[master] 4c5293804 boc: Set up transit buffer only for a backend fetch

[Walid Boudebouda]

commit 4c529380490df08be2f943d506ad034c158700a0
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Fri Jul 11 09:32:03 2025 +0200

    boc: Set up transit buffer only for a backend fetch
    
    It can otherwise lock up a client request body fetch indefinitely. An
    early setup at BOC creation time also increases the gap between updates
    to the transit_buffer parameter and its effectiveness, since BOCs can be
    created early through objcore preallocation made by worker threads.

diff --git a/bin/varnishd/cache/cache_fetch.c b/bin/varnishd/cache/cache_fetch.c
index 0521d0314..0b3685e45 100644
--- a/bin/varnishd/cache/cache_fetch.c
+++ b/bin/varnishd/cache/cache_fetch.c
@@ -1175,6 +1175,7 @@ VBF_Fetch(struct worker *wrk, struct req *req, struct objcore *oc,
 
 	boc = HSH_RefBoc(oc);
 	CHECK_OBJ_NOTNULL(boc, BOC_MAGIC);
+	boc->transit_buffer = cache_param->transit_buffer;
 
 	switch (mode) {
 	case VBF_PASS:
diff --git a/bin/varnishd/cache/cache_obj.c b/bin/varnishd/cache/cache_obj.c
index dfc7929a0..c85ecd618 100644
--- a/bin/varnishd/cache/cache_obj.c
+++ b/bin/varnishd/cache/cache_obj.c
@@ -109,7 +109,6 @@ obj_newboc(void)
 	Lck_New(&boc->mtx, lck_busyobj);
 	PTOK(pthread_cond_init(&boc->cond, NULL));
 	boc->refcount = 1;
-	boc->transit_buffer = cache_param->transit_buffer;
 	return (boc);
 }
 
diff --git a/bin/varnishtest/tests/r04362.vtc b/bin/varnishtest/tests/r04362.vtc
new file mode 100644
index 000000000..3ca74e72e
--- /dev/null
+++ b/bin/varnishtest/tests/r04362.vtc
@@ -0,0 +1,24 @@
+varnishtest "No transit buffer for req.body and vcl_synth"
+
+varnish v1 -cliok "param.set transit_buffer 4k"
+varnish v1 -vcl {
+	import std;
+
+	backend be none;
+
+	sub vcl_recv {
+		if (!std.cache_req_body(10MB)) {
+			return (synth(503));
+		}
+		return (synth(200));
+	}
+} -start
+
+client c1 {
+	txreq -bodylen 10240
+	rxresp
+	expect resp.status == 200
+} -run
+
+varnish v1 -expect transit_stored > 10240
+varnish v1 -expect transit_buffered == 0