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prefix.c revision 1.6 
      1 /*	$NetBSD: prefix.c,v 1.6 2003/09/02 22:56:11 itojun Exp $	*/
      2 /*	$KAME: prefix.c,v 1.13 2003/09/02 22:50:17 itojun Exp $	*/
      3 
      4 /*
      5  * Copyright (C) 2000 WIDE Project.
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. Neither the name of the project nor the names of its contributors
     17  *    may be used to endorse or promote products derived from this software
     18  *    without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30  * SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/types.h>
     34 #include <sys/socket.h>
     35 #include <netinet/in.h>
     36 #include <stdio.h>
     37 #include <netdb.h>
     38 #include <string.h>
     39 #include <stddef.h>
     40 #include <stdlib.h>
     41 #include <limits.h>
     42 
     43 #ifndef offsetof
     44 #define	offsetof(type, member)	((size_t)(u_long)(&((type *)0)->member))
     45 #endif
     46 
     47 #include "faithd.h"
     48 #include "prefix.h"
     49 
     50 static int prefix_set __P((const char *, struct prefix *, int));
     51 static struct config *config_load1 __P((const char *));
     52 #if 0
     53 static void config_show1 __P((const struct config *));
     54 static void config_show __P((void));
     55 #endif
     56 
     57 struct config *config_list = NULL;
     58 const int niflags = NI_NUMERICHOST;
     59 
     60 static int
     61 prefix_set(const char *s, struct prefix *prefix, int slash)
     62 {
     63 	char *p = NULL, *q, *r;
     64 	struct addrinfo hints, *res = NULL;
     65 	int max;
     66 	char *a;
     67 
     68 	p = strdup(s);
     69 	if (!p)
     70 		goto fail;
     71 	q = strchr(p, '/');
     72 	if (q) {
     73 		if (!slash)
     74 			goto fail;
     75 		*q++ = '\0';
     76 	}
     77 
     78 	memset(&hints, 0, sizeof(hints));
     79 	hints.ai_family = PF_UNSPEC;
     80 	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
     81 	hints.ai_flags = AI_NUMERICHOST;
     82 	if (getaddrinfo(p, "0", &hints, &res))
     83 		goto fail;
     84 	if (res->ai_next || res->ai_addrlen > sizeof(prefix->a))
     85 		goto fail;
     86 	memcpy(&prefix->a, res->ai_addr, res->ai_addrlen);
     87 
     88 	switch (prefix->a.ss_family) {
     89 	case AF_INET:
     90 		max = 32;
     91 		a = (char *)&((struct sockaddr_in *)&prefix->a)->sin_addr;
     92 		break;
     93 	case AF_INET6:
     94 		max = 128;
     95 		a = (char *)&((struct sockaddr_in6 *)&prefix->a)->sin6_addr;
     96 		break;
     97 	default:
     98 		a = NULL;
     99 		max = -1;
    100 		break;
    101 	}
    102 
    103 	if (q) {
    104 		r = NULL;
    105 		prefix->l = (int)strtoul(q, &r, 10);
    106 		if (!*q || *r)
    107 			goto fail;
    108 		if (prefix->l < 0 || prefix->l > max)
    109 			goto fail;
    110 	} else
    111 		prefix->l = max;
    112 
    113 	if (p)
    114 		free(p);
    115 	if (res)
    116 		freeaddrinfo(res);
    117 	return 0;
    118 
    119 fail:
    120 	if (p)
    121 		free(p);
    122 	if (res)
    123 		freeaddrinfo(res);
    124 	return -1;
    125 }
    126 
    127 const char *
    128 prefix_string(const struct prefix *prefix)
    129 {
    130 	static char buf[NI_MAXHOST + 20];
    131 	char hbuf[NI_MAXHOST];
    132 
    133 	if (getnameinfo((const struct sockaddr *)&prefix->a, prefix->a.ss_len,
    134 	    hbuf, sizeof(hbuf), NULL, 0, niflags))
    135 		return NULL;
    136 	snprintf(buf, sizeof(buf), "%s/%d", hbuf, prefix->l);
    137 	return buf;
    138 }
    139 
    140 int
    141 prefix_match(const struct prefix *prefix, const struct sockaddr *sa)
    142 {
    143 	struct sockaddr_storage a, b;
    144 	char *pa, *pb;
    145 	int off, l;
    146 
    147 	if (prefix->a.ss_family != sa->sa_family ||
    148 	    prefix->a.ss_len != sa->sa_len)
    149 		return 0;
    150 
    151 	if (prefix->a.ss_len > sizeof(a) || sa->sa_len > sizeof(b))
    152 		return 0;
    153 
    154 	switch (prefix->a.ss_family) {
    155 	case AF_INET:
    156 		off = offsetof(struct sockaddr_in, sin_addr);
    157 		break;
    158 	case AF_INET6:
    159 		off = offsetof(struct sockaddr_in6, sin6_addr);
    160 		break;
    161 	default:
    162 		if (memcmp(&prefix->a, sa, prefix->a.ss_len) != 0)
    163 			return 0;
    164 		else
    165 			return 1;
    166 	}
    167 
    168 	memcpy(&a, &prefix->a, prefix->a.ss_len);
    169 	memcpy(&b, sa, sa->sa_len);
    170 	l = prefix->l / 8 + (prefix->l % 8 ? 1 : 0);
    171 
