/*      $OpenBSD: conflex.c,v 1.19 2017/04/24 14:58:36 krw Exp $        */

/* Lexical scanner for dhcpd config file... */

/*
 * Copyright (c) 1995, 1996, 1997 The Internet Software Consortium.
 * 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 Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <net/if.h>

#include <netinet/in.h>

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "dhcp.h"
#include "tree.h"
#include "dhcpd.h"
#include "dhctoken.h"

int lexline;
int lexchar;
char *token_line;
char *prev_line;
char *cur_line;
char *tlname;
int eol_token;

static char line1[81];
static char line2[81];
static int lpos;
static int line;
static int tlpos;
static int tline;
static int token;
static int ugflag;
static char *tval;
static char tokbuf[1500];

static int get_char(FILE *);
static int get_token(FILE *);
static void skip_to_eol(FILE *);
static int read_string(FILE *);
static int read_num_or_name(int, FILE *);
static int intern(char *, int);
static int kw_cmp(const void *, const void *);

void
new_parse(char *name)
{
        tlname = name;
        lpos = line = 1;
        cur_line = line1;
        prev_line = line2;
        token_line = cur_line;
        cur_line[0] = prev_line[0] = 0;
        warnings_occurred = 0;
}

static int
get_char(FILE *cfile)
{
        int c = getc(cfile);
        if (!ugflag) {
                if (c == '\n') {
                        if (cur_line == line1) {
                                cur_line = line2;
                                prev_line = line1;
                        } else {
                                cur_line = line1;
                                prev_line = line2;
                        }
                        line++;
                        lpos = 1;
                        cur_line[0] = 0;
                } else if (c != EOF) {
                        if (lpos < sizeof(line1)) {
                                cur_line[lpos - 1] = c;
                                cur_line[lpos] = 0;
                        }
                        lpos++;
                }
        } else
                ugflag = 0;
        return (c);
}

static int
get_token(FILE *cfile)
{
        int             c, ttok;
        static char     tb[2];
        int             l, p;

        do {
                l = line;
                p = lpos;

                c = get_char(cfile);

                if (!(c == '\n' && eol_token) && isascii(c) && isspace(c))
                        continue;
                if (c == '#') {
                        skip_to_eol(cfile);
                        continue;
                }
                lexline = l;
                lexchar = p;
                if (c == '"') {
                        ttok = read_string(cfile);
                        break;
                } else if (c == '-' || (isascii(c) && isalnum(c))) {
                        ttok = read_num_or_name(c, cfile);
                        break;
                } else {
                        tb[0] = c;
                        tb[1] = 0;
                        tval = tb;
                        ttok = c;
                        break;
                }
        } while (1);
        return (ttok);
}

int
next_token(char **rval, FILE *cfile)
{
        int     rv;

        if (token) {
                if (lexline != tline)
                        token_line = cur_line;
                lexchar = tlpos;
                lexline = tline;
                rv = token;
                token = 0;
        } else {
                rv = get_token(cfile);
                token_line = cur_line;
        }
        if (rval)
                *rval = tval;

        return (rv);
}

int
peek_token(char **rval, FILE *cfile)
{
        int     x;

        if (!token) {
                tlpos = lexchar;
                tline = lexline;
                token = get_token(cfile);
                if (lexline != tline)
                        token_line = prev_line;
                x = lexchar;
                lexchar = tlpos;
                tlpos = x;
                x = lexline;
                lexline = tline;
                tline = x;
        }
        if (rval)
                *rval = tval;

        return (token);
}

static void
skip_to_eol(FILE *cfile)
{
        int     c;

        do {
                c = get_char(cfile);
                if (c == EOF)
                        return;
                if (c == '\n')
                        return;
        } while (1);
}

static int
read_string(FILE *cfile)
{
        int i, c, bs;

        bs = i = 0;
        do {
                c = get_char(cfile);
                if (bs)
                        bs = 0;
                else if (c == '\\')
                        bs = 1;

                if (c != '"' && c != EOF && bs == 0)
                        tokbuf[i++] = c;

