drivers: extract splitPortProto to utility pkg

This commit extracts the function to a common method where
it will be able to be used accross multiple drivers.

Signed-off-by: André Carvalho <andre.carvalho@corp.globo.com>

drivers/util/util.go

@@ -0,0 +1,23 @@
+package util
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// SplitPortProto splits a string in the format port/protocol, defaulting
+// protocol to "tcp" if not provided.
+func SplitPortProto(raw string) (port int, protocol string, err error) {
+	parts := strings.Split(raw, "/")
+	if len(parts) == 1 {
+		protocol = "tcp"
+	} else {
+		protocol = parts[1]
+	}
+	port, err = strconv.Atoi(parts[0])
+	if err != nil {
+		return 0, "", fmt.Errorf("invalid port number %s: %s", parts[0], err)
+	}
+	return port, protocol, nil
+}

drivers/util/util_test.go

@@ -0,0 +1,32 @@
+package util
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSplitPortProtocol(t *testing.T) {
+	tests := []struct {
+		raw           string
+		expectedPort  int
+		expectedProto string
+		expectedErr   bool
+	}{
+		{"8080/tcp", 8080, "tcp", false},
+		{"90/udp", 90, "udp", false},
+		{"80", 80, "tcp", false},
+		{"abc", 0, "", true},
+	}
+
+	for _, tc := range tests {
+		port, proto, err := SplitPortProto(tc.raw)
+		assert.Equal(t, tc.expectedPort, port)
+		assert.Equal(t, tc.expectedProto, proto)
+		if tc.expectedErr {
+			assert.Error(t, err)
+		} else {
+			assert.NoError(t, err)
+		}
+	}
+}