    172 	/* overrun check */
    173 	if (off + l > a.ss_len)
    174 		return 0;
    175 
    176 	pa = ((char *)&a) + off;
    177 	pb = ((char *)&b) + off;
    178 	if (prefix->l % 8) {
    179 		pa[prefix->l / 8] &= 0xff00 >> (prefix->l % 8);
    180 		pb[prefix->l / 8] &= 0xff00 >> (prefix->l % 8);
    181 	}
    182 	if (memcmp(pa, pb, l) != 0)
    183 		return 0;
    184 	else
    185 		return 1;
    186 }
    187 
    188 /*
    189  * prefix/prefixlen permit/deny prefix/prefixlen [srcaddr]
    190  * 3ffe::/16 permit 10.0.0.0/8 10.1.1.1
    191  */
    192 static struct config *
    193 config_load1(const char *line)
    194 {
    195 	struct config *conf;
    196 	char buf[BUFSIZ];
    197 	char *p;
    198 	char *token[4];
    199 	int i;
    200 
    201 	if (strlen(line) + 1 > sizeof(buf))
    202 		return NULL;
    203 	strlcpy(buf, line, sizeof(buf));
    204 
    205 	p = strchr(buf, '\n');
    206 	if (!p)
    207 		return NULL;
    208 	*p = '\0';
    209 	p = strchr(buf, '#');
    210 	if (p)
    211 		*p = '\0';
    212 	if (strlen(buf) == 0)
    213 		return NULL;
    214 
    215 	p = buf;
    216 	memset(token, 0, sizeof(token));
    217 	for (i = 0; i < sizeof(token) / sizeof(token[0]); i++) {
    218 		token[i] = strtok(p, "\t ");
    219 		p = NULL;
    220 		if (token[i] == NULL)
    221 			break;
    222 	}
    223 	/* extra tokens? */
    224 	if (strtok(p, "\t ") != NULL)
    225 		return NULL;
    226 	/* insufficient tokens */
    227 	switch (i) {
    228 	case 3:
    229 	case 4:
    230 		break;
    231 	default:
    232 		return NULL;
    233 	}
    234 
    235 	conf = (struct config *)malloc(sizeof(*conf));
    236 	if (conf == NULL)
    237 		return NULL;
    238 	memset(conf, 0, sizeof(*conf));
    239 
    240 	if (strcasecmp(token[1], "permit") == 0)
    241 		conf->permit = 1;
    242 	else if (strcasecmp(token[1], "deny") == 0)
    243 		conf->permit = 0;
    244 	else {
    245 		/* invalid keyword is considered as "deny" */
    246 		conf->permit = 0;
    247 	}
    248 
    249 	if (prefix_set(token[0], &conf->match, 1) < 0)
    250 		goto fail;
    251 	if (prefix_set(token[2], &conf->dest, 1) < 0)
    252 		goto fail;
    253 	if (token[3]) {
    254 		if (prefix_set(token[3], &conf->src, 0) < 0)
    255 			goto fail;
    256 	}
    257 
    258 	return conf;
    259 
    260 fail:
    261 	free(conf);
    262 	return NULL;
    263 }
    264 
    265 int
    266 config_load(const char *configfile)
    267 {
    268 	FILE *fp;
    269 	char buf[BUFSIZ];
    270 	struct config *conf, *p;
    271 	struct config sentinel;
    272 
    273 	config_list = NULL;
    274 
    275 	if (!configfile)
    276 		configfile = _PATH_PREFIX_CONF;
    277 	fp = fopen(configfile, "r");
    278 	if (fp == NULL)
    279 		return -1;
    280 
    281 	p = &sentinel;
    282 	sentinel.next = NULL;
    283 	while (fgets(buf, sizeof(buf), fp) != NULL) {
    284 		conf = config_load1(buf);
    285 		if (conf) {
    286 			p->next = conf;
    287 			p = p->next;
    288 		}
    289 	}
    290 	config_list = sentinel.next;
    291 
    292 	fclose(fp);
    293 	return 0;
    294 }
    295 
    296 #if 0
    297 static void
    298 config_show1(const struct config *conf)
    299 {
    300 	const char *p;
    301 
    302 	p = prefix_string(&conf->match);
    303 	printf("%s", p ? p : "?");
    304 
    305 	if (conf->permit)
    306 		printf(" permit");
    307 	else
    308 		printf(" deny");
    309 
    310 	p = prefix_string(&conf->dest);
    311 	printf(" %s", p ? p : "?");
    312 
    313 	printf("\n");
    314 }
    315 
    316 static void
    317 config_show()
    318 {
    319 	struct config *conf;
    320 
    321 	for (conf = config_list; conf; conf = conf->next)
    322 		config_show1(conf);
    323 }
    324 #endif
    325 
    326 const struct config *
    327 config_match(struct sockaddr *sa1, struct sockaddr *sa2)
    328 {
    329 	static struct config conf;
    330 	const struct config *p;
    331 
    332 	if (sa1->sa_len > sizeof(conf.match.a) ||
    333 	    sa2->sa_len > sizeof(conf.dest.a))
    334 		return NULL;
    335 
    336 	memset(&conf, 0, sizeof(conf));
    337 	if (!config_list) {
    338 		conf.permit = 1;
    339 		memcpy(&conf.match.a, sa1, sa1->sa_len);
    340 		memcpy(&conf.dest.a, sa2, sa2->sa_len);
    341 		return &conf;
    342 	}
    343 
    344 	for (p = config_list; p; p = p->next)
    345 		if (prefix_match(&p->match, sa1) && prefix_match(&p->dest, sa2))
    346 			return p;
    347 
    348 	return NULL;
    349 }
    350