1 files changed, 75 insertions, 0 deletions
diff --git a/lib/tc.c b/lib/tc.c
new file mode 100644
index 0000000..2e45add
--- /dev/null
+++ b/lib/tc.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Traffic Control (TC) main library
+ * Copyright (C) 2022  Shichu Yang
+ */
+
+#include "tc.h"
+
+int tc_getrate(const char *str, uint64_t *rate)
+{
+	char *endp;
+	uint64_t raw = strtoull(str, &endp, 10);
+
+	if (endp == str)
+		return -1;
+
+	/* if the string only contains a number, it must be valid rate (bps) */
+	bool valid = (*endp == '\0');
+
+	const char *p = endp;
+	bool bytes = false, binary_base = false;
+	int power = 0;
+
+	while (*p) {
+		if (strcmp(p, "Bps") == 0) {
+			bytes = true;
+			valid = true;
+			break;
+		} else if (strcmp(p, "bit") == 0) {
+			valid = true;
+			break;
+		}
+		switch (*p) {
+		case 'k':
+		case 'K':
+			power = 1;
+			break;
+		case 'm':
+		case 'M':
+			power = 2;
+			break;
+		case 'g':
+		case 'G':
+			power = 3;
+			break;
+		case 't':
+		case 'T':
+			power = 4;
+			break;
+		case 'i':
+		case 'I':
+			if (power != 0)
+				binary_base = true;
+			else
+				return -1;
+			break;
+		default:
+			return -1;
+		}
+		p++;
+	}
+
+	if (!valid)
+		return -1;
+
+	for (int i = 0; i < power; i++)
+		raw *= binary_base ? 1024ULL : 1000ULL;
+
+	if (bytes)
+		*rate = raw;
+	else
+		*rate = raw / 8ULL;
+
+	return 0;
+}