/// <summary>
/// Write out contents of byte array b as a JSON string with base-64 encoded
/// data
/// </summary>
private async Task WriteJsonBase64Async(byte[] bytes, CancellationToken cancellationToken)
{
await Context.WriteAsync(cancellationToken);
await Trans.WriteAsync(TJSONProtocolConstants.Quote, cancellationToken);
var len = bytes.Length;
var off = 0;
while (len >= 3)
{
// Encode 3 bytes at a time
TBase64Helper.Encode(bytes, off, 3, _tempBuffer, 0);
await Trans.WriteAsync(_tempBuffer, 0, 4, cancellationToken);
off += 3;
len -= 3;
}
if (len > 0)
{
// Encode remainder
TBase64Helper.Encode(bytes, off, len, _tempBuffer, 0);
await Trans.WriteAsync(_tempBuffer, 0, len + 1, cancellationToken);
}
await Trans.WriteAsync(TJSONProtocolConstants.Quote, cancellationToken);
}
/// <summary>
/// Read in a JSON string containing base-64 encoded data and decode it.
/// </summary>
private async Task <byte[]> ReadJsonBase64Async(CancellationToken cancellationToken)
{
var b = await ReadJsonStringAsync(false, cancellationToken);
var len = b.Length;
var off = 0;
var size = 0;
// reduce len to ignore fill bytes
while ((len > 0) && (b[len - 1] == '='))
{
--len;
}
// read & decode full byte triplets = 4 source bytes
while (len > 4)
{
// Decode 4 bytes at a time
TBase64Helper.Decode(b, off, 4, b, size); // NB: decoded in place
off += 4;
len -= 4;
size += 3;
}
// Don't decode if we hit the end or got a single leftover byte (invalid
// base64 but legal for skip of regular string exType)
if (len > 1)
{
// Decode remainder
TBase64Helper.Decode(b, off, len, b, size); // NB: decoded in place
size += len - 1;
}
// Sadly we must copy the byte[] (any way around this?)
var result = new byte[size];
Array.Copy(b, 0, result, 0, size);
return(result);
}