I faced a similar problem while writting Net::SFTP::Foreign.

My solution was to create a set of functions which pop the data from the buffer, allowing me to write code as the following:

my $buffer = read ...;

my $len = get_int32($buffer);
my $cmd = get_int8($buffer);
my $txt = get_string($buffer);
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This is the module implementing those functions: Net::SFTP::Foreign::Buffer.