proxy_cache.c

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    dates = ap_table_get(resp_hdrs, "Date");
    if (dates != NULL)
        date = ap_parseHTTPdate(dates);
    else
        date = BAD_DATE;

    now = time(NULL);

    if (date == BAD_DATE) {     /* No, or bad date */
/* no date header! */
/* add one; N.B. use the time _now_ rather than when we were checking the cache
 */
        date = now;
        dates = ap_gm_timestr_822(r->pool, now);
        ap_table_set(resp_hdrs, "Date", dates);
        ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Added date header");
    }

/* set response_time for HTTP/1.1 age calculations */
    c->resp_time = now;

/* check last-modified date */
    if (lmod != BAD_DATE && lmod > date)
/* if its in the future, then replace by date */
    {
        lmod = date;
        lmods = dates;
        ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Last modified is in the future, replacing with now");
    }
/* if the response did not contain the header, then use the cached version */
    if (lmod == BAD_DATE && c->fp != NULL) {
        lmod = c->lmod;
        ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Reusing cached last modified");
    }

/* we now need to calculate the expire data for the object. */
    if (expire == NULL && c->fp != NULL) {      /* no expiry data sent in
                                                 * response */
        expire = ap_table_get(c->hdrs, "Expires");
        if (expire != NULL)
            expc = ap_parseHTTPdate(expire);
    }
/* so we now have the expiry date */
/* if no expiry date then
 *   if lastmod
 *      expiry date = now + min((date - lastmod) * factor, maxexpire)
 *   else
 *      expire date = now + defaultexpire
 */
    ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Expiry date is %ld", (long)expc);
    if (expc == BAD_DATE) {
        if (lmod != BAD_DATE) {
            double x = (double)(date - lmod) * conf->cache.lmfactor;
            double maxex = conf->cache.maxexpire;
            if (x > maxex)
                x = maxex;
            expc = now + (int)x;
        }
        else
            expc = now + conf->cache.defaultexpire;
        ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Expiry date calculated %ld", (long)expc);
    }

/* get the content-length header */
    clen = ap_table_get(resp_hdrs, "Content-Length");
    if (clen == NULL)
        c->len = -1;
    else
        c->len = ap_strtol(clen, NULL, 10);

/* we have all the header information we need - write it to the cache file */
    c->version++;
    ap_proxy_sec2hex(date, buff + 17 * (0));
    buff[17 * (1) - 1] = ' ';
    ap_proxy_sec2hex(lmod, buff + 17 * (1));
    buff[17 * (2) - 1] = ' ';
    ap_proxy_sec2hex(expc, buff + 17 * (2));
    buff[17 * (3) - 1] = ' ';
    ap_proxy_sec2hex(c->version, buff + 17 * (3));
    buff[17 * (4) - 1] = ' ';
    ap_proxy_sec2hex(c->req_time, buff + 17 * (4));
    buff[17 * (5) - 1] = ' ';
    ap_proxy_sec2hex(c->resp_time, buff + 17 * (5));
    buff[17 * (6) - 1] = ' ';
    ap_proxy_sec2hex(c->len, buff + 17 * (6));
    buff[17 * (7) - 1] = '\n';
    buff[17 * (7)] = '\0';

/* Was the server response a 304 Not Modified?
 *
 * If it was, it means that we requested a revalidation, and that
 * the result of that revalidation was that the object was fresh.
 *
 */

/* if response from server 304 not modified */
    if (r->status == HTTP_NOT_MODIFIED) {

/* Have the headers changed?
 *
 * if not - we fulfil the request and return now.
 */

        if (c->hdrs) {
            /* recall at this point that c->len is already set from resp_hdrs.
               If Content-Length was NULL, then c->len is -1, otherwise it's
               set to whatever the value was. */
            if (c->len == 0 || c->len == -1) {
                const char *c_clen_str;
                off_t c_clen;
                if ( (c_clen_str = ap_table_get(c->hdrs, "Content-Length")) &&
                   ( (c_clen = ap_strtol(c_clen_str, NULL, 10)) > 0) ) {
                        ap_table_set(resp_hdrs, "Content-Length", c_clen_str);
                        c->len = c_clen;
                        ap_proxy_sec2hex(c->len, buff + 17 * (6));
                        buff[17 * (7) - 1] = '\n';
                        buff[17 * (7)] = '\0';
                }
            }
            if (!ap_proxy_table_replace(c->hdrs, resp_hdrs)) {
                c->xcache = ap_pstrcat(r->pool, "HIT from ", ap_get_server_name(r), " (with revalidation)", NULL);
                return ap_proxy_cache_conditional(r, c, c->fp);
            }
        }
        else
            c->hdrs = resp_hdrs;
/* if we get here - the headers have changed. Go through the motions
 * of creating a new temporary cache file below, we'll then serve
 * the request like we would have in ap_proxy_cache_conditional()
 * above, and at the same time we will also rewrite the contents
 * to the new temporary file.
 */
    }

