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/* redirect - simple redirection CGI program
**
** Copyright 1995 by Jef Poskanzer <jef@acme.com>.
** 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 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 AUTHOR 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.
*/
/* Three steps to set up a redirection:
** 1. Make sure your web server is set up to allow CGI programs.
** 2. Make a symbolic link from the file you want to redirect,
** pointing at this program in the CGI bin directory.
** 3. Add an entry to the file ".redirects" in the directory where your
** http server runs CGI programs. For most servers, this is the
** directory where the given CGI program lives. The format of the
** file is a bunch of lines with a filename, whitespace, and the new
** URL. For example:
/test/oldfile.html http://www.acme.com/test/newfile.html
** The easiest way to figure out precisely what filename to put into
** .redirects is to set up the symlink and then click on it. You'll get
** back a "404 Not Found" page which includes the filename as received by
** the redirect program, and that's what you want to use.
**
** Note: this is designed for thttpd (http://www.acme.com/software/thttpd/)
** and using it with other web servers may require some hacking. A possible
** gotcha is with the symbolic link from the old file pointing at this
** script - servers other than thttpd may not allow that link to be run
** as a CGI program, because they don't check the link to see that it
** points into the allowed CGI directory.
**
** Note two: It would be really cool to have this program look for
** the .redirects file in the same directory as the file being redirected,
** instead of in the binaries directory. Unfortunately, this appears
** to be impossible with the information CGI gives, plus the non-standardized
** but widespread practice of running CGI programs in the directory where
** the binary lives. Perhaps CGI 1.2 will address this.
*/
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
static char* argv0;
static void
internal_error( char* reason )
{
char* title = "500 Internal Error";
(void) printf( "\
Status: %s\n\
Content-type: text/html\n\
\n\
<HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
<BODY><H2>%s</H2>\n\
Something unusual went wrong during a redirection request:\n\
<BLOCKQUOTE>\n\
%s\n\
</BLOCKQUOTE>\n\
</BODY></HTML>\n", title, title, title, reason );
}
static void
not_found( char* script_name )
{
char* title = "404 Not Found";
(void) printf( "\
Status: %s\n\
Content-type: text/html\n\
\n\
<HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
<BODY><H2>%s</H2>\n\
The requested filename, %s, is set up to be redirected to another URL;\n\
however, the new URL has not yet been specified.\n\
</BODY></HTML>\n", title, title, title, script_name );
}
static void
moved( char* script_name, char* url )
{
char* title = "Moved";
(void) printf( "\
Location: %s\n\
Content-type: text/html\n\
\n\
<HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
<BODY><H2>%s</H2>\n\
The requested filename, %s, has moved to a new URL:\n\
<A HREF=\"%s\">%s</A>.\n\
</BODY></HTML>\n", url, title, title, script_name, url, url );
}
int
main( int argc, char** argv )
{
char* script_name;
char* path_info;
char* cp;
FILE* fp;
char *star;
char buf[5000], file[5000], url[5000];
argv0 = argv[0];
/* Get the name that we were run as, which is the filename being
** redirected.
*/
script_name = getenv( "SCRIPT_NAME" );
if ( script_name == (char*) 0 )
{
internal_error( "Couldn't get SCRIPT_NAME environment variable." );
exit( 1 );
}
/* Append the PATH_INFO, if any. This allows redirection of whole
** directories.
*/
path_info = getenv( "PATH_INFO" );
if ( path_info != (char*) 0 )
{
cp = (char*) malloc( strlen( script_name ) + strlen( path_info ) + 1 );
if ( cp == (char*) 0 )
{
internal_error( "Out of memory." );
exit( 1 );
}
(void) sprintf( cp, "%s%s", script_name, path_info );
script_name = cp;
}
/* Open the redirects file. */
fp = fopen( ".redirects", "r" );
if ( fp == (FILE*) 0 )
{
internal_error( "Couldn't open .redirects file." );
exit( 1 );
}
/* Search the file for a matching entry. */
while ( fgets( buf, sizeof(buf), fp ) != (char*) 0 )
{
/* Remove comments. */
cp = strchr( buf, '#' );
if ( cp != (char*) 0 )
*cp = '\0';
/* Skip leading whitespace. */
cp = buf;
cp += strspn( cp, " \t" );
/* Check for blank line. */
if ( *cp != '\0' )
{
/* Parse line. */
if ( sscanf( cp, "%[^ \t\n] %[^ \t\n]", file, url ) == 2 )
{
/* Check for wildcard match. */
star = strchr( file, '*' );
if ( star != (char*) 0 )
{
/* Check for leading match. */
if ( strncmp( file, script_name, star - file ) == 0 )
{
/* Got it; put together the full name. */
strcat( url, script_name + ( star - file ) );
/* XXX Whack the script_name, too? */
moved( script_name, url );
exit( 0 );
}
}
/* Check for exact match. */
if ( strcmp( file, script_name ) == 0 )
{
/* Got it. */
moved( script_name, url );
exit( 0 );
}
}
}
}
/* No match found. */
not_found( script_name );
exit( 1 );
}
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