/*      $OpenBSD: parse.c,v 1.11 2004/05/05 23:07:47 deraadt Exp $      */

/* Common parser code for dhcpd and dhclient. */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1995, 1996, 1997, 1998 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/cdefs.h>
#include <stdbool.h>

#include "dhcpd.h"
#include "dhctoken.h"

/* Skip to the semicolon ending the current statement.   If we encounter
 * braces, the matching closing brace terminates the statement.   If we
 * encounter a right brace but haven't encountered a left brace, return
 * leaving the brace in the token buffer for the caller.   If we see a
 * semicolon and haven't seen a left brace, return.   This lets us skip
 * over:
 *
 *      statement;
 *      statement foo bar { }
 *      statement foo bar { statement { } }
 *      statement}
 *
 *      ...et cetera.
 */
void
skip_to_semi(FILE *cfile)
{
        int brace_count = 0, token;
        char *val;

        do {
                token = peek_token(&val, cfile);
                if (token == RBRACE) {
                        if (brace_count) {
                                token = next_token(&val, cfile);
                                if (!--brace_count)
                                        return;
                        } else
                                return;
                } else if (token == LBRACE) {
                        brace_count++;
                } else if (token == SEMI && !brace_count) {
                        token = next_token(&val, cfile);
                        return;
                } else if (token == '\n') {
                        /*
                         * EOL only happens when parsing
                         * /etc/resolv.conf, and we treat it like a
                         * semicolon because the resolv.conf file is
                         * line-oriented.
                         */
                        token = next_token(&val, cfile);
                        return;
                }
                token = next_token(&val, cfile);
        } while (token != EOF);
}

int
parse_semi(FILE *cfile)
{
        int token;
        char *val;

        token = next_token(&val, cfile);
        if (token != SEMI) {
                parse_warn("semicolon expected.");
                skip_to_semi(cfile);
                return (0);
        }
        return (1);
}

/*
 * string-parameter :== STRING SEMI
 */
char *
parse_string(FILE *cfile)
{
        char *val, *s;
        size_t valsize;
        int token;

        token = next_token(&val, cfile);
        if (token != STRING) {
                parse_warn("filename must be a string");
                skip_to_semi(cfile);
                return (NULL);
        }
        valsize = strlen(val) + 1;
        s = malloc(valsize);
        if (!s)
                error("no memory for string %s.", val);
        memcpy(s, val, valsize);

        if (!parse_semi(cfile)) {
                free(s);
                return (NULL);
        }
        return (s);
}

int
parse_ip_addr(FILE *cfile, struct iaddr *addr)
{
        addr->len = 4;
        if (parse_numeric_aggregate(cfile, addr->iabuf,
            &addr->len, DOT, 10, 8))
                return (1);
        return (0);
}

/*
 * hardware-parameter :== HARDWARE ETHERNET csns SEMI
 * csns :== NUMBER | csns COLON NUMBER
 */
void
parse_hardware_param(FILE *cfile, struct hardware *hardware)
{
        unsigned char *t;
        int token;
        size_t hlen;
        char *val;

        token = next_token(&val, cfile);
        switch (token) {
        case ETHERNET:
                hardware->htype = HTYPE_ETHER;
                break;
        case TOKEN_RING:
                hardware->htype = HTYPE_IEEE802;
                break;
        case FDDI:
                hardware->htype = HTYPE_FDDI;
                break;
        default:
                parse_warn("expecting a network hardware type");
                skip_to_semi(cfile);
                return;
        }

        /*
         * Parse the hardware address information.   Technically, it
         * would make a lot of sense to restrict the length of the data
         * we'll accept here to the length of a particular hardware
         * address type.   Unfortunately, there are some broken clients
         * out there that put bogus data in the chaddr buffer, and we
         * accept that data in the lease file rather than simply failing
         * on such clients.   Yuck.
         */
        hlen = 0;
        t = parse_numeric_aggregate(cfile, NULL, &hlen, COLON, 16, 8);
        if (!t)
                return;
        if (hlen > sizeof(hardware->haddr)) {
                free(t);
                parse_warn("hardware address too long");
        } else {
                hardware->hlen = hlen;
                memcpy((unsigned char *)&hardware->haddr[0], t,
                    hardware->hlen);
                if (hlen < sizeof(hardware->haddr))
                        memset(&hardware->haddr[hlen], 0,
                            sizeof(hardware->haddr) - hlen);
                free(t);
        }

        token = next_token(&val, cfile);
        if (token != SEMI) {
                parse_warn("expecting semicolon.");
                skip_to_semi(cfile);
        }
}

