src/thttpd-2.27/cgi-src/redirect.c

   1 /* redirect - simple redirection CGI program
   2 **
   3 ** Copyright © 1995 by Jef Poskanzer <jef@mail.acme.com>.
   4 ** All rights reserved.
   5 **
   6 ** Redistribution and use in source and binary forms, with or without
   7 ** modification, are permitted provided that the following conditions
   8 ** are met:
   9 ** 1. Redistributions of source code must retain the above copyright
  10 **    notice, this list of conditions and the following disclaimer.
  11 ** 2. Redistributions in binary form must reproduce the above copyright
  12 **    notice, this list of conditions and the following disclaimer in the
  13 **    documentation and/or other materials provided with the distribution.
  14 **
  15 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25 ** SUCH DAMAGE.
  26 */
  27
  28 /* Three steps to set up a redirection:
  29 **  1. Make sure your web server is set up to allow CGI programs.
  30 **  2. Make a symbolic link from the file you want to redirect,
  31 **     pointing at this program in the CGI bin directory.
  32 **  3. Add an entry to the file ".redirects" in the directory where your
  33 **     http server runs CGI programs.  For most servers, this is the
  34 **     directory where the given CGI program lives.  The format of the
  35 **     file is a bunch of lines with a filename, whitespace, and the new
  36 **     URL.  For example:
  37
  38 /test/oldfile.html    http://www.acme.com/test/newfile.html
  39
  40 **     The easiest way to figure out precisely what filename to put into
  41 **     .redirects is to set up the symlink and then click on it.  You'll get
  42 **     back a "404 Not Found" page which includes the filename as received by
  43 **     the redirect program, and that's what you want to use.
  44 **
  45 ** Note: this is designed for thttpd (http://www.acme.com/software/thttpd/)
  46 ** and using it with other web servers may require some hacking.  A possible
  47 ** gotcha is with the symbolic link from the old file pointing at this
  48 ** script - servers other than thttpd may not allow that link to be run
  49 ** as a CGI program, because they don't check the link to see that it
  50 ** points into the allowed CGI directory.
  51 **
  52 ** Note two: It would be really cool to have this program look for
  53 ** the .redirects file in the same directory as the file being redirected,
  54 ** instead of in the binaries directory.  Unfortunately, this appears
  55 ** to be impossible with the information CGI gives, plus the non-standardized
  56 ** but widespread practice of running CGI programs in the directory where
  57 ** the binary lives.  Perhaps CGI 1.2 will address this.
  58 */
  59
  60 #include <sys/types.h>
  61
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65
  66 #include "config.h"
  67
  68
  69 static char* argv0;
  70
  71
  72 static void
  73 internal_error( char* reason )
  74     {
  75     char* title = "500 Internal Error";
  76
  77     (void) printf( "\
  78 Status: %s\n\
  79 Content-type: text/html\n\
  80 \n\
  81 <HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
  82 <BODY><H2>%s</H2>\n\
  83 Something unusual went wrong during a redirection request:\n\
  84 <BLOCKQUOTE>\n\
  85 %s\n\
  86 </BLOCKQUOTE>\n\
  87 </BODY></HTML>\n", title, title, title, reason );
  88     }
  89
  90
  91 static void
  92 not_found( char* script_name )
  93     {
  94     char* title = "404 Not Found";
  95
  96     (void) printf( "\
  97 Status: %s\n\
  98 Content-type: text/html\n\
  99 \n\
 100 <HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
 101 <BODY><H2>%s</H2>\n\
 102 The requested filename, %s, is set up to be redirected to another URL;\n\
 103 however, the new URL has not yet been specified.\n\
 104 </BODY></HTML>\n", title, title, title, script_name );
 105     }
 106
 107
 108 static void
 109 moved( char* script_name, char* url )
 110     {
 111     char* title = "Moved";
 112
 113     (void) printf( "\
 114 Location: %s\n\
 115 Content-type: text/html\n\
 116 \n\
 117 <HTML><HEAD><TITLE>%s</TITLE></HEAD>\n\
 118 <BODY><H2>%s</H2>\n\
 119 The requested filename, %s, has moved to a new URL:\n\
 120 <A HREF=\"%s\">%s</A>.\n\
 121 </BODY></HTML>\n", url, title, title, script_name, url, url );
 122     }
 123
 124
 125 int
 126 main( int argc, char** argv )
 127     {
 128     char* script_name;
 129     char* path_info;
 130     char* cp;
 131     FILE* fp;
 132     char *star;
 133     char buf[5000], file[5000], url[5000];
 134
 135     argv0 = argv[0];
 136
 137     /* Get the name that we were run as, which is the filename being
 138     ** redirected.
 139     */
 140     script_name = getenv( "SCRIPT_NAME" );
 141     if ( script_name == (char*) 0 )
 142         {
 143         internal_error( "Couldn't get SCRIPT_NAME environment variable." );
 144         exit( 1 );
 145         }
 146
 147     /* Append the PATH_INFO, if any.  This allows redirection of whole
 148     ** directories.
 149     */
 150     path_info = getenv( "PATH_INFO" );
 151     if ( path_info != (char*) 0 )
 152         {
 153         cp = (char*) malloc( strlen( script_name ) + strlen( path_info ) + 1 );
 154         if ( cp == (char*) 0 )
 155             {
 156             internal_error( "Out of memory." );
 157             exit( 1 );
 158             }
 159         (void) sprintf( cp, "%s%s", script_name, path_info );
 160         script_name = cp;
 161         }
 162
 163     /* Open the redirects file. */
 164     fp = fopen( ".redirects", "r" );
 165     if ( fp == (FILE*) 0 )
 166         {
 167         internal_error( "Couldn't open .redirects file." );
 168         exit( 1 );
 169         }
 170
 171     /* Search the file for a matching entry. */
 172     while ( fgets( buf, sizeof(buf), fp ) != (char*) 0 )
 173         {
 174         /* Remove comments. */
 175         cp = strchr( buf, '#' );
 176         if ( cp != (char*) 0 )
 177             *cp = '\0';
 178         /* Skip leading whitespace. */
 179         cp = buf;
 180         cp += strspn( cp, " \t" );
 181         /* Check for blank line. */
 182         if ( *cp != '\0' )
 183             {
 184             /* Parse line. */
 185             if ( sscanf( cp, "%[^ \t\n] %[^ \t\n]", file, url ) == 2 )
 186                 {
 187                 /* Check for wildcard match. */
 188                 star = strchr( file, '*' );
 189                 if ( star != (char*) 0 )
 190                     {
 191                     /* Check for leading match. */
 192                     if ( strncmp( file, script_name, star - file ) == 0 )
 193                         {
 194                         /* Got it; put together the full name. */
 195                         strcat( url, script_name + ( star - file ) );
 196                         /* XXX Whack the script_name, too? */
 197                         moved( script_name, url );
 198                         exit( 0 );
 199                         }
 200                     }
 201                 /* Check for exact match. */
 202                 if ( strcmp( file, script_name ) == 0 )
 203                     {
 204                     /* Got it. */
 205                     moved( script_name, url );
 206                     exit( 0 );
 207                     }
 208                 }
 209             }
 210         }
 211
 212     /* No match found. */
 213     not_found( script_name );
 214     exit( 1 );
 215     }