6 // Written by Curtis Olson, started November 1999.
8 // Copyright (C) 1999 Curtis L. Olson - http://www.flightgear.org/~curt
10 // This program is free software; you can redistribute it and/or
11 // modify it under the terms of the GNU General Public License as
12 // published by the Free Software Foundation; either version 2 of the
13 // License, or (at your option) any later version.
15 // This program is distributed in the hope that it will be useful, but
16 // WITHOUT ANY WARRANTY; without even the implied warranty of
17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 // General Public License for more details.
20 // You should have received a copy of the GNU General Public License
21 // along with this program; if not, write to the Free Software
22 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 #ifndef _SG_SOCKET_HXX
28 #define _SG_SOCKET_HXX
30 #include <simgear/compiler.h>
34 #include <simgear/math/sg_types.hxx>
35 #include <simgear/io/iochannel.hxx>
36 #include <simgear/io/raw_socket.hxx>
38 #define SG_MAX_SOCKET_QUEUE 32
42 * A socket I/O class based on SGIOChannel.
44 class SGSocket : public SGIOChannel {
50 char save_buf[ 2 * SG_IO_MAX_MSG_SIZE ];
54 simgear::Socket* client;
63 // make a server (master listening) socket
64 bool make_server_socket();
66 // make a client socket
67 bool make_client_socket();
69 // Poll for new connections or data to read.
75 * Create an instance of SGSocket.
77 * When calling the constructor you need to provide a host name, a
78 * port number, and a socket style. The convention used by the
79 * SGSocket class is that the server side listens and the client
80 * side sends. For a server socket, the host name should be
81 * empty. For a server, the port number is optional, if you do not
82 * specify a port, the system will assign one. For a client
83 * socket, you need to specify both a destination host and
84 * destination port. For both client and server sockets you must
85 * specify the socket type. Type must be either udp or tcp. Here's
86 * a quick breakdown of the major differences between UDP and TCP
89 * TCP sockets are the type where you establish a connection and
90 * then can read and write to the socket from both ends. If one
91 * end of TCP socket connect quits, the other end will likely
92 * segfault if it doesn't take special precautions. But, the nice
93 * thing about TCP connections is that the underlying protocol
94 * guarantees that your message will get through. This imposes a
95 * certain performance overhead though on the communication
96 * because the protocol must resend failed messages. TCP sockets
97 * are good for sending periodic command/response type messages
98 * where performance isn't a big issues, but reliability is.
100 * UDP sockets on the other hand are a lower level protocol and
101 * don't have the same sort of connection as TCP sockets. With UDP
102 * sockets, the server end just sits and listens for incoming
103 * packets from anywhere. The client end sends it's message and
104 * forgets about it. It doesn't care if there isn't even a server
105 * out there listening and all the packets are getting
106 * lost. Although systems/networks usually do a pretty good job
107 * (statistically) of getting your UDP packets to their
108 * destination, there is no guarantee that any particular packet
109 * will make it. But, because of this low level implementation and
110 * lack of error checking, UDP packets are much faster and
111 * efficient. UDP packets are good for sending positional
112 * information to synchronize two applications. In this case, you
113 * want the information to arrive as quickly as possible, and if
114 * you lose a packet, you'd rather get new updated information
115 * rather than have the system waste time resending a packet that
116 * is becoming older and older with every retry.
117 * @param host name of host if direction is SG_IO_OUT or SG_IO_BI
118 * @param port port number if we care to choose one.
119 * @param style specify "udp" or "tcp"
121 SGSocket( const std::string& host, const std::string& port, const std::string& style );
126 // If specified as a server (in direction for now) open the master
127 // listening socket. If specified as a client (out direction),
128 // open a connection to a server.
129 bool open( const SGProtocolDir d );
131 // read data from socket
132 int read( char *buf, int length );
134 // read data from socket
135 int readline( char *buf, int length );
137 // write data to a socket
138 int write( const char *buf, const int length );
140 // write null terminated string to a socket
141 int writestring( const char *str );
147 * Enable non-blocking mode.
148 * @return success/failure
152 // set timeout (default: 0)
153 inline void set_timeout(int i) { timeout = i; }
155 /** @return the remote host name */
156 inline std::string get_hostname() const { return hostname; }
158 /** @return the port number (in string form) */
159 inline std::string get_port_str() const { return port_str; }
163 #endif // _SG_SOCKET_HXX