/*      $OpenBSD: acl.c,v 1.17 2022/12/28 21:30:19 jmc Exp $ */

/*
 * Copyright (c) 1994 Mats O Jansson <moj@stacken.kth.se>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <netdb.h>
#include "acl.h"

#define TRUE 1
#define FALSE 0

static  struct aclent *acl_root = NULL;

static int
acl_read_line(FILE *fp, char *buf, int size)
{
        int      len = 0;
        char *c, *p, l;

        /* Read a line, and remove any comment, trim space */

        do {
                while (fgets(buf, size, fp)) {
                        c = buf;
                        while (*c != '\0') {
                                if (*c == '#' || *c == '\n') {
                                        *c = '\0';
                                } else {
                                        c++;
                                }
                        }

                        c = p = buf; l = ' ';
                        while (*c != '\0') {
                                if (isspace((unsigned char)l) &&
                                    isspace((unsigned char)*c)) {
                                        c++;
                                } else {
                                        l = *c++; *p = l; p++;
                                }
                        }
                        *p = '\0';

                        if (p != buf) {
                                --p;
                                if (isspace((unsigned char)*p) != 0) {
                                        *p = '\0';
                                }
                        }

                        len = strlen(buf);
                        return len + 1;
                }
        } while (size > 0 && !feof(fp));
        return len;
}

int
acl_check_host(struct in_addr *addr)
{
        struct aclent *p;

        p = acl_root;
        while (p != NULL) {
                if ((addr->s_addr & p->s_mask) == p->s_addr)
                        return(p->allow);
                p = p->next;
        }
        return(TRUE);
}

static void
acl_add_net(int allow, struct in_addr *addr, struct in_addr *mask)
{
        struct aclent *acl, *p;

        acl = malloc(sizeof(struct aclent));
        acl->next        = NULL;
        acl->allow      = allow;
        acl->s_addr = addr->s_addr;
        acl->s_mask = mask->s_addr;

        if (acl_root == NULL) {
                acl_root = acl;
        } else {
                p = acl_root;
                while (p->next != NULL)
                        p = p->next;
                p->next = acl;
        }
}

static void
acl_add_host(int allow, struct in_addr *addr)
{
        struct in_addr mask;

        mask.s_addr = htonl(0xffffffff);
        acl_add_net(allow, addr, &mask);
}

int
acl_init(char *file)
{
        char data_line[1024], *p, *k;
        int line_no = 0, len, i, state;
        int allow = TRUE, error_cnt = 0;
        struct in_addr addr, mask, *host_addr;
        struct hostent *host;
        FILE *data_file = NULL;

        if (file != NULL)
                data_file = fopen(file, "r");

        while (data_file != NULL &&
            acl_read_line(data_file, data_line, sizeof(data_line))) {

                line_no++;
                len = strlen(data_line);
                if (len == 0)
                        continue;
                p = (char *) &data_line;

                /* State 1: Initial State */

                state = ACLS_INIT;
                addr.s_addr = mask.s_addr = 0;

                k = p;                  /* save start of verb */
                i = 0;
                while (*p != '\0' &&
                    !isspace((*p = tolower(*p)))) {
                        p++;
                        i++;
                }

                if (*p != '\0')
                        *p++ = '\0';

                if (strcmp(k, "allow") == 0) {
                        allow = TRUE;
                        state = ACLS_ALLOW;
                }

                if (strcmp(k, "deny") == 0) {
                        allow = FALSE;
                        state = ACLS_DENY;
                }

                if (state == ACLS_INIT)
                        state = ACLE_UVERB;

                /* State 2: allow row */
                /* State 3: deny row */

                if (*p != '\0' &&
                    (state == ACLS_ALLOW || state == ACLS_DENY)) {
                        k = p;                  /* save start of verb */
                        i = 0;
                        while (*p != '\0' &&
                            !isspace((*p = tolower(*p)))) {
                                p++;
                                i++;
                        }

                        if (*p != '\0')
                                *p++ = '\0';

                        if (strcmp(k, "all") == 0)
                                state = state + ACLD_ALL;

                        if (strcmp(k, "host") == 0)
                                state = state + ACLD_HOST;

                        if (strcmp(k, "net") == 0)
                                state = state + ACLD_NET;

                        if (state == ACLS_ALLOW || state == ACLS_DENY)
                                state = ACLE_U2VERB;
                }

                if (state == ACLS_ALLOW || state == ACLS_DENY)
                        state = ACLE_UEOL;

                /* State 4 & 5: all state, remove any comment */

                if (*p == '\0' &&
                    (state == ACLS_ALLOW_ALL || state == ACLS_DENY_ALL)) {
                        acl_add_net(allow, &addr, &mask);
                        state = ACLE_OK;
                }

