEN)
! 224: {
! 225: my_syslog(MS_DHCP | LOG_WARNING, _("DHCP request for unsupported hardware type (%d) received on %s"),
! 226: mess->htype, ifr->ifr_name);
! 227: return;
! 228: }
! 229:
! 230: ifr->ifr_addr.sa_family = AF_LINK;
! 231: if (ioctl(daemon->dhcpfd, SIOCGIFADDR, ifr) < 0)
! 232: return;
! 233:
! 234: memcpy(ether.ether_shost, LLADDR((struct sockaddr_dl *)&ifr->ifr_addr), ETHER_ADDR_LEN);
! 235: ether.ether_type = htons(ETHERTYPE_IP);
! 236:
! 237: if (ntohs(mess->flags) & 0x8000)
! 238: {
! 239: memset(ether.ether_dhost, 255, ETHER_ADDR_LEN);
! 240: ip.ip_dst.s_addr = INADDR_BROADCAST;
! 241: }
! 242: else
! 243: {
! 244: memcpy(ether.ether_dhost, mess->chaddr, ETHER_ADDR_LEN);
! 245: ip.ip_dst.s_addr = mess->yiaddr.s_addr;
! 246: }
! 247:
! 248: ip.ip_p = IPPROTO_UDP;
! 249: ip.ip_src.s_addr = iface_addr.s_addr;
! 250: ip.ip_len = htons(sizeof(struct ip) +
! 251: sizeof(struct udphdr) +
! 252: len) ;
! 253: ip.ip_hl = sizeof(struct ip) / 4;
! 254: ip.ip_v = IPVERSION;
! 255: ip.ip_tos = 0;
! 256: ip.ip_id = htons(0);
! 257: ip.ip_off = htons(0x4000); /* don't fragment */
! 258: ip.ip_ttl = IPDEFTTL;
! 259: ip.ip_sum = 0;
! 260: for (sum = 0, i = 0; i < sizeof(struct ip) / 2; i++)
! 261: sum += ((u16 *)&ip)[i];
! 262: while (sum>>16)
! 263: sum = (sum & 0xffff) + (sum >> 16);
! 264: ip.ip_sum = (sum == 0xffff) ? sum : ~sum;
! 265:
! 266: udp.uh_sport = htons(daemon->dhcp_server_port);
! 267: udp.uh_dport = htons(daemon->dhcp_client_port);
! 268: if (len & 1)
! 269: ((char *)mess)[len] = 0; /* for checksum, in case length is odd. */
! 270: udp.uh_sum = 0;
! 271: udp.uh_ulen = sum = htons(sizeof(struct udphdr) + len);
! 272: sum += htons(IPPROTO_UDP);
! 273: sum += ip.ip_src.s_addr & 0xffff;
! 274: sum += (ip.ip_src.s_addr >> 16) & 0xffff;
! 275: sum += ip.ip_dst.s_addr & 0xffff;
! 276: sum += (ip.ip_dst.s_addr >> 16) & 0xffff;
! 277: for (i = 0; i < sizeof(struct udphdr)/2; i++)
! 278: sum += ((u16 *)&udp)[i];
! 279: for (i = 0; i < (len + 1) / 2; i++)
! 280: sum += ((u16 *)mess)[i];
! 281: while (sum>>16)
! 282: sum = (sum & 0xffff) + (sum >> 16);
! 283: udp.uh_sum = (sum == 0xffff) ? sum : ~sum;
! 284:
! 285: ioctl(daemon->dhcp_raw_fd, BIOCSETIF, ifr);
! 286:
! 287: iov[0].iov_base = ðer;
! 288: iov[0].iov_len = sizeof(ether);
! 289: iov[1].iov_base = &ip;
! 290: iov[1].iov_len = sizeof(ip);
! 291: iov[2].iov_base = &udp;
! 292: iov[2].iov_len = sizeof(udp);
! 293: iov[3].iov_base = mess;
! 294: iov[3].iov_len = len;
! 295:
! 296: while (writev(daemon->dhcp_raw_fd, iov, 4) == -1 && retry_send());
! 297: }
! 298:
! 299: #endif
! 300:
! 301:
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