1 /* $OpenBSD: inet.c,v 1.28 2024/08/28 11:41:42 op Exp $ */
2
3 /*
4 * Copyright (c) 1994, 1995, 1996, 1997, 1998
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the Computer Systems
18 * Engineering Group at Lawrence Berkeley Laboratory.
19 * 4. Neither the name of the University nor of the Laboratory may be used
20 * to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36
37 #include <sys/file.h>
38 #include <sys/ioctl.h>
39 #include <sys/socket.h>
40 #ifdef HAVE_SYS_SOCKIO_H
41 #include <sys/sockio.h>
42 #endif
43 #include <sys/time.h> /* concession to AIX */
44
45 #include <net/if.h>
46 #include <netinet/in.h>
47
48 #include <ctype.h>
49 #include <errno.h>
50 #include <limits.h>
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <string.h>
54 #include <unistd.h>
55 #ifdef HAVE_IFADDRS_H
56 #include <ifaddrs.h>
57 #endif
58
59 #include "pcap-int.h"
60
61 #ifdef HAVE_OS_PROTO_H
62 #include "os-proto.h"
63 #endif
64
65 /*
66 * Free a list of interfaces.
67 */
68 void
pcap_freealldevs(pcap_if_t * alldevs)69 pcap_freealldevs(pcap_if_t *alldevs)
70 {
71 pcap_if_t *curdev, *nextdev;
72 pcap_addr_t *curaddr, *nextaddr;
73
74 for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
75 nextdev = curdev->next;
76
77 /*
78 * Free all addresses.
79 */
80 for (curaddr = curdev->addresses; curaddr != NULL;
81 curaddr = nextaddr) {
82 nextaddr = curaddr->next;
83 free(curaddr->addr);
84 free(curaddr->netmask);
85 free(curaddr->broadaddr);
86 free(curaddr->dstaddr);
87 free(curaddr);
88 }
89
90 /*
91 * Free the name string.
92 */
93 free(curdev->name);
94
95 /*
96 * Free the description string, if any.
97 */
98 free(curdev->description);
99
100 /*
101 * Free the interface.
102 */
103 free(curdev);
104 }
105 }
106
107 /*
108 * Return the name of a network interface attached to the system, or NULL
109 * if none can be found. The interface must be configured up; the
110 * lowest unit number is preferred; loopback is ignored.
111 */
112 char *
pcap_lookupdev(char * errbuf)113 pcap_lookupdev(char *errbuf)
114 {
115 #ifdef HAVE_IFADDRS_H
116 struct ifaddrs *ifap, *ifa, *mp;
117 int n, minunit;
118 char *cp;
119 const char *errstr;
120 static char device[IF_NAMESIZE + 1];
121
122 if (getifaddrs(&ifap) != 0) {
123 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
124 "getifaddrs: %s", pcap_strerror(errno));
125 return NULL;
126 }
127
128 mp = NULL;
129 minunit = 666;
130 for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
131 if ((ifa->ifa_flags & IFF_UP) == 0)
132 continue;
133 if (ISLOOPBACK(ifa->ifa_name, ifa->ifa_flags))
134 continue;
135 for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp)
136 continue;
137 n = strtonum(cp, 0, INT_MAX, &errstr);
138 if (errstr != NULL)
139 continue;
140 if (n < minunit) {
141 minunit = n;
142 mp = ifa;
143 }
144 }
145 if (mp == NULL) {
146 (void)strlcpy(errbuf, "no suitable device found",
147 PCAP_ERRBUF_SIZE);
148 freeifaddrs(ifap);
149 return (NULL);
150 }
151
152 (void)strlcpy(device, mp->ifa_name, sizeof(device));
153 freeifaddrs(ifap);
154 return (device);
155 #else
156 int fd, minunit, n;
157 char *cp;
158 const char *errstr;
159 struct ifreq *ifrp, *ifend, *ifnext, *mp;
160 struct ifconf ifc;
161 struct ifreq ibuf[16], ifr;
162 static char device[sizeof(ifrp->ifr_name) + 1];
163
164 fd = socket(AF_INET, SOCK_DGRAM, 0);
165 if (fd == -1) {
166 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
167 pcap_strerror(errno));
168 return (NULL);
169 }
170 ifc.ifc_len = sizeof ibuf;
171 ifc.ifc_buf = (caddr_t)ibuf;
172
173 memset((char *)ibuf, 0, sizeof(ibuf));
174 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) == -1 ||
175 ifc.ifc_len < sizeof(struct ifreq)) {
176 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "SIOCGIFCONF: %s",
177 pcap_strerror(errno));
178 (void)close(fd);
179 return (NULL);
180 }
181 ifrp = ibuf;
182 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
183
184 mp = NULL;
185 minunit = 666;
186 for (; ifrp < ifend; ifrp = ifnext) {
187 #ifdef HAVE_SOCKADDR_SA_LEN
188 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
189 if (n < sizeof(*ifrp))
190 ifnext = ifrp + 1;
191 else
192 ifnext = (struct ifreq *)((char *)ifrp + n);
193 if (ifrp->ifr_addr.sa_family != AF_INET)
194 continue;
195 #else
196 ifnext = ifrp + 1;
197 #endif
198 /*
199 * Need a template to preserve address info that is
200 * used below to locate the next entry. (Otherwise,
201 * SIOCGIFFLAGS stomps over it because the requests
202 * are returned in a union.)
