router stub

router

@@ -14,6 +14,25 @@
   [info sock-in sock-out]
   #:transparent)
 
+;; alist : [Listof [Cons IP Route]]
+(struct router
+  [(alist #:mutable)]
+  #:transparent)
+
+;; -> Router
+(define (make-router)
+  (router '()))
+
+;; Router Route IP -> Void
+(define (router-add! rs r src)
+  (set-router-alist! rs
+                     (cons (cons src r)
+                           (router-alist rs))))
+
+;; Router IP -> (U IP #f)
+(define (router-find-best rs src)
+  #f)
+
 ;; Str [Listof Peer-Conn] -> Void
 ;; --
 ;; Runs router logic, given a list of peer connections.
@@ -33,9 +52,38 @@
                   (channel-put mail (list peer msg))
                   (loop))))))
 
+  (define (ip->peer-conn ip)
+    (findf (λ (p)
+             (equal? ip (peer-ip (peer-conn-info p))))
+           peer-conns))
+
+  (define router
+    (make-router))
+
   (define (loop)
-    (match-define (list peer data) (channel-get mail))
-    (printf "from ~a:\n~s\n" peer data)
+    (match-define (list src-peer msg) (channel-get mail))
+    (printf "====\nfrom ~a:\n~s\n" src-peer msg)
+    (match msg
+
+      [(msg:update src dst r)
+       (router-add! router r src)]
+
+      [(msg:data src dst data)
+       (define-values [dst-peer resp-msg]
+         (match (router-find-best router dst)
+           [#f
+            (values peer
+                    (msg:no-route src
+                                  dst))]
+           [dst-peer-ip
+            (values (ip->peer-conn dst-peer-ip)
+                    msg)]))
+       (printf "----\nwant to send back ~a to ~a\n"
+               dst-peer
+               resp-msg)]
+
+      [_
+       (printf "----\nignored\n")])
     (loop))
 
   (printf "waiting for messages...\n")