From 4b84fc7b48e1a9ecca4832cf6445f2ca246ec4ef Mon Sep 17 00:00:00 2001
From: Jay McCarthy <jay@racket-lang.org>
Date: Mon, 29 Apr 2013 13:20:24 -0600
Subject: [PATCH] Ignoring some bad network errors re Robby

---
 .../private/dispatch-server-unit.rkt          | 82 ++++++++++---------
 1 file changed, 45 insertions(+), 37 deletions(-)

diff --git a/collects/web-server/private/dispatch-server-unit.rkt b/collects/web-server/private/dispatch-server-unit.rkt
index aae838b0fa..d07d180815 100644
--- a/collects/web-server/private/dispatch-server-unit.rkt
+++ b/collects/web-server/private/dispatch-server-unit.rkt
@@ -73,40 +73,48 @@
   (define conn
     (new-connection config:initial-connection-timeout
                     ip op (current-custodian) #f))
-  ;; HTTP/1.1 allows any number of requests to come from this input
-  ;; port. However, there is no explicit cancellation of a
-  ;; connection---the browser will just close the port. This leaves
-  ;; the Web server in the unfortunate state of config:read-request
-  ;; trying to read an HTTP and failing---with an ugly error
-  ;; message. This call to peek here will block until at least one
-  ;; character is available and then transfer to read-request. At
-  ;; that point, an error message would be reasonable because the
-  ;; request would be badly formatted or ended early. However, if
-  ;; the connection is closed, then peek will get the EOF and the
-  ;; connection will be closed. This shouldn't change any other
-  ;; behavior: read-request is already blocking, peeking doesn't
-  ;; consume a byte, etc.
-  (define the-evt
-    (choice-evt
-     (handle-evt
-      (port-closed-evt ip)
-      (λ (res)
-        (kill-connection! conn)))
-     (handle-evt
-      (peek-bytes-evt 1 0 #f ip)
-      (λ (res)
-        (cond
-          [(eof-object? res)
-           (kill-connection! conn)]
-          [else
-           (define-values
-             (req close?)
-             (config:read-request conn config:port port-addresses))
-           (set-connection-close?! conn close?)
-           (config:dispatch conn req)
-           (if (connection-close? conn)
-             (kill-connection! conn)
-             (connection-loop))])))))
-  (define (connection-loop)
-    (sync the-evt))
-  (connection-loop))
+  (with-handlers
+      ([(λ (x)
+          ;; This error is "Connection reset by peer" and doesn't
+          ;; really indicate a problem with the server.
+          (and (exn:fail:network:errno? x)
+               (= 54 (exn:fail:network:errno-errno x))))
+        (λ (x)
+          (kill-connection! conn))])
+    ;; HTTP/1.1 allows any number of requests to come from this input
+    ;; port. However, there is no explicit cancellation of a
+    ;; connection---the browser will just close the port. This leaves
+    ;; the Web server in the unfortunate state of config:read-request
+    ;; trying to read an HTTP and failing---with an ugly error
+    ;; message. This call to peek here will block until at least one
+    ;; character is available and then transfer to read-request. At
+    ;; that point, an error message would be reasonable because the
+    ;; request would be badly formatted or ended early. However, if
+    ;; the connection is closed, then peek will get the EOF and the
+    ;; connection will be closed. This shouldn't change any other
+    ;; behavior: read-request is already blocking, peeking doesn't
+    ;; consume a byte, etc.  
+    (define the-evt
+      (choice-evt
+       (handle-evt
+        (port-closed-evt ip)
+        (λ (res)
+          (kill-connection! conn)))
+       (handle-evt
+        (peek-bytes-evt 1 0 #f ip)
+        (λ (res)
+          (cond
+            [(eof-object? res)
+             (kill-connection! conn)]
+            [else
+             (define-values
+               (req close?)
+               (config:read-request conn config:port port-addresses))
+             (set-connection-close?! conn close?)
+             (config:dispatch conn req)
+             (if (connection-close? conn)
+               (kill-connection! conn)
+               (connection-loop))])))))
+    (define (connection-loop)
+      (sync the-evt))
+    (connection-loop)))