Re: [Boost-users] Enhancing the boost::asio::connect() socket interface

Subject: Re: [Boost-users] Enhancing the boost::asio::connect() socket interface
From: Vinnie Falco (vinnie.falco_at_[hidden])
Date: 2017-09-24 17:37:32

>On Sun, Sep 24, 2017 at 1:15 AM, martin doc via Boost-users <boost-users_at_[hidden]> wrote:
> As boost::asio::connect() closes an open socket passed to it before making
> the remote connection, it's not possible to pass connect() a prebaked
> socket.

What makes you think that? My reading of the implementation is that
the socket is only closed when:

1. The range of addresses passed to connect() has more than one element, and
2. The connection attempt for the first address fails.

See:

<https://github.com/boostorg/asio/blob/b002097359f246b7b1478775251dfb153ab3ff4b/include/boost/asio/impl/connect.hpp#L108

You can avoid the socket closure by only attempting to connect to one address.

> In fact the amount of code required to use boost when binding a
> socket to a local address is more complicated than simply not using boost.

That ignores all of the other benefits that Boost.Asio brings to the
table once the connection is made. And what happens when the
Networking-TS is merged into the standard? Will you just avoid using
the standard library?

Thanks

On Sun, Sep 24, 2017 at 1:15 AM, martin doc via Boost-users
<boost-users_at_[hidden]> wrote:
> (apologies if this should be on -developers...)
>
>
> The connect() interface provided by boost caters to most common use and
> through access to the socket, various options can be managed without much
> hindrance. But there's one situation that boost does not handle well - when
> it is desirable to specify the local address to bind to.
>
>
> Going back to C, the usual program flow in this situation is something like
> this:
>
>
> fd = socket()
>
> bind(fd, local ip address)
>
> connect(fd, remote ip address)
>
>
> As boost::asio::connect() closes an open socket passed to it before making
> the remote connection, it's not possible to pass connect() a prebaked
> socket. In fact the amount of code required to use boost when binding a
> socket to a local address is more complicated than simply not using boost.
>
>
> What I'd like the boost community to consider is extending boost::asio to
> provide one or more variants of connect() that allows for a local endpoint
> (whether or not as an iterator I'll leave to others to debate but this isn't
> necessary - and then there's the M*N behavior or paired to decide) to be
> supplied in addition to the remote endpoint.
>
>
> I suppose I'm open minded as to whether or not the local address is supplied
> as an Iterator/endpoint as an extra arg or whether connect() is adopted to
> take endpoint pairs.
>
>
> Thoughts?
>
>
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