mod_cern_meta.c revision bc8fd1b0b1afdf89b8d28eefa8cd74e26ba97986
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/*
* mod_cern_meta.c
* version 0.1.0
* status beta
*
* Andrew Wilson <Andrew.Wilson@cm.cf.ac.uk> 25.Jan.96
*
* *** IMPORTANT ***
* This version of mod_cern_meta.c controls Meta File behaviour on a
* per-directory basis. Previous versions of the module defined behaviour
* on a per-server basis. The upshot is that you'll need to revisit your
* configuration files in order to make use of the new module.
* ***
*
* Emulate the CERN HTTPD Meta file semantics. Meta files are HTTP
* headers that can be output in addition to the normal range of
* headers for each file accessed. They appear rather like the Apache
* .asis files, and are able to provide a crude way of influencing
* the Expires: header, as well as providing other curiosities.
* There are many ways to manage meta information, this one was
* chosen because there is already a large number of CERN users
* who can exploit this module. It should be noted that there are probably
* more sensitive ways of managing the Expires: header specifically.
*
* The module obeys the following directives, which can appear
* in the server's .conf files and in .htaccess files.
*
* MetaFiles <on|off>
*
* turns on|off meta file processing for any directory.
* Default value is off
*
* # turn on MetaFiles in this directory
* MetaFiles on
*
* MetaDir <directory name>
*
* specifies the name of the directory in which Apache can find
* meta information files. The directory is usually a 'hidden'
* subdirectory of the directory that contains the file being
* accessed. eg:
*
* # .meta files are in the *same* directory as the
* # file being accessed
* MetaDir .
*
* the default is to look in a '.web' subdirectory. This is the
* same as for CERN 3.+ webservers and behaviour is the same as
* for the directive:
*
* MetaDir .web
*
* MetaSuffix <meta file suffix>
*
* specifies the file name suffix for the file containing the
* meta information. eg:
*
* # our meta files are suffixed with '.cern_meta'
* MetaSuffix .cern_meta
*
* the default is to look for files with the suffix '.meta'. This
* behaviour is the same as for the directive:
*
* MetaSuffix .meta
*
* When accessing the file
*
* DOCUMENT_ROOT/somedir/index.html
*
* this module will look for the file
*
* DOCUMENT_ROOT/somedir/.web/index.html.meta
*
* and will use its contents to generate additional MIME header
* information.
*
* For more information on the CERN Meta file semantics see:
*
* http://www.w3.org/hypertext/WWW/Daemon/User/Config/General.html#MetaDir
*
* Change-log:
* 29.Jan.96 pfopen/pfclose instead of fopen/fclose
* DECLINE when real file not found, we may be checking each
* of the index.html/index.shtml/index.htm variants and don't
* need to report missing ones as spurious errors.
* 31.Jan.96 log_error reports about a malformed .meta file, rather
* than a script error.
* 20.Jun.96 MetaFiles <on|off> default off, added, so that module
* can be configured per-directory. Prior to this the module
* was running for each request anywhere on the server, naughty..
* 29.Jun.96 All directives made per-directory.
*/
#include "apr.h"
#include "apr_strings.h"
#define APR_WANT_STRFUNC
#include "apr_want.h"
#if APR_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "util_script.h"
#include "http_log.h"
#include "http_request.h"
#include "apr_lib.h"
#define DIR_CMD_PERMS OR_INDEXES
#define DEFAULT_METADIR ".web"
#define DEFAULT_METASUFFIX ".meta"
#define DEFAULT_METAFILES 0
module AP_MODULE_DECLARE_DATA cern_meta_module;
typedef struct {
const char *metadir;
const char *metasuffix;
int metafiles;
} cern_meta_dir_config;
static void *create_cern_meta_dir_config(apr_pool_t *p, char *dummy)
{
cern_meta_dir_config *new =
(cern_meta_dir_config *) apr_palloc(p, sizeof(cern_meta_dir_config));
new->metadir = NULL;
new->metasuffix = NULL;
new->metafiles = DEFAULT_METAFILES;
return new;
}
static void *merge_cern_meta_dir_configs(apr_pool_t *p, void *basev, void *addv)
{
cern_meta_dir_config *base = (cern_meta_dir_config *) basev;
cern_meta_dir_config *add = (cern_meta_dir_config *) addv;
cern_meta_dir_config *new =
(cern_meta_dir_config *) apr_palloc(p, sizeof(cern_meta_dir_config));
new->metadir = add->metadir ? add->metadir : base->metadir;
new->metasuffix = add->metasuffix ? add->metasuffix : base->metasuffix;
new->metafiles = add->metafiles;
return new;
}
static const char *set_metadir(cmd_parms *parms, void *in_dconf, const char *arg)
{
cern_meta_dir_config *dconf = in_dconf;
dconf->metadir = arg;
return NULL;
}
static const char *set_metasuffix(cmd_parms *parms, void *in_dconf, const char *arg)
{
cern_meta_dir_config *dconf = in_dconf;
dconf->metasuffix = arg;
return NULL;
}
static const char *set_metafiles(cmd_parms *parms, void *in_dconf, int arg)
{
cern_meta_dir_config *dconf = in_dconf;
dconf->metafiles = arg;
return NULL;
}
static const command_rec cern_meta_cmds[] =
{
AP_INIT_FLAG("MetaFiles", set_metafiles, NULL, DIR_CMD_PERMS,
"Limited to 'on' or 'off'"),
AP_INIT_TAKE1("MetaDir", set_metadir, NULL, DIR_CMD_PERMS,
"the name of the directory containing meta files"),
AP_INIT_TAKE1("MetaSuffix", set_metasuffix, NULL, DIR_CMD_PERMS,
"the filename suffix for meta files"),
{NULL}
};
/* XXX: this is very similar to ap_scan_script_header_err_core...
