Adding DeregisterDialContext (#1422)

Co-authored-by: jypelle <jy@fabriks.eu>

AUTHORS

@@ -47,6 +47,7 @@ INADA Naoki <songofacandy at gmail.com>
 Jacek Szwec <szwec.jacek at gmail.com>
 James Harr <james.harr at gmail.com>
 Janek Vedock <janekvedock at comcast.net>
+Jean-Yves Pellé <jy at pelle.link>
 Jeff Hodges <jeff at somethingsimilar.com>
 Jeffrey Charles <jeffreycharles at gmail.com>
 Jerome Meyer <jxmeyer at gmail.com>

driver.go

@@ -55,6 +55,17 @@ func RegisterDialContext(net string, dial DialContextFunc) {
 	dials[net] = dial
 }
 
+// DeregisterDialContext removes the custom dial function registered with the given net.
+func DeregisterDialContext(net string) {
+	dialsLock.Lock()
+	defer dialsLock.Unlock()
+	if dials != nil {
+		if _, ok := dials[net]; ok {
+			delete(dials, net)
+		}
+	}
+}
+
 // RegisterDial registers a custom dial function. It can then be used by the
 // network address mynet(addr), where mynet is the registered new network.
 // addr is passed as a parameter to the dial function.