feat(protocol): allow override of dial func

reach/client/socketio/options.go

@@ -1,6 +1,13 @@
 package socketio
 
-import "time"
+import (
+	"net"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+type DialFunc func(network, addr string) (net.Conn, error)
 
 type Options struct {
 	PingInterval   time.Duration
@@ -8,6 +15,7 @@ type Options struct {
 	ReceiveTimeout time.Duration
 	SendTimeout    time.Duration
 	BufferSize     int
+	DialFunc       DialFunc
 }
 
 type OptionFunc func(opts *Options)
@@ -19,6 +27,7 @@ func NewOptions(funcs ...OptionFunc) *Options {
 		ReceiveTimeout: 60 * time.Second,
 		SendTimeout:    60 * time.Second,
 		BufferSize:     1024 * 32,
+		DialFunc:       DefaultDialFunc,
 	}
 	for _, fn := range funcs {
 		fn(opts)
@@ -60,3 +69,19 @@ func WithBufferSize(size int) OptionFunc {
 		opts.BufferSize = size
 	}
 }
+
+var DefaultDialFunc = func(network, addr string) (net.Conn, error) {
+	conn, err := net.Dial(network, addr)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	return conn, nil
+}
+
+// WithDialFunc configures the client to use the given dial func
+func WithDialFunc(dial DialFunc) OptionFunc {
+	return func(opts *Options) {
+		opts.DialFunc = dial
+	}
+}