Annotation of embedaddon/dnsmasq/src/bpf.c, revision 1.1.1.1
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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