-// sg_socket.hxx -- Socket I/O routines
-//
+/**
+ * \file sg_socket.hxx
+ * Socket I/O routines.
+ */
+
// Written by Curtis Olson, started November 1999.
//
// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
#include <simgear/compiler.h>
-#include <string>
+#include STL_STRING
-#include <simgear/math/fg_types.hxx>
+#include <simgear/math/sg_types.hxx>
+#include <simgear/io/iochannel.hxx>
-#include "iochannel.hxx"
-
-FG_USING_STD(string);
+SG_USING_STD(string);
+#if defined(_MSC_VER) || defined(__MINGW32__)
+# include <winsock.h>
+#endif
#define SG_MAX_SOCKET_QUEUE 32
+/**
+ * A socket I/O class based on SGIOChannel.
+ */
class SGSocket : public SGIOChannel {
+public:
+#if defined(_MSC_VER) || defined(__MINGW32__)
+ typedef SOCKET SocketType;
+#else
+ typedef int SocketType;
+# define INVALID_SOCKET (-1)
+#endif
+private:
string hostname;
string port_str;
char save_buf[ 2 * SG_IO_MAX_MSG_SIZE ];
int save_len;
- int sock;
+ SocketType sock;
+ SocketType msgsock;
short unsigned int port;
+ int sock_style; // SOCK_STREAM or SOCK_DGRAM
+
+ bool first_read;
// make a server (master listening) socket
- int make_server_socket();
+ SocketType make_server_socket();
// make a client socket
- int make_client_socket();
+ SocketType make_client_socket();
- int_list client_connections;
+ // wrapper functions
+ size_t readsocket( int fd, void *buf, size_t count );
+ size_t writesocket( int fd, const void *buf, size_t count );
+#if !defined(_MSC_VER) && !defined(__MINGW32__)
+ int closesocket(int fd);
+#endif
+
+#if defined(_MSC_VER) || defined(__MINGW32__)
+ // Ensure winsock has been initialised.
+ static bool wsock_init;
+ static bool wsastartup();
+#endif
public:
- SGSocket();
+ /**
+ * Create an instance of SGSocket.
+ *
+ * When calling the constructor you need to provide a host name, a
+ * port number, and a socket style. The convention used by the
+ * SGSocket class is that the server side listens and the client
+ * side sends. For a server socket, the host name should be
+ * empty. For a server, the port number is optional, if you do not
+ * specify a port, the system will assign one. For a client
+ * socket, you need to specify both a destination host and
+ * destination port. For both client and server sockets you must
+ * specify the socket type. Type must be either udp or tcp. Here's
+ * a quick breakdown of the major differences between UDP and TCP
+ * type sockets.
+ *
+ * TCP sockets are the type where you establish a connection and
+ * then can read and write to the socket from both ends. If one
+ * end of TCP socket connect quits, the other end will likely
+ * segfault if it doesn't take special precautions. But, the nice
+ * thing about TCP connections is that the underlying protocol
+ * guarantees that your message will get through. This imposes a
+ * certain performance overhead though on the communication
+ * because the protocol must resend failed messages. TCP sockets
+ * are good for sending periodic command/response type messages
+ * where performance isn't a big issues, but reliability is.
+ *
+ * UDP sockets on the other hand are a lower level protocol and
+ * don't have the same sort of connection as TCP sockets. With UDP
+ * sockets, the server end just sits and listens for incoming
+ * packets from anywhere. The client end sends it's message and
+ * forgets about it. It doesn't care if there isn't even a server
+ * out there listening and all the packets are getting
+ * lost. Although systems/networks usually do a pretty good job
+ * (statistically) of getting your UDP packets to their
+ * destination, there is no guarantee that any particular packet
+ * will make it. But, because of this low level implementation and
+ * lack of error checking, UDP packets are much faster and
+ * efficient. UDP packets are good for sending positional
+ * information to synchronize two applications. In this case, you
+ * want the information to arrive as quickly as possible, and if
+ * you lose a packet, you'd rather get new updated information
+ * rather than have the system waste time resending a packet that
+ * is becoming older and older with every retry.
+ * @param host name of host if direction is SG_IO_OUT or SG_IO_BI
+ * @param port port number if we care to choose one.
+ * @param style specify "udp" or "tcp"
+ */
+ SGSocket( const string& host, const string& port, const string& style );
+
+ /** Destructor */
~SGSocket();
- // open the file based on specified direction
- bool open( SGProtocolDir dir );
+ // If specified as a server (in direction for now) open the master
+ // listening socket. If specified as a client (out direction),
+ // open a connection to a server.
+ bool open( const SGProtocolDir d );
// read data from socket
int read( char *buf, int length );
int readline( char *buf, int length );
// write data to a socket
- int write( char *buf, int length );
+ int write( const char *buf, const int length );
// write null terminated string to a socket
- int writestring( char *str );
+ int writestring( const char *str );
// close file
bool close();
+ /**
+ * Enable non-blocking mode.
+ * @return success/failure
+ */
+ bool nonblock();
+
+ /** @return the remote host name */
inline string get_hostname() const { return hostname; }
- inline void set_hostname( const string& hn ) { hostname = hn; }
+
+ /** @return the port number (in string form) */
inline string get_port_str() const { return port_str; }
- inline void set_port_str( const string& p ) { port_str = p; }
};
#endif // _SG_SOCKET_HXX
-
-
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