| // Copyright 2019 The Bazel Authors. All rights reserved. |
| // |
| // 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 |
| // limitations under the License. |
| |
| package com.google.devtools.build.lib.bazel.repository.downloader; |
| |
| import com.google.common.base.Ascii; |
| import com.google.common.hash.HashCode; |
| import com.google.devtools.build.lib.bazel.repository.cache.RepositoryCache.KeyType; |
| import java.util.Base64; |
| |
| /** The content checksum for an HTTP download, which knows its own type. */ |
| public class Checksum { |
| /** Exception thrown to indicate that a string is not a valid checksum for that key type. */ |
| public static final class InvalidChecksumException extends Exception { |
| private InvalidChecksumException(KeyType keyType, String hash) { |
| super("Invalid " + keyType + " checksum '" + hash + "'"); |
| } |
| |
| private InvalidChecksumException(String msg) { |
| super(msg); |
| } |
| } |
| |
| private final KeyType keyType; |
| private final HashCode hashCode; |
| private final boolean useSubresourceIntegrity; |
| |
| private Checksum(KeyType keyType, HashCode hashCode, boolean useSubresourceIntegrity) { |
| this.keyType = keyType; |
| this.hashCode = hashCode; |
| this.useSubresourceIntegrity = useSubresourceIntegrity; |
| } |
| |
| /** Constructs a new Checksum for a given key type and hash, in hex format. */ |
| public static Checksum fromString(KeyType keyType, String hash) throws InvalidChecksumException { |
| return fromString(keyType, hash, /* useSubresourceIntegrity= */ false); |
| } |
| |
| private static Checksum fromString(KeyType keyType, String hash, boolean useSubresourceIntegrity) |
| throws InvalidChecksumException { |
| if (!keyType.isValid(hash)) { |
| throw new InvalidChecksumException(keyType, hash); |
| } |
| return new Checksum( |
| keyType, HashCode.fromString(Ascii.toLowerCase(hash)), useSubresourceIntegrity); |
| } |
| |
| /** Constructs a new Checksum from a hash in Subresource Integrity format. */ |
| public static Checksum fromSubresourceIntegrity(String integrity) |
| throws InvalidChecksumException { |
| Base64.Decoder decoder = Base64.getDecoder(); |
| KeyType keyType = null; |
| byte[] hash = null; |
| int expectedLength = 0; |
| |
| if (integrity.startsWith("sha1-")) { |
| keyType = KeyType.SHA1; |
| expectedLength = 20; |
| hash = decoder.decode(integrity.substring(5)); |
| } |
| if (integrity.startsWith("sha256-")) { |
| keyType = KeyType.SHA256; |
| expectedLength = 32; |
| hash = decoder.decode(integrity.substring(7)); |
| } |
| if (integrity.startsWith("sha384-")) { |
| keyType = KeyType.SHA384; |
| expectedLength = 48; |
| hash = decoder.decode(integrity.substring(7)); |
| } |
| if (integrity.startsWith("sha512-")) { |
| keyType = KeyType.SHA512; |
| expectedLength = 64; |
| hash = decoder.decode(integrity.substring(7)); |
| } |
| |
| if (keyType == null) { |
| throw new InvalidChecksumException( |
| "Unsupported checksum algorithm: '" |
| + integrity |
| + "' (expected SHA-1, SHA-256, SHA-384, or SHA-512)"); |
| } |
| |
| if (hash.length != expectedLength) { |
| throw new InvalidChecksumException( |
| "Invalid " + keyType + " SRI checksum '" + integrity + "'"); |
| } |
| |
| return Checksum.fromString( |
| keyType, HashCode.fromBytes(hash).toString(), /* useSubresourceIntegrity= */ true); |
| } |
| |
| private static String toSubresourceIntegrity(KeyType keyType, HashCode hashCode) { |
| String encoded = Base64.getEncoder().encodeToString(hashCode.asBytes()); |
| return keyType.getHashName() + "-" + encoded; |
| } |
| |
| public String toSubresourceIntegrity() { |
| return toSubresourceIntegrity(keyType, hashCode); |
| } |
| |
| @Override |
| public String toString() { |
| return hashCode.toString(); |
| } |
| |
| public HashCode getHashCode() { |
| return hashCode; |
| } |
| |
| public KeyType getKeyType() { |
| return keyType; |
| } |
| |
| public String emitOtherHashInSameFormat(HashCode otherHash) { |
| if (useSubresourceIntegrity) { |
| return toSubresourceIntegrity(keyType, otherHash); |
| } else { |
| return otherHash.toString(); |
| } |
| } |
| } |