implement RFC 8628: Device authorization grant

WIP

Related #264

pkg/op/device_test.go

@@ -0,0 +1,204 @@
+package op
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"io"
+	mr "math/rand"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type errReader struct {
+}
+
+func (errReader) Read([]byte) (int, error) {
+	return 0, io.ErrUnexpectedEOF
+}
+
+func runWithRandReader(r io.Reader, f func()) {
+	originalReader := rand.Reader
+	rand.Reader = r
+	defer func() {
+		rand.Reader = originalReader
+	}()
+
+	f()
+}
+
+func TestNewDeviceCode(t *testing.T) {
+	t.Run("reader error", func(t *testing.T) {
+		runWithRandReader(errReader{}, func() {
+			_, err := NewDeviceCode(16)
+			require.Error(t, err)
+		})
+	})
+
+	t.Run("dirrent lengths, rand reader", func(t *testing.T) {
+		for i := 1; i <= 32; i++ {
+			got, err := NewDeviceCode(i)
+			require.NoError(t, err)
+			assert.Len(t, got, base64.RawURLEncoding.EncodedLen(i))
+		}
+	})
+
+}
+
+func TestNewUserCode(t *testing.T) {
+	type args struct {
+		charset      []rune
+		charAmount   int
+		dashInterval int
+	}
+	tests := []struct {
+		name    string
+		args    args
+		reader  io.Reader
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "reader error",
+			args: args{
+				charset:      []rune(CharSetBase20),
+				charAmount:   8,
+				dashInterval: 4,
+			},
+			reader:  errReader{},
+			wantErr: true,
+		},
+		{
+			name: "base20",
+			args: args{
+				charset:      []rune(CharSetBase20),
+				charAmount:   8,
+				dashInterval: 4,
+			},
+			reader: mr.New(mr.NewSource(1)),
+			want:   "XKCD-HTTD",
+		},
+		{
+			name: "digits",
+			args: args{
+				charset:      []rune(CharSetDigits),
+				charAmount:   9,
+				dashInterval: 3,
+			},
+			reader: mr.New(mr.NewSource(1)),
+			want:   "271-256-225",
+		},
+		{
+			name: "no dashes",
+			args: args{
+				charset:    []rune(CharSetDigits),
+				charAmount: 9,
+			},
+			reader: mr.New(mr.NewSource(1)),
+			want:   "271256225",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			runWithRandReader(tt.reader, func() {
+				got, err := NewUserCode(tt.args.charset, tt.args.charAmount, tt.args.dashInterval)
+				if tt.wantErr {
+					require.ErrorIs(t, err, io.ErrUnexpectedEOF)
+				} else {
+					require.NoError(t, err)
+				}
+				assert.Equal(t, tt.want, got)
+			})
+
+		})
+	}
+
+	t.Run("crypto/rand", func(t *testing.T) {
+		const testN = 100000
+
+		for _, c := range []UserCodeConfig{UserCodeBase20, UserCodeDigits} {
+			t.Run(c.CharSet, func(t *testing.T) {
+				results := make(map[string]int)
+
+				for i := 0; i < testN; i++ {
+					code, err := NewUserCode([]rune(c.CharSet), c.CharAmount, c.DashInterval)
+					require.NoError(t, err)
+					results[code]++
+				}
+
+				t.Log(results)
+
+				var duplicates int
+				for code, count := range results {
+					assert.Less(t, count, 3, code)
+					if count == 2 {
+						duplicates++
+					}
+				}
+
+			})
+		}
+	})
+}
+
+func BenchmarkNewUserCode(b *testing.B) {
+	type args struct {
+		charset      []rune
+		charAmount   int
+		dashInterval int
+	}
+	tests := []struct {
+		name   string
+		args   args
+		reader io.Reader
+	}{
+		{
+			name: "math rand, base20",
+			args: args{
+				charset:      []rune(CharSetBase20),
+				charAmount:   8,
+				dashInterval: 4,
+			},
+			reader: mr.New(mr.NewSource(1)),
+		},
+		{
+			name: "math rand, digits",
+			args: args{
+				charset:      []rune(CharSetDigits),
+				charAmount:   9,
+				dashInterval: 3,
+			},
+			reader: mr.New(mr.NewSource(1)),
+		},
+		{
+			name: "crypto rand, base20",
+			args: args{
+				charset:      []rune(CharSetBase20),
+				charAmount:   8,
+				dashInterval: 4,
+			},
+			reader: rand.Reader,
+		},
+		{
+			name: "crypto rand, digits",
+			args: args{
+				charset:      []rune(CharSetDigits),
+				charAmount:   9,
+				dashInterval: 3,
+			},
+			reader: rand.Reader,
+		},
+	}
+	for _, tt := range tests {
+		runWithRandReader(tt.reader, func() {
+			b.Run(tt.name, func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					_, err := NewUserCode(tt.args.charset, tt.args.charAmount, tt.args.dashInterval)
+					require.NoError(b, err)
+				}
+			})
+
+		})
+	}
+}