mod_expires.c

apache简化版

    /* <base> [plus] {<num> <type>}*
     */

    /* <base>
     */
    word = ap_getword_conf(p, &code);
    if (!strncasecmp(word, "now", 1) ||
        !strncasecmp(word, "access", 1)) {
        base = 'A';
    }
    else if (!strncasecmp(word, "modification", 1)) {
        base = 'M';
    }
    else {
        return ap_pstrcat(p, "bad expires code, unrecognised <base> '",
                       word, "'", NULL);
    };

    /* [plus]
     */
    word = ap_getword_conf(p, &code);
    if (!strncasecmp(word, "plus", 1)) {
        word = ap_getword_conf(p, &code);
    };

    /* {<num> <type>}*
     */
    while (word[0]) {
        /* <num>
         */
        if (ap_isdigit(word[0])) {
            num = atoi(word);
        }
        else {
            return ap_pstrcat(p, "bad expires code, numeric value expected <num> '",
                           word, "'", NULL);
        };

        /* <type>
         */
        word = ap_getword_conf(p, &code);
        if (word[0]) {
            /* do nothing */
        }
        else {
            return ap_pstrcat(p, "bad expires code, missing <type>", NULL);
        };

        factor = 0;
        if (!strncasecmp(word, "years", 1)) {
            factor = 60 * 60 * 24 * 365;
        }
        else if (!strncasecmp(word, "months", 2)) {
            factor = 60 * 60 * 24 * 30;
        }
        else if (!strncasecmp(word, "weeks", 1)) {
            factor = 60 * 60 * 24 * 7;
        }
        else if (!strncasecmp(word, "days", 1)) {
            factor = 60 * 60 * 24;
        }
        else if (!strncasecmp(word, "hours", 1)) {
            factor = 60 * 60;
        }
        else if (!strncasecmp(word, "minutes", 2)) {
            factor = 60;
        }
        else if (!strncasecmp(word, "seconds", 1)) {
            factor = 1;
        }
        else {
            return ap_pstrcat(p, "bad expires code, unrecognised <type>",
                           "'", word, "'", NULL);
        };

        modifier = modifier + factor * num;

        /* next <num>
         */
        word = ap_getword_conf(p, &code);
    };

    *real_code = ap_psprintf(p, "%c%d", base, modifier);

    return NULL;
}

static const char *set_expiresbytype(cmd_parms *cmd, expires_dir_config * dir_config, char *mime, char *code)
{
    char *response, *real_code;

    if ((response = check_code(cmd->pool, code, &real_code)) == NULL) {
        ap_table_setn(dir_config->expiresbytype, mime, real_code);
        return NULL;
    };
    return ap_pstrcat(cmd->pool,
                 "'ExpiresByType ", mime, " ", code, "': ", response, NULL);
}

static const char *set_expiresdefault(cmd_parms *cmd, expires_dir_config * dir_config, char *code)
{
    char *response, *real_code;

    if ((response = check_code(cmd->pool, code, &real_code)) == NULL) {
        dir_config->expiresdefault = real_code;
        return NULL;
    };
    return ap_pstrcat(cmd->pool,
                   "'ExpiresDefault ", code, "': ", response, NULL);
}

static const command_rec expires_cmds[] =
{
    {"ExpiresActive", set_expiresactive, NULL, DIR_CMD_PERMS, FLAG,
     "Limited to 'on' or 'off'"},
    {"ExpiresBytype", set_expiresbytype, NULL, DIR_CMD_PERMS, TAKE2,
     "a MIME type followed by an expiry date code"},
    {"ExpiresDefault", set_expiresdefault, NULL, DIR_CMD_PERMS, TAKE1,
     "an expiry date code"},
    {NULL}
};

static void *merge_expires_dir_configs(pool *p, void *basev, void *addv)
{
    expires_dir_config *new = (expires_dir_config *) ap_pcalloc(p, sizeof(expires_dir_config));
    expires_dir_config *base = (expires_dir_config *) basev;
    expires_dir_config *add = (expires_dir_config *) addv;

