mod_negotiation.c

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                for (cp = desc; *cp; ++cp) {
                    if (*cp=='\n') *cp=' ';
                }
                if (cp>desc) *(cp-1)=0;
                mime_info.description = desc;
            }
        }
        else {
            if (*mime_info.file_name && has_content) {
                void *new_var = ap_push_array(neg->avail_vars);

                memcpy(new_var, (void *) &mime_info, sizeof(var_rec));
            }

            clean_var_rec(&mime_info);
            has_content = 0;
        }
    } while (hstate != header_eof);

    ap_pfclose(neg->pool, map);

    set_vlist_validator(r, rr);

    return OK;
}


/* Sort function used by read_types_multi. */
static int variantsortf(var_rec *a, var_rec *b) {

    /* First key is the source quality, sort in descending order. */

    /* XXX: note that we currently implement no method of setting the
     * source quality for multiviews variants, so we are always comparing
     * 1.0 to 1.0 for now
     */
    if (a->source_quality < b->source_quality)
        return 1;
    if (a->source_quality > b->source_quality)
        return -1;

    /* Second key is the variant name */
    return strcmp(a->file_name, b->file_name);
}

/*****************************************************************
 *
 * Same as read_type_map, except we use a filtered directory listing
 * as the map...  
 */

static int read_types_multi(negotiation_state *neg)
{
    request_rec *r = neg->r;

    char *filp;
    int prefix_len;
    DIR *dirp;
    struct DIR_TYPE *dir_entry;
    struct var_rec mime_info;
    struct accept_rec accept_info;
    void *new_var;
    struct { int any, all; } forbidden;

    clean_var_rec(&mime_info);

    if (!(filp = strrchr(r->filename, '/'))) {
        return DECLINED;        /* Weird... */
    }

    if (strncmp(r->filename, "proxy:", 6) == 0) {
        return DECLINED;
    }

    ++filp;
    prefix_len = strlen(filp);

    dirp = ap_popendir(neg->pool, neg->dir_name);

    if (dirp == NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
                    "cannot read directory for multi: %s", neg->dir_name);
        return HTTP_FORBIDDEN;
    }

    forbidden.any = 0;
    forbidden.all = 1;

    while ((dir_entry = readdir(dirp))) {
        array_header *exception_list;
        request_rec *sub_req;

        /* Do we have a match? */
#ifdef CASE_BLIND_FILESYSTEM
        if (strncasecmp(dir_entry->d_name, filp, prefix_len)) {
#else
        if (strncmp(dir_entry->d_name, filp, prefix_len)) {
#endif
            continue;
        }
        if (dir_entry->d_name[prefix_len] != '.') {
            continue;
        }

        /* Yep.  See if it's something which we have access to, and 
         * which has a known type and encoding (as opposed to something
         * which we'll be slapping default_type on later).
         */

        sub_req = ap_sub_req_lookup_file(dir_entry->d_name, r);

        /* If it has a handler, we'll pretend it's a CGI script,
         * since that's a good indication of the sort of thing it
         * might be doing.
         */
        if (sub_req->handler && !sub_req->content_type) {
            sub_req->content_type = CGI_MAGIC_TYPE;
        }

        /* HTTP_FORBIDDEN is returned, e.g., if the path length limit was exceeded */
        /* HTTP_OK does NOT necessarily mean that the file is really readable! */
        if (sub_req->status == HTTP_OK)
            forbidden.all = 0;
        else if (sub_req->status == HTTP_FORBIDDEN)
            forbidden.any = 1;

        /* 
         * mod_mime will _always_ provide us the base name in the
         * ap-mime-exception-list, if it processed anything.  If
         * this list is empty, give up immediately, there was
         * nothing interesting.  For example, looking at the files
         * readme.txt and readme.foo, we will throw away .foo if
         * it's an insignificant file (e.g. did not identify a 
         * language, charset, encoding, content type or handler,)
         */
        exception_list = 
            (array_header *) ap_table_get(sub_req->notes,
                                          "ap-mime-exceptions-list");
        if (!exception_list) {
            ap_destroy_sub_req(sub_req);
            continue;
        }

