interfaces: added package with interface facilities

1 files changed, 41 insertions, 0 deletions

diff --git a/interfaces/interfaces.go b/interfaces/interfaces.go
new file mode 100644
index 0000000..5761669
--- /dev/null
+++ b/interfaces/interfaces.go
@@ -0,0 +1,41 @@
+package interfaces
+
+import "net"
+
+// InterfaceMatcher is a function type used to match the interfaces we want. See
+// GetInterfacesFunc below for usage.
+type InterfaceMatcher func(net.Interface) bool
+
+// interfaceGetter is used for testing purposes
+var interfaceGetter = net.Interfaces
+
+// GetInterfacesFunc loops through the available network interfaces, and returns
+// a list of interfaces for which the passed InterfaceMatcher function returns
+// true.
+func GetInterfacesFunc(matcher InterfaceMatcher) ([]net.Interface, error) {
+	ifaces, err := interfaceGetter()
+	if err != nil {
+		return nil, err
+	}
+	ret := make([]net.Interface, 0)
+	for _, iface := range ifaces {
+		if matcher(iface) {
+			ret = append(ret, iface)
+		}
+	}
+	return ret, nil
+}
+
+// GetLoopbackInterfaces returns a list of loopback interfaces.
+func GetLoopbackInterfaces() ([]net.Interface, error) {
+	return GetInterfacesFunc(func(iface net.Interface) bool {
+		return iface.Flags&net.FlagLoopback != 0
+	})
+}
+
+// GetNonLoopbackInterfaces returns a list of non-loopback interfaces.
+func GetNonLoopbackInterfaces() ([]net.Interface, error) {
+	return GetInterfacesFunc(func(iface net.Interface) bool {
+		return iface.Flags&net.FlagLoopback == 0
+	})
+}