3fb8dcfd4c
* 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>
61 lines
2.0 KiB
Go
61 lines
2.0 KiB
Go
// Copyright 2016 CNI authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package utils
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import (
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"crypto/sha512"
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"fmt"
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)
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const (
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maxChainLength = 28
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chainPrefix = "CNI-"
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)
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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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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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// rule identification within iptables.
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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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