1 files changed, 96 insertions, 0 deletions
diff --git a/src/quic_fctl.c b/src/quic_fctl.c
new file mode 100644
index 0000000..b797e55
--- /dev/null
+++ b/src/quic_fctl.c
@@ -0,0 +1,96 @@
+#include <haproxy/quic_fctl.h>
+
+#include <haproxy/api.h>
+
+void qfctl_init(struct quic_fctl *fctl, uint64_t limit)
+{
+	fctl->limit = limit;
+	fctl->off_real = 0;
+	fctl->off_soft = 0;
+}
+
+/* Returns true if real limit is blocked for <fctl> flow control instance.
+ * This happens if it is equal than current max value.
+ */
+int qfctl_rblocked(const struct quic_fctl *fctl)
+{
+	/* Real limit must never be exceeded. */
+	BUG_ON(fctl->off_real > fctl->limit);
+	return fctl->off_real == fctl->limit;
+}
+
+/* Returns true if soft limit is blocked for <fctl> flow control instance.
+ * This happens if it is equal or greater than current max value.
+ */
+int qfctl_sblocked(const struct quic_fctl *fctl)
+{
+	return fctl->off_soft >= fctl->limit;
+}
+
+/* Set a new <val> maximum value for <fctl> flow control instance. If current
+ * offset is already equal or more, the new value is ignored. Additionally,
+ * <unblocked_soft> and <unblocked_real> can be used as output parameters to
+ * detect if the current update result in one or both of these offsets to be
+ * unblocked.
+ *
+ * Returns true if max is incremented else false.
+ */
+int qfctl_set_max(struct quic_fctl *fctl, uint64_t val,
+                  int *out_unblock_soft, int *out_unblock_real)
+{
+	int unblock_soft = 0, unblock_real = 0;
+	int ret = 0;
+
+	if (fctl->limit < val) {
+		if (fctl->off_soft >= fctl->limit && fctl->off_soft < val)
+			unblock_soft = 1;
+		if (fctl->off_real == fctl->limit && fctl->off_real < val)
+			unblock_real = 1;
+
+		fctl->limit = val;
+		ret = 1;
+	}
+
+	if (out_unblock_soft)
+		*out_unblock_soft = unblock_soft;
+	if (out_unblock_real)
+		*out_unblock_real = unblock_real;
+
+	return ret;
+}
+
+/* Increment real offset of <fctl> flow control instance by <diff>. This cannot
+ * exceed <fctl> limit.
+ *
+ * Returns true if limit is reached after increment.
+ */
+int qfctl_rinc(struct quic_fctl *fctl, uint64_t diff)
+{
+	/* Real limit must never be exceeded. */
+	BUG_ON(fctl->off_real + diff > fctl->limit);
+	fctl->off_real += diff;
+
+	return fctl->off_real == fctl->limit;
+}
+
+/* Increment soft offset of <fctl> flow control instance by <diff>. This cannot
+ * be done if <fctl> limit was already reached.
+ *
+ * Returns true if limit is reached after increment.
+ */
+int qfctl_sinc(struct quic_fctl *fctl, uint64_t diff)
+{
+	/* Soft limit must not be incremented if already in excess. */
+	BUG_ON(qfctl_sblocked(fctl));
+	fctl->off_soft += diff;
+
+	return fctl->off_soft >= fctl->limit;
+}
+
+/* Return the remaining offset before reaching <fctl> limit. */
+uint64_t qfctl_rcap(const struct quic_fctl *fctl)
+{
+	/* Real limit must never be exceeded. */
+	BUG_ON(fctl->off_real > fctl->limit);
+	return fctl->limit - fctl->off_real;
+}