/*      $NetBSD: prefix.c,v 1.9 2018/01/23 21:06:24 sevan Exp $ */
/*      $KAME: prefix.c,v 1.13 2003/09/02 22:50:17 itojun Exp $ */

/*
* Copyright (C) 2000 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stddef.h>
#include <stdlib.h>
#include <limits.h>

#ifndef offsetof
#define offsetof(type, member)  ((size_t)(u_long)(&((type *)0)->member))
#endif

#include "faithd.h"
#include "prefix.h"

static int prefix_set(const char *, struct prefix *, int);
static struct config *config_load1(const char *);
#if 0
static void config_show1(const struct config *);
static void config_show(void);
#endif

struct config *config_list = NULL;
const int niflags = NI_NUMERICHOST;

static int
prefix_set(const char *s, struct prefix *prefix, int slash)
{
       char *p = NULL, *q, *r;
       struct addrinfo hints, *res = NULL;
       int max;

       p = strdup(s);
       if (!p)
               goto fail;
       q = strchr(p, '/');
       if (q) {
               if (!slash)
                       goto fail;
               *q++ = '\0';
       }

       memset(&hints, 0, sizeof(hints));
       hints.ai_family = PF_UNSPEC;
       hints.ai_socktype = SOCK_DGRAM; /*dummy*/
       hints.ai_flags = AI_NUMERICHOST;
       if (getaddrinfo(p, "0", &hints, &res))
               goto fail;
       if (res->ai_next || res->ai_addrlen > sizeof(prefix->a))
               goto fail;
       memcpy(&prefix->a, res->ai_addr, res->ai_addrlen);

       switch (prefix->a.ss_family) {
       case AF_INET:
               max = 32;
               break;
       case AF_INET6:
               max = 128;
               break;
       default:
               max = -1;
               break;
       }

       if (q) {
               r = NULL;
               prefix->l = (int)strtoul(q, &r, 10);
               if (!*q || *r)
                       goto fail;
               if (prefix->l < 0 || prefix->l > max)
                       goto fail;
       } else
               prefix->l = max;

       if (p)
               free(p);
       if (res)
               freeaddrinfo(res);
       return 0;

fail:
       if (p)
               free(p);
       if (res)
               freeaddrinfo(res);
       return -1;
}

const char *
prefix_string(const struct prefix *prefix)
{
       static char buf[NI_MAXHOST + 20];
       char hbuf[NI_MAXHOST];

       if (getnameinfo((const void *)&prefix->a, (socklen_t)prefix->a.ss_len,
           hbuf, (socklen_t)sizeof(hbuf), NULL, 0, niflags))
               return NULL;
       (void)snprintf(buf, sizeof(buf), "%s/%d", hbuf, prefix->l);
       return buf;
}

int
prefix_match(const struct prefix *prefix, const struct sockaddr *sa)
{
       struct sockaddr_storage a, b;
       char *pa, *pb;
       int off, l;

       if (prefix->a.ss_family != sa->sa_family ||
           prefix->a.ss_len != sa->sa_len)
               return 0;

       if (prefix->a.ss_len > sizeof(a) || sa->sa_len > sizeof(b))
               return 0;

       switch (prefix->a.ss_family) {
       case AF_INET:
               off = offsetof(struct sockaddr_in, sin_addr);
               break;
       case AF_INET6:
               off = offsetof(struct sockaddr_in6, sin6_addr);
               break;
       default:
               if (memcmp(&prefix->a, sa, prefix->a.ss_len) != 0)
                       return 0;
               else
                       return 1;
       }

       memcpy(&a, &prefix->a, prefix->a.ss_len);
       memcpy(&b, sa, sa->sa_len);
       l = prefix->l / 8 + (prefix->l % 8 ? 1 : 0);

       /* overrun check */
       if (off + l > a.ss_len)
               return 0;

       pa = ((char *)(void *)&a) + off;
       pb = ((char *)(void *)&b) + off;
       if (prefix->l % 8) {
               pa[prefix->l / 8] &= 0xff00 >> (prefix->l % 8);
               pb[prefix->l / 8] &= 0xff00 >> (prefix->l % 8);
       }
       if (memcmp(pa, pb, l) != 0)
               return 0;
       else
               return 1;
}

