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1 | /* |
2 | * Copyright (c) 1997-2009 Red Hat, Inc. All rights reserved. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License, version 2, | |
6 | * as published by the Free Software Foundation. | |
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, write to the Free Software | |
15 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA | |
16 | * | |
17 | * Authors: | |
18 | * Erik Troan <ewt@redhat.com> | |
19 | * Preston Brown <pbrown@redhat.com> | |
20 | * David Cantrell <dcantrell@redhat.com> | |
21 | */ | |
22 | ||
23 | #include <ctype.h> | |
24 | #include <popt.h> | |
25 | #include <stdio.h> | |
26 | #include <stdlib.h> | |
27 | #include <string.h> | |
28 | #include <sys/socket.h> | |
29 | #include <sys/types.h> | |
30 | #include <netinet/in.h> | |
31 | #include <arpa/inet.h> | |
32 | #include <netdb.h> | |
33 | ||
34 | /*! | |
35 | \file ipcalc.c | |
36 | \brief provides utilities for manipulating IP addresses. | |
37 | ||
38 | ipcalc provides utilities and a front-end command line interface for | |
39 | manipulating IP addresses, and calculating various aspects of an ip | |
40 | address/netmask/network address/prefix/etc. | |
41 | ||
42 | Functionality can be accessed from other languages from the library | |
43 | interface, documented here. To use ipcalc from the shell, read the | |
44 | ipcalc(1) manual page. | |
45 | ||
46 | When passing parameters to the various functions, take note of whether they | |
47 | take host byte order or network byte order. Most take host byte order, and | |
48 | return host byte order, but there are some exceptions. | |
49 | */ | |
50 | ||
51 | /*! | |
52 | \fn struct in_addr prefix2mask(int bits) | |
53 | \brief creates a netmask from a specified number of bits | |
54 | ||
55 | This function converts a prefix length to a netmask. As CIDR (classless | |
56 | internet domain internet domain routing) has taken off, more an more IP | |
57 | addresses are being specified in the format address/prefix | |
58 | (i.e. 192.168.2.3/24, with a corresponding netmask 255.255.255.0). If you | |
59 | need to see what netmask corresponds to the prefix part of the address, this | |
60 | is the function. See also \ref mask2prefix. | |
61 | ||
62 | \param prefix is the number of bits to create a mask for. | |
63 | \return a network mask, in network byte order. | |
64 | */ | |
65 | struct in_addr prefix2mask(int prefix) { | |
66 | struct in_addr mask; | |
67 | memset(&mask, 0, sizeof(mask)); | |
68 | if (prefix) { | |
69 | mask.s_addr = htonl(~((1 << (32 - prefix)) - 1)); | |
70 | } else { | |
71 | mask.s_addr = htonl(0); | |
72 | } | |
73 | return mask; | |
74 | } | |
75 | ||
76 | /*! | |
77 | \fn int mask2prefix(struct in_addr mask) | |
78 | \brief calculates the number of bits masked off by a netmask. | |
79 | ||
80 | This function calculates the significant bits in an IP address as specified by | |
81 | a netmask. See also \ref prefix2mask. | |
82 | ||
83 | \param mask is the netmask, specified as an struct in_addr in network byte order. | |
84 | \return the number of significant bits. */ | |
85 | int mask2prefix(struct in_addr mask) | |
86 | { | |
87 | int count; | |
88 | uint32_t saddr = ntohl(mask.s_addr); | |
89 | ||