                /* State 6 & 7: host line */
                /* State 8 & 9: net line */

                if (*p != '\0' &&
                    state >= ACLS_ALLOW_HOST && state <= ACLS_DENY_NET) {

                        k = p;                  /* save start of verb */
                        i = 0;
                        while (*p != '\0' &&
                            !isspace((*p = tolower(*p)))) {
                                p++;
                                i++;
                        }

                        if (*p != '\0')
                                *p++ = '\0';

                        if (state == ACLS_ALLOW_HOST || state == ACLS_DENY_HOST) {
                                if (*k >= '0' && *k <= '9') {
                                        (void)inet_aton(k, &addr);
                                        acl_add_host(allow, &addr);
                                        state = state + ACLD_HOST_DONE;
                                } else {
                                        host = gethostbyname(k);
                                        if (host == NULL) {
                                                state = ACLE_NOHOST;
                                        } else {
                                                if (host->h_addrtype == AF_INET) {
                                                        while ((host_addr = (struct in_addr *) *host->h_addr_list++) != NULL)
                                                                acl_add_host(allow, host_addr);
                                                }
                                                state = state + ACLD_HOST_DONE;
                                        }
                                }
                        }

                        if (state == ACLS_ALLOW_NET || state == ACLS_DENY_NET) {
                                if (*k >= '0' && *k <= '9') {
                                        (void)inet_aton(k, &addr);
                                        state = state + ACLD_NET_DONE;
                                } else
                                        state = ACLE_NONET;
                        }

                }

                if (state >= ACLS_ALLOW_HOST && state <= ACLS_DENY_NET)
                        state = ACLE_UEOL;


                /* State 10 & 11: allow/deny host line */
                if (*p == '\0' &&
                    (state == ACLS_ALLOW_HOST_DONE || state == ACLS_DENY_HOST_DONE))
                        state = ACLE_OK;

                /* State 12 & 13: allow/deny net line */
                if (*p == '\0' &&
                    (state == ACLS_ALLOW_NET_DONE || state == ACLS_DENY_NET_DONE)) {
                        mask.s_addr = htonl(0xffffff00);
                        if (ntohl(addr.s_addr) < 0xc0000000)
                                mask.s_addr = htonl(0xffff0000);
                        if (ntohl(addr.s_addr) < 0x80000000)
                                mask.s_addr = htonl(0xff000000);
                        acl_add_net(allow, &addr, &mask);
                        state = ACLE_OK;
                }

                if (*p != '\0' &&
                    (state == ACLS_ALLOW_NET_DONE || state == ACLS_DENY_NET_DONE)) {

                        k = p;                  /* save start of verb */
                        i = 0;
                        while (*p != '\0' &&
                            !isspace((*p = tolower(*p)))) {
                                p++;
                                i++;
                        }

                        if (*p != '\0')
                                *p++ = '\0';

                        if (strcmp(k, "netmask") == 0)
                                state = state + ACLD_NET_MASK;

                        if (state == ACLS_ALLOW_NET_DONE ||
                            state == ACLS_DENY_NET_DONE)
                                state = ACLE_NONETMASK;
                }

                /* State 14 & 15: allow/deny net netmask line */
                if (*p != '\0' &&
                    (state == ACLS_ALLOW_NET_MASK || state == ACLS_DENY_NET_MASK)) {

                        k = p;          /* save start of verb */
                        i = 0;
                        while (*p != '\0' &&
                            !isspace((*p = tolower(*p)))) {
                                p++;
                                i++;
                        }

                        if (*p != '\0')
                                *p++ = '\0';

                        if (state == ACLS_ALLOW_NET_MASK ||
                            state == ACLS_DENY_NET_MASK) {
                                if (*k >= '0' && *k <= '9') {
                                        (void)inet_aton(k, &mask);
                                        state = state + ACLD_NET_EOL;
                                } else
                                        state = ACLE_NONET;
                        }

                }

                if (state == ACLS_ALLOW_NET_MASK || state == ACLS_DENY_NET_MASK)
                        state = ACLE_UEOL;

