url: fix logic in connection reuse to deny reuse on "unclean" connections

- add parameter to `conn_is_alive()` cfilter method that returns
  if there is input data waiting on the connection
- refrain from re-using connnection from the cache that have
  input pending
- adapt http/2 and http/3 alive checks to digest pending input
  to check the connection state
- remove check_cxn method from openssl as that was just doing
  what the socket filter now does.
- add tests for connection reuse with special server configs

Closes #10690

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/vquic/curl_msh3.c b/lib/vquic/curl_msh3.c
index a74f7ceaa..530899977 100644
--- a/lib/vquic/curl_msh3.c
+++ b/lib/vquic/curl_msh3.c
@@ -769,11 +769,13 @@ static CURLcode cf_msh3_query(struct Curl_cfilter *cf,
 }
 
 static bool cf_msh3_conn_is_alive(struct Curl_cfilter *cf,
-                                  struct Curl_easy *data)
+                                  struct Curl_easy *data,
+                                  bool *input_pending)
 {
   struct cf_msh3_ctx *ctx = cf->ctx;
 
   (void)data;
+  *input_pending = FALSE;
   return ctx && ctx->sock[SP_LOCAL] != CURL_SOCKET_BAD && ctx->qconn &&
          ctx->connected;
 }