90 | for (count=0; saddr > 0; count++) { | |
91 | saddr=saddr << 1; | |
92 | } | |
93 | ||
94 | return count; | |
95 | } | |
96 | ||
97 | /*! | |
98 | \fn struct in_addr default_netmask(struct in_addr addr) | |
99 | ||
100 | \brief returns the default (canonical) netmask associated with specified IP | |
101 | address. | |
102 | ||
103 | When the Internet was originally set up, various ranges of IP addresses were | |
104 | segmented into three network classes: A, B, and C. This function will return | |
105 | a netmask that is associated with the IP address specified defining where it | |
106 | falls in the predefined classes. | |
107 | ||
108 | \param addr an IP address in network byte order. | |
109 | \return a netmask in network byte order. */ | |
110 | struct in_addr default_netmask(struct in_addr addr) | |
111 | { | |
112 | uint32_t saddr = addr.s_addr; | |
113 | struct in_addr mask; | |
114 | ||
115 | memset(&mask, 0, sizeof(mask)); | |
116 | ||
117 | if (((ntohl(saddr) & 0xFF000000) >> 24) <= 127) | |
118 | mask.s_addr = htonl(0xFF000000); | |
119 | else if (((ntohl(saddr) & 0xFF000000) >> 24) <= 191) | |
120 | mask.s_addr = htonl(0xFFFF0000); | |
121 | else | |
122 | mask.s_addr = htonl(0xFFFFFF00); | |
123 | ||
124 | return mask; | |
125 | } | |
126 | ||
127 | /*! | |
128 | \fn struct in_addr calc_broadcast(struct in_addr addr, int prefix) | |
129 | ||
130 | \brief calculate broadcast address given an IP address and a prefix length. | |
131 | ||
132 | \param addr an IP address in network byte order. | |
133 | \param prefix a prefix length. | |
134 | ||
135 | \return the calculated broadcast address for the network, in network byte | |
136 | order. | |
137 | */ | |
138 | struct in_addr calc_broadcast(struct in_addr addr, int prefix) | |
139 | { | |
140 | struct in_addr mask = prefix2mask(prefix); | |
141 | struct in_addr broadcast; | |
142 | ||
143 | memset(&broadcast, 0, sizeof(broadcast)); | |
144 | broadcast.s_addr = (addr.s_addr & mask.s_addr) | ~mask.s_addr; | |
145 | return broadcast; | |
146 | } | |
147 | ||
148 | /*! | |
149 | \fn struct in_addr calc_network(struct in_addr addr, int prefix) | |
150 | \brief calculates the network address for a specified address and prefix. | |
151 | ||
152 | \param addr an IP address, in network byte order | |
153 | \param prefix the network prefix | |
154 | \return the base address of the network that addr is associated with, in | |
155 | network byte order. | |
156 | */ | |
157 | struct in_addr calc_network(struct in_addr addr, int prefix) | |
158 | { | |
159 | struct in_addr mask = prefix2mask(prefix); | |
160 | struct in_addr network; | |
161 | ||
162 | memset(&network, 0, sizeof(network)); | |
163 | network.s_addr = addr.s_addr & mask.s_addr; | |
164 | return network; | |
165 | } | |
166 | ||
167 | /*! | |
168 | \fn const char *get_hostname(int family, void *addr) | |
169 | \brief returns the hostname associated with the specified IP address | |
170 | ||
171 | \param family the address family, either AF_INET or AF_INET6. | |
172 | \param addr an IP address to find a hostname for, in network byte order, | |
173 | should either be a pointer to a struct in_addr or a struct in6_addr. | |
174 | ||
175 | \return a hostname, or NULL if one cannot be determined. Hostname is stored | |