                /* State 16 & 17: allow/deny host line */
                if (*p == '\0' &&
                    (state == ACLS_ALLOW_NET_EOL || state == ACLS_DENY_NET_EOL)) {
                        acl_add_net(allow, &addr, &mask);
                        state = ACLE_OK;
                }

                switch (state) {
                case ACLE_NONETMASK:
                        fprintf(stderr,
                            "acl: expected \"netmask\" missing at line %d\n",
                            line_no);
                        break;
                case ACLE_NONET:
                        error_cnt++;
                        fprintf(stderr, "acl: unknown network at line %d\n",
                            line_no);
                        break;
                case ACLE_NOHOST:
                        error_cnt++;
                        fprintf(stderr, "acl: unknown host at line %d\n",
                            line_no);
                        break;
                case ACLE_UVERB:
                        error_cnt++;
                        fprintf(stderr, "acl: unknown verb at line %d\n",
                            line_no);
                        break;
                case ACLE_U2VERB:
                        error_cnt++;
                        fprintf(stderr,
                            "acl: unknown secondary verb at line %d\n",
                            line_no);
                        break;
                case ACLE_UEOL:
                        error_cnt++;
                        fprintf(stderr,
                            "acl: unexpected end of line at line %d\n",
                            line_no);
                        break;
                case ACLE_OK:
                        break;
                default:
                        error_cnt++;
                        fprintf(stderr, "acl: unexpected state %d %s\n",
                            state, k);
                }

        }

        if (data_file != NULL) {
                (void)fflush(stderr);
                (void)fclose(data_file);
        }

        /* Always add a last allow all if file don't exists or */
        /* the file doesn't cover all cases. */
        addr.s_addr = mask.s_addr = 0;
        allow = TRUE;
        acl_add_net(allow, &addr, &mask);
        return(error_cnt);
}

int
acl_securenet(char *file)
{
        char data_line[1024], *p, *k;
        int line_no = 0, len, i, allow = TRUE, state;
        int error_cnt = 0;
        struct in_addr addr, mask;
        FILE *data_file = NULL;

        if (file != NULL)
                data_file = fopen(file, "r");

        /* Always add a localhost allow first, to be compatible with sun */
        addr.s_addr = htonl(0x7f000001);
        mask.s_addr = htonl(0xffffffff);
        allow = TRUE;
        acl_add_net(allow, &addr, &mask);

        while (data_file != NULL &&
            acl_read_line(data_file, data_line, sizeof(data_line))) {
                line_no++;
                len = strlen(data_line);
                if (len == 0)
                        continue;
                p = (char *) &data_line;

                /* State 1: Initial State */
                state = ACLS_INIT;
                addr.s_addr = mask.s_addr = 0;

                k = p;                          /* save start of verb */
                i = 0;
                while (*p != '\0' &&
                    !isspace((*p = tolower(*p)))) {
                        p++;
                        i++;
                }

                if (*p != '\0') {
                        *p++ = '\0';
                        state = ACLS_ALLOW_NET_MASK;
                }

                if (state == ACLS_INIT)
                        state = ACLE_UEOL;

                if (state == ACLS_ALLOW_NET_MASK) {
                        if (*k >= '0' && *k <= '9') {
                                (void)inet_aton(k, &mask);
                                state = ACLS_ALLOW_NET;
                        } else
                                state = ACLE_NONET;

                        k = p;                          /* save start of verb */
                        i = 0;
                        while (*p != '\0' &&
                            !isspace((*p = tolower(*p)))) {
                                p++;
                                i++;
                        }

                        if (*p != '\0')
                                *p++ = '\0';
                }

                if (state == ACLS_ALLOW_NET_MASK)
                        state = ACLE_UEOL;

                if (state == ACLS_ALLOW_NET) {
                        if (*k >= '0' && *k <= '9') {
                                (void)inet_aton(k, &addr);
                                state = ACLS_ALLOW_NET_EOL;
                        } else
                                state = ACLE_NONET;
                }

                if (state == ACLS_ALLOW_NET)
                        state = ACLE_UEOL;

                if (*p == '\0' && state == ACLS_ALLOW_NET_EOL) {
                        acl_add_net(allow, &addr, &mask);
                        state = ACLE_OK;
                }

                switch (state) {
                case ACLE_NONET:
                        error_cnt++;
                        fprintf(stderr,
                            "securenet: unknown network at line %d\n",
                            line_no);
                        break;
                case ACLE_UEOL:
                        error_cnt++;
                        fprintf(stderr,
                            "securenet: unexpected end of line at line %d\n",
                            line_no);
                        break;
                case ACLE_OK:
                        break;
                default:
                        error_cnt++;
                        fprintf(stderr, "securenet: unexpected state %d %s\n",
                            state, k);
                }
        }

        if (data_file != NULL) {
                (void)fflush(stderr);
                (void)fclose(data_file);

                /* Always add a last deny all if file exists */
                addr.s_addr = mask.s_addr = 0;
                allow = FALSE;
                acl_add_net(allow, &addr, &mask);
        }

        /* Always add a last allow all if file don't exists */

        addr.s_addr = mask.s_addr = 0;
        allow = TRUE;
        acl_add_net(allow, &addr, &mask);
        return(error_cnt);
}

void
acl_reset(void)
{
        struct aclent *p;

        while (acl_root != NULL) {
                p = acl_root->next;
                free(acl_root);
                acl_root = p;
        }
}