/*
* 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.coyote.http2;
import java.nio.ByteBuffer;
import org.apache.tomcat.util.http.Method;
import org.apache.tomcat.util.res.StringManager;
final class Hpack {
private static final StringManager sm = StringManager.getManager(Hpack.class);
private static final byte LOWER_DIFF = 'a' - 'A';
static final int DEFAULT_TABLE_SIZE = 4096;
/*
* The HPack specification says there SHOULD be an upper bound on this.
*
* Tomcat has opted to limit values to INTEGER.MAX_VALUE. Give that there is the prefix byte and then each octet
* provides up to 7-bits, a total a 5 octets plus the prefix may be required.
*
* Note: The maximum value represented by 5 octets is greater than INTEGER.MAX_VALUE.
*
*/
private static final int MAX_INTEGER_OCTETS = 5;
/**
* table that contains powers of two, used as both bitmask and to quickly calculate 2^n
*/
private static final int[] PREFIX_TABLE;
static final HeaderField[] STATIC_TABLE;
static final int STATIC_TABLE_LENGTH;
static {
PREFIX_TABLE = new int[32];
for (int i = 0; i < 32; ++i) {
int n = 0;
for (int j = 0; j < i; ++j) {
n = n << 1;
n |= 1;
}
PREFIX_TABLE[i] = n;
}
HeaderField[] fields = new HeaderField[62];
// note that zero is not used
fields[1] = new HeaderField(":authority", null);
fields[2] = new HeaderField(":method", Method.GET);
fields[3] = new HeaderField(":method", Method.POST);
fields[4] = new HeaderField(":path", "/");
fields[5] = new HeaderField(":path", "/index.html");
fields[6] = new HeaderField(":scheme", "http");
fields[7] = new HeaderField(":scheme", "https");
fields[8] = new HeaderField(":status", "200");
fields[9] = new HeaderField(":status", "204");
fields[10] = new HeaderField(":status", "206");
fields[11] = new HeaderField(":status", "304");
fields[12] = new HeaderField(":status", "400");
fields[13] = new HeaderField(":status", "404");
fields[14] = new HeaderField(":status", "500");
fields[15] = new HeaderField("accept-charset", null);
fields[16] = new HeaderField("accept-encoding", "gzip, deflate");
fields[17] = new HeaderField("accept-language", null);
fields[18] = new HeaderField("accept-ranges", null);
fields[19] = new HeaderField("accept", null);
fields[20] = new HeaderField("access-control-allow-origin", null);
fields[21] = new HeaderField("age", null);
fields[22] = new HeaderField("allow", null);
fields[23] = new HeaderField("authorization", null);
fields[24] = new HeaderField("cache-control", null);
fields[25] = new HeaderField("content-disposition", null);
fields[26] = new HeaderField("content-encoding", null);
fields[27] = new HeaderField("content-language", null);
fields[28] = new HeaderField("content-length", null);
fields[29] = new HeaderField("content-location", null);
fields[30] = new HeaderField("content-range", null);
fields[31] = new HeaderField("content-type", null);
fields[32] = new HeaderField("cookie", null);
fields[33] = new HeaderField("date", null);
fields[34] = new HeaderField("etag", null);
fields[35] = new HeaderField("expect", null);
fields[36] = new HeaderField("expires", null);
fields[37] = new HeaderField("from", null);
fields[38] = new HeaderField("host", null);
fields[39] = new HeaderField("if-match", null);
fields[40] = new HeaderField("if-modified-since", null);
fields[41] = new HeaderField("if-none-match", null);
fields[42] = new HeaderField("if-range", null);
fields[43] = new HeaderField("if-unmodified-since", null);
fields[44] = new HeaderField("last-modified", null);
fields[45] = new HeaderField("link", null);
fields[46] = new HeaderField("location", null);
fields[47] = new HeaderField("max-forwards", null);
fields[48] = new HeaderField("proxy-authenticate", null);
fields[49] = new HeaderField("proxy-authorization", null);
fields[50] = new HeaderField("range", null);
fields[51] = new HeaderField("referer", null);
fields[52] = new HeaderField("refresh", null);
fields[53] = new HeaderField("retry-after", null);
fields[54] = new HeaderField("server", null);
fields[55] = new HeaderField("set-cookie", null);
fields[56] = new HeaderField("strict-transport-security", null);
fields[57] = new HeaderField("transfer-encoding", null);
fields[58] = new HeaderField("user-agent", null);
fields[59] = new HeaderField("vary", null);
fields[60] = new HeaderField("via", null);
fields[61] = new HeaderField("www-authenticate", null);
STATIC_TABLE = fields;
STATIC_TABLE_LENGTH = STATIC_TABLE.length - 1;
}
static class HeaderField {
final String name;
final String value;
final int size;
HeaderField(String name, String value) {
this.name = name;
this.value = value;
if (value != null) {
this.size = 32 + name.length() + value.length();
} else {
this.size = -1;
}
}
}
/**
* Decodes an integer in the HPACK prefix format. If the return value is -1 it means that there was not enough data
* in the buffer to complete the decoding sequence.
* <p/>
* If this method returns -1 then the source buffer will not have been modified.
*
* @param source The buffer that contains the integer
* @param n The encoding prefix length
*
* @return The encoded integer, or -1 if there was not enough data
*/
static int decodeInteger(ByteBuffer source, int n) throws HpackException {
if (source.remaining() == 0) {
return -1;
}
int count = 1;
int sp = source.position();
int mask = PREFIX_TABLE[n];
// Use long internally as the value may exceed Integer.MAX_VALUE
long result = mask & source.get();
int b;
if (result < PREFIX_TABLE[n]) {
// Casting is safe as result must be less than 255 at this point.
return (int) result;
} else {
int m = 0;
do {
if (count++ > MAX_INTEGER_OCTETS) {
throw new HpackException(
sm.getString("hpack.integerEncodedOverTooManyOctets", Integer.valueOf(MAX_INTEGER_OCTETS)));
}
if (source.remaining() == 0) {
// we have run out of data
// reset
source.position(sp);
return -1;
}
b = source.get();
result = result + (b & 127) * (PREFIX_TABLE[m] + 1L);
if (result > Integer.MAX_VALUE) {
throw new HpackException(sm.getString("hpack.integerEncodedTooBig"));
}
m += 7;
} while ((b & 128) == 128);
}
// Casting is safe as result must be less than Integer.MAX_VALUE at this point
return (int) result;
}
/**
* Encodes an integer in the HPACK prefix format.
* <p/>
* This method assumes that the buffer has already had the first 8-n bits filled. As such it will modify the last
* byte that is already present in the buffer, and potentially add more if required
*
* @param source The buffer that contains the integer
* @param value The integer to encode
* @param n The encoding prefix length
*/
static void encodeInteger(ByteBuffer source, int value, int n) {
int twoNminus1 = PREFIX_TABLE[n];
int pos = source.position() - 1;
if (value < twoNminus1) {
source.put(pos, (byte) (source.get(pos) | value));
} else {
source.put(pos, (byte) (source.get(pos) | twoNminus1));
value = value - twoNminus1;
while (value >= 128) {
source.put((byte) (value % 128 + 128));
value = value / 128;
}
source.put((byte) value);
}
}
static char toLower(char c) {
if (c >= 'A' && c <= 'Z') {
return (char) (c + LOWER_DIFF);
}
return c;
}
private Hpack() {
}
}