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SSU2: First fragments can be 5 bytes larger than followon fragments

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zzz
2022-06-20 12:05:45 -04:00
parent c5323a8d36
commit 723257d6ef
1 changed files with 25 additions and 11 deletions
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36
router/java/src/net/i2p/router/transport/udp/OutboundMessageState.java
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@@ -100,9 +100,16 @@ class OutboundMessageState implements CDPQEntry {
else
_i2npMessage.toRawByteArray(_messageBuf);
_fragmentSize = _peer.fragmentSize();
int numFragments = totalSize / _fragmentSize;
if (numFragments * _fragmentSize < totalSize)
numFragments++;
// SSU2 first frag can be 5 bytes bigger
int first = _fragmentSize;
if (peer.getVersion() > 1)
first += SSU2Util.DATA_FOLLOWON_EXTRA_SIZE;
int numFragments = 1;
if (first < totalSize) {
numFragments += (totalSize - first) / _fragmentSize;
if (first + ((numFragments - 1) * _fragmentSize) < totalSize)
numFragments++;
}
// This should never happen, as 534 bytes * 64 fragments > 32KB, and we won't bid on > 32KB
if (numFragments > InboundMessageState.MAX_FRAGMENTS)
throw new IllegalArgumentException("Fragmenting a " + totalSize + " message into " + numFragments + " fragments - too many!");
@@ -441,19 +448,23 @@ class OutboundMessageState implements CDPQEntry {
/**
* The size in bytes of the fragment.
* Does NOT include any SSU overhead.
* Does NOT include any SSU overhead (SSU2 is 3 for all fragments, + 5 for followon fragments)
*
* @param fragmentNum the number of the fragment
* @return the size of the fragment specified by the number
*/
public int fragmentSize(int fragmentNum) {
if (fragmentNum + 1 == _numFragments) {
int valid = _messageBuf.length;
if (valid <= _fragmentSize)
return valid;
// bugfix 0.8.12
int mod = valid % _fragmentSize;
return mod == 0 ? _fragmentSize : mod;
if (fragmentNum == 0) {
// SSU2 first frag is 5 bytes bigger
int fs = _fragmentSize;
if (_peer.getVersion() > 1)
fs += SSU2Util.DATA_FOLLOWON_EXTRA_SIZE;
return Math.min(_messageBuf.length, fs);
} else if (fragmentNum + 1 == _numFragments) {
int last = _messageBuf.length - (fragmentNum * _fragmentSize);
if (_peer.getVersion() > 1)
last -= SSU2Util.DATA_FOLLOWON_EXTRA_SIZE;
return last;
} else {
return _fragmentSize;
}
@@ -469,6 +480,9 @@ class OutboundMessageState implements CDPQEntry {
*/
public int writeFragment(byte out[], int outOffset, int fragmentNum) {
int start = _fragmentSize * fragmentNum;
// SSU2 first frag is 5 bytes bigger
if (fragmentNum > 0 && _peer.getVersion() > 1)
start += SSU2Util.DATA_FOLLOWON_EXTRA_SIZE;
int toSend = fragmentSize(fragmentNum);
int end = start + toSend;
if (end <= _messageBuf.length && outOffset + toSend <= out.length) {