    if (add->active == ACTIVE_DONTCARE) {
        new->active = base->active;
    }
    else {
        new->active = add->active;
    };

    if (add->expiresdefault != '\0') {
        new->expiresdefault = add->expiresdefault;
    };

    new->expiresbytype = ap_overlay_tables(p, add->expiresbytype,
                                        base->expiresbytype);
    return new;
}

static int add_expires(request_rec *r)
{
    expires_dir_config *conf;
    char *code;
    time_t base;
    time_t additional;
    time_t expires;
    char age[20];

    if (ap_is_HTTP_ERROR(r->status))       /* Don't add Expires headers to errors */
        return DECLINED;

    if (r->main != NULL)        /* Say no to subrequests */
        return DECLINED;

    conf = (expires_dir_config *) ap_get_module_config(r->per_dir_config, &expires_module);
    if (conf == NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
                    "internal error: %s", r->filename);
        return SERVER_ERROR;
    };

    if (conf->active != ACTIVE_ON)
        return DECLINED;

    /* we perhaps could use the default_type(r) in its place but that
     * may be 2nd guesing the desired configuration...  calling table_get
     * with a NULL key will SEGV us
     *
     * I still don't know *why* r->content_type would ever be NULL, this
     * is possibly a result of fixups being called in many different
     * places.  Fixups is probably the wrong place to be doing all this
     * work...  Bah.
     *
     * Changed as of 08.Jun.96 don't DECLINE, look for an ExpiresDefault.
     */
    if (r->content_type == NULL)
        code = NULL;
    else
        code = (char *) ap_table_get(conf->expiresbytype, r->content_type);

    if (code == NULL) {
        /* no expires defined for that type, is there a default? */
        code = conf->expiresdefault;

        if (code[0] == '\0')
            return OK;
    };

    /* we have our code */

    switch (code[0]) {
    case 'M':
	if (r->finfo.st_mode == 0) { 
	    /* file doesn't exist on disk, so we can't do anything based on
	     * modification time.  Note that this does _not_ log an error.
	     */
	    return DECLINED;
	}
        base = r->finfo.st_mtime;
        additional = atoi(&code[1]);
        break;
    case 'A':
        /* there's been some discussion and it's possible that 
         * 'access time' will be stored in request structure
         */
        base = r->request_time;
        additional = atoi(&code[1]);
        break;
    default:
        /* expecting the add_* routines to be case-hardened this 
         * is just a reminder that module is beta
         */
        ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
                    "internal error: bad expires code: %s", r->filename);
        return SERVER_ERROR;
    };

    expires = base + additional;
    ap_snprintf(age, sizeof(age), "max-age=%d", (int) expires - (int) r->request_time);
    ap_table_setn(r->headers_out, "Cache-Control", ap_pstrdup(r->pool, age));
    tzset();                    /* redundant? called implicitly by localtime, at least 
                                 * under FreeBSD
                                 */
    ap_table_setn(r->headers_out, "Expires", ap_gm_timestr_822(r->pool, expires));
    return OK;
}

module MODULE_VAR_EXPORT expires_module =
{
    STANDARD_MODULE_STUFF,
    NULL,                       /* initializer */
    create_dir_expires_config,  /* dir config creater */
    merge_expires_dir_configs,  /* dir merger --- default is to override */
    NULL,                       /* server config */
    NULL,                       /* merge server configs */
    expires_cmds,               /* command table */
    NULL,                       /* handlers */
    NULL,                       /* filename translation */
    NULL,                       /* check_user_id */
    NULL,                       /* check auth */
    NULL,                       /* check access */
    NULL,                       /* type_checker */
    add_expires,                /* fixups */
    NULL,                       /* logger */
    NULL,                       /* header parser */
    NULL,                       /* child_init */
    NULL,                       /* child_exit */
    NULL                        /* post read-request */
};