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102 lines
3.0 KiB
Go
102 lines
3.0 KiB
Go
/*
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* Copyright (c) 2014, Yawning Angel <yawning at schwanenlied dot me>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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// Package csrand implements the math/rand interface over crypto/rand, along
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// with some utility functions for common random number/byte related tasks.
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//
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// Not all of the convinience routines are replicated, only those that are
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// immediately useful. The Rand variable provides access to the full math/rand
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// API.
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package csrand // import "gitlab.com/yawning/obfs4.git/common/csrand"
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import (
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cryptRand "crypto/rand"
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"encoding/binary"
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"fmt"
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"io"
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"math/rand"
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)
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var (
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csRandSourceInstance csRandSource
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// Rand is a math/rand instance backed by crypto/rand CSPRNG.
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Rand = rand.New(csRandSourceInstance) //nolint:gosec
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)
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type csRandSource struct {
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// This does not keep any state as it is backed by crypto/rand.
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}
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func (r csRandSource) Int63() int64 {
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var src [8]byte
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if err := Bytes(src[:]); err != nil {
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panic(err)
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}
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val := binary.BigEndian.Uint64(src[:])
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val &= (1<<63 - 1)
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return int64(val)
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}
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func (r csRandSource) Seed(_ int64) {
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// No-op.
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}
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// Intn returns, as a int, a pseudo random number in [0, n).
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func Intn(n int) int {
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return Rand.Intn(n)
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}
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// Float64 returns, as a float64, a pesudo random number in [0.0,1.0).
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func Float64() float64 {
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return Rand.Float64()
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}
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// IntRange returns a uniformly distributed int [min, max].
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func IntRange(min, max int) int {
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if max < min {
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panic(fmt.Sprintf("IntRange: min > max (%d, %d)", min, max))
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}
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r := (max + 1) - min
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ret := Rand.Intn(r)
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return ret + min
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}
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// Bytes fills the slice with random data.
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func Bytes(buf []byte) error {
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if _, err := io.ReadFull(cryptRand.Reader, buf); err != nil {
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return err
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}
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return nil
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}
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// Reader is a alias of rand.Reader.
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var Reader = cryptRand.Reader
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