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 * as indicated by the @author tags.
 *
 * Licensed 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
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package io.undertow.protocols.http2;

import java.nio.ByteBuffer;

import io.undertow.UndertowMessages;
import io.undertow.util.HttpString;

Author:Stuart Douglas
/** * @author Stuart Douglas */
final class Hpack { private static final byte LOWER_DIFF = 'a' - 'A'; static final int DEFAULT_TABLE_SIZE = 4096; private static final int MAX_INTEGER_OCTETS = 8; //not sure what a good value for this is, but the spec says we need to provide an upper bound
table that contains powers of two, used as both bitmask and to quickly calculate 2^n
/** * 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(new HttpString(":authority"), null); fields[2] = new HeaderField(new HttpString(":method"), "GET"); fields[3] = new HeaderField(new HttpString(":method"), "POST"); fields[4] = new HeaderField(new HttpString(":path"), "/"); fields[5] = new HeaderField(new HttpString(":path"), "/index.html"); fields[6] = new HeaderField(new HttpString(":scheme"), "http"); fields[7] = new HeaderField(new HttpString(":scheme"), "https"); fields[8] = new HeaderField(new HttpString(":status"), "200"); fields[9] = new HeaderField(new HttpString(":status"), "204"); fields[10] = new HeaderField(new HttpString(":status"), "206"); fields[11] = new HeaderField(new HttpString(":status"), "304"); fields[12] = new HeaderField(new HttpString(":status"), "400"); fields[13] = new HeaderField(new HttpString(":status"), "404"); fields[14] = new HeaderField(new HttpString(":status"), "500"); fields[15] = new HeaderField(new HttpString("accept-charset"), null); fields[16] = new HeaderField(new HttpString("accept-encoding"), "gzip, deflate"); fields[17] = new HeaderField(new HttpString("accept-language"), null); fields[18] = new HeaderField(new HttpString("accept-ranges"), null); fields[19] = new HeaderField(new HttpString("accept"), null); fields[20] = new HeaderField(new HttpString("access-control-allow-origin"), null); fields[21] = new HeaderField(new HttpString("age"), null); fields[22] = new HeaderField(new HttpString("allow"), null); fields[23] = new HeaderField(new HttpString("authorization"), null); fields[24] = new HeaderField(new HttpString("cache-control"), null); fields[25] = new HeaderField(new HttpString("content-disposition"), null); fields[26] = new HeaderField(new HttpString("content-encoding"), null); fields[27] = new HeaderField(new HttpString("content-language"), null); fields[28] = new HeaderField(new HttpString("content-length"), null); fields[29] = new HeaderField(new HttpString("content-location"), null); fields[30] = new HeaderField(new HttpString("content-range"), null); fields[31] = new HeaderField(new HttpString("content-type"), null); fields[32] = new HeaderField(new HttpString("cookie"), null); fields[33] = new HeaderField(new HttpString("date"), null); fields[34] = new HeaderField(new HttpString("etag"), null); fields[35] = new HeaderField(new HttpString("expect"), null); fields[36] = new HeaderField(new HttpString("expires"), null); fields[37] = new HeaderField(new HttpString("from"), null); fields[38] = new HeaderField(new HttpString("host"), null); fields[39] = new HeaderField(new HttpString("if-match"), null); fields[40] = new HeaderField(new HttpString("if-modified-since"), null); fields[41] = new HeaderField(new HttpString("if-none-match"), null); fields[42] = new HeaderField(new HttpString("if-range"), null); fields[43] = new HeaderField(new HttpString("if-unmodified-since"), null); fields[44] = new HeaderField(new HttpString("last-modified"), null); fields[45] = new HeaderField(new HttpString("link"), null); fields[46] = new HeaderField(new HttpString("location"), null); fields[47] = new HeaderField(new HttpString("max-forwards"), null); fields[48] = new HeaderField(new HttpString("proxy-authenticate"), null); fields[49] = new HeaderField(new HttpString("proxy-authorization"), null); fields[50] = new HeaderField(new HttpString("range"), null); fields[51] = new HeaderField(new HttpString("referer"), null); fields[52] = new HeaderField(new HttpString("refresh"), null); fields[53] = new HeaderField(new HttpString("retry-after"), null); fields[54] = new HeaderField(new HttpString("server"), null); fields[55] = new HeaderField(new HttpString("set-cookie"), null); fields[56] = new HeaderField(new HttpString("strict-transport-security"), null); fields[57] = new HeaderField(new HttpString("transfer-encoding"), null); fields[58] = new HeaderField(new HttpString("user-agent"), null); fields[59] = new HeaderField(new HttpString("vary"), null); fields[60] = new HeaderField(new HttpString("via"), null); fields[61] = new HeaderField(new HttpString("www-authenticate"), null); STATIC_TABLE = fields; STATIC_TABLE_LENGTH = STATIC_TABLE.length - 1; } static class HeaderField { final HttpString name; final String value; final int size; HeaderField(HttpString 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 prefex format. If the return value is -1 it means that there was not enough data in the buffer to complete the decoding sequence.

If this method returns -1 then the source buffer will not have been modified.

Params:
  • source – The buffer that contains the integer
  • n – The encoding prefix length
Returns:The encoded integer, or -1 if there was not enough data
/** * Decodes an integer in the HPACK prefex 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; } if(n >= PREFIX_TABLE.length) { throw UndertowMessages.MESSAGES.integerEncodedOverTooManyOctets(MAX_INTEGER_OCTETS); } int count = 1; int sp = source.position(); int mask = PREFIX_TABLE[n]; int i = mask & source.get(); int b; if (i < PREFIX_TABLE[n]) { return i; } else { int m = 0; do { if(count++ > MAX_INTEGER_OCTETS) { throw UndertowMessages.MESSAGES.integerEncodedOverTooManyOctets(MAX_INTEGER_OCTETS); } if (source.remaining() == 0) { //we have run out of data //reset source.position(sp); return -1; } if(m >= PREFIX_TABLE.length) { throw UndertowMessages.MESSAGES.integerEncodedOverTooManyOctets(MAX_INTEGER_OCTETS); } b = source.get(); i = i + (b & 127) * (PREFIX_TABLE[m] + 1); m += 7; } while ((b & 128) == 128); } return i; }
Encodes an integer in the HPACK prefix format.

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

Params:
  • source – The buffer that contains the integer
  • value – The integer to encode
  • n – The encoding prefix length
/** * 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 byte toLower(byte b) { if (b >= 'A' && b <= 'Z') { return (byte) (b + LOWER_DIFF); } return b; } private Hpack() {} }