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C++ Socket Class for Windows | ||
Here, I present the source code for a socket class that faciliates using Sockets in Windows Programming. I also
want to say thanks Fabien Le Lez, www.infflux.com
and Tamas Kaskoto who have improved this source.
This socket class is being used for BROADCAST chat client.
These are actually four classes: Socket (the base class) from which SocketServer and SocketClient are derived. Also,
there is SocketSelect
which can be used to do a Select call on more than one Socket. The
constructors of Socket are protected; this should be a taken as a hint
not to use Socket, but either SocketServer or SocketClient.
When you compile this files, make sure you link them against Ws2_32.lib.
Jump to the header file, the implementation file, the test programm and the
Echo Server. Here's also a Proxy and a Web Server.
You can also download the files.
A small description of the socket class:
Every program that uses Windows Sockets needs to call WSAStartup. This call is wrapped into Socket::Start, which in turn is called by
the Socket's constructor. I pass 2.0 as version here as I expect that version to be installed.
The Socket's constructor also calls socket() (note the small s) which actually creates the socket. It passes the SOCK_STREAM parameter, indicating TCP. If UDP were wished, you'd have to pass SOCK_DGRAM.
SocketClient: SocketClient is inherited from Socket.
The constructor of SocketClient takes a host as parameter, which is the name of the server that this client wishes to communicate to. This name is resolved into an IP Address by gethostbyname().
SocketServer: SocketServer is inherited from Socket.
The constructor of the SocketServer class listens on the port indicated in its parameter. This is made by calling bind(). As SOCK_STREAM type sockets have the ability to queue incoming connection requests, we need to know the maximum number of connections to be queued which can be stated by the connections parameter (and which is passed to listen()). SocketServer::Accept(): simply waits for an incoming connection request (or removes one from the queue) by calling accept (note the small a). The header filesocket.h
/* Socket.h Copyright (C) 2002-2004 René Nyffenegger This source code is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this source code must not be misrepresented; you must not claim that you wrote the original source code. If you use this source code in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original source code. 3. This notice may not be removed or altered from any source distribution. René Nyffenegger rene.nyffenegger@adp-gmbh.ch */ #ifndef SOCKET_H #define SOCKET_H #include <WinSock2.h> #include <string> enum TypeSocket {BlockingSocket, NonBlockingSocket}; class Socket { public: virtual ~Socket(); Socket(const Socket&); Socket& operator=(Socket&); std::string ReceiveLine(); std::string ReceiveBytes(); void Close(); // The parameter of SendLine is not a const reference // because SendLine modifes the std::string passed. void SendLine (std::string); // The parameter of SendBytes is a const reference // because SendBytes does not modify the std::string passed // (in contrast to SendLine). void SendBytes(const std::string&); protected: friend class SocketServer; friend class SocketSelect; Socket(SOCKET s); Socket(); SOCKET s_; int* refCounter_; private: static void Start(); static void End(); static int nofSockets_; }; class SocketClient : public Socket { public: SocketClient(const std::string& host, int port); }; class SocketServer : public Socket { public: SocketServer(int port, int connections, TypeSocket type=BlockingSocket); Socket* Accept(); }; // http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winsock/wsapiref_2tiq.asp class SocketSelect { public: SocketSelect(Socket const * const s1, Socket const * const s2=NULL, TypeSocket type=BlockingSocket); bool Readable(Socket const * const s); private: fd_set fds_; }; #endif The implementation filesocket.cpp