176 | in a static buffer that may disappear at any time, the caller should copy the | |
177 | data if it needs permanent storage. | |
178 | */ | |
179 | char *get_hostname(int family, void *addr) | |
180 | { | |
181 | struct hostent * hostinfo = NULL; | |
182 | int x; | |
183 | struct in_addr addr4; | |
184 | struct in6_addr addr6; | |
185 | ||
186 | if (family == AF_INET) { | |
187 | memset(&addr4, 0, sizeof(addr4)); | |
188 | memcpy(&addr4, addr, sizeof(addr4)); | |
189 | hostinfo = gethostbyaddr((const void *) &addr4, | |
190 | sizeof(addr4), family); | |
191 | } else if (family == AF_INET6) { | |
192 | memset(&addr6, 0, sizeof(addr6)); | |
193 | memcpy(&addr6, addr, sizeof(addr6)); | |
194 | hostinfo = gethostbyaddr((const void *) &addr6, | |
195 | sizeof(addr6), family); | |
196 | } | |
197 | ||
198 | if (!hostinfo) | |
199 | return NULL; | |
200 | ||
201 | for (x=0; hostinfo->h_name[x]; x++) { | |
202 | hostinfo->h_name[x] = tolower(hostinfo->h_name[x]); | |
203 | } | |
204 | return hostinfo->h_name; | |
205 | } | |
206 | ||
207 | /*! | |
208 | \fn main(int argc, const char **argv) | |
209 | \brief wrapper program for ipcalc functions. | |
210 | ||
211 | This is a wrapper program for the functions that the ipcalc library provides. | |
212 | It can be used from shell scripts or directly from the command line. | |
213 | ||
214 | For more information, please see the ipcalc(1) man page. | |
215 | */ | |
216 | int main(int argc, const char **argv) { | |
217 | int showBroadcast = 0, showPrefix = 0, showNetwork = 0; | |
218 | int showHostname = 0, showNetmask = 0; | |
219 | int beSilent = 0; | |
220 | int doCheck = 0, familyIPv4 = 0, familyIPv6 = 0; | |
221 | int rc; | |
222 | poptContext optCon; | |
223 | char *ipStr, *prefixStr, *netmaskStr, *chptr; | |
224 | char *hostName = NULL; | |
225 | char namebuf[INET6_ADDRSTRLEN+1]; | |
226 | struct in_addr ip, netmask, network, broadcast; | |
227 | struct in6_addr ip6; | |
228 | int prefix = -1; | |
229 | char errBuf[250]; | |
230 | struct poptOption optionsTable[] = { | |
231 | { "check", 'c', 0, &doCheck, 0, | |
232 | "Validate IP address for specified address family", }, | |
233 | { "ipv4", '4', 0, &familyIPv4, 0, | |
234 | "IPv4 address family (default)", }, | |
235 | { "ipv6", '6', 0, &familyIPv6, 0, | |
236 | "IPv6 address family", }, | |
237 | { "broadcast", 'b', 0, &showBroadcast, 0, | |
238 | "Display calculated broadcast address", }, | |
239 | { "hostname", 'h', 0, &showHostname, 0, | |
240 | "Show hostname determined via DNS" }, | |
241 | { "netmask", 'm', 0, &showNetmask, 0, | |
242 | "Display default netmask for IP (class A, B, or C)" }, | |
243 | { "network", 'n', 0, &showNetwork, 0, | |
244 | "Display network address", }, | |
245 | { "prefix", 'p', 0, &showPrefix, 0, | |
246 | "Display network prefix", }, | |
247 | { "silent", 's', 0, &beSilent, 0, | |
248 | "Don't ever display error messages" }, | |
249 | POPT_AUTOHELP | |
250 | { NULL, '\0', 0, 0, 0, NULL, NULL } | |
251 | }; | |
252 | ||
253 | optCon = poptGetContext("ipcalc", argc, argv, optionsTable, 0); | |
254 | poptReadDefaultConfig(optCon, 1); | |
255 | ||
256 | if ((rc = poptGetNextOpt(optCon)) < -1) { | |
257 | if (!beSilent) { | |
258 | fprintf(stderr, "ipcalc: bad argument %s: %s\n", | |
