Index: lib/net/http.rb
===================================================================
--- lib/net/http.rb	(revision 28770)
+++ lib/net/http.rb	(working copy)
@@ -517,6 +517,7 @@ module Net   #:nodoc:
       @started = false
       @open_timeout = nil
       @read_timeout = 60
+      @continue_timeout = 0.5
       @debug_output = nil
       @use_ssl = false
       @ssl_context = nil
@@ -570,6 +571,16 @@ module Net   #:nodoc:
       @read_timeout = sec
     end
 
+    # Seconds to wait for 100 Continue response.  If the HTTP object does not
+    # receive a response in this many seconds it sends the request body.
+    attr_reader :continue_timeout
+
+    # Setter for the continue_timeout attribute.
+    def continue_timout=(sec)
+      @socket.continue_timeout = sec if @socket
+      @continue_timeout = sec
+    end
+
     # returns true if the HTTP session is started.
     def started?
       @started
@@ -1190,10 +1201,10 @@ module Net   #:nodoc:
 
     def transport_request(req)
       begin_transport req
-      req.exec @socket, @curr_http_version, edit_path(req.path)
+      res = req.exec @socket, @curr_http_version, edit_path(req.path)
       begin
         res = HTTPResponse.read_new(@socket)
-      end while res.kind_of?(HTTPContinue)
+      end while res.kind_of?(HTTPContinue) unless res
       res.reading_body(@socket, req.response_body_permitted?) {
         yield res if block_given?
       }
@@ -1740,7 +1751,13 @@ module Net   #:nodoc:
       delete 'Transfer-Encoding'
       supply_default_content_type
       write_header sock, ver, path
+
+      res = wait_for_continue sock, ver
+      return res if res
+
       sock.write body
+
+      nil
     end
 
     def send_request_with_body_stream(sock, ver, path, f)
@@ -1750,6 +1767,10 @@ module Net   #:nodoc:
       end
       supply_default_content_type
       write_header sock, ver, path
+
+      res = wait_for_continue sock, ver
+      return res if res
+
       if chunked?
         while s = f.read(1024)
           sock.write(sprintf("%x\r\n", s.length) << s << "\r\n")
@@ -1760,6 +1781,8 @@ module Net   #:nodoc:
           sock.write s
         end
       end
+
+      nil
     end
 
     def supply_default_content_type
@@ -1768,6 +1791,21 @@ module Net   #:nodoc:
       set_content_type 'application/x-www-form-urlencoded'
     end
 
+    ##
+    # Waits up to the continue timeout for a response from the server provided
+    # we're speaking HTTP 1.1 and are expecting a 100-continue response.
+
+    def wait_for_continue(sock, ver)
+      if ver >= '1.1' and @header['expect'].include?('100-continue') then
+        if IO.select [sock.io], nil, nil, sock.continue_timeout then
+          res = HTTPResponse.read_new sock
+          return res unless res.kind_of?(Net::HTTPContinue)
+        end
+      end
+
+      nil
+    end
+
     def write_header(sock, ver, path)
       buf = "#{@method} #{path} HTTP/#{ver}\r\n"
       each_capitalized do |k,v|
Index: lib/net/protocol.rb
===================================================================
--- lib/net/protocol.rb	(revision 28770)
+++ lib/net/protocol.rb	(working copy)
@@ -50,12 +50,14 @@ module Net # :nodoc:
     def initialize(io)
       @io = io
       @read_timeout = 60
+      @continue_timeout = 0.5
       @debug_output = nil
       @rbuf = ''
     end
 
     attr_reader :io
     attr_accessor :read_timeout
+    attr_accessor :continue_timeout
     attr_accessor :debug_output
 
     def inspect