/* Socket.cpp Copyright (C) 2002-2004 René Nyffenegger This source code is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this source code must not be misrepresented; you must not claim that you wrote the original source code. If you use this source code in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original source code. 3. This notice may not be removed or altered from any source distribution. René Nyffenegger rene.nyffenegger@adp-gmbh.ch */ #include "Socket.h" #include <iostream> using namespace std; int Socket::nofSockets_= 0; void Socket::Start() { if (!nofSockets_) { WSADATA info; if (WSAStartup(MAKEWORD(2,0), &info)) { throw "Could not start WSA"; } } ++nofSockets_; } void Socket::End() { WSACleanup(); } Socket::Socket() : s_(0) { Start(); // UDP: use SOCK_DGRAM instead of SOCK_STREAM s_ = socket(AF_INET,SOCK_STREAM,0); if (s_ == INVALID_SOCKET) { throw "INVALID_SOCKET"; } refCounter_ = new int(1); } Socket::Socket(SOCKET s) : s_(s) { Start(); refCounter_ = new int(1); }; Socket::~Socket() { if (! --(*refCounter_)) { Close(); delete refCounter_; } --nofSockets_; if (!nofSockets_) End(); } Socket::Socket(const Socket& o) { refCounter_=o.refCounter_; (*refCounter_)++; s_ =o.s_; nofSockets_++; } Socket& Socket::operator=(Socket& o) { (*o.refCounter_)++; refCounter_=o.refCounter_; s_ =o.s_; nofSockets_++; return *this; } void Socket::Close() { closesocket(s_); } std::string Socket::ReceiveBytes() { std::string ret; char buf[1024]; while (1) { u_long arg = 0; if (ioctlsocket(s_, FIONREAD, &arg) != 0) break; if (arg == 0) break; if (arg > 1024) arg = 1024; int rv = recv (s_, buf, arg, 0); if (rv <= 0) break; std::string t; t.assign (buf, rv); ret += t; } return ret; } std::string Socket::ReceiveLine() { std::string ret; while (1) { char r; switch(recv(s_, &r, 1, 0)) { case 0: // not connected anymore; return ""; case -1: if (errno == EAGAIN) { return ret; } else { // not connected anymore return ""; } } ret += r; if (r == '\n') return ret; } } void Socket::SendLine(std::string s) { s += '\n'; send(s_,s.c_str(),s.length(),0); } void Socket::SendBytes(const std::string& s) { send(s_,s.c_str(),s.length(),0); } SocketServer::SocketServer(int port, int connections, TypeSocket type) { sockaddr_in sa; memset(&sa, 0, sizeof(sa)); sa.sin_family = PF_INET; sa.sin_port = htons(port); s_ = socket(AF_INET, SOCK_STREAM, 0); if (s_ == INVALID_SOCKET) { throw "INVALID_SOCKET"; } if(type==NonBlockingSocket) { u_long arg = 1; ioctlsocket(s_, FIONBIO, &arg); } /* bind the socket to the internet address */ if (bind(s_, (sockaddr *)&sa, sizeof(sockaddr_in)) == SOCKET_ERROR) { closesocket(s_); throw "INVALID_SOCKET"; } listen(s_, connections); } Socket* SocketServer::Accept() { SOCKET new_sock = accept(s_, 0, 0); if (new_sock == INVALID_SOCKET) { int rc = WSAGetLastError(); if(rc==WSAEWOULDBLOCK) { return 0; // non-blocking call, no request pending } else { throw "Invalid Socket"; } } Socket* r = new Socket(new_sock); return r; } SocketClient::SocketClient(const std::string& host, int port) : Socket() { std::string error; hostent *he; if ((he = gethostbyname(host.c_str())) == 0) { error = strerror(errno); throw error; } sockaddr_in addr; addr.sin_family = AF_INET; addr.sin_port = htons(port); addr.sin_addr = *((in_addr *)he->h_addr); memset(&(addr.sin_zero), 0, 8); if (::connect(s_, (sockaddr *) &addr, sizeof(sockaddr))) { error = strerror(WSAGetLastError()); throw error; } } SocketSelect::SocketSelect(Socket const * const s1, Socket const * const s2, TypeSocket type) { FD_ZERO(&fds_); FD_SET(const_cast<Socket*>(s1)->s_,&fds_); if(s2) { FD_SET(const_cast<Socket*>(s2)->s_,&fds_); } TIMEVAL tval; tval.tv_sec = 0; tval.tv_usec = 1; TIMEVAL *ptval; if(type==NonBlockingSocket) { ptval = &tval; } else { ptval = 0; } if (select (0, &fds_, (fd_set*) 0, (fd_set*) 0, ptval) == SOCKET_ERROR) throw "Error in select"; } bool SocketSelect::Readable(Socket const* const s) { if (FD_ISSET(s->s_,&fds_)) return true; return false; } A simple Client
The following simple client connects to www.google.ch and get its front-website.
#include "Socket.h" #include <iostream> using namespace std; int main() { try { SocketClient s("www.google.com", 80); s.SendLine("GET / HTTP/1.0"); s.SendLine("Host: www.google.com"); s.SendLine(""); while (1) { string l = s.ReceiveLine(); if (l.empty()) break; cout << l; cout.flush(); } } catch (const char* s) { cerr << s << endl; } catch (String s) { cerr << s << endl; } catch (...) { cerr << "unhandled exception\n"; } return 0; } A simple echo Server The
following simple Server opens a port on 2000 and waits for incoming
connections. Each connection is answered with the same line as was
written (echoed).
