I have some working code, but the error handling is fairly crude at the moment - it generally sends an error string to standard error and exits. So I would like it to throw an exception and allow the user to deal with it as they choose with a typical handler.
However, having added a try catch block to the code it is giving me a compiler error that I don't understand at all.
My code looks like this:
// -------------------------------------------------------------------------
sockets::TCPSocket::TCPSocket(const char* address, const int port)
{
this->address = address;
this->port = port;
this->bufferSize = sockets::TCPSocket::DEF_BUFFER;
sockets::TCPSocket::init();
}
// -------------------------------------------------------------------------
sockets::TCPSocket::~TCPSocket()
{
freeaddrinfo(this->addressInfoList);
close(this->filedes);
}
// -------------------------------------------------------------------------
void sockets::TCPSocket::init()
{
memset(&(this->addressInfo), 0, sizeof this->addressInfo);
addressInfo.ai_family = AF_UNSPEC; // Either IPv4 or IPv6
addressInfo.ai_socktype = SOCK_STREAM; // Uses TCP
addressInfo.ai_flags = AI_PASSIVE; // Accept any IP
// get the address info
int status = getaddrinfo(
this->address,
std::to_string(this->port).c_str(),
&(this->addressInfo),
&(this->addressInfoList)
);
if (status != 0) // any error- segfault if addressInfoList not allocated
{
throw GetAddrinfoException();
}
// create socket
this->filedes = socket(
this->addressInfoList->ai_family,
this->addressInfoList->ai_socktype,
this->addressInfoList->ai_protocol
);
if (this->filedes == -1)
{
std::cerr << "Create socket error: " << strerror(errno) << std::endl;
exit(EXIT_FAILURE);
}
}
// -------------------------------------------------------------------------
As you see I am calling a (private) init() function from my constructor. And I throw a GetAddrinfoException in my init() function. If I wrap the call to init() in a try catch wihtin the constructor it works fine. But when I call it from my main - expecting the stack to unwind - I get a compiler error.. like this:
int main()
{
using namespace std;
// Test as client
const char* TEST_ADDR = "www.google.com";
try
{
sockets::TCPSocket socket = sockets::TCPSocket(TEST_ADDR, 80);
}
catch (sockets::GetAddrinfoException e) { /* do something */ }
return 0;
}
The compiler error lists each of the member functions of TCPSocket and gives this message:
TCPSocket/test.cpp: In function ‘int main()’:
TCPSocket/test.cpp:22:12: error: request for member ‘doConnect’ in ‘socket’, which is of non-class type ‘int(int, int, int) throw ()’
socket.doConnect();
^
TCPSocket/test.cpp:23:12: error: request for member ‘doSend’ in ‘socket’, which is of non-class type ‘int(int, int, int) throw ()’
socket.doSend("GET / HTTP/1.1\r\nHost: www.redway-soft.com\r\n\r\n");
^
TCPSocket/test.cpp:24:20: error: request for member ‘doRecv’ in ‘socket’, which is of non-class type ‘int(int, int, int) throw ()’
cout << socket.doRecv() << endl;
^
TCPSocket/test.cpp:34:12: error: request for member ‘restart’ in ‘socket’, which is of non-class type ‘int(int, int, int) throw ()’
socket.restart();
^
TCPSocket/test.cpp:35:30: error: request for member ‘doListen’ in ‘socket’, which is of non-class type ‘int(int, int, int) throw ()’
string received = socket.doListen();
^
Despite searching through multiple tutorials and guides I cannot find any reason for this problem. Any help would be much appreciated.
EDIT:
The class definition looks like this:
#ifndef __TCPSOCKET_HPP__
#define __TCPSOCKET_HPP__
#include <cstring>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <string>
#include <vector>
#include <iostream>
#include <cerrno>
#include <exception>
namespace sockets
{
class GetAddrinfoException: std::exception
{
public:
virtual const char* what() const throw()
{
return "getAddressinfo() failure";
}
};
/**
* @class TCPSocket, creates a HTTP/TCP Socket. TCPSocket is designed with the idea
* that it should usually be instantiated in its own thread for most use cases.
* @param const char* address, e.g. www.google.com
* @param int port, which port defaults 80
*/
class TCPSocket
{
private:
/**
* Instance vars
*/
struct addrinfo addressInfo;
struct addrinfo* addressInfoList;
int filedes;
const char* address;
int port;
int bufferSize;
/**
* @function init, allows socket to be re-assigned a new address and port
*/
void init();
public:
/**
* pulbic class vars
*/
static const int DEF_BUFFER = 2000;
static const int DEF_PORT = 5556;
static const int DEF_TIMEOUT = 200000;
static const int DEF_NUMTRIES = 5;
/**
* @constructor
* @param address, to connect to default is NULL siffnifying server socket
* @param port, port to connect/listen on
*/
TCPSocket(const char* address = NULL, const int port = DEF_PORT);
/**
* @destructor
*/
~TCPSocket();
/**
* public getters
*/
inline const char* getAddress() {return this->address;}
inline const int& getPort() {return this->port;}
inline const struct addrinfo& getAddressInfo() {return this->addressInfo;}
inline const int& getFiledes() {return this->filedes;}
inline const struct addrinfo* getAddressInfoList() {return this->addressInfoList;}
/**
* @function setBuffer, set bufferSize to custom size
* @param buffer, the size to set the read in buffer
*/
inline void setBuffer(int buffer) {this->bufferSize = buffer;}
/**
* @function restart, cleans up and then re-initialises the socket with new params
* @param address, to connect to
* @param port, port to connect
*/
void restart(const char* address = NULL, const int port = DEF_PORT);
/**
* @function doConnect, connect to target address
*/
void doConnect();
/**
* @function doSend - sends specific message,
* @param message e.g. "GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n"
* would send a simple get request, or a html string could be sent back
* in the case of send from a server socket which is responding to a
* request.
*/
void doSend(const char* message);
/**
* @function doRecv, gets return data from server
* @param timeout, length of time to wait (micros) for data def = 100 000
* @param numtries, number of attempts at reading data if none recv
* @return message that has been received
*/
std::string doRecv(int timeout = DEF_TIMEOUT, int numtries = DEF_NUMTRIES);
/**
* @function doListen, listens at given port and accepts a connection
* note that this function is blocking and so any implementation should
* probably normally be on its own thread/process, a server class should
* be in charge of managing individual threads and sockets.
*/
std::string doListen();
/**
* @function doClose, closes the filedescripter.
*/
void doClose();
};
}
#endif
