ber_test.go

package pkcs7

import (
	"bytes"
	"encoding/asn1"
	"encoding/pem"
	"fmt"
	"strings"
	"testing"
)

func TestBer2Der(t *testing.T) {
	// indefinite length fixture
	ber := []byte{0x30, 0x80, 0x02, 0x01, 0x01, 0x00, 0x00}
	expected := []byte{0x30, 0x03, 0x02, 0x01, 0x01}
	der, err := ber2der(ber)
	if err != nil {
		t.Fatalf("ber2der failed with error: %v", err)
	}
	if !bytes.Equal(der, expected) {
		t.Errorf("ber2der result did not match.\n\tExpected: % X\n\tActual: % X", expected, der)
	}

	if der2, err := ber2der(der); err != nil {
		t.Errorf("ber2der on DER bytes failed with error: %v", err)
	} else {
		if !bytes.Equal(der, der2) {
			t.Error("ber2der is not idempotent")
		}
	}
	var thing struct {
		Number int
	}
	rest, err := asn1.Unmarshal(der, &thing)
	if err != nil {
		t.Errorf("Cannot parse resulting DER because: %v", err)
	} else if len(rest) > 0 {
		t.Errorf("Resulting DER has trailing data: % X", rest)
	}
}

func TestBer2Der_Negatives(t *testing.T) {
	fixtures := []struct {
		Input         []byte
		ErrorContains string
	}{
		{[]byte{0x30, 0x85}, "tag length too long"},
		{[]byte{0x30, 0x84, 0x80, 0x0, 0x0, 0x0}, "length is negative"},
		{[]byte{0x30, 0x82, 0x0, 0x1}, "length has leading zero"},
		{[]byte{0x30, 0x80, 0x1, 0x2, 0x1, 0x2}, "Invalid BER format"},
		{[]byte{0x30, 0x80, 0x1, 0x2}, "BER tag length is more than available data"},
		{[]byte{0x30, 0x03, 0x01, 0x02}, "length is more than available data"},
		{[]byte{0x30}, "end of ber data reached"},
	}

	for _, fixture := range fixtures {
		_, err := ber2der(fixture.Input)
		if err == nil {
			t.Errorf("No error thrown. Expected: %s", fixture.ErrorContains)
		}
		if !strings.Contains(err.Error(), fixture.ErrorContains) {
			t.Errorf("Unexpected error thrown.\n\tExpected: /%s/\n\tActual: %s", fixture.ErrorContains, err.Error())
		}
	}
}

func TestBer2Der_NestedMultipleIndefinite(t *testing.T) {
	// indefinite length fixture
	ber := []byte{0x30, 0x80, 0x30, 0x80, 0x02, 0x01, 0x01, 0x00, 0x00, 0x30, 0x80, 0x02, 0x01, 0x02, 0x00, 0x00, 0x00, 0x00}
	expected := []byte{0x30, 0x0A, 0x30, 0x03, 0x02, 0x01, 0x01, 0x30, 0x03, 0x02, 0x01, 0x02}

	der, err := ber2der(ber)
	if err != nil {
		t.Fatalf("ber2der failed with error: %v", err)
	}
	if bytes.Compare(der, expected) != 0 {
		t.Errorf("ber2der result did not match.\n\tExpected: % X\n\tActual: % X", expected, der)
	}

	if der2, err := ber2der(der); err != nil {
		t.Errorf("ber2der on DER bytes failed with error: %v", err)
	} else {
		if !bytes.Equal(der, der2) {
			t.Error("ber2der is not idempotent")
		}
	}
	var thing struct {
		Nest1 struct {
			Number int
		}
		Nest2 struct {
			Number int
		}
	}
	rest, err := asn1.Unmarshal(der, &thing)
	if err != nil {
		t.Errorf("Cannot parse resulting DER because: %v", err)
	} else if len(rest) > 0 {
		t.Errorf("Resulting DER has trailing data: % X", rest)
	}
}

func TestVerifyIndefiniteLengthBer(t *testing.T) {
	decoded := mustDecodePEM([]byte(testPKCS7))

	_, err := ber2der(decoded)
	if err != nil {
		t.Errorf("cannot parse indefinite length ber: %v", err)
	}
}

func mustDecodePEM(data []byte) []byte {
	var block *pem.Block
	block, rest := pem.Decode(data)
	if len(rest) != 0 {
		panic(fmt.Errorf("unexpected remaining PEM block during decode"))
	}
	return block.Bytes
}

const testPKCS7 = `
-----BEGIN PKCS7-----
MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0B
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ggWbMIIEg6ADAgECAhAGrjFMK45t2jcNHtjY1DjEMA0GCSqGSIb3DQEBCwUAMEYx
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Cgl8Nlvalz7YxXEf2clFEiEVa1fVaGMl9pCyedAmTfd6hoivcpAsopvXfVaaaR2y
iuZidpUfFhSk+Ls7TU/kB74ckfUGj5q/5HcKJgb/S+FYUV7eu0ewzTyW1uRl/d0U
Tb7e7EjgDGJsjOTMdTrMfv8ho8kAAAAAAAA=
-----END PKCS7-----
`