/*
 * Ok - lets prepare and open the cached file
 *
 * If a cached file (in c->fp) is already open, then we want to
 * update that cached file. Copy the c->fp to c->origfp and open
 * up a new one.
 *
 * If the cached file (in c->fp) is NULL, we must open a new cached
 * file from scratch.
 *
 * The new cache file will be moved to it's final location in the
 * directory tree later, overwriting the old cache file should it exist.
 */

/* if a cache file was already open */
    if (c->fp != NULL) {
        c->origfp = c->fp;
    }

    while (1) {
/* create temporary filename */
#ifndef TPF
#define TMPFILESTR    "/tmpXXXXXX"
        if (conf->cache.root == NULL) {
            c = ap_proxy_cache_error(c);
            break;
        }
        c->tempfile = ap_palloc(r->pool, strlen(conf->cache.root) + sizeof(TMPFILESTR));
        strcpy(c->tempfile, conf->cache.root);
        strcat(c->tempfile, TMPFILESTR);
#undef TMPFILESTR
        p = mktemp(c->tempfile);
#else
        if (conf->cache.root == NULL) {
            c = ap_proxy_cache_error(c);
            break;
        }
        c->tempfile = ap_palloc(r->pool, strlen(conf->cache.root) + 1 + L_tmpnam);
        strcpy(c->tempfile, conf->cache.root);
        strcat(c->tempfile, "/");
        p = tmpnam(NULL);
        strcat(c->tempfile, p);
#endif
        if (p == NULL) {
            c = ap_proxy_cache_error(c);
            break;
        }

        ap_log_error(APLOG_MARK, APLOG_DEBUG | APLOG_NOERRNO, r->server, "Create temporary file %s", c->tempfile);

/* create the new file */
        c->fp = ap_proxy_create_cachefile(r, c->tempfile);
        if (NULL == c->fp) {
            c = ap_proxy_cache_error(c);
            break;
        }

/* write away the cache header and the URL */
        if (ap_bvputs(c->fp, buff, "X-URL: ", c->url, "\n", NULL) == -1) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
                        "proxy: error writing cache file(%s)", c->tempfile);
            c = ap_proxy_cache_error(c);
            break;
        }

/* get original request headers */
        if (c->req_hdrs)
            req_hdrs = ap_copy_table(r->pool, c->req_hdrs);
        else
            req_hdrs = ap_copy_table(r->pool, r->headers_in);

/* remove hop-by-hop headers */
        ap_proxy_clear_connection(r->pool, req_hdrs);

/* save original request headers */
        if (c->req_hdrs)
            ap_table_do(ap_proxy_send_hdr_line, c, c->req_hdrs, NULL);
        else
            ap_table_do(ap_proxy_send_hdr_line, c, r->headers_in, NULL);
        if (ap_bputs(CRLF, c->fp) == -1) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, c->req,
                          "proxy: error writing request headers terminating CRLF to %s", c->tempfile);
            c = ap_proxy_cache_error(c);
            break;
        }
        break;
    }

/* Was the server response a 304 Not Modified?
 *
 * If so, we have some work to do that we didn't do when we first
 * checked above. We need to fulfil the request, and we need to
 * copy the body from the old object to the new one.
 */

/* if response from server 304 not modified */
    if (r->status == HTTP_NOT_MODIFIED) {

/* fulfil the request */
        c->xcache = ap_pstrcat(r->pool, "HIT from ", ap_get_server_name(r), " (with revalidation)", NULL);
        return ap_proxy_cache_conditional(r, c, c->fp);

