http.server: ignore preceding whitespace before request lines. Fixes #252.

basis/http/server/server-tests.factor

@@ -29,6 +29,11 @@ IN: http.server.tests
     unparse-content-type
 ] unit-test
 
+
+! RFC 2616: Section 19.3
+! The line terminator for message-header fields is the sequence CRLF.
+! However, we recommend that applications, when parsing such headers,
+! recognize a single LF as a line terminator and ignore the leading CR.
 [ t ] [
     {
         "GET / HTTP/1.1"
@@ -38,3 +43,22 @@ IN: http.server.tests
     } [ "\n" join ] [ "\r\n" join ] bi
     [ [ read-request ] with-string-reader ] bi@ =
 ] unit-test
+
+! RFC 2616: Section 4.1
+! In the interest of robustness, servers SHOULD ignore any empty
+! line(s) received where a Request-Line is expected. In other words, if
+! the server is reading the protocol stream at the beginning of a
+! message and receives a CRLF first, it should ignore the CRLF.
+[
+    T{ request
+        { method "GET" }
+        { url URL" /" }
+        { version "1.0" }
+        { header H{ } }
+        { cookies V{ } }
+        { redirects 10 }
+    }
+] [
+    "\r\n\r\n\r\nGET / HTTP/1.0\r\n\r\n"
+    [ read-request ] with-string-reader
+] unit-test

basis/http/server/server.factor

@@ -37,7 +37,8 @@ IN: http.server
     dup path>> "/" head? [ "Bad request: URL" throw ] unless ; inline
 
 : read-request-line ( request -- request )
-    read-?crlf parse-request-line first3
+    read-?crlf [ dup empty? ] [ drop read-?crlf ] while
+    parse-request-line first3
     [ >>method ] [ >url check-absolute >>url ] [ >>version ] tri* ;
 
 : read-request-header ( request -- request )