/*
* prefix/prefixlen permit/deny prefix/prefixlen [srcaddr]
* 3ffe::/16 permit 10.0.0.0/8 10.1.1.1
*/
static struct config *
config_load1(const char *line)
{
       struct config *conf;
       char buf[BUFSIZ];
       char *p;
       char *token[4];
       size_t i;

       if (strlen(line) + 1 > sizeof(buf))
               return NULL;
       (void)strlcpy(buf, line, sizeof(buf));

       p = strchr(buf, '\n');
       if (!p)
               return NULL;
       *p = '\0';
       p = strchr(buf, '#');
       if (p)
               *p = '\0';
       if (strlen(buf) == 0)
               return NULL;

       p = buf;
       memset(token, 0, sizeof(token));
       for (i = 0; i < sizeof(token) / sizeof(token[0]); i++) {
               token[i] = strtok(p, "\t ");
               p = NULL;
               if (token[i] == NULL)
                       break;
       }
       /* extra tokens? */
       if (strtok(p, "\t ") != NULL)
               return NULL;
       /* insufficient tokens */
       switch (i) {
       case 3:
       case 4:
               break;
       default:
               return NULL;
       }

       conf = (struct config *)malloc(sizeof(*conf));
       if (conf == NULL)
               return NULL;
       memset(conf, 0, sizeof(*conf));

       if (strcasecmp(token[1], "permit") == 0)
               conf->permit = 1;
       else if (strcasecmp(token[1], "deny") == 0)
               conf->permit = 0;
       else {
               /* invalid keyword is considered as "deny" */
               conf->permit = 0;
       }

       if (prefix_set(token[0], &conf->match, 1) < 0)
               goto fail;
       if (prefix_set(token[2], &conf->dest, 1) < 0)
               goto fail;
       if (token[3]) {
               if (prefix_set(token[3], &conf->src, 0) < 0)
                       goto fail;
       }

       return conf;

fail:
       free(conf);
       return NULL;
}

int
config_load(const char *configfile)
{
       FILE *fp;
       char buf[BUFSIZ];
       struct config *conf, *p;
       struct config sentinel;

       config_list = NULL;

       if (!configfile)
               configfile = _PATH_PREFIX_CONF;
       fp = fopen(configfile, "r");
       if (fp == NULL)
               return -1;

       p = &sentinel;
       sentinel.next = NULL;
       while (fgets(buf, (int)sizeof(buf), fp) != NULL) {
               conf = config_load1(buf);
               if (conf) {
                       p->next = conf;
                       p = p->next;
               }
       }
       config_list = sentinel.next;

       (void)fclose(fp);
       return 0;
}

#if 0
static void
config_show1(const struct config *conf)
{
       const char *p;

       p = prefix_string(&conf->match);
       printf("%s", p ? p : "?");

       if (conf->permit)
               printf(" permit");
       else
               printf(" deny");

       p = prefix_string(&conf->dest);
       printf(" %s", p ? p : "?");

       printf("\n");
}

static void
config_show()
{
       struct config *conf;

       for (conf = config_list; conf; conf = conf->next)
               config_show1(conf);
}
#endif

const struct config *
config_match(struct sockaddr *sa1, struct sockaddr *sa2)
{
       static struct config conf;
       const struct config *p;

       if (sa1->sa_len > sizeof(conf.match.a) ||
           sa2->sa_len > sizeof(conf.dest.a))
               return NULL;

       memset(&conf, 0, sizeof(conf));
       if (!config_list) {
               conf.permit = 1;
               memcpy(&conf.match.a, sa1, sa1->sa_len);
               memcpy(&conf.dest.a, sa2, sa2->sa_len);
               return &conf;
       }

       for (p = config_list; p; p = p->next)
               if (prefix_match(&p->match, sa1) && prefix_match(&p->dest, sa2))
                       return p;

       return NULL;
}

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