Interview Question

You have a stream of bytes in char array buf[]:
00 00 00 0A 68 65 6C 6C 6F 77 6F 72 6C 64

You know the bytes follow a protocol with this spec:
<1 byte> message type (0 == hello, 1 == goodbye)
<3 bytes> message length
<N> message content (UTF-8 characters)

Determine if this is a hello message, and, if it is, print the content as a string to stdout.