asio::connect

The connect function is a composed operation that establishes a socket connection by trying each endpoint in a sequence. More...

Functions
template<typename Protocol , typename Executor , typename EndpointSequence >
Protocol::endpoint	asio::connect (basic_socket< Protocol, Executor > &s, const EndpointSequence &endpoints, typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *=0)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename EndpointSequence >
Protocol::endpoint	asio::connect (basic_socket< Protocol, Executor > &s, const EndpointSequence &endpoints, asio::error_code &ec, typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *=0)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *=0)
	(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, asio::error_code &ec, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *=0)
	(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, Iterator end)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, Iterator end, asio::error_code &ec)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename EndpointSequence , typename ConnectCondition >
Protocol::endpoint	asio::connect (basic_socket< Protocol, Executor > &s, const EndpointSequence &endpoints, ConnectCondition connect_condition, typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *=0)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename EndpointSequence , typename ConnectCondition >
Protocol::endpoint	asio::connect (basic_socket< Protocol, Executor > &s, const EndpointSequence &endpoints, ConnectCondition connect_condition, asio::error_code &ec, typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *=0)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, ConnectCondition connect_condition, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *=0)
	(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, ConnectCondition connect_condition, asio::error_code &ec, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *=0)
	(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, Iterator end, ConnectCondition connect_condition)
	Establishes a socket connection by trying each endpoint in a sequence. More...
template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >
Iterator	asio::connect (basic_socket< Protocol, Executor > &s, Iterator begin, Iterator end, ConnectCondition connect_condition, asio::error_code &ec)
	Establishes a socket connection by trying each endpoint in a sequence. More...

Detailed Description

The connect function is a composed operation that establishes a socket connection by trying each endpoint in a sequence.

Function Documentation

connect() [1/12]

template<typename Protocol , typename Executor , typename EndpointSequence >

Protocol::endpoint asio::connect	(	basic_socket< Protocol, Executor > &	s,
		const EndpointSequence &	endpoints,
		typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *	= 0
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
endpoints	A sequence of endpoints.

Returns

The successfully connected endpoint.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Example

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::socket s(my_context);
asio::connect(s, r.resolve(q)); 

connect() [2/12]

template<typename Protocol , typename Executor , typename EndpointSequence >

Protocol::endpoint asio::connect	(	basic_socket< Protocol, Executor > &	s,
		const EndpointSequence &	endpoints,
		asio::error_code &	ec,
		typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *	= 0
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
endpoints	A sequence of endpoints.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, the successfully connected endpoint. Otherwise, a default-constructed endpoint.

Example

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::socket s(my_context);
asio::error_code ec;
asio::connect(s, r.resolve(q), ec);
if (ec)
{
  // An error occurred.
} 

connect() [3/12]

template<typename Protocol , typename Executor , typename Iterator >

Iterator asio::connect	(	basic_socket< Protocol, Executor > &	s,
		Iterator	begin,
		typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *	= 0
	)

(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Note

This overload assumes that a default constructed object of type Iterator represents the end of the sequence. This is a valid assumption for iterator types such as asio::ip::tcp::resolver::iterator.

connect() [4/12]

template<typename Protocol , typename Executor , typename Iterator >

Iterator asio::connect ( basic_socket< Protocol, Executor > &  s, Iterator  begin, asio::error_code &  ec, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *  = 0  )

inline

(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Note

This overload assumes that a default constructed object of type Iterator represents the end of the sequence. This is a valid assumption for iterator types such as asio::ip::tcp::resolver::iterator.

connect() [5/12]

template<typename Protocol , typename Executor , typename Iterator >

Iterator asio::connect	(	basic_socket< Protocol, Executor > &	s,
		Iterator	begin,
		Iterator	end
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
end	An iterator pointing to the end of a sequence of endpoints.

Returns

An iterator denoting the successfully connected endpoint.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Example

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::resolver::results_type e = r.resolve(q);
tcp::socket s(my_context);
asio::connect(s, e.begin(), e.end()); 

connect() [6/12]

template<typename Protocol , typename Executor , typename Iterator >

Iterator asio::connect ( basic_socket< Protocol, Executor > &  s, Iterator  begin, Iterator  end, asio::error_code &  ec  )

inline

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
end	An iterator pointing to the end of a sequence of endpoints.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Example

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::resolver::results_type e = r.resolve(q);
tcp::socket s(my_context);
asio::error_code ec;
asio::connect(s, e.begin(), e.end(), ec);
if (ec)
{
  // An error occurred.
} 

connect() [7/12]

template<typename Protocol , typename Executor , typename EndpointSequence , typename ConnectCondition >

Protocol::endpoint asio::connect	(	basic_socket< Protocol, Executor > &	s,
		const EndpointSequence &	endpoints,
		ConnectCondition	connect_condition,
		typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *	= 0
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
endpoints	A sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.

