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ReaderImpl now maintains either one or two bytes of lookahead,

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depending on the value of the first byte, so that an object's initial
tag is included in the data seen by the ObjectReader. Digests and
signatures can therefore be calculated over objects by their readers
without any risk of ambiguity.
This commit is contained in:
akwizgran
2011-07-22 17:39:59 +01:00
parent b5220b096a
commit a573e87c04
16 changed files with 244 additions and 200 deletions
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34
components/net/sf/briar/protocol/MessageReader.java
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@@ -32,40 +32,42 @@ class MessageReader implements ObjectReader<Message> {
this.messageDigest = messageDigest;
}
public Message readObject(Reader reader) throws IOException {
public Message readObject(Reader r) throws IOException {
CopyingConsumer copying = new CopyingConsumer();
CountingConsumer counting = new CountingConsumer(Message.MAX_SIZE);
reader.addConsumer(copying);
reader.addConsumer(counting);
r.addConsumer(copying);
r.addConsumer(counting);
// Read the initial tag
r.readUserDefinedTag(Tags.MESSAGE);
// Read the parent's message ID
reader.readUserDefinedTag(Tags.MESSAGE_ID);
byte[] b = reader.readRaw();
r.readUserDefinedTag(Tags.MESSAGE_ID);
byte[] b = r.readRaw();
if(b.length != UniqueId.LENGTH) throw new FormatException();
MessageId parent = new MessageId(b);
// Read the group ID
reader.readUserDefinedTag(Tags.GROUP_ID);
b = reader.readRaw();
r.readUserDefinedTag(Tags.GROUP_ID);
b = r.readRaw();
if(b.length != UniqueId.LENGTH) throw new FormatException();
GroupId group = new GroupId(b);
// Read the timestamp
long timestamp = reader.readInt64();
long timestamp = r.readInt64();
if(timestamp < 0L) throw new FormatException();
// Hash the author's nick and public key to get the author ID
DigestingConsumer digesting = new DigestingConsumer(messageDigest);
messageDigest.reset();
reader.addConsumer(digesting);
reader.readString();
byte[] encodedKey = reader.readRaw();
reader.removeConsumer(digesting);
r.addConsumer(digesting);
r.readString();
byte[] encodedKey = r.readRaw();
r.removeConsumer(digesting);
AuthorId author = new AuthorId(messageDigest.digest());
// Skip the message body
reader.readRaw();
r.readRaw();
// Record the length of the signed data
int messageLength = (int) counting.getCount();
// Read the signature
byte[] sig = reader.readRaw();
reader.removeConsumer(counting);
reader.removeConsumer(copying);
byte[] sig = r.readRaw();
r.removeConsumer(counting);
r.removeConsumer(copying);
// Verify the signature
PublicKey publicKey;
try {