259 | poptBadOption(optCon, POPT_BADOPTION_NOALIAS), | |
260 | poptStrerror(rc)); | |
261 | poptPrintHelp(optCon, stderr, 0); | |
262 | } | |
263 | return 1; | |
264 | } | |
265 | ||
266 | if (!(ipStr = (char *) poptGetArg(optCon))) { | |
267 | if (!beSilent) { | |
268 | fprintf(stderr, "ipcalc: ip address expected\n"); | |
269 | poptPrintHelp(optCon, stderr, 0); | |
270 | } | |
271 | return 1; | |
272 | } | |
273 | ||
274 | /* if there is a : in the address, it is an IPv6 address */ | |
275 | if (strchr(ipStr,':') != NULL) { | |
276 | familyIPv6=1; | |
277 | } | |
278 | ||
279 | if (strchr(ipStr,'/') != NULL) { | |
280 | prefixStr = strchr(ipStr, '/') + 1; | |
281 | prefixStr--; | |
282 | *prefixStr = '\0'; /* fix up ipStr */ | |
283 | prefixStr++; | |
284 | } else { | |
285 | prefixStr = NULL; | |
286 | } | |
287 | ||
288 | if (prefixStr != NULL) { | |
289 | prefix = atoi(prefixStr); | |
290 | if (prefix < 0 || ((familyIPv6 && prefix > 128) || (!familyIPv6 && prefix > 32))) { | |
291 | if (!beSilent) | |
292 | fprintf(stderr, "ipcalc: bad prefix: %s\n", prefixStr); | |
293 | return 1; | |
294 | } | |
295 | } | |
296 | ||
297 | if (showBroadcast || showNetwork || showPrefix) { | |
298 | if (!(netmaskStr = (char *) poptGetArg(optCon)) && (prefix < 0)) { | |
299 | if (!beSilent) { | |
300 | fprintf(stderr, "ipcalc: netmask or prefix expected\n"); | |
301 | poptPrintHelp(optCon, stderr, 0); | |
302 | } | |
303 | return 1; | |
304 | } else if (netmaskStr && prefix >= 0) { | |
305 | if (!beSilent) { | |
306 | fprintf(stderr, "ipcalc: both netmask and prefix specified\n"); | |
307 | poptPrintHelp(optCon, stderr, 0); | |
308 | } | |
309 | return 1; | |
310 | } else if (netmaskStr) { | |
311 | if (inet_pton(AF_INET, netmaskStr, &netmask) <= 0) { | |
312 | if (!beSilent) | |
313 | fprintf(stderr, "ipcalc: bad netmask: %s\n", netmaskStr); | |
314 | return 1; | |
315 | } | |
316 | prefix = mask2prefix(netmask); | |
317 | } | |
318 | } | |
319 | ||
320 | if ((chptr = (char *) poptGetArg(optCon))) { | |
321 | if (!beSilent) { | |
322 | fprintf(stderr, "ipcalc: unexpected argument: %s\n", chptr); | |
323 | poptPrintHelp(optCon, stderr, 0); | |
324 | } | |
325 | return 1; | |
326 | } | |
327 | ||
328 | if (!familyIPv4 && !familyIPv6) | |
329 | familyIPv4 = 1; | |
330 | ||
331 | if (familyIPv4 && familyIPv6) { | |
332 | if (!beSilent) { | |
333 | fprintf(stderr, "ipcalc: cannot specify both address families\n"); | |
334 | } | |
335 | return 1; | |
336 | } | |
337 | ||
338 | /* Handle CIDR entries such as 172/8 */ | |
339 | if (prefix >= 0 && familyIPv4) { | |
340 | char *tmp = ipStr; | |
341 | int i; | |
342 | ||
343 | for (i=3; i> 0; i--) { | |
344 | tmp = strchr(tmp,'.'); | |
345 | if (!tmp) | |
346 | break; | |
347 | else | |
348 | tmp++; | |
349 | } | |
350 | ||
351 | tmp = NULL; | |
352 | for (; i>0; i--) { | |
353 | if (asprintf(&tmp, "%s.0", ipStr) == -1) { | |
354 | fprintf(stderr, "Memory allocation failure line %d\n", __LINE__); | |
355 | abort(); | |
356 | } | |
357 | ipStr = tmp; | |
358 | } | |
359 | } | |
360 | ||
361 | if (familyIPv4) { | |
362 | if (inet_pton(AF_INET, ipStr, &ip) <= 0) { | |
363 | if (!beSilent) | |
364 | fprintf(stderr, "ipcalc: bad IPv4 address: %s\n", ipStr); | |
365 | return 1; | |
