Implement uPER decoding of bools, IA5Strings and bitmaps

autotests/uperdecodertest.cpp

@@ -20,7 +20,12 @@ private Q_SLOTS:
     void testReadNumbers()
     {
         UPERDecoder d(BitVector(QByteArray::fromHex("723004D580D1845E168AEAE4C2D2D840845CAC5C500550E8")));
-        d.seek(20);
+        QCOMPARE(d.readBoolean(), false);
+        QCOMPARE(d.readBitset<4>(), std::bitset<4>(0b1110));
+        QCOMPARE(d.offset(), 5);
+        QCOMPARE(d.readBoolean(), false);
+        QCOMPARE(d.readBitset<14>(), std::bitset<14>(0b10001100000000));
+        QCOMPARE(d.offset(), 20);
         QCOMPARE(d.readConstrainedWholeNumber(1, 32000), 9901);
         QCOMPARE(d.offset(), 35);
         QCOMPARE(d.readConstrainedWholeNumber(2016, 2269), 2022);
@@ -31,6 +36,14 @@ private Q_SLOTS:
         QCOMPARE(d.offset(), 63);
         QCOMPARE(d.readUtf8String(), QLatin1String("Eurail B.V."));
         QCOMPARE(d.offset(), 159);
+        QCOMPARE(d.readBoolean(), false);
+        QCOMPARE(d.readBoolean(), false);
+        QCOMPARE(d.readBoolean(), true);
+        QCOMPARE(d.offset(), 162);
+
+        d = UPERDecoder(BitVector(QByteArray::fromHex("22FB162E1BC9")));
+        d.seek(13);
+        QCOMPARE(d.readIA5String(4, 4), "1187");
     }
 };
 

src/lib/asn1/bitvector.h

@@ -9,6 +9,7 @@
 #include <QByteArray>
 #include <QDebug>
 
+#include <bitset>
 #include <cassert>
 #include <type_traits>
 
@@ -51,6 +52,17 @@ public:
     /** Returns @p bytes starting at bit offset @p index. */
     QByteArray byteArrayAt(size_type index, size_type bytes) const;
 
+    /** Reads a std::bitset from @p index. */
+    template <std::size_t N>
+    std::bitset<N> bitsetAt(size_type index) const
+    {
+        std::bitset<N> result = {};
+        for (size_type i = 0; i < (size_type)N; ++i) {
+            result[N - i - 1] = at(index + i);
+        }
+        return result;
+    }
+
 private:
     QByteArray m_data;
 };

src/lib/asn1/uperdecoder.cpp

@@ -30,6 +30,9 @@ int64_t UPERDecoder::readConstrainedWholeNumber(int64_t minimum, int64_t maximum
 {
     assert(minimum <= maximum);
     const uint64_t range = maximum - minimum + 1;
+    if (range == 1) {
+        return 0;
+    }
     const size_type bits = 64 - std::countl_zero(range);
     const auto result = m_data.valueAtMSB<int64_t>(m_idx, bits);
     m_idx += bits;
@@ -56,3 +59,30 @@ QString UPERDecoder::readUtf8String()
     m_idx += len * 8;
     return res;
 }
+
+bool UPERDecoder::readBoolean()
+{
+    return m_data.at(m_idx++) != 0;
+}
+
+QByteArray UPERDecoder::readIA5String(size_type minLength, size_type maxLength)
+{
+    size_type len = 0;
+    if (minLength == maxLength) {
+        len = minLength;
+    } else if (maxLength > 0) {
+        len = readConstrainedWholeNumber(minLength, maxLength);
+    } else {
+        len = readLengthDeterminant();
+    }
+
+    QByteArray result;
+    result.reserve(len);
+    for (size_type i = 0; i < len; ++i) {
+        const auto c = m_data.valueAtMSB<char>(m_idx, 7);
+        m_idx += 7;
+        result.push_back(c);
+    }
+
+    return result;
+}

src/lib/asn1/uperdecoder.h

@@ -35,6 +35,23 @@ public:
     /** Read UTF-8 string. */
     QString readUtf8String();
 
+    /** Read boolean value. */
+    bool readBoolean();
+
+    /** Read a IA5String (7 bit ASCII).
+     *  @see X.691 §30
+     */
+    QByteArray readIA5String(size_type minLenght = 0, size_type maxLength = -1);
+
+    /** Read an @tparam N sized bitmap. */
+    template <std::size_t N>
+    inline std::bitset<N> readBitset()
+    {
+        auto result = m_data.bitsetAt<N>(m_idx);
+        m_idx += N;
+        return result;
+    }
+
 private:
     BitVector m_data;
     size_type m_idx = {};