Support connection over Unix socket

[HugoDelval]

Fix #16

[HugoDelval]

I've updated the PR to preserve retro-compatibility.
It introduces a new method for those who want to use something else than TCP for the communication protocol. Otherwise it defaults to TCP.

[arp242]

I was thinking that maybe it's better to change the New() function to something like:

type Dialer func(context.Context) (net.Conn, error)

func new (Dialer d) {
    return &Client{dialer: d}
}

And then it can be used with both TCP and Unix connections:

dialer := net.Dialer{Timeout: 20 * time.Second}.
New(func(ctx context.Context) (net.Conn, error) {
    conn := dialer.DialContext(ctx, "tcp", "17.0.0.1")
    conn.SetDeadline(time.Now().Add(dialer.Timeout))
    return conn, nil
})

The Client.dial() calls can be replaced with this. We can add two standard functions for easy usage:

func TCPDialer(addr string) Dialer {
    return func(ctx context.Context) (net.Conn, error) {
        // ...
    }
}

So you can connect with:

client := New(TCPDialer("127.0.0.1"))

What do you think?

[arp242]

btw another common use case that should work without a lot of effort is connecting over TLS/SSL.

[HugoDelval]

It would look way better but it will break retro-compatibility. If that's not an issue then let's go for it !

[arp242]

Compatibility isn't an issue as far as I'm concerned. I don't think there are a lot of people using it, and there is no "1.0" (exactly so that I could change the connection logic).

[HugoDelval]

Okay perfect, then I'll try to update the PR! :)

[HugoDelval]

Is it close that what you had in mind?

[codecov]

Codecov Report

Merging #18 into master will decrease coverage by 0.47%.
The diff coverage is 64.7%.

@@            Coverage Diff             @@
##           master      #18      +/-   ##
==========================================
- Coverage   75.66%   75.19%   -0.48%     
==========================================
  Files           2        2              
  Lines         374      379       +5     
==========================================
+ Hits          283      285       +2     
- Misses         53       55       +2     
- Partials       38       39       +1

Impacted Files	Coverage Δ
spamc.go	79.27% <100%> (+0.99%)	⬆️
api.go	70.96% <62.5%> (-1.76%)	⬇️

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[HugoDelval]

Do you need the coverage check to pass?

[HugoDelval]

FYI I've tested it on a personal project and it works 🎉

[arp242]

Thanks! Look good at a glance; I'll test and go over it later.

[HugoDelval]

@Carpetsmoker This was useful because it provided a way to specify the timeout. Without it the 20sec timeout is imposed.

[HugoDelval]

@Carpetsmoker any update on this PR? :)