        /* Each unregonized bit better match our base name, in sequence.
         * A test of index.html.foo will match index.foo or index.html.foo,
         * but it will never transpose the segments and allow index.foo.html
         * because that would introduce too much CPU consumption.  Better that
         * we don't attempt a many-to-many match here.
         */
        {
            int nexcept = exception_list->nelts;
            char **cur_except = (char**)exception_list->elts;
            char *segstart = filp, *segend, saveend;

            while (*segstart && nexcept) {
                if (!(segend = strchr(segstart, '.')))
                    segend = strchr(segstart, '\0');
                saveend = *segend;
                *segend = '\0';

#ifdef CASE_BLIND_FILESYSTEM
                if (strcasecmp(segstart, *cur_except) == 0) {
#else
                if (strcmp(segstart, *cur_except) == 0) {
#endif
                    --nexcept;
                    ++cur_except;
                }

                if (!saveend)
                    break;

                *segend = saveend;
                segstart = segend + 1;
            }

            if (nexcept) {
                /* Something you don't know is, something you don't know...
                 */
                ap_destroy_sub_req(sub_req);
                continue;
            }
        }

        /* 
         * ###: be warned, the _default_ content type is already
         * picked up here!  If we failed the subrequest, or don't 
         * know what we are serving, then continue.
         */
        if (sub_req->status != HTTP_OK || (!sub_req->content_type)) {
            ap_destroy_sub_req(sub_req);
            continue;
        }

        /* If it's a map file, we use that instead of the map
         * we're building...
         */
        if (((sub_req->content_type) &&
             !strcmp(sub_req->content_type, MAP_FILE_MAGIC_TYPE)) ||
            ((sub_req->handler) &&
             !strcmp(sub_req->handler, "type-map"))) {

            ap_pclosedir(neg->pool, dirp);
            neg->avail_vars->nelts = 0;
            if (sub_req->status != HTTP_OK) {
                return sub_req->status;
            }
            return read_type_map(neg, sub_req);
        }

        /* Have reasonable variant --- gather notes. */

        mime_info.sub_req = sub_req;
        mime_info.file_name = ap_pstrdup(neg->pool, dir_entry->d_name);
        if (sub_req->content_encoding) {
            mime_info.content_encoding = sub_req->content_encoding;
        }
        if (sub_req->content_languages) {
            mime_info.content_languages = sub_req->content_languages;
        }

        get_entry(neg->pool, &accept_info, sub_req->content_type);
        set_mime_fields(&mime_info, &accept_info);

        new_var = ap_push_array(neg->avail_vars);
        memcpy(new_var, (void *) &mime_info, sizeof(var_rec));

        neg->count_multiviews_variants++;

        clean_var_rec(&mime_info);
    }

    ap_pclosedir(neg->pool, dirp);

    /* If all variants we considered turn out to be forbidden, then return FORBIDDEN */
    if (forbidden.any && forbidden.all)
        return HTTP_FORBIDDEN;

    set_vlist_validator(r, r);

    /* Sort the variants into a canonical order.  The negotiation
     * result sometimes depends on the order of the variants.  By
     * sorting the variants into a canonical order, rather than using
     * the order in which readdir() happens to return them, we ensure
     * that the negotiation result will be consistent over filesystem
     * backup/restores and over all mirror sites.
     */
       
    qsort((void *) neg->avail_vars->elts, neg->avail_vars->nelts,
          sizeof(var_rec), (int (*)(const void *, const void *)) variantsortf);

    return OK;
}


/*****************************************************************
 * And now for the code you've been waiting for... actually
 * finding a match to the client's requirements.  
 */

