YASQ - Proper way to convert byte[] <--> string

[Steve Teale]

I have a byte[] A that contains an AJP13 packet, presumably including UTF8 strings.  I need to extract such strings and to place strings in such a buffer.  I'm using:

string s = A[n .. m].dup;  // n and m from prefixed string length/position
return s;

to get strings, and

byte[] ba = cast(byte[]) s;
A[n .. n+ba.length] = ba[0 .. $].dup;

to put them.  Are these a) sensible, b) optimal?