/*      $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;
}