1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.location.cts.asn1.base; 18 19 import static android.location.cts.asn1.base.PerAlignedUtils.SIXTYFOUR_K; 20 21 import com.google.common.base.Preconditions; 22 import com.google.common.collect.ImmutableList; 23 24 import java.nio.ByteBuffer; 25 import java.util.Collection; 26 27 /** 28 * A general string is any ISO 646 related 8-bit encoding, presumably agreed on 29 * 30 * Implements ASN.1 functionality. 31 * 32 */ 33 public class Asn1GeneralString extends Asn1Object { 34 private static final Collection<Asn1Tag> possibleFirstTags = 35 ImmutableList.of(Asn1Tag.GENERAL_STRING); 36 37 private byte[] value; 38 private int minimumSize = 0; 39 private Integer maximumSize = null; // Null == unconstrained. 40 41 public static Collection<Asn1Tag> getPossibleFirstTags() { 42 return possibleFirstTags; 43 } 44 45 @Override Asn1Tag getDefaultTag() { 46 return Asn1Tag.GENERAL_STRING; 47 } 48 49 @Override int getBerValueLength() { 50 throw new UnsupportedOperationException(); 51 } 52 53 @Override void encodeBerValue(ByteBuffer buf) { 54 throw new UnsupportedOperationException(); 55 } 56 57 @Override void decodeBerValue(ByteBuffer buf) { 58 throw new UnsupportedOperationException(); 59 } 60 61 protected void setMinSize(int min) { 62 minimumSize = min; 63 } 64 65 protected void setMaxSize(int max) { 66 maximumSize = max; 67 } 68 69 public byte[] getValue() { 70 return value; 71 } 72 73 public void setValue(byte[] value) { 74 this.value = value; 75 } 76 77 private Iterable<BitStream> encodePerImpl(boolean aligned) { 78 Preconditions.checkNotNull(value, "No value set."); 79 Preconditions.checkState(value.length >= minimumSize, "Value too short."); 80 Preconditions.checkState(maximumSize == null || value.length <= maximumSize, 81 "Value too long."); 82 int characterBitCount = 8; 83 if (maximumSize == null) { 84 throw new UnsupportedOperationException("unconstrained unimplemented"); 85 } 86 87 BitStream result = new BitStream(); 88 for (byte b : value) { 89 result.appendByte(b); 90 } 91 if (aligned && maximumSize * characterBitCount > 16) { 92 result.setBeginByteAligned(); 93 } 94 95 if (minimumSize == maximumSize 96 && maximumSize < SIXTYFOUR_K) { 97 return ImmutableList.of(result); 98 } 99 100 if (maximumSize >= SIXTYFOUR_K) { 101 throw new UnsupportedOperationException("large string unimplemented"); 102 } 103 104 // A little oddity when maximumSize != minimumSize. 105 if (aligned && maximumSize * characterBitCount == 16) { 106 result.setBeginByteAligned(); 107 } 108 109 // Must be preceded by a count. The count and the bit field may be 110 // independently aligned. 111 BitStream count = null; 112 if (aligned) { 113 count = PerAlignedUtils.encodeSmallConstrainedWholeNumber( 114 value.length, minimumSize, maximumSize); 115 } else { 116 count = PerUnalignedUtils.encodeConstrainedWholeNumber( 117 value.length, minimumSize, maximumSize); 118 } 119 return ImmutableList.of(count, result); 120 } 121 122 @Override public Iterable<BitStream> encodePerUnaligned() { 123 return encodePerImpl(false); 124 } 125 126 @Override public Iterable<BitStream> encodePerAligned() { 127 return encodePerImpl(true); 128 } 129 130 private void decodePerImpl(BitStreamReader reader, boolean aligned) { 131 int characterBitCount = 8; 132 if (maximumSize == null) { 133 throw new UnsupportedOperationException("unconstrained unimplemented"); 134 } 135 136 if (minimumSize == maximumSize 137 && maximumSize < SIXTYFOUR_K) { 138 if (aligned && maximumSize * characterBitCount > 16) { 139 reader.spoolToByteBoundary(); 140 } 141 value = new byte[maximumSize]; 142 for (int i = 0; i < maximumSize; i++) { 143 value[i] = reader.readByte(); 144 } 145 return; 146 } 147 148 if (maximumSize >= SIXTYFOUR_K) { 149 throw new UnsupportedOperationException("large string unimplemented"); 150 } 151 152 // Value is preceded by a count. 153 int count = 0; 154 if (aligned) { 155 count = PerAlignedUtils.decodeSmallConstrainedWholeNumber( 156 reader, minimumSize, maximumSize); 157 } else { 158 count = PerUnalignedUtils.decodeConstrainedWholeNumber( 159 reader, minimumSize, maximumSize); 160 } 161 162 if (aligned && maximumSize * characterBitCount >= 16) { 163 reader.spoolToByteBoundary(); 164 } 165 166 value = new byte[count]; 167 for (int i = 0; i < count; i++) { 168 value[i] = reader.readByte(); 169 } 170 } 171 172 @Override public void decodePerUnaligned(BitStreamReader reader) { 173 decodePerImpl(reader, false); 174 } 175 176 @Override public void decodePerAligned(BitStreamReader reader) { 177 decodePerImpl(reader, true); 178 } 179 } 180
