pkg/meta/bandwidth: increase IfbDeviceName size
* Increase entroy from 2 bytes to 7 bytes to prevent collisions * Extract common library function for hash with prefix * Refactor portmap plugin to use library function fixes #347 Co-authored-by: Cameron Moreau <cmoreau@pivotal.io> Co-authored-by: Mikael Manukyan <mmanukyan@pivotal.io>
This commit is contained in:
Gabe Rosenhouse
@ -22,16 +22,22 @@ import (
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const (
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maxChainLength = 28
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chainPrefix = "CNI-"
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prefixLength = len(chainPrefix)
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)
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// Generates a chain name to be used with iptables.
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// Ensures that the generated chain name is exactly
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// maxChainLength chars in length
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// FormatChainName generates a chain name to be used
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// with iptables. Ensures that the generated chain
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// name is exactly maxChainLength chars in length.
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func FormatChainName(name string, id string) string {
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chainBytes := sha512.Sum512([]byte(name + id))
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chain := fmt.Sprintf("%s%x", chainPrefix, chainBytes)
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return chain[:maxChainLength]
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return MustFormatChainNameWithPrefix(name, id, "")
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}
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// MustFormatChainNameWithPrefix generates a chain name similar
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// to FormatChainName, but adds a custom prefix between
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// chainPrefix and unique identifier. Ensures that the
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// generated chain name is exactly maxChainLength chars in length.
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// Panics if the given prefix is too long.
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func MustFormatChainNameWithPrefix(name string, id string, prefix string) string {
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return MustFormatHashWithPrefix(maxChainLength, chainPrefix+prefix, name+id)
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}
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// FormatComment returns a comment used for easier
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@ -39,3 +45,16 @@ func FormatChainName(name string, id string) string {
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func FormatComment(name string, id string) string {
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return fmt.Sprintf("name: %q id: %q", name, id)
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}
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const MaxHashLen = sha512.Size * 2
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// MustFormatHashWithPrefix returns a string of given length that begins with the
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// given prefix. It is filled with entropy based on the given string toHash.
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func MustFormatHashWithPrefix(length int, prefix string, toHash string) string {
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if len(prefix) >= length || length > MaxHashLen {
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panic("invalid length")
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}
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output := sha512.Sum512([]byte(toHash))
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return fmt.Sprintf("%s%x", prefix, output)[:length]
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}
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@ -15,37 +15,151 @@
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package utils
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import (
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"fmt"
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"strings"
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. "github.com/onsi/ginkgo"
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. "github.com/onsi/gomega"
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)
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var _ = Describe("Utils", func() {
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It("must format a short name", func() {
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chain := FormatChainName("test", "1234")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-2bbe0c48b91a7d1b8a6753a8"))
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Describe("FormatChainName", func() {
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It("must format a short name", func() {
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chain := FormatChainName("test", "1234")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-2bbe0c48b91a7d1b8a6753a8"))
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})
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It("must truncate a long name", func() {
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chain := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-374f33fe84ab0ed84dcdebe3"))
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})
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It("must be predictable", func() {
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chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal(chain2))
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})
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It("must change when a character changes", func() {
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chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1235")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal("CNI-374f33fe84ab0ed84dcdebe3"))
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Expect(chain1).NotTo(Equal(chain2))
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})
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})
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It("must truncate a long name", func() {
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chain := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-374f33fe84ab0ed84dcdebe3"))
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Describe("MustFormatChainNameWithPrefix", func() {
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It("generates a chain name with a prefix", func() {
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chain := MustFormatChainNameWithPrefix("test", "1234", "PREFIX-")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-PREFIX-2bbe0c48b91a7d1b8"))
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})
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It("must format a short name", func() {
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chain := MustFormatChainNameWithPrefix("test", "1234", "PREFIX-")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-PREFIX-2bbe0c48b91a7d1b8"))
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})
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It("must truncate a long name", func() {
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chain := MustFormatChainNameWithPrefix("testalongnamethatdoesnotmakesense", "1234", "PREFIX-")
