Select weirdness

[Ron Garret]

In article <rNOSPAMon-36DDEF.23212021042007 at news.gha.chartermi.net>,
 Ron Garret <rNOSPAMon at flownet.com> wrote:

> Here's my code.  It's a teeny weeny little HTTP server.  (I'm not really 
> trying to reinvent the wheel here.  What I'm really doing is writing a 
> dispatching proxy server, but this is the shortest way to illustrate the 
> problem I'm having):
> 
> from SocketServer import *
> from socket import *
> from select import select
> 
> class myHandler(StreamRequestHandler):
>   def handle(self):
>     print '>>>>>>>>>>>'
>     while 1:
>       sl = select([self.rfile],[],[])[0]
>       if sl:
>         l = self.rfile.readline()
>         if len(l)<3: break
>         print l,
>         pass
>       pass
>     print>>self.wfile, 'HTTP/1.0 200 OK'
>     print>>self.wfile, 'Content-type: text/plain'
>     print>>self.wfile
>     print>>self.wfile, 'foo'
>     self.rfile.close()
>     self.wfile.close()
>     print '<<<<<<<<<<<<'
>     pass
>   pass
> 
> def main():
>   server = TCPServer(('',8080), myHandler)
>   server.serve_forever()
>   pass
> 
> if __name__ == '__main__': main()
> 
> 
> If I telnet into this server and type in an HTTP request manually it 
> works fine.  But when I try to access this with a browser (I've tried 
> Firefox and Safari -- both do the same thing) it hangs immediately after 
> reading the first line in the request (i.e. before reading the first 
> header).
> 
> When I click the "stop" button in the browser it breaks the logjam and 
> the server reads the headers (but then of course it dies trying to write 
> the response to a now-closed socket).
> 
> The only difference I can discern is that the browser send \r\n for 
> end-of-line while telnet just sends \n.  But I don't see why that should 
> make any difference.  So I'm stumped.  Any clues would be much 
> appreciated.

I have reproduced the problem using Telnet, so that proves it's not an 
EOL issue.  The problem seems to be timing-related.  If I type the 
request in manually it works.  If I paste it in all at once, it hangs.  
It's actually even weirder than that: if I pipe the request into a 
telnet client then it hangs after the request line, just with a browser 
(or wget).  But if I literally paste the request into a window running a 
telnet client, it gets past the request line and four out of seven 
headers before it hangs.

rg