QByteArray: add a strict mode to fromBase64

QByteArray::fromBase64 was liberal in its input, simply skipping
over invalid characters. As a side-effect of this, it had
no error reporting, meaning it could not be used to convert
fromBase64 _and_ validate the input in one go.

Add more option flags to make fromBase64 strictly validate
its input. Since we want to know whether it has succeeded
or not, and the existing fromBase64 overloads do not
allow for that, introduce a new function that returns
an optional-like datatype.

While at it: base64 decoding can be done in-place; add an
rvalue overload to enable this use case.

[ChangeLog][QtCore][QByteArray] Added the new fromBase64Encoding
function.

[ChangeLog][QtCore][QByteArray] Added new flags to make
fromBase64 / fromBase64Encoding strictly validate their input,
instead of skipping over invalid characters.

Change-Id: I99cd5f2230f3d62970b28b4cb102913301da6ccd
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 138 insertions, 34 deletions

diff --git a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
index 90dfcaef25..48dd7a241e 100644
--- a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
+++ b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
@@ -239,6 +239,8 @@ QByteArray verifyZeroTermination(const QByteArray &ba)
     } while (0)                                                         \
     /**/
 
+Q_DECLARE_METATYPE(QByteArray::Base64DecodingStatus);
+
 tst_QByteArray::tst_QByteArray()
 {
 }
@@ -637,9 +639,16 @@ void tst_QByteArray::base64()
 {
     QFETCH(QByteArray, rawdata);
     QFETCH(QByteArray, base64);
+    QByteArray::FromBase64Result result;
+
+    result = QByteArray::fromBase64Encoding(base64, QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
 
-    QByteArray arr = QByteArray::fromBase64(base64);
-    QCOMPARE(arr, rawdata);
+    QByteArray arr = base64;
+    result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
 
     QByteArray arr64 = rawdata.toBase64();
     QCOMPARE(arr64, base64);
@@ -668,21 +677,22 @@ void tst_QByteArray::fromBase64_data()
 {
     QTest::addColumn<QByteArray>("rawdata");
     QTest::addColumn<QByteArray>("base64");
-
-    QTest::newRow("1") << QByteArray("") << QByteArray("  ");
-    QTest::newRow("2") << QByteArray("1") << QByteArray("MQ");
-    QTest::newRow("3") << QByteArray("12") << QByteArray("MTI       ");
-    QTest::newRow("4") << QByteArray("123") << QByteArray("M=TIz");
-    QTest::newRow("5") << QByteArray("1234") << QByteArray("MTI zN A ");
-    QTest::newRow("6") << QByteArray("\n") << QByteArray("Cg");
-    QTest::newRow("7") << QByteArray("a\n") << QByteArray("======YQo=");
-    QTest::newRow("8") << QByteArray("ab\n") << QByteArray("Y\nWIK");
-    QTest::newRow("9") << QByteArray("abc\n") << QByteArray("YWJjCg==");
-    QTest::newRow("a") << QByteArray("abcd\n") << QByteArray("YWJ\1j\x9cZAo=");
-    QTest::newRow("b") << QByteArray("abcde\n") << QByteArray("YW JjZ\n G\tUK");
-    QTest::newRow("c") << QByteArray("abcdef\n") << QByteArray("YWJjZGVmCg=");
-    QTest::newRow("d") << QByteArray("abcdefg\n") << QByteArray("YWJ\rjZGVmZwo");
-    QTest::newRow("e") << QByteArray("abcdefgh\n") << QByteArray("YWJjZGVmZ2gK");
+    QTest::addColumn<QByteArray::Base64DecodingStatus>("status");
+
+    QTest::newRow("1") << QByteArray("") << QByteArray("  ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("2") << QByteArray("1") << QByteArray("MQ=") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("3") << QByteArray("12") << QByteArray("MTI       ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("4") << QByteArray("123") << QByteArray("M=TIz") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("5") << QByteArray("1234") << QByteArray("MTI zN A ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("6") << QByteArray("\n") << QByteArray("Cg@") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("7") << QByteArray("a\n") << QByteArray("======YQo=") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("8") << QByteArray("ab\n") << QByteArray("Y\nWIK ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("9") << QByteArray("abc\n") << QByteArray("YWJjCg=") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("a") << QByteArray("abcd\n") << QByteArray("YWJ\1j\x9cZAo=") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("b") << QByteArray("abcde\n") << QByteArray("YW JjZ\n G\tUK") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("c") << QByteArray("abcdef\n") << QByteArray("YWJjZGVmCg=") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("d") << QByteArray("abcdefg\n") << QByteArray("YWJ\rjZGVmZwo") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("e") << QByteArray("abcdefgh\n") << QByteArray("YWJjZGVmZ2gK====") << QByteArray::Base64DecodingStatus::IllegalPadding;
 
     QByteArray ba;
     ba.resize(256);
@@ -692,13 +702,12 @@ void tst_QByteArray::fromBase64_data()
                                            "c4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1u\n"
                                            "b3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpa\n"
                                            "anqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd\n"
-                                           "3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==                            ");
+                                           "3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==                            ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
 
