/**
* Parsing method for metafile headers, saving each value into separate variable.
*
* @param s String containing metafile
* @return Boolean value notifying whether header ended or not (true = end of header)
*/
private boolean parseHeader(String s) {
String subs;
int colonIndex;
if (s.equals("")) {
// timto prazdnym radkem skoncil header, muzeme prestat cist
return true;
}
colonIndex = s.indexOf(":");
subs = s.substring(0, colonIndex);
if (subs.equalsIgnoreCase("zsync")) {
headers.version = s.substring(colonIndex + 2);
// zkontrolujeme kompatibilitu
if (headers.version.equals("0.0.4") || headers.version.equals("0.0.2")) {
throw new RuntimeException(
"This version is not compatible with zsync streams in versions up to 0.0.4");
}
} else if (subs.equalsIgnoreCase("Blocksize")) {
headers.blocksize = Integer.parseInt(s.substring(colonIndex + 2));
} else if (subs.equalsIgnoreCase("Length")) {
headers.length = Long.parseLong(s.substring(colonIndex + 2));
} else if (subs.equalsIgnoreCase("Hash-Lengths")) {
int comma = s.indexOf(",");
int seqNum = Integer.parseInt(s.substring((colonIndex + 2), comma));
headers.setSeqNum(seqNum);
int nextComma = s.indexOf(",", comma + 1);
headers.setRsumBytes(Integer.parseInt(s.substring(comma + 1, nextComma)));
headers.setChecksumBytes(Integer.parseInt(s.substring(nextComma + 1)));
if ((headers.getSeqNum() < 1 || headers.getSeqNum() > 2)
|| (headers.getRsumButes() < 1 || headers.getRsumButes() > 4)
|| (headers.getChecksumBytes() < 3 || headers.getChecksumBytes() > 16)) {
throw new RuntimeException("Nonsensical hash lengths line " + s.substring(colonIndex + 2));
}
} else if (subs.equalsIgnoreCase("URL")) {
headers.url = s.substring(colonIndex + 2);
} else if (subs.equalsIgnoreCase("Z-URL")) {
// not implemented yet
} else if (subs.equalsIgnoreCase("SHA-1")) {
headers.sha1 = s.substring(colonIndex + 2);
} else if (subs.equalsIgnoreCase("Z-Map2")) {
// not implemented yet
}
return false;
}
/**
* Fills a chaining hash table with ChecksumPairs
*
* @param checksums Byte array with bytes of whole metafile
*/
private void fillHashTable(byte[] checksums) {
int i = 16;
// spocteme velikost hashtable podle poctu bloku dat
while ((2 << (i - 1)) > blockNum && i > 4) {
i--;
}
// vytvorime hashtable o velikosti 2^i (max. 2^16, min. 2^4)
hashtable = new ChainingHash(2 << (i - 1));
ChecksumPair p = null;
// Link item;
int offset = 0;
int weakSum = 0;
int seq = 0;
int off = fileOffset;
byte[] weak = new byte[4];
byte[] strongSum = new byte[headers.getChecksumBytes()];
while (seq < blockNum) {
for (int w = 0; w < headers.getRsumButes(); w++) {
weak[w] = checksums[off];
off++;
}
for (int s = 0; s < strongSum.length; s++) {
strongSum[s] = checksums[off];
off++;
}
weakSum = 0;
weakSum += (weak[2] & 0x000000FF) << 24;
weakSum += (weak[3] & 0x000000FF) << 16;
weakSum += (weak[0] & 0x000000FF) << 8;
weakSum += (weak[1] & 0x000000FF);
p = new ChecksumPair(weakSum, strongSum.clone(), offset, headers.blocksize, seq);
offset += headers.blocksize;
seq++;
// item = new Link(p);
hashtable.insert(p);
}
}
/**
* Length of used strong sum
*
* @return Length of strong sum
*/
public int getChecksumBytes() {
return headers.getChecksumBytes();
}
