Added a socket packet data filter - preparing for a nice STUN implementation.

git-svn-id: http://yate.null.ro/svn/yate/trunk@1058 acf43c95-373e-0410-b603-e72c3f656dc1

engine/Socket.cpp

@@ -295,6 +295,30 @@ bool SocketAddr::supports(int family)
 }
 
 
+SocketFilter::SocketFilter()
+    : m_socket(0)
+{
+}
+
+SocketFilter::~SocketFilter()
+{
+    if (m_socket)
+	m_socket->removeFilter(this);
+}
+
+void* SocketFilter::getObject(const String& name) const
+{
+    if (name == "SocketFilter")
+	return const_cast<SocketFilter*>(this);
+    return GenObject::getObject(name);
+}
+
+bool SocketFilter::valid() const
+{
+    return m_socket && m_socket->valid();
+}
+
+
 Stream::~Stream()
 {
 }
@@ -650,6 +674,7 @@ Socket::Socket(int domain, int type, int protocol)
 Socket::~Socket()
 {
     DDebug(DebugAll,"Socket::~Socket() handle=%d [%p]",m_handle,this);
+    clearFilters();
     terminate();
 }
 
@@ -891,6 +916,8 @@ bool Socket::getPeerName(SocketAddr& addr)
 
 int Socket::sendTo(const void* buffer, int length, const struct sockaddr* addr, socklen_t adrlen, int flags)
 {
+    if (!addr)
+	return send(buffer,length,flags);
     if (!buffer)
 	length = 0;
     int res = ::sendto(m_handle,(const char*)buffer,length,flags,addr,adrlen);
@@ -927,7 +954,10 @@ int Socket::recvFrom(void* buffer, int length, struct sockaddr* addr, socklen_t*
     if (adrlen && !addr)
 	*adrlen = 0;
     int res = ::recvfrom(m_handle,(char*)buffer,length,flags,addr,adrlen);
-    checkError(res,true);
+    if (checkError(res,true) && applyFilters(buffer,res,flags,addr,(adrlen ? *adrlen : 0))) {
+	m_error = EAGAIN;
+	res = socketError();
+    }
     return res;
 }
 
@@ -946,7 +976,10 @@ int Socket::recv(void* buffer, int length, int flags)
     if (!buffer)
 	length = 0;
     int res = ::recv(m_handle,(char*)buffer,length,flags);
-    checkError(res,true);
+    if (checkError(res,true) && applyFilters(buffer,res,flags)) {
+	m_error = EAGAIN;
+	res = socketError();
+    }
     return res;
 }
 
@@ -1108,4 +1141,36 @@ bool Socket::createPair(Socket& sock1, Socket& sock2, int domain)
     return false;
 }
 
+bool Socket::installFilter(SocketFilter* filter)
+{
+    if (!filter || filter->socket())
+	return false;
+    if (m_filters.find(filter))
+	return false;
+    filter->m_socket = this;
+    m_filters.append(filter);
+    return true;
+}
+
+void Socket::removeFilter(SocketFilter* filter, bool delobj)
+{
+    if (m_filters.remove(filter,delobj))
+	filter->m_socket = 0;
+}
+
+void Socket::clearFilters()
+{
+    m_filters.clear();
+}
+
+bool Socket::applyFilters(void* buffer, int length, int flags, const struct sockaddr* addr, socklen_t adrlen)
+{
+    for (ObjList* l = &m_filters; l; l = l->next()) {
+	SocketFilter* filter = static_cast<SocketFilter*>(l->get());
+	if (filter && filter->received(buffer,length,flags,addr,adrlen))
+	    return true;
+    }
+    return false;
+}
+
 /* vi: set ts=8 sw=4 sts=4 noet: */

yateclass.h

@@ -3258,6 +3258,8 @@ private:
     bool m_locking;
 };
 
+class Socket;
+
 /**
  * Wrapper class to keep a socket address
  * @short A socket address holder
@@ -3425,6 +3427,59 @@ protected:
     String m_host;
 };
 
+/**
+ * Abstract interface for an object that filters socket received data packets
+ * @short A filter for received socket data
+ */
+class YATE_API SocketFilter : public GenObject
+{
+    friend class Socket;
+public:
+    /**
+     * Constructor
+     */
+    SocketFilter();
+
+    /**
+     * Destructor, unregisters from socket
+     */
+    virtual ~SocketFilter();
+
+    /**
+     * Get a pointer to a derived class given that class name
+     * @param name Name of the class we are asking for
+     * @return Pointer to the requested class or NULL if this object doesn't implement it
+     */
+    virtual void* getObject(const String& name) const;
+
+    /**
+     * Notify this filter about a received block of data
+     * @param buffer Buffer for received data
+     * @param length Length of the data in buffer
+     * @param flags Operating system specific bit flags of the operation
+     * @param addr Address of the incoming data, may be NULL
+     * @param adrlen Length of the valid data in address structure
+     * @return True if this filter claimed the data
+     */
+    virtual bool received(void* buffer, int length, int flags, const struct sockaddr* addr, socklen_t adrlen) = 0;
+
+    /**
+     * Get the socket to which the filter is currently attached
+     * @return Pointer to the socket of this filter
+     */
+    inline Socket* socket() const
+	{ return m_socket; }
+
+    /**
+     * Check if the socket of this filter is valid
+     * @return True if the filter has a valid socket
+     */
+    bool valid() const;
+
+private:
+    Socket* m_socket;
+};
+
 /**
  * Base class for encapsulating system dependent stream capable objects
  * @short An abstract stream class capable of reading and writing
@@ -3954,7 +4009,7 @@ public:
      * Send a message over a connected or unconnected socket
      * @param buffer Buffer for data transfer
      * @param length Length of the buffer
-     * @param addr Address to send the message to
+     * @param addr Address to send the message to, if NULL will behave like @ref send()
      * @param adrlen Length of the address structure
      * @param flags Operating system specific bit flags that change the behaviour
      * @return Number of bytes transferred, @ref socketError() if an error occurred
@@ -4047,6 +4102,24 @@ public:
      */
     bool select(bool* readok, bool* writeok, bool* except, int64_t timeout);
 
+    /**
+     * Install a new packet filter in the socket
+     * @param filter Pointer to the packet filter to install
+     * @return True if the filter was installed
+     */
+    bool installFilter(SocketFilter* filter);
+
+    /**
+     * Removes a packet filter and optionally destroys it
+     * @param delobj Set to true to also delete the filter
+     */
+    void removeFilter(SocketFilter* filter, bool delobj = false);
+
+    /**
+     * Removes and destroys all packet filters
+     */
+    void clearFilters();
+
     /**
      * Create a pair of bidirectionally connected sockets
      * @param sock1 Reference to first Socket to be paired
@@ -4071,7 +4144,19 @@ protected:
      */
     bool checkError(int retcode, bool strict = false);
 
+    /**
+     * Apply installed filters to a received block of data
+     * @param buffer Buffer for received data
+     * @param length Length of the data in buffer
+     * @param flags Operating system specific bit flags of the operation
+     * @param addr Address of the incoming data, may be NULL
+     * @param adrlen Length of the valid data in address structure
+     * @return True if one of the filters claimed the data
+     */
+    bool applyFilters(void* buffer, int length, int flags, const struct sockaddr* addr = 0, socklen_t adrlen = 0);
+
     SOCKET m_handle;
+    ObjList m_filters;
 };
 
 /**