 
-    QTest::newRow("g") << QByteArray("foo\0bar", 7) << QByteArray("Zm9vAGJhcg");
-    QTest::newRow("h") << QByteArray("f\xd1oo\x9ctar") << QByteArray("ZtFvb5x0YXI=");
-    QTest::newRow("i") << QByteArray("\"\0\0\0\0\0\0\"", 8) << QByteArray("IgAAAAAAACI");
-
+    QTest::newRow("g") << QByteArray("foo\0bar", 7) << QByteArray("Zm9vAGJhcg=") << QByteArray::Base64DecodingStatus::IllegalInputLength;
+    QTest::newRow("h") << QByteArray("f\xd1oo\x9ctar") << QByteArray("ZtFvb5x 0YXI") << QByteArray::Base64DecodingStatus::IllegalCharacter;
+    QTest::newRow("i") << QByteArray("\"\0\0\0\0\0\0\"", 8) << QByteArray("IgAAAAAAACI ") << QByteArray::Base64DecodingStatus::IllegalCharacter;
 }
 
 
@@ -706,25 +715,120 @@ void tst_QByteArray::fromBase64()
 {
     QFETCH(QByteArray, rawdata);
     QFETCH(QByteArray, base64);
-
-    QByteArray arr = QByteArray::fromBase64(base64);
-    QCOMPARE(arr, rawdata);
-
-    arr = QByteArray::fromBase64(base64, QByteArray::Base64Encoding);
-    QCOMPARE(arr, rawdata);
+    QFETCH(QByteArray::Base64DecodingStatus, status);
+
+    QByteArray::FromBase64Result result;
+
+    result = QByteArray::fromBase64Encoding(base64);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
+
+    result = QByteArray::fromBase64Encoding(base64, QByteArray::Base64Encoding);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
+
+    result = QByteArray::fromBase64Encoding(base64, QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(!result);
+    QCOMPARE(result.decodingStatus, status);
+    QVERIFY(result.decoded.isEmpty());
+
+    QByteArray arr = base64;
+    QVERIFY(!arr.isDetached());
+    result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(!arr.isEmpty());
+    QVERIFY(!result);
+    QCOMPARE(result.decodingStatus, status);
+    QVERIFY(result.decoded.isEmpty());
+
+    arr.detach();
+    QVERIFY(arr.isDetached());
+    result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(arr.isEmpty());
+    QVERIFY(!result);
+    QCOMPARE(result.decodingStatus, status);
+    QVERIFY(result.decoded.isEmpty());
 
     // try "base64url" encoding
     QByteArray base64url = base64;
     base64url.replace('/', '_').replace('+', '-');
-    arr = QByteArray::fromBase64(base64url, QByteArray::Base64UrlEncoding);
-    QCOMPARE(arr, rawdata);
+    result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64UrlEncoding);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
+
+    result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(!result);
+    QCOMPARE(result.decodingStatus, status);
+    QVERIFY(result.decoded.isEmpty());
+
+    arr = base64url;
+    arr.detach();
+    result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(arr.isEmpty());
+    QVERIFY(!result);
+    QCOMPARE(result.decodingStatus, status);
+    QVERIFY(result.decoded.isEmpty());
 
     if (base64 != base64url) {
         // check that the invalid decodings fail
-        arr = QByteArray::fromBase64(base64, QByteArray::Base64UrlEncoding);
-        QVERIFY(arr != rawdata);
-        arr = QByteArray::fromBase64(base64url, QByteArray::Base64Encoding);
-        QVERIFY(arr != rawdata);
+        result = QByteArray::fromBase64Encoding(base64, QByteArray::Base64UrlEncoding);
+        QVERIFY(result);
+        QVERIFY(result.decoded != rawdata);
+        result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64Encoding);
+        QVERIFY(result);
+        QVERIFY(result.decoded != rawdata);
+
+        result = QByteArray::fromBase64Encoding(base64, QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+        QVERIFY(!result);
+        QVERIFY(result.decoded.isEmpty());
+
+        arr = base64;
+        arr.detach();
+        result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+        QVERIFY(arr.isEmpty());
+        QVERIFY(!result);
+        QVERIFY(result.decoded.isEmpty());
+
+        result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+        QVERIFY(!result);
+        QVERIFY(result.decoded.isEmpty());
+
+        arr = base64url;
+        arr.detach();
+        result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64Encoding | QByteArray::AbortOnBase64DecodingErrors);
+        QVERIFY(arr.isEmpty());
+        QVERIFY(!result);
+        QVERIFY(result.decoded.isEmpty());
+    }
+
+    // also remove padding, if any, and test again. note that by doing
+    // that we might be sanitizing the illegal input, so we can't assume now
+    // that result will be invalid in all cases
+    {
+        auto rightmostNotEqualSign = std::find_if_not(base64url.rbegin(), base64url.rend(), [](char c) { return c == '='; });
+        base64url.chop(std::distance(base64url.rbegin(), rightmostNotEqualSign)); // no QByteArray::erase...
+    }
+
+    result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64UrlEncoding);
+    QVERIFY(result);
+    QCOMPARE(result.decoded, rawdata);
+
+    result = QByteArray::fromBase64Encoding(base64url, QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+    if (result) {
+        QCOMPARE(result.decoded, rawdata);
+    } else {
+        QCOMPARE(result.decodingStatus, status);
+        QVERIFY(result.decoded.isEmpty());
+    }
+
+    arr = base64url;
+    arr.detach();
+    result = QByteArray::fromBase64Encoding(std::move(arr), QByteArray::Base64UrlEncoding | QByteArray::AbortOnBase64DecodingErrors);
+    QVERIFY(arr.isEmpty());
+    if (result) {
+        QCOMPARE(result.decoded, rawdata);
+    } else {
+        QCOMPARE(result.decodingStatus, status);
+        QVERIFY(result.decoded.isEmpty());
     }
 }