Returns

The successfully connected endpoint.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Example

The following connect condition function object can be used to output information about the individual connection attempts:

 struct my_connect_condition
{
  bool operator()(
      const asio::error_code& ec,
      const::tcp::endpoint& next)
  {
    if (ec) std::cout << "Error: " << ec.message() << std::endl;
    std::cout << "Trying: " << next << std::endl;
    return true;
  }
}; 

It would be used with the asio::connect function as follows:

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::socket s(my_context);
tcp::endpoint e = asio::connect(s,
    r.resolve(q), my_connect_condition());
std::cout << "Connected to: " << e << std::endl; 

connect() [8/12]

template<typename Protocol , typename Executor , typename EndpointSequence , typename ConnectCondition >

Protocol::endpoint asio::connect	(	basic_socket< Protocol, Executor > &	s,
		const EndpointSequence &	endpoints,
		ConnectCondition	connect_condition,
		asio::error_code &	ec,
		typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type *	= 0
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
endpoints	A sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, the successfully connected endpoint. Otherwise, a default-constructed endpoint.

Example

The following connect condition function object can be used to output information about the individual connection attempts:

 struct my_connect_condition
{
  bool operator()(
      const asio::error_code& ec,
      const::tcp::endpoint& next)
  {
    if (ec) std::cout << "Error: " << ec.message() << std::endl;
    std::cout << "Trying: " << next << std::endl;
    return true;
  }
}; 

It would be used with the asio::connect function as follows:

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::socket s(my_context);
asio::error_code ec;
tcp::endpoint e = asio::connect(s,
    r.resolve(q), my_connect_condition(), ec);
if (ec)
{
  // An error occurred.
}
else
{
  std::cout << "Connected to: " << e << std::endl;
} 

connect() [9/12]

template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >

Iterator asio::connect	(	basic_socket< Protocol, Executor > &	s,
		Iterator	begin,
		ConnectCondition	connect_condition,
		typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *	= 0
	)

(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Note

This overload assumes that a default constructed object of type Iterator represents the end of the sequence. This is a valid assumption for iterator types such as asio::ip::tcp::resolver::iterator.

connect() [10/12]

template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >

Iterator asio::connect ( basic_socket< Protocol, Executor > &  s, Iterator  begin, ConnectCondition  connect_condition, asio::error_code &  ec, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type *  = 0  )

inline

(Deprecated: Use range overload.) Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Note

This overload assumes that a default constructed object of type Iterator represents the end of the sequence. This is a valid assumption for iterator types such as asio::ip::tcp::resolver::iterator.

connect() [11/12]

template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >

Iterator asio::connect	(	basic_socket< Protocol, Executor > &	s,
		Iterator	begin,
		Iterator	end,
		ConnectCondition	connect_condition
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
end	An iterator pointing to the end of a sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.

Returns

An iterator denoting the successfully connected endpoint.

Exceptions

asio::system_error

Thrown on failure. If the sequence is empty, the associated error_code is asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Example

The following connect condition function object can be used to output information about the individual connection attempts:

 struct my_connect_condition
{
  bool operator()(
      const asio::error_code& ec,
      const::tcp::endpoint& next)
  {
    if (ec) std::cout << "Error: " << ec.message() << std::endl;
    std::cout << "Trying: " << next << std::endl;
    return true;
  }
}; 

It would be used with the asio::connect function as follows:

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::resolver::results_type e = r.resolve(q);
tcp::socket s(my_context);
tcp::resolver::results_type::iterator i = asio::connect(
    s, e.begin(), e.end(), my_connect_condition());
std::cout << "Connected to: " << i->endpoint() << std::endl; 

connect() [12/12]

template<typename Protocol , typename Executor , typename Iterator , typename ConnectCondition >

Iterator asio::connect	(	basic_socket< Protocol, Executor > &	s,
		Iterator	begin,
		Iterator	end,
		ConnectCondition	connect_condition,
		asio::error_code &	ec
	)

Establishes a socket connection by trying each endpoint in a sequence.

This function attempts to connect a socket to one of a sequence of endpoints. It does this by repeated calls to the socket's connect member function, once for each endpoint in the sequence, until a connection is successfully established.

Parameters

s	The socket to be connected. If the socket is already open, it will be closed.
begin	An iterator pointing to the start of a sequence of endpoints.
end	An iterator pointing to the end of a sequence of endpoints.
connect_condition	A function object that is called prior to each connection attempt. The signature of the function object must be: bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next); The ec parameter contains the result from the most recent connect operation. Before the first connection attempt, ec is always set to indicate success. The next parameter is the next endpoint to be tried. The function object should return true if the next endpoint should be tried, and false if it should be skipped.
ec	Set to indicate what error occurred, if any. If the sequence is empty, set to asio::error::not_found. Otherwise, contains the error from the last connection attempt.

Returns

On success, an iterator denoting the successfully connected endpoint. Otherwise, the end iterator.

Example

The following connect condition function object can be used to output information about the individual connection attempts:

 struct my_connect_condition
{
  bool operator()(
      const asio::error_code& ec,
      const::tcp::endpoint& next)
  {
    if (ec) std::cout << "Error: " << ec.message() << std::endl;
    std::cout << "Trying: " << next << std::endl;
    return true;
  }
}; 

It would be used with the asio::connect function as follows:

 tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::resolver::results_type e = r.resolve(q);
tcp::socket s(my_context);
asio::error_code ec;
tcp::resolver::results_type::iterator i = asio::connect(
    s, e.begin(), e.end(), my_connect_condition());
if (ec)
{
  // An error occurred.
}
else
{
  std::cout << "Connected to: " << i->endpoint() << std::endl;
}