        } while (i < (sizeof(tokbuf) - 1) && c != EOF && c != '"');

        if (c == EOF)
                parse_warn("eof in string constant");
        else if (c != '"')
                parse_warn("string constant larger than internal buffer");

        tokbuf[i] = 0;
        tval = tokbuf;

        return (TOK_STRING);
}

static int
read_num_or_name(int c, FILE *cfile)
{
        int i, rv, xdigits;

        xdigits = isxdigit(c) ? 1 : 0;

        tokbuf[0] = c;
        for (i = 1; i < sizeof(tokbuf); i++) {
                c = get_char(cfile);
                if (!isascii(c) || (c != '-' && c != '_' && !isalnum(c))) {
                        ungetc(c, cfile);
                        ugflag = 1;
                        break;
                }
                if (isxdigit(c))
                        xdigits++;
                tokbuf[i] = c;
        }
        if (i == sizeof(tokbuf)) {
                parse_warn("token larger than internal buffer");
                i--;
                c = tokbuf[i];
                if (isxdigit(c))
                        xdigits--;
        }
        tokbuf[i] = 0;
        tval = tokbuf;

        c = (unsigned int)tokbuf[0];

        if (c == '-')
                rv = TOK_NUMBER;
        else
                rv = intern(tval, TOK_NUMBER_OR_NAME);

        if (rv == TOK_NUMBER_OR_NAME && xdigits != i)
                rv = TOK_NAME;

        return (rv);
}

static const struct keywords {
        const char      *k_name;
        int             k_val;
} keywords[] = {
        { "abandoned",                  TOK_ABANDONED },
        { "allow",                      TOK_ALLOW },
        { "always-reply-rfc1048",       TOK_ALWAYS_REPLY_RFC1048 },
        { "authoritative",              TOK_AUTHORITATIVE },
        { "booting",                    TOK_BOOTING },
        { "bootp",                      TOK_BOOTP },
        { "class",                      TOK_CLASS },
        { "client-hostname",            TOK_CLIENT_HOSTNAME },
        { "default-lease-time",         TOK_DEFAULT_LEASE_TIME },
        { "deny",                       TOK_DENY },
        { "domain",                     TOK_DOMAIN },
        { "dynamic-bootp",              TOK_DYNAMIC_BOOTP },
        { "dynamic-bootp-lease-cutoff", TOK_DYNAMIC_BOOTP_LEASE_CUTOFF },
        { "dynamic-bootp-lease-length", TOK_DYNAMIC_BOOTP_LEASE_LENGTH },
        { "echo-client-id",             TOK_ECHO_CLIENT_ID },
        { "ends",                       TOK_ENDS },
        { "ethernet",                   TOK_ETHERNET },
        { "filename",                   TOK_FILENAME },
        { "fixed-address",              TOK_FIXED_ADDR },
        { "get-lease-hostnames",        TOK_GET_LEASE_HOSTNAMES },
        { "group",                      TOK_GROUP },
        { "hardware",                   TOK_HARDWARE },
        { "host",                       TOK_HOST },
        { "hostname",                   TOK_HOSTNAME },
        { "ipsec-tunnel",               TOK_IPSEC_TUNNEL },
        { "lease",                      TOK_LEASE },
        { "max-lease-time",             TOK_MAX_LEASE_TIME },
        { "netmask",                    TOK_NETMASK },
        { "next-server",                TOK_NEXT_SERVER },
        { "not",                        TOK_TOKEN_NOT },
        { "option",                     TOK_OPTION },
        { "range",                      TOK_RANGE },
        { "server-identifier",          TOK_SERVER_IDENTIFIER },
        { "server-name",                TOK_SERVER_NAME },
        { "shared-network",             TOK_SHARED_NETWORK },
        { "starts",                     TOK_STARTS },
        { "subnet",                     TOK_SUBNET },
        { "timeout",                    TOK_TIMEOUT },
        { "timestamp",                  TOK_TIMESTAMP },
        { "uid",                        TOK_UID },
        { "unknown-clients",            TOK_UNKNOWN_CLIENTS },
        { "use-host-decl-names",        TOK_USE_HOST_DECL_NAMES },
        { "use-lease-addr-for-default-route",
                                        TOK_USE_LEASE_ADDR_FOR_DEFAULT_ROUTE },
        { "user-class",                 TOK_USER_CLASS },
        { "vendor-class",               TOK_VENDOR_CLASS }
};

static int
kw_cmp(const void *k, const void *e)
{
        return (strcasecmp(k, ((const struct keywords *)e)->k_name));
}

static int
intern(char *atom, int dfv)
{
        const struct keywords *p;

        p = bsearch(atom, keywords, sizeof(keywords)/sizeof(keywords[0]),
            sizeof(keywords[0]), kw_cmp);
        if (p)
                return (p->k_val);
        return (dfv);
}