/*
 * lease-time :== NUMBER SEMI
 */
void
parse_lease_time(FILE *cfile, time_t *timep)
{
        char *val;
        int token;

        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("Expecting numeric lease time");
                skip_to_semi(cfile);
                return;
        }
        convert_num((unsigned char *)timep, val, 10, 32);
        /* Unswap the number - convert_num returns stuff in NBO. */
        *timep = ntohl(*timep); /* XXX */

        parse_semi(cfile);
}

/*
 * No BNF for numeric aggregates - that's defined by the caller.  What
 * this function does is to parse a sequence of numbers separated by the
 * token specified in separator.  If max is zero, any number of numbers
 * will be parsed; otherwise, exactly max numbers are expected.  Base
 * and size tell us how to internalize the numbers once they've been
 * tokenized.
 */
unsigned char *
parse_numeric_aggregate(FILE *cfile, unsigned char *buf, size_t *max,
    int separator, unsigned base, int size)
{
        unsigned char *bufp = buf, *s = NULL;
        int token;
        char *val, *t;
        size_t valsize, count = 0;
        pair c = NULL;
        unsigned char *lbufp = NULL;

        if (!bufp && *max) {
                lbufp = bufp = malloc(*max * size / 8);
                if (!bufp)
                        error("can't allocate space for numeric aggregate");
        } else
                s = bufp;

        do {
                if (count) {
                        token = peek_token(&val, cfile);
                        if (token != separator) {
                                if (!*max)
                                        break;
                                if (token != RBRACE && token != LBRACE)
                                        token = next_token(&val, cfile);
                                parse_warn("too few numbers.");
                                if (token != SEMI)
                                        skip_to_semi(cfile);
                                free(lbufp);
                                return (NULL);
                        }
                        token = next_token(&val, cfile);
                }
                token = next_token(&val, cfile);

                if (token == EOF) {
                        parse_warn("unexpected end of file");
                        break;
                }

                /* Allow NUMBER_OR_NAME if base is 16. */
                if (token != NUMBER &&
                    (base != 16 || token != NUMBER_OR_NAME)) {
                        parse_warn("expecting numeric value.");
                        skip_to_semi(cfile);
                        free(lbufp);
                        return (NULL);
                }
                /*
                 * If we can, convert the number now; otherwise, build a
                 * linked list of all the numbers.
                 */
                if (s) {
                        convert_num(s, val, base, size);
                        s += size / 8;
                } else {
                        valsize = strlen(val) + 1;
                        t = malloc(valsize);
                        if (!t)
                                error("no temp space for number.");
                        memcpy(t, val, valsize);
                        c = cons(t, c);
                }
        } while (++count != *max);

        /* If we had to cons up a list, convert it now. */
        if (c) {
                free(lbufp);
                bufp = malloc(count * size / 8);
                if (!bufp)
                        error("can't allocate space for numeric aggregate.");
                s = bufp + count - size / 8;
                *max = count;
        }
        while (c) {
                pair cdr = c->cdr;
                convert_num(s, (char *)c->car, base, size);
                s -= size / 8;
                /* Free up temp space. */
                free(c->car);
                free(c);
                c = cdr;
        }
        return (bufp);
}

void
convert_num(unsigned char *buf, char *str, unsigned base, int size)
{
        bool negative = false;
        unsigned tval, max;
        u_int32_t val = 0;
        char *ptr = str;

        if (*ptr == '-') {
                negative = true;
                ptr++;
        }