* are the differences deliberate, or just a result of bit rot?
*/
static int scan_meta_file(request_rec *r, apr_file_t *f)
{
char w[MAX_STRING_LEN];
char *l;
int p;
apr_table_t *tmp_headers;
tmp_headers = apr_table_make(r->pool, 5);
while (apr_file_gets(w, MAX_STRING_LEN - 1, f) == APR_SUCCESS) {
/* Delete terminal (CR?)LF */
p = strlen(w);
if (p > 0 && w[p - 1] == '\n') {
if (p > 1 && w[p - 2] == '\015')
w[p - 2] = '\0';
else
w[p - 1] = '\0';
}
if (w[0] == '\0') {
return OK;
}
/* if we see a bogus header don't ignore it. Shout and scream */
if (!(l = strchr(w, ':'))) {
ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
"malformed header in meta file: %s", r->filename);
return HTTP_INTERNAL_SERVER_ERROR;
}
*l++ = '\0';
while (*l && apr_isspace(*l))
++l;
if (!strcasecmp(w, "Content-type")) {
char *tmp;
/* Nuke trailing whitespace */
char *endp = l + strlen(l) - 1;
while (endp > l && apr_isspace(*endp))
*endp-- = '\0';
tmp = apr_pstrdup(r->pool, l);
ap_content_type_tolower(tmp);
r->content_type = tmp;
}
else if (!strcasecmp(w, "Status")) {
sscanf(l, "%d", &r->status);
r->status_line = apr_pstrdup(r->pool, l);
}
else {
apr_table_set(tmp_headers, w, l);
}
}
apr_table_overlap(r->headers_out, tmp_headers, APR_OVERLAP_TABLES_SET);
return OK;
}
static int add_cern_meta_data(request_rec *r)
{
char *metafilename;
char *leading_slash;
char *last_slash;
char *real_file;
char *scrap_book;
apr_file_t *f = NULL;
apr_status_t retcode;
cern_meta_dir_config *dconf;
int rv;
request_rec *rr;
dconf = ap_get_module_config(r->per_dir_config, &cern_meta_module);
if (!dconf->metafiles) {
return DECLINED;
};
/* if ./.web/$1.meta exists then output 'asis' */
if (r->finfo.filetype == 0) {
return DECLINED;
};
/* is this a directory? */
if (r->finfo.filetype == APR_DIR || r->uri[strlen(r->uri) - 1] == '/') {
return DECLINED;
};
/* what directory is this file in? */
scrap_book = apr_pstrdup(r->pool, r->filename);
leading_slash = strchr(scrap_book, '/');
last_slash = strrchr(scrap_book, '/');
if ((last_slash != NULL) && (last_slash != leading_slash)) {
/* skip over last slash */
real_file = last_slash;
real_file++;
*last_slash = '\0';
}
else {
/* no last slash, buh?! */
ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
"internal error in mod_cern_meta: %s", r->filename);
/* should really barf, but hey, let's be friends... */
return DECLINED;
};
metafilename = apr_pstrcat(r->pool, scrap_book, "/",
dconf->metadir ? dconf->metadir : DEFAULT_METADIR,
"/", real_file,
dconf->metasuffix ? dconf->metasuffix : DEFAULT_METASUFFIX,
NULL);
/* It sucks to require this subrequest to complete, because this
* means people must leave their meta files accessible to the world.
* A better solution might be a "safe open" feature of pfopen to avoid
* pipes, symlinks, and crap like that.
*
* In fact, this doesn't suck. Because <Location > blocks are never run
* against sub_req_lookup_file, the meta can be somewhat protected by
* either masking it with a <Location > directive or alias, or stowing
* the file outside of the web document tree, while providing the
* appropriate directory blocks to allow access to it as a file.
*/
rr = ap_sub_req_lookup_file(metafilename, r, NULL);
if (rr->status != HTTP_OK) {
ap_destroy_sub_req(rr);
return DECLINED;
}
ap_destroy_sub_req(rr);
retcode = apr_file_open(&f, metafilename, APR_READ | APR_CREATE, APR_OS_DEFAULT, r->pool);
if (retcode != APR_SUCCESS) {
if (APR_STATUS_IS_ENOENT(retcode)) {
return DECLINED;
}
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
"meta file permissions deny server access: %s", metafilename);
return HTTP_FORBIDDEN;
};
/* read the headers in */
rv = scan_meta_file(r, f);
apr_file_close(f);
return rv;
}
static void register_hooks(apr_pool_t *p)
{
ap_hook_fixups(add_cern_meta_data,NULL,NULL,APR_HOOK_MIDDLE);
}
module AP_MODULE_DECLARE_DATA cern_meta_module =
{
STANDARD20_MODULE_STUFF,
create_cern_meta_dir_config,/* dir config creater */
merge_cern_meta_dir_configs,/* dir merger --- default is to override */
NULL, /* server config */
NULL, /* merge server configs */
cern_meta_cmds, /* command apr_table_t */
register_hooks /* register hooks */
};