From b87cf1ba9c0e51552300c8149e41f89e9d563dc0 Mon Sep 17 00:00:00 2001
From: Abhishek Chanda <abhishek.becs@gmail.com>
Date: Tue, 22 Mar 2016 17:16:59 -0700
Subject: [PATCH] pkg: add a function to generate chain names

Adds a function to generate chain names for use in iptables and
ports all drivers to use that function. Also adds tests for the
said function.
---
 utils/utils.go            | 20 ++++++++++++++++++++
 utils/utils_suite_test.go | 13 +++++++++++++
 utils/utils_test.go       | 18 ++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 utils/utils.go
 create mode 100644 utils/utils_suite_test.go
 create mode 100644 utils/utils_test.go

diff --git a/utils/utils.go b/utils/utils.go
new file mode 100644
index 00000000..eaf48d0b
--- /dev/null
+++ b/utils/utils.go
@@ -0,0 +1,20 @@
+package utils
+
+import (
+	"crypto/sha512"
+	"fmt"
+)
+
+// 29 - len('CNI') - 2*len('-')
+const maxNameLen = 16
+
+// Generates a chain name to be used with iptables.
+// Ensures that the generated name is less than
+// 29 chars in length
+func FormatChainName(name string, id string) string {
+	h := sha512.Sum512([]byte(id))
+	if len(name) > maxNameLen {
+		return fmt.Sprintf("CNI-%s-%x", name[:len(name)-maxNameLen], h[:8])
+	}
+	return fmt.Sprintf("CNI-%s-%x", name, h[:8])
+}
diff --git a/utils/utils_suite_test.go b/utils/utils_suite_test.go
new file mode 100644
index 00000000..f160db60
--- /dev/null
+++ b/utils/utils_suite_test.go
@@ -0,0 +1,13 @@
+package utils_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestUtils(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Utils Suite")
+}
diff --git a/utils/utils_test.go b/utils/utils_test.go
new file mode 100644
index 00000000..e9b9f9bf
--- /dev/null
+++ b/utils/utils_test.go
@@ -0,0 +1,18 @@
+package utils
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Utils", func() {
+	It("should format a short name", func() {
+		chain := FormatChainName("test", "1234")
+		Expect(chain).To(Equal("CNI-test-d404559f602eab6f"))
+	})
+
+	It("should truncate a long name", func() {
+		chain := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
+		Expect(chain).To(Equal("CNI-testalongnamethat-d404559f602eab6f"))
+	})
+})