Save 15% on your bandwidth...

I have downloaded the multi-megabyte files from Netscape and Microsoft that
our users like to download from every mirror in the world, defeating the usual
caching.

I put these files in a separate directory and installed a basic redirector
for Squid that checks if the file (so hostname and pathname are disregarded)
is present in this directory.

After a few days of testing (the redirector looks very stable) it looks like
this is saving us approx. 15% on our cache flow. Also, our own WWW server has
become more popular than ever :)

I'm sure this code will be useful to others too, so I've attached it at the end
of this message. Improvements, extensions etc. are welcome.

I'm going on holidays now, so I won't be able to respond to e-mail quickly.

Enjoy, Richard.

/*
** rredir - redirect to local directory
**
** version 0.1, 7 sep 1996
** - initial version (Richard Huveneers <Richard.Huveneers@hekkihek.hacom.nl>)
*/

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>

#define ACCESS_LOCAL_DIR "/var/lib/httpd/htdocs/local/rredir"
#define REDIRECT_TO_URL "http://www.hacom.nl/local/rredir"
#define BUFFER_SIZE (16*1024)

int main()
{
        char buf[BUFFER_SIZE];
        char *s, *t;
        int tlu = 0;

        /* make standard output line buffered */
        if (setvbuf(stdout, NULL, _IOLBF, 0) != 0) return 1;

        /* speed up the access() calls below */
        if (chdir(ACCESS_LOCAL_DIR) == -1) return 1;

        /* scan standard input */
        while (fgets(buf, BUFFER_SIZE, stdin) != NULL)
        {
                /* check for too long urls */
                if (strchr(buf, '\n') == NULL)
                {
                        tlu = 1;
                        continue;
                }
                if (tlu) goto dont_redirect;

                /* determine end of url */
                if ((s = strchr(buf, ' ')) == NULL) goto dont_redirect;
                *s = '\0';

                /* determine first character of filename */
                if ((s = strrchr(buf, '/')) == NULL) goto dont_redirect;
                s++;

                /* security: do not redirect to hidden files, the current
                ** directory or the parent directory */
                if (*s == '.' || *s == '\0') goto dont_redirect;

                /* map filename to lower case */
                for (t = s; *t != '\0'; t++) *t = (char) tolower((int) *t);

                /* check for a local copy of this file */
                if (access(s, R_OK) == 0)
                {
                        (void) printf("%s/%s\n", REDIRECT_TO_URL, s);
                        continue;
                }

dont_redirect:
                tlu = 0;
                (void) printf("\n");
        }

        return 0;
}
Received on Thu Sep 12 1996 - 14:35:17 MDT