Skunkware 98/Skunkware 98.iso/src/net/bind-contrib.tar.gz/bind-contrib.tar/contrib/dnsparse/dnslex.c

C/C++ Source or Header | 1996-10-25 | 5.2 KB | 248 lines

#ifndef lint
char rcsid[] = "$Id: dnslex.c,v 8.1 1996/10/25 04:57:11 vixie Exp $";
#endif /* lint */

/*
 * A lexical analyzer for DNS master files.
 *   Marion Hakanson ([e-mail])
 *   Oregon Graduate Institute of Science and Technology
 *
 * Copyright (c) 1990, Marion Hakanson.
 *
 * You may distribute under the terms of the GNU General Public License
 * as specified in the README file that comes with the dnsparse kit.
 *
 * This program accepts as input DNS master files, as described
 * in RFC-1035.  It breaks up the input in such a way that a single
 * resource record (RR) is output on a single line, with a delimiter
 * character between each token (or field) of the RR.
 *
 * The output format was designed for consumption by programs such
 * as awk or perl, so the delimiter character can be used to quickly
 * split the RR into its components.
 *
 * It is likely that one could change the add_*char, end_word, and
 * end_line macros to put chars into a separate buffer or perform
 * some other function, and thus use do_dblex() inside a full parser
 * program (such as a DNS server).
 *
 * One other thing.  This program could probably have been written
 * in lex instead of C, but lex has a number of builtin limits to
 * the length of expressions (where RFC-1035 does not, in all cases).
 * I probably should have used flex instead, but the simple state
 * machine below was not that tough to implement, and it's also
 * pretty quick and pretty small.
 */

#include <stdio.h>

#ifdef BSD
#define strchr index    /* system dependent */
#define strrchr rindex
#endif /* BSD */
extern char *strchr(), *strrchr();

extern getopt(), optind, opterr;
extern char *optarg;

#define FALSE 0
#define TRUE  1

/* Globals */
char *prog;


usage_and_die()
{
    fprintf(stderr, "usage: %s [-d <char>]\n", prog);
    exit(1);
}



/* Special (to DNS) chars we output in printed (non-decimal-escaped) form */
#define SPECS " \t\n;()\\.@"    /* for consumption by strchr() */
#define SPECP " \\t\\n;()\\.@"    /* for consumption by fprintf() */


main(argc, argv)
    int  argc;
    char **argv;
{
int opt;

/* Defaults */
register FILE    *ifile = stdin,
        *ofile = stdout;
char delim = ':';

if ( prog = strrchr(argv[0], '/') )
    prog++;
else
    prog = argv[0];

/* Parse the arguments */
opterr = 0;
while ( (opt = getopt(argc, argv, "d:")) != EOF )
    switch ((char)opt)
    {
    case '?':
        usage_and_die();
        break;
    case 'd':
        delim = *optarg;
        break;
    default:
        /* Not supposed to happen. */
        fprintf(stderr, "%s: Hey getopt(3)!  Wake up!\n", prog);
        usage_and_die();
        break;
    }


/* This saves checking every char output against delim */
if ( strchr(SPECS, delim) != NULL ) {
    fprintf(stderr, "%s: delimiter '%c' cannot be one of '%s'.\n",
            prog, delim, SPECP);
    exit(1);
}

(void) do_dblex(ifile, ofile, delim);

exit(0);
}



int
do_dblex (ifile, ofile, delim)
    register FILE *ifile, *ofile;
    char delim;
{
register int c;
register int newword = FALSE;
register int wordlen = 0;
register int linelen = 0;
int inbrackets = FALSE;
int inquotes = FALSE;

/* no delim after last word on a line */
#define add_char(c) \
( \
    (newword ? (newword = FALSE, putc(delim,ofile)) : 0), \
    putc((c),ofile), \
    wordlen++ \
)

/* don't count the backslash, but do check for delim */
#define add_esc_char(c) ( add_char('\\'), putc((c),ofile) )
#define add_dec_char(c) ( add_char('\\'), fprintf(ofile,"%3.3d",(char)(c)) )

/* ignore empty words except at beginning of a line */
#define end_word() \
( \
    (wordlen > 0 || linelen == 0) ? ( \
    newword = TRUE, \
    wordlen = 0, \
    linelen++ \
    ) : (0) \
)

/* no delim at beginning of line; ignore empty lines */
#define end_line() \
( \
    (wordlen > 0) ? linelen++ : (0), \
    newword = FALSE, \
    wordlen = 0, \
    (linelen > 0) ? ( \
    putc('\n', ofile), \
    linelen = 0 \
    ) : (0) \
)



while ( ! feof(ifile) ) {

    c = getc(ifile);
    switch (c) {
    case EOF:
        break;
    case ' ':
    case '\t':
        if ( inquotes )
        add_esc_char(c);
        else {
        end_word();
        while ( (c = getc(ifile)) != EOF && (c == ' ' || c == '\t') );
        ungetc(c, ifile);
        }
        break;
    case '\n':
        if ( inquotes )
        ; /* do nothing */
        else if ( inbrackets )
        end_word();
        else
        end_line();
        break;
    case ';':
        if ( inquotes )
        add_esc_char(c);
        else {
        if ( ! inbrackets )
            end_line();
        while ( (c = getc(ifile)) != EOF && c != '\n' ); /* skip */
        }
        break;
    case '"':
        if ( inquotes )
        inquotes = FALSE;
        else
        inquotes = TRUE;
        break;
    case '(':
        if ( inbrackets || inquotes )
        add_esc_char(c);
        else {
        inbrackets = TRUE;
        end_word();
        }
        break;
    case ')':
        if ( inbrackets && (! inquotes) ) {
        inbrackets = FALSE;
        end_word();
        } else
        add_esc_char(c);
        break;
    case '\\':
        if ( (c = getc(ifile)) == EOF ) {
        add_esc_char('\\');
        end_line();
        } else if ( c == '\n' ) {
        if ( ! inquotes )
            end_word();
        } else if ( c == delim )
        add_dec_char(c);    /* no delims inside fields */
        else
        add_esc_char(c);
        break;
    case '.':
    case '@':
        if ( inquotes )
        add_esc_char(c);
        else
        add_char(c);
        break;
    default:
        if ( c == delim )
        add_dec_char(c);    /* no delims inside fields */
        else
        add_char(c);
    }
}

}