enh(UDPHandler): helper functions for data buffer member offsets

Author: matejk

Net/include/Poco/Net/UDPHandler.h

@@ -225,13 +225,13 @@ class UDPHandlerImpl: public Runnable, public RefCountedObject
 	AtomicCounter::ValueType setError(char* pBuf, const std::string& err)
 		/// Sets the error into the buffer.
 	{
-		std::size_t availLen = S - sizeof(MsgSizeT);
-		std::memset(pBuf + sizeof(MsgSizeT), 0, availLen);
+		std::size_t availLen = S - errorOffset();
+		std::memset(pBuf + errorOffset(), 0, availLen);
 		std::size_t msgLen = err.length();
 		if (msgLen)
 		{
 			if (msgLen >= availLen) msgLen = availLen;
-			std::memcpy(pBuf + sizeof(MsgSizeT), err.data(), msgLen);
+			std::memcpy(pBuf + errorOffset(), err.data(), msgLen);
 		}
 		setStatus(pBuf, BUF_STATUS_ERROR);
 		return --_errorBacklog;
@@ -251,10 +251,28 @@ class UDPHandlerImpl: public Runnable, public RefCountedObject
 		return *reinterpret_cast<const MsgSizeT*>(pBuf) == BUF_STATUS_ERROR;
 	}
 
-	static Poco::UInt16 offset()
+	static constexpr Poco::UInt16 errorOffset()
+		/// Returns offset of address length.
+	{
+		return sizeof(MsgSizeT);
+	}
+
+	static constexpr Poco::UInt16 addressLengthOffset()
+		/// Returns offset of address length.
+	{
+		return sizeof(MsgSizeT);
+	}
+
+	static constexpr Poco::UInt16 addressOffset()
+		/// Returns offset of address.
+	{
+		return addressLengthOffset() + sizeof(poco_socklen_t);
+	}
+
+	static constexpr Poco::UInt16 payloadOffset()
 		/// Returns buffer data offset.
 	{
-		return sizeof(MsgSizeT) + sizeof(poco_socklen_t) + SocketAddress::MAX_ADDRESS_LENGTH;
+		return addressOffset() + SocketAddress::MAX_ADDRESS_LENGTH;
 	}
 
 	static MsgSizeT payloadSize(const char* buf)
@@ -264,8 +282,10 @@ class UDPHandlerImpl: public Runnable, public RefCountedObject
 
 	static SocketAddress address(const char* buf)
 	{
-		const auto* len = reinterpret_cast<const poco_socklen_t*>(buf + sizeof(MsgSizeT));
-		const auto* pSA = reinterpret_cast<const struct sockaddr*>(buf + sizeof(MsgSizeT) + sizeof(poco_socklen_t));
+		const auto* len = reinterpret_cast<const poco_socklen_t*>(buf + addressLengthOffset());
+		const auto* pSA = reinterpret_cast<const struct sockaddr*>(buf + addressOffset());
+		poco_assert(*len <= SocketAddress::MAX_ADDRESS_LENGTH);
+
 		return SocketAddress(pSA, *len);
 	}
 
@@ -280,7 +300,7 @@ class UDPHandlerImpl: public Runnable, public RefCountedObject
 		/// | sizeof(MsgSizeT) bytes | sizeof(poco_socklen_t) | SocketAddress::MAX_ADDRESS_LENGTH |    payload    |
 		/// +------------------------+------------------------+-----------------------------------+--------- ~ ---+
 	{
-		return buf + offset();
+		return buf + payloadOffset();
 	}
 
 	static Poco::StringTokenizer payload(const char* buf, char delimiter)

Net/include/Poco/Net/UDPSocketReader.h

@@ -112,10 +112,10 @@ class UDPSocketReader
 			p = handler().next(sockfd);
 			if (p)
 			{
-				Poco::UInt16 off = handler().offset();
-				poco_socklen_t* pAL = reinterpret_cast<poco_socklen_t*>(p + sizeof(RT));
+				Poco::UInt16 off = handler().payloadOffset();
+				auto* pAL = reinterpret_cast<poco_socklen_t*>(p + handler().addressLengthOffset());
 				*pAL = SocketAddress::MAX_ADDRESS_LENGTH;
-				struct sockaddr* pSA = reinterpret_cast<struct sockaddr*>(p + sizeof(RT) + sizeof(poco_socklen_t));
+				struct sockaddr* pSA = reinterpret_cast<struct sockaddr*>(p + handler().addressOffset());
 				RT ret = sock.receiveFrom(p + off, S - off - 1, &pSA, &pAL);
 				if (ret < 0)
 				{