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randutil: get randutil from snapd (canonical#17)
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// -*- Mode: Go; indent-tabs-mode: t -*- | ||
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/* | ||
* Copyright (C) 2020 Canonical Ltd | ||
* | ||
* This program is free software: you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License version 3 as | ||
* published by the Free Software Foundation. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
* GNU General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
* | ||
*/ | ||
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package randutil | ||
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import ( | ||
cryptorand "crypto/rand" | ||
"encoding/base64" | ||
"fmt" | ||
"io/ioutil" | ||
"strings" | ||
) | ||
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// CryptoTokenBytes returns a crypthographically secure token of | ||
// nbytes random bytes. | ||
func CryptoTokenBytes(nbytes int) ([]byte, error) { | ||
b := make([]byte, nbytes) | ||
_, err := cryptorand.Read(b) | ||
if err != nil { | ||
return nil, fmt.Errorf("cannot obtain %d crypto random bytes: %v", nbytes, err) | ||
} | ||
return b, nil | ||
} | ||
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// CryptoToken returns a crypthographically secure token string | ||
// encoding nbytes random bytes. | ||
// The result is URL-safe. | ||
func CryptoToken(nbytes int) (string, error) { | ||
b, err := CryptoTokenBytes(nbytes) | ||
if err != nil { | ||
return "", err | ||
} | ||
return base64.RawURLEncoding.EncodeToString(b), nil | ||
} | ||
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// RandomKernelUUID will return a UUID from the kernel's procfs API at | ||
// /proc/sys/kernel/random/uuid. Only to be used in very specific uses, most | ||
// random code should use CryptoToken(Bytes) instead. | ||
func RandomKernelUUID() string { | ||
b, err := ioutil.ReadFile("/proc/sys/kernel/random/uuid") | ||
if err != nil { | ||
panic("cannot read kernel generated uuid") | ||
} | ||
return strings.TrimSpace(string(b)) | ||
} |
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// -*- Mode: Go; indent-tabs-mode: t -*- | ||
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/* | ||
* Copyright (C) 2020 Canonical Ltd | ||
* | ||
* This program is free software: you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License version 3 as | ||
* published by the Free Software Foundation. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
* GNU General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
* | ||
*/ | ||
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package randutil_test | ||
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import ( | ||
"encoding/base64" | ||
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. "gopkg.in/check.v1" | ||
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"github.com/canonical/x-go/randutil" | ||
) | ||
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type cryptoRandutilSuite struct{} | ||
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var _ = Suite(&cryptoRandutilSuite{}) | ||
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func (s *cryptoRandutilSuite) TestCryptoTokenBytes(c *C) { | ||
x, err := randutil.CryptoTokenBytes(5) | ||
c.Assert(err, IsNil) | ||
c.Check(x, HasLen, 5) | ||
} | ||
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func (s *cryptoRandutilSuite) TestCryptoToken(c *C) { | ||
x, err := randutil.CryptoToken(5) | ||
c.Assert(err, IsNil) | ||
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b, err := base64.RawURLEncoding.DecodeString(x) | ||
c.Assert(err, IsNil) | ||
c.Check(b, HasLen, 5) | ||
} |
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// -*- Mode: Go; indent-tabs-mode: t -*- | ||
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/* | ||
* Copyright (C) 2014-2020 Canonical Ltd | ||
* | ||
* This program is free software: you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License version 3 as | ||
* published by the Free Software Foundation. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
* GNU General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
* | ||
*/ | ||
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// Package randutil initialises properly random value generation and | ||
// exposes a streamlined set of functions for it, including for crypto | ||
// random tokens. | ||
package randutil | ||
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import ( | ||
"crypto/sha256" | ||
"encoding/binary" | ||
"math/rand" | ||
"net" | ||
"os" | ||
"sync" | ||
"time" | ||
) | ||
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func init() { | ||
// golang does not init Seed() itself | ||
rand.Seed(time.Now().UnixNano() + int64(os.Getpid())) | ||
} | ||
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var moreMixedSeedOnce sync.Once | ||
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func moreMixedSeed() { | ||
moreMixedSeedOnce.Do(func() { | ||
h := sha256.New224() | ||
// do this instead of asking for time and pid again | ||
var b [8]byte | ||
rand.Read(b[:]) | ||
h.Write(b[:]) | ||
// mix in the hostname | ||
if hostname, err := os.Hostname(); err == nil { | ||
h.Write([]byte(hostname)) | ||
} | ||
// mix in net interfaces hw addresses (MACs etc) | ||
if ifaces, err := net.Interfaces(); err == nil { | ||
for _, iface := range ifaces { | ||
h.Write(iface.HardwareAddr) | ||
} | ||
} | ||
hs := h.Sum(nil) | ||
s := binary.LittleEndian.Uint64(hs[0:]) | ||
rand.Seed(int64(s)) | ||
}) | ||
} | ||
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const letters = "BCDFGHJKLMNPQRSTVWXYbcdfghjklmnpqrstvwxy0123456789" | ||
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// RandomString returns a random string of length length. | ||
// | ||
// The vowels are omitted to avoid that words are created by pure | ||
// chance. Numbers are included. | ||
// | ||
// Not cryptographically secure. | ||
func RandomString(length int) string { | ||
out := "" | ||
for i := 0; i < length; i++ { | ||
out += string(letters[rand.Intn(len(letters))]) | ||
} | ||
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return out | ||
} | ||
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// Re-exported from math/rand for streamlining. | ||
var ( | ||
Intn = rand.Intn | ||
Int63n = rand.Int63n | ||
) | ||
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// RandomDuration returns a random duration up to the given length. | ||
func RandomDuration(d time.Duration) time.Duration { | ||
// try to switch to more mixed seed to avoid subsets of a | ||
// fleet of machines with similar initial conditions to behave | ||
// the same | ||
moreMixedSeed() | ||
return time.Duration(Int63n(int64(d))) | ||
} |
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// -*- Mode: Go; indent-tabs-mode: t -*- | ||
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/* | ||
* Copyright (C) 2014-2020 Canonical Ltd | ||
* | ||
* This program is free software: you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License version 3 as | ||
* published by the Free Software Foundation. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
* GNU General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
* | ||
*/ | ||
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package randutil_test | ||
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import ( | ||
"math/rand" | ||
"testing" | ||
"time" | ||
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. "gopkg.in/check.v1" | ||
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"github.com/canonical/x-go/randutil" | ||
) | ||
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func Test(t *testing.T) { TestingT(t) } | ||
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type randutilSuite struct{} | ||
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var _ = Suite(&randutilSuite{}) | ||
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func (s *randutilSuite) TestRandomString(c *C) { | ||
// for our tests | ||
rand.Seed(1) | ||
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s1 := randutil.RandomString(10) | ||
c.Assert(s1, Equals, "pw7MpXh0JB") | ||
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s2 := randutil.RandomString(5) | ||
c.Assert(s2, Equals, "4PQyl") | ||
} | ||
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func (s *randutilSuite) TestRandomDuration(c *C) { | ||
// ensure moreMixedSeed is done | ||
d := randutil.RandomDuration(time.Hour) | ||
c.Check(d < time.Hour, Equals, true) | ||
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// for our tests | ||
rand.Seed(1) | ||
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d1 := randutil.RandomDuration(time.Hour) | ||
c.Assert(d1, Equals, time.Duration(1991947779410)) | ||
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d2 := randutil.RandomDuration(4 * time.Hour) | ||
c.Assert(d2, Equals, time.Duration(4423082153551)) | ||
} |