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Expect(len(chain)).To(Equal(maxChainLength))
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Expect(chain).To(Equal("CNI-PREFIX-374f33fe84ab0ed84"))
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})
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It("must be predictable", func() {
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chain1 := MustFormatChainNameWithPrefix("testalongnamethatdoesnotmakesense", "1234", "PREFIX-")
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chain2 := MustFormatChainNameWithPrefix("testalongnamethatdoesnotmakesense", "1234", "PREFIX-")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal(chain2))
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})
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It("must change when a character changes", func() {
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chain1 := MustFormatChainNameWithPrefix("testalongnamethatdoesnotmakesense", "1234", "PREFIX-")
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chain2 := MustFormatChainNameWithPrefix("testalongnamethatdoesnotmakesense", "1235", "PREFIX-")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal("CNI-PREFIX-374f33fe84ab0ed84"))
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Expect(chain1).NotTo(Equal(chain2))
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})
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It("panics when prefix is too large", func() {
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longPrefix := strings.Repeat("PREFIX-", 4)
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Expect(func() {
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MustFormatChainNameWithPrefix("test", "1234", longPrefix)
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}).To(Panic())
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})
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})
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It("must be predictable", func() {
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chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal(chain2))
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Describe("MustFormatHashWithPrefix", func() {
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It("always returns a string with the given prefix", func() {
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Expect(MustFormatHashWithPrefix(10, "AAA", "some string")).To(HavePrefix("AAA"))
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Expect(MustFormatHashWithPrefix(10, "foo", "some string")).To(HavePrefix("foo"))
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Expect(MustFormatHashWithPrefix(10, "bar", "some string")).To(HavePrefix("bar"))
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})
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It("always returns a string of the given length", func() {
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Expect(MustFormatHashWithPrefix(10, "AAA", "some string")).To(HaveLen(10))
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Expect(MustFormatHashWithPrefix(15, "AAA", "some string")).To(HaveLen(15))
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Expect(MustFormatHashWithPrefix(5, "AAA", "some string")).To(HaveLen(5))
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})
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It("is deterministic", func() {
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val1 := MustFormatHashWithPrefix(10, "AAA", "some string")
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val2 := MustFormatHashWithPrefix(10, "AAA", "some string")
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val3 := MustFormatHashWithPrefix(10, "AAA", "some string")
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Expect(val1).To(Equal(val2))
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Expect(val1).To(Equal(val3))
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})
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It("is (nearly) perfect (injective function)", func() {
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hashes := map[string]int{}
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for i := 0; i < 1000; i++ {
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name := fmt.Sprintf("string %d", i)
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hashes[MustFormatHashWithPrefix(8, "", name)]++
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}
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for key, count := range hashes {
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Expect(count).To(Equal(1), "for key "+key+" got non-unique correspondence")
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}
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})
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assertPanicWith := func(f func(), expectedErrorMessage string) {
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defer func() {
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Expect(recover()).To(Equal(expectedErrorMessage))
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}()
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f()
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Fail("function should have panicked but did not")
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}
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It("panics when prefix is longer than the length", func() {
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assertPanicWith(
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func() { MustFormatHashWithPrefix(3, "AAA", "some string") },
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"invalid length",
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)
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})
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It("panics when length is not positive", func() {
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assertPanicWith(
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func() { MustFormatHashWithPrefix(0, "", "some string") },
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"invalid length",
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)
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})
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It("panics when length is larger than MaxLen", func() {
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assertPanicWith(
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func() { MustFormatHashWithPrefix(MaxHashLen+1, "", "some string") },
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"invalid length",
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)
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})
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})
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It("must change when a character changes", func() {
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chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
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chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1235")
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Expect(len(chain1)).To(Equal(maxChainLength))
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Expect(len(chain2)).To(Equal(maxChainLength))
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Expect(chain1).To(Equal("CNI-374f33fe84ab0ed84dcdebe3"))
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Expect(chain1).NotTo(Equal(chain2))
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})
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})
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