[Openbts-discuss] [PATCH 2/2] common: Add mandatory length field to UDP receive calls

[Tom T. <tom...@et...>]

Current UDP receive reads up to MAX_UDP_LENGTH bytes into the
passed in buffer, which may lead to buffer overflow if the
write buffer is of insufficient size.

Add mandatory length argument to UDP socket receive calls.

Reported-by: Simone Margaritelli <si...@zi...>
Signed-off-by: Tom Tsou <tom...@et...>
---
 Sockets.cpp     | 22 +++++++++-------------
 Sockets.h       |  4 ++--
 SocketsTest.cpp |  4 ++--
 3 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/Sockets.cpp b/Sockets.cpp
index bb00e9f..6880c3e 100644
--- a/Sockets.cpp
+++ b/Sockets.cpp
@@ -199,25 +199,21 @@ int DatagramSocket::send(const struct sockaddr* dest, const char * message)
 	return send(dest,message,length);
 }
 
-
-
-
-
-int DatagramSocket::read(char* buffer)
+int DatagramSocket::read(char* buffer, size_t length)
 {
-	socklen_t temp_len = sizeof(mSource);
-	int length = recvfrom(mSocketFD, (void*)buffer, MAX_UDP_LENGTH, 0,
-	    (struct sockaddr*)&mSource,&temp_len);
-	if ((length==-1) && (errno!=EAGAIN)) {
+	socklen_t addr_len = sizeof(mSource);
+	int rd_length = recvfrom(mSocketFD, (void *) buffer, length, 0,
+		(struct sockaddr*) &mSource, &addr_len);
+
+	if ((rd_length==-1) && (errno!=EAGAIN)) {
 		perror("DatagramSocket::read() failed");
 		devassert(0);
 		throw SocketError();
 	}
-	return length;
+	return rd_length;
 }
 
-
-int DatagramSocket::read(char* buffer, unsigned timeout)
+int DatagramSocket::read(char* buffer, size_t length, unsigned timeout)
 {
 	fd_set fds;
 	FD_ZERO(&fds);
@@ -232,7 +228,7 @@ int DatagramSocket::read(char* buffer, unsigned timeout)
 		throw SocketError();
 	}
 	if (sel==0) return -1;
-	if (FD_ISSET(mSocketFD,&fds)) return read(buffer);
+	if (FD_ISSET(mSocketFD,&fds)) return read(buffer, length);
 	return -1;
 }
 
diff --git a/Sockets.h b/Sockets.h
index 213fcb7..365b745 100644
--- a/Sockets.h
+++ b/Sockets.h
@@ -110,7 +110,7 @@ public:
 		@param buffer A char[MAX_UDP_LENGTH] procured by the caller.
 		@return The number of bytes received or -1 on non-blocking pass.
 	*/
-	int read(char* buffer);
+	int read(char* buffer, size_t length);
 
 	/**
 		Receive a packet with a timeout.
@@ -118,7 +118,7 @@ public:
 		@param maximum wait time in milliseconds
 		@return The number of bytes received or -1 on timeout.
 	*/
-	int read(char* buffer, unsigned timeout);
+	int read(char* buffer, size_t length, unsigned timeout);
 
 
 	/** Send a packet to a given destination, other than the default. */
diff --git a/SocketsTest.cpp b/SocketsTest.cpp
index ef2fddf..7ed2744 100644
--- a/SocketsTest.cpp
+++ b/SocketsTest.cpp
@@ -45,7 +45,7 @@ void *testReaderIP(void *)
 	int rc = 0;
 	while (rc<gNumToSend) {
 		char buf[MAX_UDP_LENGTH];
-		int count = readSocket.read(buf);
+		int count = readSocket.read(buf, MAX_UDP_LENGTH);
 		if (count>0) {
 			COUT("read: " << buf);
 			rc++;
@@ -65,7 +65,7 @@ void *testReaderUnix(void *)
 	int rc = 0;
 	while (rc<gNumToSend) {
 		char buf[MAX_UDP_LENGTH];
-		int count = readSocket.read(buf);
+		int count = readSocket.read(buf, MAX_UDP_LENGTH);
 		if (count>0) {
 			COUT("read: " << buf);
 			rc++;
-- 
2.4.11