    }
    return DECLINED;
}

void ap_proxy_cache_tidy(cache_req *c)
{
    server_rec *s;
    long int bc;

    if (!c || !c->fp)
        return;

    s = c->req->server;

/* don't care how much was sent, but rather how much was written to cache
    ap_bgetopt(c->req->connection->client, BO_BYTECT, &bc);
 */
    bc = c->written;

    if (c->len != -1) {
/* file lengths don't match; don't cache it */
        if (bc != c->len) {
            ap_pclosef(c->req->pool, ap_bfileno(c->fp, B_WR));  /* no need to flush */
            unlink(c->tempfile);
            return;
        }
    }
/* don't care if aborted, cache it if fully retrieved from host!
    else if (c->req->connection->aborted) {
        ap_pclosef(c->req->pool, c->fp->fd);    / no need to flush /
        unlink(c->tempfile);
        return;
    }
*/
    else {
/* update content-length of file */
        char buff[17];
        off_t curpos;

        c->len = bc;
        ap_bflush(c->fp);
        ap_proxy_sec2hex(c->len, buff);
        curpos = lseek(ap_bfileno(c->fp, B_WR), 17 * 6, SEEK_SET);
        if (curpos == -1)
            ap_log_error(APLOG_MARK, APLOG_ERR, s,
                      "proxy: error seeking on cache file %s", c->tempfile);
        else if (write(ap_bfileno(c->fp, B_WR), buff, sizeof(buff) - 1) == -1)
            ap_log_error(APLOG_MARK, APLOG_ERR, s,
                         "proxy: error updating cache file %s", c->tempfile);
    }

    if (ap_bflush(c->fp) == -1) {
        ap_log_error(APLOG_MARK, APLOG_ERR, s,
                     "proxy: error writing to cache file %s",
                     c->tempfile);
        ap_pclosef(c->req->pool, ap_bfileno(c->fp, B_WR));
        unlink(c->tempfile);
        return;
    }

    if (ap_pclosef(c->req->pool, ap_bfileno(c->fp, B_WR))== -1) {
        ap_log_error(APLOG_MARK, APLOG_ERR, s,
                     "proxy: error closing cache file %s", c->tempfile);
        unlink(c->tempfile);
        return;
    }

    if (unlink(c->filename) == -1 && errno != ENOENT) {
        ap_log_error(APLOG_MARK, APLOG_ERR, s,
                     "proxy: error deleting old cache file %s",
                     c->filename);
        (void)unlink(c->tempfile);
    }
    else {
        char *p;
        proxy_server_conf *conf =
        (proxy_server_conf *)ap_get_module_config(s->module_config, &proxy_module);

        for (p = c->filename + strlen(conf->cache.root) + 1;;) {
            p = strchr(p, '/');
            if (!p)
                break;
            *p = '\0';
#if defined(WIN32) || defined(NETWARE)
            if (mkdir(c->filename) < 0 && errno != EEXIST)
#elif defined(__TANDEM)
                if (mkdir(c->filename, S_IRWXU | S_IRWXG | S_IRWXO) < 0 && errno != EEXIST)
#else
            if (mkdir(c->filename, S_IREAD | S_IWRITE | S_IEXEC) < 0 && errno != EEXIST)
#endif                          /* WIN32 */
                ap_log_error(APLOG_MARK, APLOG_ERR, s,
                             "proxy: error creating cache directory %s",
                             c->filename);
            *p = '/';
            ++p;
        }
#if defined(OS2) || defined(WIN32) || defined(NETWARE) || defined(MPE)
        /* Under OS/2 use rename. */
        if (rename(c->tempfile, c->filename) == -1) {
            ap_log_error(APLOG_MARK, APLOG_ERR, s,
                         "proxy: error renaming cache file %s to %s",
                         c->tempfile, c->filename);
            (void)unlink(c->tempfile);
        }
#else

        if (link(c->tempfile, c->filename) == -1)
            ap_log_error(APLOG_MARK, APLOG_INFO, s,
                         "proxy: error linking cache file %s to %s",
                         c->tempfile, c->filename);
        if (unlink(c->tempfile) == -1)
            ap_log_error(APLOG_MARK, APLOG_ERR, s,
                         "proxy: error deleting temp file %s", c->tempfile);
#endif
    }
}