client: flush buffered SSL output when tearing down client ustream

When the outer SSL ustream triggers a change notification due to
encountering EOF, the inner connection ustream might still have
pending data buffered.

Previously, such a condition led to truncated files delivered by
uhttpd via HTTPS and could be triggered by requesting large resources
via slow network links.

Mitigate the problem by propagating the EOF status indicator from
the outer ustream to the inner one and by deferring the client
connection shutdown until the inner ustream output buffer has been
completely drained.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

diff --git a/client.c b/client.c
index 05044ed9d38dc3755a80a9cd8e2c7cc2cbf631c9..04d26f11af9a0c8501b66c2dcebb48d2ab04c5e1 100644 (file)
--- a/client.c
+++ b/client.c
@@ -553,6 +553,12 @@ void uh_client_notify_state(struct client *cl)
 
                if (!s->eof || s->w.data_bytes)
                        return;
+
+               if (cl->tls && cl->ssl.conn && cl->ssl.conn->w.data_bytes) {
+                       cl->ssl.conn->eof = s->eof;
+                       if (!ustream_write_pending(cl->ssl.conn))
+                               return;
+               }
        }
 
        return client_close(cl);