        /* If base wasn't specified, figure it out from the data. */
        if (!base) {
                if (ptr[0] == '0') {
                        if (ptr[1] == 'x') {
                                base = 16;
                                ptr += 2;
                        } else if (isascii(ptr[1]) && isdigit(ptr[1])) {
                                base = 8;
                                ptr += 1;
                        } else
                                base = 10;
                } else
                        base = 10;
        }

        do {
                tval = *ptr++;
                /* XXX assumes ASCII... */
                if (tval >= 'a')
                        tval = tval - 'a' + 10;
                else if (tval >= 'A')
                        tval = tval - 'A' + 10;
                else if (tval >= '0')
                        tval -= '0';
                else {
                        warning("Bogus number: %s.", str);
                        break;
                }
                if (tval >= base) {
                        warning("Bogus number: %s: digit %d not in base %d",
                            str, tval, base);
                        break;
                }
                val = val * base + tval;
        } while (*ptr);

        if (negative)
                max = (1 << (size - 1));
        else
                max = (1 << (size - 1)) + ((1 << (size - 1)) - 1);
        if (val > max) {
                switch (base) {
                case 8:
                        warning("value %s%o exceeds max (%d) for precision.",
                            negative ? "-" : "", val, max);
                        break;
                case 16:
                        warning("value %s%x exceeds max (%d) for precision.",
                            negative ? "-" : "", val, max);
                        break;
                default:
                        warning("value %s%u exceeds max (%d) for precision.",
                            negative ? "-" : "", val, max);
                        break;
                }
        }

        if (negative)
                switch (size) {
                case 8:
                        *buf = -(unsigned long)val;
                        break;
                case 16:
                        putShort(buf, -(unsigned long)val);
                        break;
                case 32:
                        putLong(buf, -(unsigned long)val);
                        break;
                default:
                        warning("Unexpected integer size: %d", size);
                        break;
                }
        else
                switch (size) {
                case 8:
                        *buf = (u_int8_t)val;
                        break;
                case 16:
                        putUShort(buf, (u_int16_t)val);
                        break;
                case 32:
                        putULong(buf, val);
                        break;
                default:
                        warning("Unexpected integer size: %d", size);
                        break;
                }
}

/*
 * date :== NUMBER NUMBER SLASH NUMBER SLASH NUMBER
 *              NUMBER COLON NUMBER COLON NUMBER SEMI
 *
 * Dates are always in GMT; first number is day of week; next is
 * year/month/day; next is hours:minutes:seconds on a 24-hour
 * clock.
 */
time_t
parse_date(FILE *cfile)
{
        int token;
        struct tm tm;
        char *val;

        /* Day of week... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric day of week expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_wday = atoi(val);

        /* Year... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric year expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_year = atoi(val);
        if (tm.tm_year > 1900)
                tm.tm_year -= 1900;

        /* Slash separating year from month... */
        token = next_token(&val, cfile);
        if (token != SLASH) {
                parse_warn("expected slash separating year from month.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }

        /* Month... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric month expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_mon = atoi(val) - 1;

        /* Slash separating month from day... */
        token = next_token(&val, cfile);
        if (token != SLASH) {
                parse_warn("expected slash separating month from day.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }

        /* Month... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric day of month expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_mday = atoi(val);

        /* Hour... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric hour expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_hour = atoi(val);

        /* Colon separating hour from minute... */
        token = next_token(&val, cfile);
        if (token != COLON) {
                parse_warn("expected colon separating hour from minute.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }

        /* Minute... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric minute expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_min = atoi(val);

        /* Colon separating minute from second... */
        token = next_token(&val, cfile);
        if (token != COLON) {
                parse_warn("expected colon separating hour from minute.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }

        /* Minute... */
        token = next_token(&val, cfile);
        if (token != NUMBER) {
                parse_warn("numeric minute expected.");
                if (token != SEMI)
                        skip_to_semi(cfile);
                return (0);
        }
        tm.tm_sec = atoi(val);
        tm.tm_isdst = 0;

        /* XXX: We assume that mktime does not use tm_yday. */
        tm.tm_yday = 0;

        /* Make sure the date ends in a semicolon... */
        token = next_token(&val, cfile);
        if (token != SEMI) {
                parse_warn("semicolon expected.");
                skip_to_semi(cfile);
                return (0);
        }

        return (timegm(&tm));
}