Get IP addresses of system

(defun get-ip-addresses ()
  "Returns the current system IPv4 addresses as a list of
strings"
  (let* ((start 0)
;	 (match-positions ())
	 (ip-re  "[1-9][0-9]?[0-9]?\.[1-9][0-9]?[0-9]?\.[1-9][0-9]?[0-9]?\.[1-9][0-9]?[0-9]?")
	 ;; The rest of these variables try to make this platform agnostic.
	 ;; Add more on to the cond statements if you need
	 (ipconfig (cond ((eq system-type 'windows-nt)
			  "ipconfig")
			 ((eq system-type 'gnu/linux)
			  "/sbin/ifconfig")
			 (t (error "Don't know how to get-ip-address for %s"
				   system-type))))
	 (line-re (cond ((eq system-type 'windows-nt)
			 "IPv4 Address.*")
			((eq system-type 'gnu/linux)
			 (concat "inet addr:" ip-re))
			(t (error "Don't know how regex out ip line for %s"
				  system-type))))
	 ;; I lied, not all of the rest of the variables are to make it
	 ;; platform agnostic.  This is where we grab the output
	 (output (shell-command-to-string ipconfig)))
 
    ;; The inner loop is a bit funky since I can't seem to get it to behave
    ;; exactly like Common Lisp
    (loop for pos in
	  (loop named inner
		with match-positions = ()
		do (let ((ret (string-match line-re output start)))
		     (if ret
			 (setq start (1+ ret))
		       (return-from inner match-positions))
		     (setq match-positions
			   (append match-positions (list ret)))))
	  collect (progn
		    (string-match ip-re output pos)
		    (match-string 0 output)))))