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java/org/apache/tomcat/util/http/parser/Ranges.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.apache.tomcat.util.http.parser;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class Ranges {
+
+    private final String units;
+    private final List<Entry> entries;
+
+
+    private Ranges(String units, List<Entry> entries) {
+        this.units = units;
+        this.entries = Collections.unmodifiableList(entries);
+    }
+
+
+    public List<Entry> getEntries() {
+        return entries;
+    }
+
+    public String getUnits() {
+        return units;
+    }
+
+
+    public static class Entry {
+
+        private final long start;
+        private final long end;
+
+
+        public Entry(long start, long end) {
+            this.start = start;
+            this.end = end;
+        }
+
+
+        public long getStart() {
+            return start;
+        }
+
+
+        public long getEnd() {
+            return end;
+        }
+    }
+
+
+    /**
+     * Parses a Range header from an HTTP header.
+     *
+     * @param input a reader over the header text
+     *
+     * @return a set of ranges parsed from the input, or null if not valid
+     *
+     * @throws IOException if there was a problem reading the input
+     */
+    public static Ranges parse(StringReader input) throws IOException {
+
+        // Units (required)
+        String units = HttpParser.readToken(input);
+        if (units == null || units.length() == 0) {
+            return null;
+        }
+
+        // Must be followed by '='
+        if (HttpParser.skipConstant(input, "=") == SkipResult.NOT_FOUND) {
+            return null;
+        }
+
+        // Range entries
+        List<Entry> entries = new ArrayList<>();
+
+        SkipResult skipResult;
+        do {
+            long start = HttpParser.readLong(input);
+            // Must be followed by '-'
+            if (HttpParser.skipConstant(input, "-") == SkipResult.NOT_FOUND) {
+                return null;
+            }
+            long end = HttpParser.readLong(input);
+
+            if (start == -1 && end == -1) {
+                // Invalid range
+                return null;
+            }
+
+            entries.add(new Entry(start, end));
+
+            skipResult = HttpParser.skipConstant(input, ",");
+            if (skipResult == SkipResult.NOT_FOUND) {
+                // Invalid range
+                return null;
+            }
+        } while (skipResult == SkipResult.FOUND);
+
+        // There must be at least one entry
+        if (entries.size() == 0) {
+            return null;
+        }
+
+        return new Ranges(units, entries);
+    }
+}