From 5faa1d1d6021dbf8963c5396e3c8a78e491dd08c Mon Sep 17 00:00:00 2001
From: psychon <psychon@726aef4b-f618-498e-8847-2d620e286838>
Date: Tue, 31 Mar 2009 08:24:34 +0000
Subject: [PATCH] DCC only allows file transfers of up to 4 GiB big files

Make CDCCSock use uint32_t to generate the "unsigned, 4 byte integer in network
byte order" which is used to acknowledge the received data. Also make
OpenFile() abort for files bigger than 4 GiB, because we would run into
integer overflows later on. These transfers might work with some remote client,
but ZNC is (no longer?) one of them. ;)

Thanks to KiNgMaR for the original patch and some help with the uint32_t stuff.


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1461 726aef4b-f618-498e-8847-2d620e286838
---
 DCCSock.cpp | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/DCCSock.cpp b/DCCSock.cpp
index 55e945ed..a40a4609 100644
--- a/DCCSock.cpp
+++ b/DCCSock.cpp
@@ -28,12 +28,16 @@ void CDCCSock::ReadData(const char* data, int len) {
 		Close();
 	}
 
+	// DCC specs says the receiving end sends the number of bytes it
+	// received so far as a 4 byte integer in network byte order, so we need
+	// uint32_t to do the job portably. This also means that the maximum
+	// file that we can transfer is 4 GiB big (see OpenFile()).
 	if (m_bSend) {
 		m_sSendBuf.append(data, len);
 
 		while (m_sSendBuf.size() >= 4) {
-			unsigned int iRemoteSoFar;
-			memcpy(&iRemoteSoFar, m_sSendBuf.data(), 4);
+			uint32_t iRemoteSoFar;
+			memcpy(&iRemoteSoFar, m_sSendBuf.data(), sizeof(iRemoteSoFar));
 			iRemoteSoFar = ntohl(iRemoteSoFar);
 
 			if ((iRemoteSoFar + 65536) >= m_uBytesSoFar) {
@@ -45,8 +49,8 @@ void CDCCSock::ReadData(const char* data, int len) {
 	} else {
 		m_pFile->Write(data, len);
 		m_uBytesSoFar += len;
-		unsigned long uSoFar = htonl(m_uBytesSoFar);
-		Write((char*) &uSoFar, sizeof(unsigned long));
+		uint32_t uSoFar = htonl(m_uBytesSoFar);
+		Write((char*) &uSoFar, sizeof(uSoFar));
 
 		if (m_uBytesSoFar >= m_uFileSize) {
 			Close();
@@ -172,7 +176,17 @@ CFile* CDCCSock::OpenFile(bool bWrite) {
 			return NULL;
 		}
 
-		m_uFileSize = m_pFile->GetSize();
+		// The DCC specs only allow file transfers with files smaller
+		// than 4GiB (see ReadData()).
+		off_t uFileSize = m_pFile->GetSize();
+		if (uFileSize > 0xffffffff) {
+			delete m_pFile;
+			m_pFile = NULL;
+			m_pUser->PutModule(m_sModuleName, "DCC -> [" + m_sRemoteNick + "] - File too large (>4 GiB) [" + m_sLocalFile + "]");
+			return NULL;
+		}
+
+		m_uFileSize = (unsigned long) uFileSize;
 	}
 
 	m_sFileName = m_pFile->GetShortName();