This was a >630-line function, which doesn't make anybody happy. It
was also mostly composed of a bunch of if-statements that handled
different directory responses differently depending on the original
purpose of the directory connection. The logical refactoring here
is to move the body of each switch statement into a separate handler
function, and to invoke those functions from a separate switch
statement.
This commit leaves whitespace mostly untouched, for ease of review.
I'll reindent in the next commit.