366 | } else if (prefix > 32) { | |
367 | if (!beSilent) | |
368 | fprintf(stderr, "ipcalc: bad IPv4 prefix %d\n", prefix); | |
369 | return 1; | |
370 | } else { | |
371 | if (doCheck) | |
372 | return 0; | |
373 | } | |
374 | } | |
375 | ||
376 | if (familyIPv6) { | |
377 | if (inet_pton(AF_INET6, ipStr, &ip6) <= 0) { | |
378 | if (!beSilent) | |
379 | fprintf(stderr, "ipcalc: bad IPv6 address: %s\n", ipStr); | |
380 | return 1; | |
381 | } else if (prefix > 128) { | |
382 | if (!beSilent) | |
383 | fprintf(stderr, "ipcalc: bad IPv6 prefix %d\n", prefix); | |
384 | return 1; | |
385 | } else { | |
386 | if (doCheck) | |
387 | return 0; | |
388 | } | |
389 | } | |
390 | ||
391 | if (familyIPv6 && | |
392 | (showBroadcast || showNetmask || showNetwork || showPrefix)) { | |
393 | if (!beSilent) { | |
394 | fprintf(stderr, "ipcalc: unable to show setting for IPv6\n"); | |
395 | } | |
396 | return 1; | |
397 | } | |
398 | ||
399 | if (familyIPv4 && | |
400 | !(showNetmask|showPrefix|showBroadcast|showNetwork|showHostname)) { | |
401 | poptPrintHelp(optCon, stderr, 0); | |
402 | return 1; | |
403 | } | |
404 | ||
405 | poptFreeContext(optCon); | |
406 | ||
407 | /* we know what we want to display now, so display it. */ | |
408 | ||
409 | if (showNetmask) { | |
410 | if (prefix >= 0) { | |
411 | netmask = prefix2mask(prefix); | |
412 | } else { | |
413 | netmask = default_netmask(ip); | |
414 | prefix = mask2prefix(netmask); | |
415 | } | |
416 | ||
417 | memset(&namebuf, '\0', sizeof(namebuf)); | |
418 | ||
419 | if (inet_ntop(AF_INET, &netmask, namebuf, INET_ADDRSTRLEN) == NULL) { | |
420 | fprintf(stderr, "Memory allocation failure line %d\n", __LINE__); | |
421 | abort(); | |
422 | } | |
423 | ||
424 | printf("NETMASK=%s\n", namebuf); | |
425 | } | |
426 | ||
427 | if (showPrefix) { | |
428 | if (prefix == -1) | |
429 | prefix = mask2prefix(ip); | |
430 | printf("PREFIX=%d\n", prefix); | |
431 | } | |
432 | ||
433 | if (showBroadcast) { | |
434 | broadcast = calc_broadcast(ip, prefix); | |
435 | memset(&namebuf, '\0', sizeof(namebuf)); | |
436 | ||
437 | if (inet_ntop(AF_INET, &broadcast, namebuf, INET_ADDRSTRLEN) == NULL) { | |
438 | fprintf(stderr, "Memory allocation failure line %d\n", __LINE__); | |
439 | abort(); | |
440 | } | |
441 | ||
442 | printf("BROADCAST=%s\n", namebuf); | |
443 | } | |
444 | ||
445 | if (showNetwork) { | |
446 | network = calc_network(ip, prefix); | |
447 | memset(&namebuf, '\0', sizeof(namebuf)); | |
448 | ||
449 | if (inet_ntop(AF_INET, &network, namebuf, INET_ADDRSTRLEN) == NULL) { | |
450 | fprintf(stderr, "Memory allocation failure line %d\n", __LINE__); | |
451 | abort(); | |
452 | } | |
453 | ||
454 | printf("NETWORK=%s\n", namebuf); | |
455 | } | |
456 | ||
457 | if (showHostname) { | |
458 | if (familyIPv4) { | |
459 | hostName = get_hostname(AF_INET, &ip); | |
460 | } else if (familyIPv6) { | |
461 | hostName = get_hostname(AF_INET6, &ip6); | |
462 | } | |
463 | ||
464 | if (hostName == NULL) { | |
465 | if (!beSilent) { | |
466 | sprintf(errBuf, "ipcalc: cannot find hostname for %s", ipStr); | |
467 | herror(errBuf); | |
468 | } | |
469 | return 1; | |
470 | } | |
471 | ||
472 | printf("HOSTNAME=%s\n", hostName); | |
473 | } | |
474 | ||
475 | return 0; | |
476 | } |