MINOR: mux-quic: complete BUG_ON on TX flow-control enforcing

TX flow-control enforcing is not straightforward : it requires the usage
of several counters at stream and connection level, in part due to the
difficult sending API between MUX and quic-conn layers.

To strengthen this part and ensures it behaves as expected, some
existing BUG_ON statements were adjusted and new one were added. This
should help to catch errors as early as possible, as in the case with
github issue #1738.

diff --git a/src/mux_quic.c b/src/mux_quic.c
index 8fad19f63dbc8075dc1f9e9eebf30e7e65eb857d..c5e2c9e92649be6bd5c84b0a13ae856d6a02215d 100644 (file)
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -809,6 +809,7 @@ static int qcs_xfer_data(struct qcs *qcs, struct buffer *out, struct buffer *in)
 
        BUG_ON_HOT(qcs->tx.sent_offset < qcs->stream->ack_offset);
        BUG_ON_HOT(qcs->tx.offset < qcs->tx.sent_offset);
+       BUG_ON_HOT(qcc->tx.offsets < qcc->tx.sent_offsets);
 
        left = qcs->tx.offset - qcs->tx.sent_offset;
        to_xfer = QUIC_MIN(b_data(in), b_room(out));
@@ -870,6 +871,7 @@ static int qcs_build_stream_frm(struct qcs *qcs, struct buffer *out, char fin,
        }
        BUG_ON(qcs->tx.sent_offset >= qcs->tx.offset);
        BUG_ON(qcs->tx.sent_offset + total > qcs->tx.offset);
+       BUG_ON(qcc->tx.sent_offsets + total > qcc->rfctl.md);
 
        frm = pool_zalloc(pool_head_quic_frame);
        if (!frm)
@@ -923,7 +925,7 @@ void qcc_streams_sent_done(struct qcs *qcs, uint64_t data, uint64_t offset)
        uint64_t diff;
 
        BUG_ON(offset > qcs->tx.sent_offset);
-       BUG_ON(offset >= qcs->tx.offset);
+       BUG_ON(offset + data > qcs->tx.offset);
 
        /* check if the STREAM frame has already been notified. It can happen
         * for retransmission.
@@ -1065,7 +1067,9 @@ static int _qc_send_qcs(struct qcs *qcs, struct list *frms)
                }
 
                qcs->tx.offset += xfer;
+               BUG_ON_HOT(qcs->tx.offset > qcs->tx.msd);
                qcc->tx.offsets += xfer;
+               BUG_ON_HOT(qcc->tx.offsets > qcc->rfctl.md);
        }
 
        /* out buffer cannot be emptied if qcs offsets differ. */