2 files changed, 22 insertions(+), 8 deletions(-)

M bulletin.rkt
M client.rkt

@@ 186,8 186,8 @@
 
   (define-values (dispatch-route url-generator)
     (dispatch-rules
-     [("candidates") #:method "get"  candidates]
      [("register")   #:method "post" register  ]
+     [("candidates") #:method "get"  candidates]
      [("peer-count") #:method "get"  peer-count]
      [("commit")     #:method "post" commit    ]
      [("peers")      #:method "get"  peers     ]


@@ 198,7 198,9 @@
 
   (define/contract (internal-server-error url ex)
     (url? any/c . -> . can-be-response?)
-    (response/full 400 #"Bad Request" (current-seconds) #f empty empty))
+    (response/jsexpr
+     empty
+     #:code 400))
 
   (define/contract (dispatcher req)
     (request? . -> . any)


@@ 213,8 215,8 @@
    #:port 1984
    #:servlet-regexp #rx""
    #:command-line? #t
-   ;; #:servlet-responder internal-server-error
-   ))
+   ; comment out the following to get client-side tracebacks
+   #:servlet-responder internal-server-error))
 
 (module+ main
   (void (thread server))


@@ 259,8 261,8 @@
                                                       (string->symbol election)
                                                       election)])
                                    (election-set! election))]
-                       [(? eof-object?)
-                        (displayln "set what? options are `election'")]
+                      [(? eof-object?)
+                       (displayln "set what? options are `election'")]
                       [else (displayln "cannot set that")])]
               ['open
                (if (memq state '(closed registering))

@@ 286,6 286,15 @@
          (get bulletin "/candidates")
          (void))))
 
+(define (can-we-register? [bulletin : requester]) : (Values Boolean (Option String))
+  (with-handlers ([exn:fail:network:http:error?
+                   (λ ([ex : exn:fail:network:http:error])
+                     (if (eqv? (exn:fail:network:http:error-code ex) 400)
+                         (values #t #f)
+                         (values #f (exn-message ex))))])
+    (post bulletin "/register" #:data (jsexpr->string empty))
+    (values #t #f)))
+
 (module+ main
   (define point (gen))
 


@@ 294,8 303,11 @@
                               (readline "Bulletin host: "))
                  1984))
 
-  (displayln "waiting for the election to open...")
-  (wait-for-open-election bulletin)
+  ; check if we're allowed to register
+  (let-values ([(answer why) (can-we-register? bulletin)])
+    (when (not answer)
+      (displayln (format "Cannot register: ~a" why))
+      (exit)))
 
   (define token
     (let ([username (readline "Username: ")]