/* Matching MIME types ... the star/star and foo/star commenting conventions
 * are implemented here.  (You know what I mean by star/star, but just
 * try mentioning those three characters in a C comment).  Using strcmp()
 * is legit, because everything has already been smashed to lowercase.
 *
 * Note also that if we get an exact match on the media type, we update
 * level_matched for use in level_cmp below...
 * 
 * We also give a value for mime_stars, which is used later. It should
 * be 1 for star/star, 2 for type/star and 3 for type/subtype.
 */

static int mime_match(accept_rec *accept_r, var_rec *avail)
{
    char *accept_type = accept_r->name;
    char *avail_type = avail->mime_type;
    int len = strlen(accept_type);

    if (accept_type[0] == '*') {        /* Anything matches star/star */
        if (avail->mime_stars < 1) {
            avail->mime_stars = 1;
        }
        return 1;
    }
    else if ((accept_type[len - 1] == '*') &&
             !strncmp(accept_type, avail_type, len - 2)) {
        if (avail->mime_stars < 2) {
            avail->mime_stars = 2;
        }
        return 1;
    }
    else if (!strcmp(accept_type, avail_type)
             || (!strcmp(accept_type, "text/html")
                 && (!strcmp(avail_type, INCLUDES_MAGIC_TYPE)
                     || !strcmp(avail_type, INCLUDES_MAGIC_TYPE3)))) {
        if (accept_r->level >= avail->level) {
            avail->level_matched = avail->level;
            avail->mime_stars = 3;
            return 1;
        }
    }

    return OK;
}

/* This code implements a piece of the tie-breaking algorithm between
 * variants of equal quality.  This piece is the treatment of variants
 * of the same base media type, but different levels.  What we want to
 * return is the variant at the highest level that the client explicitly
 * claimed to accept.
 *
 * If all the variants available are at a higher level than that, or if
 * the client didn't say anything specific about this media type at all
 * and these variants just got in on a wildcard, we prefer the lowest
 * level, on grounds that that's the one that the client is least likely
 * to choke on.
 *
 * (This is all motivated by treatment of levels in HTML --- we only
 * want to give level 3 to browsers that explicitly ask for it; browsers
 * that don't, including HTTP/0.9 browsers that only get the implicit
 * "Accept: * / *" [space added to avoid confusing cpp --- no, that
 * syntax doesn't really work] should get HTML2 if available).
 *
 * (Note that this code only comes into play when we are choosing among
 * variants of equal quality, where the draft standard gives us a fair
 * bit of leeway about what to do.  It ain't specified by the standard;
 * rather, it is a choice made by this server about what to do in cases
 * where the standard does not specify a unique course of action).
 */

static int level_cmp(var_rec *var1, var_rec *var2)
{
    /* Levels are only comparable between matching media types */

    if (var1->is_pseudo_html && !var2->is_pseudo_html) {
        return 0;
    }

    if (!var1->is_pseudo_html && strcmp(var1->mime_type, var2->mime_type)) {
        return 0;
    }
    /* The result of the above if statements is that, if we get to
     * here, both variants have the same mime_type or both are
     * pseudo-html.
     */    

    /* Take highest level that matched, if either did match. */

    if (var1->level_matched > var2->level_matched) {
        return 1;
    }
    if (var1->level_matched < var2->level_matched) {
        return -1;
    }

    /* Neither matched.  Take lowest level, if there's a difference. */

    if (var1->level < var2->level) {
        return 1;
    }
    if (var1->level > var2->level) {
        return -1;
    }

    /* Tied */

    return 0;
}

/* Finding languages.  The main entry point is set_language_quality()
 * which is called for each variant. It sets two elements in the
 * variant record:
 *    language_quality  - the 'q' value of the 'best' matching language
 *                        from Accept-Language: header (HTTP/1.1)
 *    lang_index    -     Pre HTTP/1.1 language priority, using
 *                        position of language on the Accept-Language:
 *                        header, if present, else LanguagePriority
 *                        directive order.
 *
 * When we do the variant checking for best variant, we use language
 * quality first, and if a tie, language_index next (this only applies
 * when _not_ using the RVSA/1.0 algorithm). If using the RVSA/1.0
 * algorithm, lang_index is never used.
 *
 * set_language_quality() calls find_lang_index() and find_default_index()
 * to set lang_index.  
 */

static int find_lang_index(array_header *accept_langs, char *lang)
{
    accept_rec *accs;
    int i;

    if (!lang || !accept_langs) {
        return -1;