If you want to test the server, use
telnet localhost 2000
/* EchoServer.cpp Copyright (C) 2002-2004 René Nyffenegger This source code is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this source code must not be misrepresented; you must not claim that you wrote the original source code. If you use this source code in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original source code. 3. This notice may not be removed or altered from any source distribution. René Nyffenegger rene.nyffenegger@adp-gmbh.ch */ #include "Socket.h" #include <process.h> #include <string> unsigned __stdcall Answer(void* a) { Socket* s = (Socket*) a; while (1) { std::string r = s->ReceiveLine(); if (r.empty()) break; s->SendLine(r); } delete s; return 0; } int main(int argc, char* argv[]) { SocketServer in(2000,5); while (1) { Socket* s=in.Accept(); unsigned ret; _beginthreadex(0,0,Answer,(void*) s,0,&ret); } return 0; } A Proxy that uses the Socket class
You need the Chameleon class to compile this proxy.
Usage:
proxy <port proxy> <addr server> <port server> .
This proxy will then listen on <port proxy> and whenever it receives a connection, relays the traffic to the <port server> of <addr server>. This makes it ideal to see what an SMTP Client exchanges with a SMTP Server, or equally what a NNTP client exchanges with an NNTP Server. Proxy.cpp
/* Proxy.cpp Copyright (C) 2002-2004 René Nyffenegger This source code is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this source code must not be misrepresented; you must not claim that you wrote the original source code. If you use this source code in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original source code. 3. This notice may not be removed or altered from any source distribution. René Nyffenegger rene.nyffenegger@adp-gmbh.ch */ #include "Socket.h" #include <iostream> #include <process.h> #include <sstream> int portProxy; std::string addrServer; int portServer; unsigned __stdcall RunProxyThread (void* a) { Socket* s = (Socket*) a; SocketClient c(addrServer, portServer); while (1) { SocketSelect sel(s, &c); bool still_connected = true; if (sel.Readable(s)) { std::string bytes = s->ReceiveBytes(); c.SendBytes(bytes); std::cout << "Server: " << bytes << std::endl; if (bytes.empty()) still_connected=false; } if (sel.Readable(&c)) { std::string bytes = c.ReceiveBytes(); s->SendBytes(bytes); std::cout << "Client: " << bytes << std::endl; if (bytes.empty()) still_connected=false; } if (! still_connected) { break; } } delete s; return 0; } int main(int argc, char* argv[]) { if (argc < 4) { std::cout << "Usage:" << std::endl; std::cout << " proxy <port proxy> <addr server> <port server>" << std::endl; std::cout << std::endl; std::cout << " This proxy will then listen on <port proxy> and whenever it receives" << std::endl; std::cout << " a connection, relays the traffic to the <port server> of <addr server>." << std::endl; std::cout << " This makes it ideal to see what an SMTP Client exchanges with a SMTP Server," << std::endl; std::cout << " or equally what a NNTP client exchanges with an NNTP Server." << std::endl << std::endl; return -1; } std::stringstream s; s<<argv[1]; s>>portProxy; s.clear(); addrServer=argv[2]; s<<argv[3]; s>>portServer; SocketServer in(portProxy,5); while (1) { Socket* s=in.Accept(); unsigned ret; _beginthreadex(0, 0, RunProxyThread,(void*) s,0,&ret); } return 0; }
See also: Fiddler:
a HTTP Debugging Proxy which logs all HTTP traffic between your
computer and the Internet. Fiddler allows you to watch HTTP Traffic, set
breakpoints, and "fiddle" with incoming or outgoing data. Fiddler is designed
to be much simpler than using NetMon or Achilles.
Message Distributor Message
Distributor is a server that listens on port 2000. Any number of
clients can connect to that server. When a client sends a message to
the server, the server will broadcast this message to all other
clients, but not to the one that sent the message.
MsgDistributor.cpp
/* MsgDistributor.cpp Copyright (C) 2002-2004 René Nyffenegger This source code is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this source code must not be misrepresented; you must not claim that you wrote the original source code. If you use this source code in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original source code. 3. This notice may not be removed or altered from any source distribution. René Nyffenegger rene.nyffenegger@adp-gmbh.ch */ #include "Socket.h" #include <process.h> #include <string> #include <list> typedef std::list<Socket*> socket_list; socket_list g_connections; unsigned __stdcall Connection(void* a) { Socket* s = (Socket*) a; g_connections.push_back(s); s->SendLine("Welcome to the Message Distributor"); while (1) { std::string r = s->ReceiveLine(); if (r.empty()) break; for (socket_list::iterator os =g_connections.begin(); os!=g_connections.end(); os++) { if (*os != s) (*os)->SendLine(r); } } g_connections.remove(s); delete s; return 0; } int main() { SocketServer in(2000,5); while (1) { Socket* s=in.Accept(); unsigned ret; _beginthreadex(0,0,Connection,(void*) s,0,&ret); } return 0; } Download the files |