203 */
204 (void)strlcpy(ifr.ifr_name, ifrp->ifr_name,
205 sizeof(ifr.ifr_name));
206 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) == -1) {
207 if (errno == ENXIO)
208 continue;
209 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
210 "SIOCGIFFLAGS: %.*s: %s",
211 (int)sizeof(ifr.ifr_name), ifr.ifr_name,
212 pcap_strerror(errno));
213 (void)close(fd);
214 return (NULL);
215 }
216
217 /* Must be up and not the loopback */
218 if ((ifr.ifr_flags & IFF_UP) == 0 ||
219 ISLOOPBACK(ifr.ifr_name, ifr.ifr_flags))
220 continue;
221
222 for (cp = ifrp->ifr_name; !isdigit((unsigned char)*cp); ++cp)
223 continue;
224 n = strtonum(cp, 0, INT_MAX, &errstr);
225 if (errstr != NULL)
226 continue;
227 if (n < minunit) {
228 minunit = n;
229 mp = ifrp;
230 }
231 }
232 (void)close(fd);
233 if (mp == NULL) {
234 (void)strlcpy(errbuf, "no suitable device found",
235 PCAP_ERRBUF_SIZE);
236 return (NULL);
237 }
238
239 (void)strlcpy(device, mp->ifr_name, sizeof(device));
240 return (device);
241 #endif
242 }
243
244 int
pcap_lookupnet(const char * device,bpf_u_int32 * netp,bpf_u_int32 * maskp,char * errbuf)245 pcap_lookupnet(const char *device, bpf_u_int32 *netp, bpf_u_int32 *maskp,
246 char *errbuf)
247 {
248 int fd;
249 struct sockaddr_in *sin;
250 struct ifreq ifr;
251
252 fd = socket(AF_INET, SOCK_DGRAM, 0);
253 if (fd == -1) {
254 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
255 pcap_strerror(errno));
256 return (-1);
257 }
258 memset(&ifr, 0, sizeof(ifr));
259 #ifdef linux
260 /* XXX Work around Linux kernel bug */
261 ifr.ifr_addr.sa_family = AF_INET;
262 #endif
263 (void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
264 if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) == -1) {
265 if (errno == EADDRNOTAVAIL) {
266 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
267 "%s: no IPv4 address assigned", device);
268 } else {
269 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
270 "SIOCGIFADDR: %s: %s",
271 device, pcap_strerror(errno));
272 }
273 (void)close(fd);
274 return (-1);
275 }
276 sin = (struct sockaddr_in *)&ifr.ifr_addr;
277 *netp = sin->sin_addr.s_addr;
278 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) == -1) {
279 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
280 "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
281 (void)close(fd);
282 return (-1);
283 }
284 (void)close(fd);
285 *maskp = sin->sin_addr.s_addr;
286 if (*maskp == 0) {
287 if (IN_CLASSA(*netp))
288 *maskp = IN_CLASSA_NET;
289 else if (IN_CLASSB(*netp))
290 *maskp = IN_CLASSB_NET;
291 else if (IN_CLASSC(*netp))
292 *maskp = IN_CLASSC_NET;
293 else {
294 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
295 "inet class for 0x%x unknown", *netp);
296 return (-1);
297 }
298 }
299 *netp &= *maskp;
300 return (0);
301 }
302