DCC bouncing: Throttle the receiving side if we can't bounce the data fast enough

It could happen that ZNC was killed by the OOM killer. This was caused by
DCC bouncing receiving as fast as possible and caching everything in memory.

This throttles the receiving side via PauseRead() and UnPauseRead().


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1069 726aef4b-f618-498e-8847-2d620e286838

DCCBounce.cpp

@@ -9,6 +9,11 @@
 #include "DCCBounce.h"
 #include "User.h"
 
+// If we buffer more than this in memory, we will throttle the receiving side
+const unsigned int CDCCBounce::m_uiMaxDCCBuffer = 10 * 1024;
+// If less than this is in the buffer, the receiving side continues
+const unsigned int CDCCBounce::m_uiMinDCCBuffer = 2 * 1024;
+
 void CDCCBounce::ReadLine(const CString& sData) {
 	CString sLine = sData;
 
@@ -22,11 +27,26 @@ void CDCCBounce::ReadLine(const CString& sData) {
 }
 
 void CDCCBounce::ReadData(const char* data, int len) {
+	size_t BufLen;
+
 	if (m_pPeer) {
 		m_pPeer->Write(data, len);
+
+		BufLen = m_pPeer->GetInternalWriteBuffer().length();
+
+		if (BufLen >= m_uiMaxDCCBuffer) {
+			DEBUG_ONLY(cout << GetSockName() << " The send buffer is over the "
+					"limit (" << BufLen <<"), throttling" << endl);
+			PauseRead();
+		}
 	}
 }
 
+void CDCCBounce::ReadPaused() {
+	if (!m_pPeer || m_pPeer->GetInternalWriteBuffer().length() <= m_uiMinDCCBuffer)
+		UnPauseRead();
+}
+
 void CDCCBounce::Timeout() {
 	DEBUG_ONLY(cout << GetSockName() << " == Timeout()" << endl);
 	CString sType = (m_bIsChat) ? "Chat" : "Xfer";