1 files changed, 113 insertions, 0 deletions
diff --git a/src/org/xbill/DNS/TTL.java b/src/org/xbill/DNS/TTL.java
new file mode 100644
index 0000000..01bf416
--- /dev/null
+++ b/src/org/xbill/DNS/TTL.java
@@ -0,0 +1,113 @@
+// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
+
+package org.xbill.DNS;
+
+/**
+ * Routines for parsing BIND-style TTL values.  These values consist of
+ * numbers followed by 1 letter units of time (W - week, D - day, H - hour,
+ * M - minute, S - second).
+ *
+ * @author Brian Wellington
+ */
+
+public final class TTL {
+
+public static final long MAX_VALUE = 0x7FFFFFFFL;
+
+private
+TTL() {}
+
+static void
+check(long i) {
+	if (i < 0 || i > MAX_VALUE)
+		throw new InvalidTTLException(i);
+}
+
+/**
+ * Parses a TTL-like value, which can either be expressed as a number or a
+ * BIND-style string with numbers and units.
+ * @param s The string representing the numeric value.
+ * @param clamp Whether to clamp values in the range [MAX_VALUE + 1, 2^32 -1]
+ * to MAX_VALUE.  This should be donw for TTLs, but not other values which
+ * can be expressed in this format.
+ * @return The value as a number of seconds
+ * @throws NumberFormatException The string was not in a valid TTL format.
+ */
+public static long
+parse(String s, boolean clamp) {
+	if (s == null || s.length() == 0 || !Character.isDigit(s.charAt(0)))
+		throw new NumberFormatException();
+	long value = 0;
+	long ttl = 0;
+	for (int i = 0; i < s.length(); i++) {
+		char c = s.charAt(i);
+		long oldvalue = value;
+		if (Character.isDigit(c)) {
+			value = (value * 10) + Character.getNumericValue(c);
+			if (value < oldvalue)
+				throw new NumberFormatException();
+		} else {
+			switch (Character.toUpperCase(c)) {
+				case 'W': value *= 7;
+				case 'D': value *= 24;
+				case 'H': value *= 60;
+				case 'M': value *= 60;
+				case 'S': break;
+				default:  throw new NumberFormatException();
+			}
+			ttl += value;
+			value = 0;
+			if (ttl > 0xFFFFFFFFL)
+				throw new NumberFormatException();
+		}
+	}
+	if (ttl == 0)
+		ttl = value;
+
+	if (ttl > 0xFFFFFFFFL)
+		throw new NumberFormatException();
+	else if (ttl > MAX_VALUE && clamp)
+		ttl = MAX_VALUE;
+	return ttl;
+}
+
+/**
+ * Parses a TTL, which can either be expressed as a number or a BIND-style
+ * string with numbers and units.
+ * @param s The string representing the TTL
+ * @return The TTL as a number of seconds
+ * @throws NumberFormatException The string was not in a valid TTL format.
+ */
+public static long
+parseTTL(String s) {
+	return parse(s, true);
+}
+
+public static String
+format(long ttl) {
+	TTL.check(ttl);
+	StringBuffer sb = new StringBuffer();
+	long secs, mins, hours, days, weeks;
+	secs = ttl % 60;
+	ttl /= 60;
+	mins = ttl % 60;
+	ttl /= 60;
+	hours = ttl % 24;
+	ttl /= 24;
+	days = ttl % 7;
+	ttl /= 7;
+	weeks = ttl;
+	if (weeks > 0)
+		sb.append(weeks + "W");
+	if (days > 0)
+		sb.append(days + "D");
+	if (hours > 0)
+		sb.append(hours + "H");
+	if (mins > 0)
+		sb.append(mins + "M");
+	if (secs > 0 || (weeks == 0 && days == 0 && hours == 0 && mins == 0))
+		sb.append(secs + "S");
+	return sb.toString();
+}
+
+}