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#ifndef lint
char rcsid[] = "$Id: dnslex.c,v 2.1 1991/08/29 15:45:49 hakanson Rel $";
#endif /* lint */
/*
* A lexical analyzer for DNS master files.
* Marion Hakanson (hakanson@cse.ogi.edu)
* 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);
}
}
}
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