Function scHttpWebSocketBase64Decode

Libraries/Http/HttpWebSocket.cpp:170–216

    return -1;
}

static SC::Result scHttpWebSocketBase64Decode(SC::StringSpan value, SC::Span<uint8_t> output, size_t& decodedBytes)
{
    decodedBytes = 0;
    SC_TRY_MSG((value.sizeInBytes() % 4) == 0, "HttpWebSocketHandshake malformed base64 length");

    for (size_t offset = 0; offset < value.sizeInBytes(); offset += 4)
    {
        int sextets[4] = {0, 0, 0, 0};
        int padding    = 0;
        for (size_t idx = 0; idx < 4; ++idx)
        {
            const char current = value.bytesWithoutTerminator()[offset + idx];
            if (current == '=')
            {
                SC_TRY_MSG(offset + idx >= value.sizeInBytes() - 2, "HttpWebSocketHandshake malformed base64 padding");
                sextets[idx] = 0;
                padding++;
            }
            else
            {
                SC_TRY_MSG(padding == 0, "HttpWebSocketHandshake malformed base64 padding");
                sextets[idx] = scHttpWebSocketBase64Value(current);
                SC_TRY_MSG(sextets[idx] >= 0, "HttpWebSocketHandshake malformed base64 character");
            }
        }

        const uint32_t combined = (static_cast<uint32_t>(sextets[0]) << 18) |
                                  (static_cast<uint32_t>(sextets[1]) << 12) | (static_cast<uint32_t>(sextets[2]) << 6) |
                                  static_cast<uint32_t>(sextets[3]);
        const size_t bytesThisBlock = 3 - static_cast<size_t>(padding);
        SC_TRY_MSG(decodedBytes + bytesThisBlock <= output.sizeInBytes(),
                   "HttpWebSocketHandshake base64 decode output too small");
        if (bytesThisBlock >= 1)
        {
            output[decodedBytes++] = static_cast<uint8_t>((combined >> 16) & 0xFF);
        }
        if (bytesThisBlock >= 2)
        {
            output[decodedBytes++] = static_cast<uint8_t>((combined >> 8) & 0xFF);
        }
        if (bytesThisBlock >= 3)
        {
            output[decodedBytes++] = static_cast<uint8_t>(combined & 0xFF);
        }
    }
    return SC::Result(true);
}

static bool scHttpWebSocketForcePlatformSha1Unavailable  = false;