On Mon, Jul 19, 2004 at 03:47:45PM +0100, Nick Kew wrote:
> On Mon, 19 Jul 2004, Joe Orton wrote:
>
> > On Sat, Jul 17, 2004 at 03:22:35PM -0000, [EMAIL PROTECTED] wrote:
> > > niq 2004/07/17 08:22:35
> > >
> > > Modified: modules/filters mod_deflate.c
> > > Log:
> > > Fix previous patch to deal correctly with multiple empty brigades before
> > > we know if there's any content, and not re-process the headers.
> >
> > Is there no simpler fix for this e.g. first thing the filter does is "if
> > (APR_BRIGADE_EMPTY(bb)) return APR_SUCCESS;". And to avoid the
>
> Yes, that should work (but leaves us to reprocess the whole thing next
> time round). Is that better or worse? Or come to think of it, we can
> both return APR_SUCCESS and set a flag.
Why set a flag at all - if asked to filter nothing what interesting
state has changed since the last invocation?
> > re-process issue just ap_remove_output_filter(f) if finding an EOS-only
> > brigade?
>
> Do you recollect the discussion around when that patch went in?
> I don't in full, but I had a nagging recollection of someone having
> proposed a simpler solution but found it didn't work. Just enough
> to persuade me to preserve the loop-over-buckets test.
Nothing like that was posted to the list, at least. Patch below is
still sufficient to fix the proxy+304 case; does it work for you too?
--- mod_deflate.c 18 Jul 2004 01:18:58 -0000 1.56
+++ mod_deflate.c 19 Jul 2004 15:29:02 -0000
@@ -247,7 +247,6 @@
apr_bucket_brigade *bb, *proc_bb;
} deflate_ctx;
-static void* const deflate_yes = (void*)"YES";
static apr_status_t deflate_out_filter(ap_filter_t *f,
apr_bucket_brigade *bb)
{
@@ -255,14 +254,14 @@
request_rec *r = f->r;
deflate_ctx *ctx = f->ctx;
int zRC;
- char* buf;
- int eos_only = 1;
- apr_bucket *bkt;
- char *token;
- const char *encoding = NULL;
deflate_filter_config *c = ap_get_module_config(r->server->module_config,
&deflate_module);
+ /* Do nothing if asked to filter nothing. */
+ if (APR_BRIGADE_EMPTY(bb)) {
+ return APR_SUCCESS;
+ }
+
/* If we don't have a context, we need to ensure that it is okay to send
* the deflated content. If we have a context, that means we've done
* this before and we liked it.
@@ -270,6 +269,8 @@
* we're in better shape.
*/
if (!ctx) {
+ char *buf, *token;
+ const char *encoding;
/* only work on main request/no subrequests */
if (r->main) {
@@ -349,7 +350,13 @@
*/
apr_table_setn(r->headers_out, "Vary", "Accept-Encoding");
-
+ /* Deflating a zero-length response would make it longer; the
+ * proxy may pass through an empty response for a 304 too. */
+ if (APR_BUCKET_IS_EOS(APR_BRIGADE_FIRST(bb))) {
+ ap_remove_output_filter(f);
+ return ap_pass_brigade(f->next, bb);
+ }
+
/* force-gzip will just force it out regardless if the browser
* can actually do anything with it.
*/
@@ -383,41 +390,6 @@
return ap_pass_brigade(f->next, bb);
}
}
-
- /* don't deflate responses with zero length e.g. proxied 304's but
- * we do set the header on eos_only at this point for headers_filter
- *
- * if we get eos_only and come round again, we want to avoid redoing
- * what we've already done, so set f->ctx to a flag here
- */
- f->ctx = ctx = deflate_yes;
- }
- if (ctx == deflate_yes) {
- /* deal with the pathological case of lots of empty brigades and
- * no knowledge of whether content will follow
- */
- for (bkt = APR_BRIGADE_FIRST(bb);
- bkt != APR_BRIGADE_SENTINEL(bb);
- bkt = APR_BUCKET_NEXT(bkt))
- {
- if (!APR_BUCKET_IS_EOS(bkt)) {
- eos_only = 0;
- break;
- }
- }
- if (eos_only) {
- if (!encoding || !strcasecmp(encoding, "identity")) {
- apr_table_set(r->headers_out, "Content-Encoding", "gzip");
- }
- else {
- apr_table_merge(r->headers_out, "Content-Encoding", "gzip");
- }
- apr_table_unset(r->headers_out, "Content-Length");
- return ap_pass_brigade(f->next, bb);
- }
- }
- if (!ctx || (ctx==deflate_yes)) {
-
/* We're cool with filtering this. */
ctx = f->ctx = apr_pcalloc(r->pool, sizeof(*ctx));
ctx->bb = apr_brigade_create(r->pool, f->c->bucket_alloc);
